Wilkes NSG533 Advanced Pharmacology Exam Bank

WILKES NSG533 ADVANCED PHARMACOLOGY EXAM BANK 2026 Edition – Complete Exam Questions with Detailed Rationales Question 1 A 72-year-old male with atrial fibrillation is started on digoxin 0.25 mg daily. He is also prescribed amiodarone for rhythm control. The nurse practitioner should recognize which pharmacokinetic interaction? A. Amiodarone induces CYP3A4, decreasing digoxin levels. B. Amiodarone inhibits P-glycoprotein, increasing digoxin levels. C. Amiodarone increases digoxin renal clearance via tubular secretion. D. Amiodarone displaces digoxin from alpha-1 acid glycoprotein binding sites. ANSWER: B. Amiodarone inhibits P-glycoprotein, increasing digoxin levels. RATIONALE: Amiodarone inhibits P-glycoprotein (an efflux transporter in the GI tract and kidneys), which increases digoxin bioavailability and decreases its renal elimination. This raises digoxin levels and increases toxicity risk. Digoxin has a narrow therapeutic index (0.82.0 ng/mL), so levels should be monitored closely when amiodarone is added. Question 2 A patient with epilepsy on carbamazepine is started on oral contraceptives. The nurse practitioner counsels the patient that: A. Carbamazepine inhibits CYP3A4, increasing estrogen levels and thrombosis risk. B. Carbamazepine induces CYP3A4, decreasing contraceptive efficacy and increasing pregnancy risk. C. Carbamazepine displaces progestin from albumin, enhancing contraceptive effect. D. Carbamazepine inhibits glucuronidation, prolonging progestin half-life. ANSWER: B. Carbamazepine induces CYP3A4, decreasing contraceptive efficacy and increasing pregnancy risk. RATIONALE: Carbamazepine is a potent CYP3A4 inducer that increases metabolism of estrogen and progestin components in oral contraceptives, reducing their efficacy. Patients should use alternative or backup contraception. This is a classic enzyme induction interaction. Question 3 A 68-year-old female with heart failure is prescribed lisinopril. She reports using ibuprofen regularly for arthritis. The nurse practitioner explains the primary concern is: A. Ibuprofen inhibits ACE, reducing lisinopril efficacy. B. NSAIDs reduce prostaglandin-mediated renal vasodilation, causing acute kidney injury and hyperkalemia with ACE inhibitors. C. Ibuprofen increases lisinopril absorption via enhanced gastric emptying. D. NSAIDs induce CYP2C9, increasing lisinopril metabolism. ANSWER: B. NSAIDs reduce prostaglandin-mediated renal vasodilation, causing acute kidney injury and hyperkalemia with ACE inhibitors. RATIONALE: NSAIDs inhibit prostaglandin synthesis, which normally maintains renal perfusion through vasodilation. Combined with ACE inhibitors (which also affect renal hemodynamics), this significantly increases risk of acute kidney injury, hyperkalemia, and fluid retention. Question 4 A patient on warfarin (INR 2.5) is started on trimethoprim-sulfamethoxazole for a UTI. The nurse practitioner should anticipate: A. TMP-SMX induces CYP2C9, requiring increased warfarin dosing. B. TMP-SMX inhibits CYP2C9 and displaces warfarin from albumin, increasing bleeding risk. C. TMP-SMX increases vitamin K absorption, antagonizing warfarin effect. D. TMP-SMX enhances warfarin renal excretion, decreasing INR. ANSWER: B. TMP-SMX inhibits CYP2C9 and displaces warfarin from albumin, increasing bleeding risk. RATIONALE: TMP-SMX inhibits CYP2C9 (the primary enzyme metabolizing S-warfarin) and displaces warfarin from albumin binding sites, increasing free warfarin concentration. This potentiates anticoagulant effect and increases bleeding risk. INR should be monitored closely. Question 5 A 55-year-old male with liver cirrhosis is prescribed lorazepam for alcohol withdrawal. The rationale for choosing lorazepam over diazepam is: A. Lorazepam undergoes Phase I oxidation via CYP3A4, which is preserved in cirrhosis. B. Lorazepam undergoes Phase II glucuronidation, which is relatively preserved in hepatic impairment. C. Lorazepam is a prodrug activated by hepatic first-pass metabolism. D. Lorazepam has a larger volume of distribution, minimizing hepatic exposure. ANSWER: B. Lorazepam undergoes Phase II glucuronidation, which is relatively preserved in hepatic impairment. RATIONALE: Lorazepam is metabolized via glucuronidation (Phase II), which is less affected by hepatic impairment compared to oxidation (Phase I). Diazepam undergoes extensive Phase I metabolism via CYP2C19 and CYP3A4, which is significantly impaired in cirrhosis, leading to prolonged half-life and accumulation. Question 6 A patient receiving gentamicin has a peak level of 12 mcg/mL and trough of 3 mcg/mL. Based on pharmacokinetic principles, the nurse practitioner determines: A. Levels are therapeutic; no dose adjustment needed. B. The trough is too high, indicating accumulation and increased nephrotoxicity risk. C. The peak is subtherapeutic; the dose should be increased. D. Gentamicin follows zero-order kinetics at these concentrations. ANSWER: B. The trough is too high, indicating accumulation and increased nephrotoxicity risk. RATIONALE: For gentamicin, target trough is typically <2 mcg/mL (or <1 mcg/mL for extended-interval dosing). A trough of 3 mcg/mL indicates drug accumulation, which increases risk of nephrotoxicity and ototoxicity. The dose should be extended or reduced. Aminoglycosides exhibit concentration-dependent killing and follow first-order kinetics. Question 7 A 45-year-old female with depression is prescribed fluoxetine. She has been taking tamoxifen for breast cancer prevention. The nurse practitioner's greatest concern is: A. Fluoxetine inhibits CYP2D6, reducing conversion of tamoxifen to its active metabolite endoxifen. B. Fluoxetine induces CYP3A4, increasing tamoxifen metabolism. C. Fluoxetine displaces tamoxifen from alpha-1 acid glycoprotein, increasing toxicity. D. Fluoxetine increases tamoxifen absorption via delayed gastric emptying. ANSWER: A. Fluoxetine inhibits CYP2D6, reducing conversion of tamoxifen to its active metabolite endoxifen. RATIONALE: Tamoxifen is a prodrug requiring CYP2D6-mediated conversion to endoxifen for efficacy. Fluoxetine (and paroxetine) are potent CYP2D6 inhibitors that significantly reduce endoxifen levels, potentially compromising tamoxifen's antiestrogenic effect. Alternative antidepressants with minimal CYP2D6 inhibition should be considered. Question 8 A patient with a history of organ transplant on cyclosporine drinks grapefruit juice daily. The nurse practitioner explains that grapefruit juice: A. Inhibits CYP3A4 in the gut, increasing cyclosporine levels and toxicity risk B. Induces CYP3A4, decreasing cyclosporine levels and rejection risk C. Inhibits P-glycoprotein, decreasing cyclosporine absorption D. Increases renal clearance of cyclosporine, lowering levels ANSWER: A. Inhibits CYP3A4 in the gut, increasing cyclosporine levels and toxicity risk. RATIONALE: Grapefruit juice inhibits intestinal CYP3A4, reducing the presystemic metabolism of cyclosporine and increasing its bioavailability. This can lead to elevated drug levels and nephrotoxicity. Patients on cyclosporine should avoid grapefruit juice. Question 9 A patient is prescribed a medication that is a weak base with a pKa of 8.4. The drug's absorption is most enhanced in which environment? A. Stomach (pH 1-2) B. Small intestine (pH 6-7) C. Blood (pH 7.4) D. Colon (pH 8-9) ANSWER: B. Small intestine (pH 6-7). RATIONALE: Weak bases are better absorbed in environments where they are more unionized. At pH 6-7 (small intestine), a weak base with pKa 8.4 will be partially unionized, favoring absorption. The stomach's acidic environment ionizes weak bases, reducing absorption. Question 10 A patient is prescribed a drug with a high first-pass metabolism. Which route of administration would most effectively bypass this effect? A. Oral B. Sublingual C. Intramuscular D. Rectal ANSWER: B. Sublingual. RATIONALE: Sublingual administration bypasses first-pass metabolism because the drug is absorbed directly into the systemic circulation through the sublingual mucosa, avoiding the portal circulation and hepatic metabolism. Oral drugs are subject to first-pass metabolism in the liver. Question 11 A patient is prescribed a drug that is highly protein-bound (98%). Which condition would most significantly increase the risk of drug toxicity? A. Renal impairment B. Hepatic impairment C. Hypoalbuminemia D. Dehydration ANSWER: C. Hypoalbuminemia. RATIONALE: In hypoalbuminemia, there are fewer protein binding sites available, resulting in higher free (unbound) drug concentrations. This increases the risk of toxicity for highly protein-bound drugs. Renal and hepatic impairment affect elimination, while dehydration affects distribution volume. Question 12 A patient is prescribed phenytoin. The nurse practitioner understands that phenytoin follows which type of kinetics? A. First-order kinetics at all doses B. Zero-order kinetics at all doses C. First-order kinetics at low doses and zero-order kinetics at high doses D. Zero-order kinetics at low doses and first-order kinetics at high doses ANSWER: C. First-order kinetics at low doses and zero-order kinetics at high doses. RATIONALE: Phenytoin is metabolized by CYP2C9 and CYP2C19, which are saturable. At therapeutic doses, the enzymes become saturated, and phenytoin follows zero-order kinetics (nonlinear), where a small dose increase can cause a large increase in serum levels. This increases toxicity risk. Question 13 A 78-year-old patient with renal impairment is prescribed a medication that is renally eliminated. The nurse practitioner should anticipate which change in pharmacokinetics? A. Decreased half-life B. Decreased volume of distribution C. Increased half-life and drug accumulation D. Increased protein binding ANSWER: C. Increased half-life and drug accumulation. RATIONALE: Renal impairment reduces the clearance of renally eliminated drugs, leading to a prolonged half-life and drug accumulation. Doses should be adjusted based on creatinine clearance. Volume of distribution and protein binding are not directly affected. Question 14 A patient is prescribed a drug with a narrow therapeutic index. Which statement is true regarding this drug? A. The drug has a wide margin of safety B. The drug requires therapeutic drug monitoring C. The drug has minimal adverse effects D. The drug is safe in all patient populations ANSWER: B. The drug requires therapeutic drug monitoring. RATIONALE: Drugs with a narrow therapeutic index (e.g., digoxin, lithium, warfarin, phenytoin) have a small margin between therapeutic and toxic doses. Therapeutic drug monitoring is essential to maintain levels within the therapeutic range and avoid toxicity. Question 15 A patient is prescribed a drug that is a CYP3A4 inhibitor. Which effect would the nurse practitioner anticipate? A. Increased metabolism of CYP3A4 substrates B. Decreased metabolism of CYP3A4 substrates C. Increased renal clearance of CYP3A4 substrates D. Decreased protein binding of CYP3A4 substrates ANSWER: B. Decreased metabolism of CYP3A4 substrates. RATIONALE: CYP3A4 inhibitors reduce the metabolism of drugs that are substrates for this enzyme, leading to increased serum levels and potential toxicity. Examples of CYP3A4 inhibitors include ketoconazole, erythromycin, and grapefruit juice. Question 16 A patient is prescribed a drug that is a CYP3A4 inducer. Which effect would the nurse practitioner anticipate? A. Increased metabolism of CYP3A4 substrates B. Decreased metabolism of CYP3A4 substrates C. Increased protein binding of CYP3A4 substrates D. Decreased renal clearance of CYP3A4 substrates ANSWER: A. Increased metabolism of CYP3A4 substrates. RATIONALE: CYP3A4 inducers increase the metabolism of drugs that are substrates for this enzyme, leading to decreased serum levels and potential treatment failure. Examples of CYP3A4 inducers include carbamazepine, phenytoin, and rifampin. Question 17 A patient is prescribed a drug with a high volume of distribution (Vd). This indicates that the drug: A. Is primarily confined to the plasma compartment B. Is extensively distributed into tissues C. Is highly protein-bound D. Has a short half-life ANSWER: B. Is extensively distributed into tissues. RATIONALE: A high volume of distribution indicates that the drug is extensively distributed into tissues and is not confined to the plasma compartment. Drugs with high Vd are often lipophilic and have long half-lives. Question 18 A patient is prescribed a drug that is a weak acid with a pKa of 4.4. Which condition would increase the urinary excretion of this drug? A. Acidic urine (pH 5.0) B. Alkaline urine (pH 8.0) C. Decreased renal blood flow D. Increased protein binding ANSWER: B. Alkaline urine (pH 8.0). RATIONALE: Weak acids are more ionized in alkaline urine, which traps them in the renal tubules and promotes excretion. Ionized drugs are less likely to be reabsorbed. Acidic urine favors reabsorption of weak acids. Question 19 A patient is prescribed a drug that is a substrate for P-glycoprotein. Which drug would compete for this transporter and potentially increase absorption? A. Digoxin B. Verapamil C. Amiodarone D. All of the above ANSWER: D. All of the above. RATIONALE: P-glycoprotein is an efflux transporter that pumps drugs out of cells. Digoxin, verapamil, and amiodarone are all P-glycoprotein substrates. Co-administration can lead to competition and increased absorption of the substrate. Question 20 A patient is prescribed a drug that undergoes extensive hepatic metabolism. Which patient condition would most significantly reduce the drug's clearance? A. Renal failure B. Liver cirrhosis C. Heart failure D. Dehydration ANSWER: B. Liver cirrhosis. RATIONALE: Hepatic metabolism is the primary route of clearance for many drugs. Liver cirrhosis reduces hepatic blood flow and metabolic capacity, significantly reducing drug clearance. Renal failure affects drugs that are renally eliminated, while heart failure and dehydration affect distribution. Question 21 A patient is prescribed a drug with a half-life of 4 hours. How many hours will it take to reach steady state? A. 8 hours B. 12 hours C. 16 hours D. 20 hours ANSWER: D. 20 hours. RATIONALE: Steady state is reached after approximately 5 half-lives. For a drug with a 4hour half-life, steady state is reached in about 20 hours (5 × 4 = 20 hours). Question 22 A patient is prescribed morphine for severe pain. The nurse practitioner understands that morphine is primarily metabolized by which pathway? A. CYP2D6 B. CYP3A4 C. UGT2B7 (glucuronidation) D. CYP2C9 ANSWER: C. UGT2B7 (glucuronidation). RATIONALE: Morphine is primarily metabolized by UGT2B7 via glucuronidation to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). M6G is an active metabolite with analgesic properties. CYP-mediated metabolism is a minor pathway. Question 23 A patient is prescribed codeine for pain. The nurse practitioner understands that codeine is a prodrug that requires conversion to its active metabolite. Which enzyme is responsible for this conversion? A. CYP3A4 B. CYP2D6 C. CYP2C9 D. UGT2B7 ANSWER: B. CYP2D6. RATIONALE: Codeine is a prodrug that is converted to morphine by CYP2D6. Patients who are poor CYP2D6 metabolizers will not receive adequate analgesia from codeine, while ultrarapid metabolizers may experience toxicity. Question 24 A patient is prescribed tramadol. The nurse practitioner understands that tramadol's analgesic effect is mediated by: A. Mu-opioid receptor activation only B. Serotonin and norepinephrine reuptake inhibition only C. Both mu-opioid receptor activation and serotonin/norepinephrine reuptake inhibition D. Dopamine receptor activation ANSWER: C. Both mu-opioid receptor activation and serotonin/norepinephrine reuptake inhibition. RATIONALE: Tramadol has a dual mechanism of action: it is a weak mu-opioid receptor agonist and inhibits serotonin and norepinephrine reuptake. This combination contributes to its analgesic effect. Question 25 A patient is prescribed a medication that is an acetylcholinesterase inhibitor. Which condition is this drug most likely used for? A. Parkinson's disease B. Alzheimer's disease C. Depression D. Anxiety ANSWER: B. Alzheimer's disease. RATIONALE: Acetylcholinesterase inhibitors (e.g., donepezil, rivastigmine, galantamine) are used for mild to moderate Alzheimer's disease to increase acetylcholine levels in the brain. They are not used for Parkinson's disease, depression, or anxiety. Question 26 A patient is prescribed levodopa-carbidopa for Parkinson's disease. The nurse practitioner understands that carbidopa is added to: A. Increase the central conversion of levodopa to dopamine B. Decrease the peripheral conversion of levodopa to dopamine C. Increase the half-life of levodopa D. Decrease the adverse effects of levodopa ANSWER: B. Decrease the peripheral conversion of levodopa to dopamine. RATIONALE: Carbidopa is a peripheral decarboxylase inhibitor that prevents the conversion of levodopa to dopamine in the periphery, reducing peripheral adverse effects (nausea, vomiting, cardiac effects) and allowing more levodopa to reach the brain. Question 27 A patient is prescribed haloperidol for schizophrenia. The nurse practitioner should monitor for which adverse effect? A. Weight gain B. Extrapyramidal symptoms C. Metabolic syndrome D. Sedation ANSWER: B. Extrapyramidal symptoms. RATIONALE: Haloperidol is a typical (first-generation) antipsychotic with a high risk of extrapyramidal symptoms (EPS), including parkinsonism, dystonia, akathisia, and tardive dyskinesia. Atypical antipsychotics (e.g., olanzapine, risperidone) have lower EPS risk but higher metabolic side effects. Question 28 A patient is prescribed olanzapine for schizophrenia. Which adverse effect should the nurse practitioner monitor closely? A. Extrapyramidal symptoms B. Weight gain and metabolic syndrome C. Agranulocytosis D. Dry mouth ANSWER: B. Weight gain and metabolic syndrome. RATIONALE: Olanzapine is an atypical antipsychotic associated with significant weight gain, hyperglycemia, dyslipidemia, and metabolic syndrome. EPS risk is lower than with typical antipsychotics. Agranulocytosis is associated with clozapine. Question 29 A patient is prescribed clozapine for treatment-resistant schizophrenia. Which laboratory parameter must be monitored closely? A. Liver function tests B. Complete blood count (for agranulocytosis) C. Serum potassium D. Serum sodium ANSWER: B. Complete blood count (for agranulocytosis). RATIONALE: Clozapine can cause agranulocytosis (severe neutropenia), a life-threatening adverse effect. CBC must be monitored regularly (weekly initially, then biweekly). Patients must be enrolled in a REMS program. Question 30 A patient is prescribed lithium for bipolar disorder. Which laboratory value should be monitored regularly? A. Serum lithium level B. Serum potassium C. Serum sodium D. Serum calcium ANSWER: A. Serum lithium level. RATIONALE: Lithium has a narrow therapeutic range (0.6-1.2 mEq/L). Toxicity occurs at levels >1.5 mEq/L. Symptoms of toxicity include nausea, vomiting, diarrhea, tremors, and confusion. Dehydration can increase lithium levels. Question 31 A patient is prescribed fluoxetine for depression. Which adverse effect is most concerning when combined with other serotonergic drugs? A. Weight gain B. Serotonin syndrome C. Sedation D. Dry mouth ANSWER: B. Serotonin syndrome. RATIONALE: Fluoxetine is an SSRI that can cause serotonin syndrome when combined with other serotonergic drugs (MAOIs, triptans, St. John's wort). Symptoms include confusion, agitation, diaphoresis, tachycardia, and tremors. Question 32 A patient is prescribed sertraline for depression. The nurse practitioner should inform the patient that therapeutic effects may take: A. 1-3 days B. 1-2 weeks C. 2-4 weeks D. 6-8 weeks ANSWER: C. 2-4 weeks. RATIONALE: SSRIs (sertraline, fluoxetine) typically take 2-4 weeks to achieve therapeutic effects. Initial adverse effects may occur before therapeutic benefits. Patients should be encouraged to continue taking the medication. Question 33 A patient is prescribed buspirone for generalized anxiety disorder. The nurse practitioner should inform the patient that buspirone: A. Is a benzodiazepine with high abuse potential B. Is a non-benzodiazepine anxiolytic with no abuse potential C. Has immediate onset of action D. Causes significant sedation ANSWER: B. Is a non-benzodiazepine anxiolytic with no abuse potential. RATIONALE: Buspirone is a non-benzodiazepine anxiolytic used for generalized anxiety disorder. It does not cause sedation, dependence, or withdrawal. It takes 1-2 weeks to become effective and does not have immediate onset. Question 34 A patient is prescribed alprazolam for anxiety. Which adverse effect should the nurse practitioner monitor? A. Sedation and dependence B. Serotonin syndrome C. Weight gain D. Extrapyramidal symptoms ANSWER: A. Sedation and dependence. RATIONALE: Alprazolam is a benzodiazepine that causes sedation and has high abuse potential and dependence risk. Long-term use leads to tolerance and withdrawal symptoms upon discontinuation. Question 35 A patient is prescribed zolpidem for insomnia. The nurse practitioner should instruct the patient to: A. Take the medication with food B. Take the medication immediately before bedtime and ensure 7-8 hours of sleep C. Take the medication in the morning D. Take the medication as needed during the day ANSWER: B. Take the medication immediately before bedtime and ensure 7-8 hours of sleep. RATIONALE: Zolpidem is a non-benzodiazepine hypnotic used for insomnia. It should be taken immediately before bedtime, and the patient should ensure 7-8 hours of sleep to avoid next-day sedation. It is not for daytime use. Question 36 A patient is prescribed methylphenidate for ADHD. Which adverse effect should the nurse practitioner monitor? A. Insomnia and decreased appetite B. Sedation and weight gain C. Bradycardia D. Hypotension ANSWER: A. Insomnia and decreased appetite. RATIONALE: Methylphenidate is a CNS stimulant used for ADHD. Adverse effects include insomnia, decreased appetite, weight loss, and tachycardia. It should be taken early in the day to minimize insomnia. Question 37 A patient is prescribed atomoxetine for ADHD. The nurse practitioner understands that this medication works by: A. Stimulating dopamine release B. Inhibiting norepinephrine reuptake C. Blocking serotonin reuptake D. Inhibiting acetylcholinesterase ANSWER: B. Inhibiting norepinephrine reuptake. RATIONALE: Atomoxetine is a selective norepinephrine reuptake inhibitor (SNRI) used for ADHD. It is non-stimulant and not a controlled substance. It does not affect dopamine or serotonin. Question 38 A patient is prescribed sumatriptan for migraines. The nurse practitioner understands that this medication works by: A. Blocking serotonin receptors B. Stimulating serotonin (5-HT1) receptors, causing vasoconstriction C. Blocking dopamine receptors D. Inhibiting prostaglandin synthesis ANSWER: B. Stimulating serotonin (5-HT1) receptors, causing vasoconstriction. RATIONALE: Sumatriptan is a triptan that stimulates serotonin (5-HT1B/1D) receptors, causing vasoconstriction of cranial blood vessels and inhibiting release of inflammatory neuropeptides. It is used for acute migraine treatment. Question 39 A patient is prescribed propranolol for migraine prophylaxis. The nurse practitioner understands that this medication works by: A. Blocking serotonin receptors B. Blocking beta-adrenergic receptors C. Blocking calcium channels D. Inhibiting prostaglandin synthesis ANSWER: B. Blocking beta-adrenergic receptors. RATIONALE: Propranolol is a non-selective beta-blocker used for migraine prophylaxis. The exact mechanism is unknown but may involve reduction in vasodilation. Triptans are for acute treatment. Question 40 A patient is prescribed ondansetron for chemotherapy-induced nausea. The nurse practitioner understands that this medication works by: A. Blocking dopamine receptors B. Blocking serotonin (5-HT3) receptors C. Blocking histamine receptors D. Blocking acetylcholine receptors ANSWER: B. Blocking serotonin (5-HT3) receptors. RATIONALE: Ondansetron is a 5-HT3 receptor antagonist used for chemotherapy-induced nausea and vomiting. It is more effective than dopamine antagonists for this indication. Metoclopramide blocks dopamine. Question 41 A patient is prescribed metoclopramide for gastroparesis. Which adverse effect should the nurse practitioner monitor? A. Extrapyramidal symptoms B. Sedation C. Tachycardia D. Hyperglycemia ANSWER: A. Extrapyramidal symptoms. RATIONALE: Metoclopramide is a dopamine antagonist that increases gastric motility. It can cause EPS, especially with long-term use. Tardive dyskinesia is a risk. Patients should be monitored for involuntary movements. Question 42 A patient is prescribed docusate sodium for constipation. The nurse practitioner understands that this medication works by: A. Stimulating peristalsis B. Drawing water into the intestine C. Softening stool by increasing water and fat penetration D. Lubricating the intestinal wall ANSWER: C. Softening stool by increasing water and fat penetration. RATIONALE: Docusate is a stool softener (surfactant) that increases water and fat penetration into stool, softening it. It is used for prevention of constipation, not for acute treatment. Question 43 A patient is prescribed loperamide for diarrhea. The nurse practitioner understands that this medication works by: A. Stimulating peristalsis B. Inhibiting peristalsis and increasing water absorption C. Blocking prostaglandin synthesis D. Killing intestinal bacteria ANSWER: B. Inhibiting peristalsis and increasing water absorption. RATIONALE: Loperamide is an antidiarrheal that slows intestinal motility (peristalsis) and increases water and electrolyte absorption. It is an opioid receptor agonist but does not cross the blood-brain barrier. Question 44 A patient is prescribed mesalamine for ulcerative colitis. The nurse practitioner understands that this medication works by: A. Suppressing the immune system B. Decreasing inflammation in the GI tract C. Killing bacteria D. Coating the intestinal lining ANSWER: B. Decreasing inflammation in the GI tract. RATIONALE: Mesalamine is a 5-aminosalicylate (5-ASA) that reduces inflammation in the GI tract. It is used for ulcerative colitis and Crohn's disease. It is not immunosuppressive, antibacterial, or a coating agent. Question 45 A patient is prescribed infliximab for Crohn's disease. The nurse practitioner understands that this medication is: A. An oral aminosalicylate B. A tumor necrosis factor (TNF) inhibitor given intravenously C. A corticosteroid given orally D. An immunomodulator given orally ANSWER: B. A tumor necrosis factor (TNF) inhibitor given intravenously. RATIONALE: Infliximab is a monoclonal antibody that inhibits TNF-alpha. It is given IV and used for inflammatory bowel disease, rheumatoid arthritis, and psoriasis. It is a biologic, not a small molecule. Question 46 A patient is prescribed allopurinol for gout. The nurse practitioner understands that this medication works by: A. Increasing uric acid excretion B. Inhibiting xanthine oxidase, decreasing uric acid production C. Inhibiting prostaglandin synthesis D. Blocking interleukin-1 ANSWER: B. Inhibiting xanthine oxidase, decreasing uric acid production. RATIONALE: Allopurinol is a xanthine oxidase inhibitor that decreases uric acid production. It is used for prophylaxis of gout, not acute treatment. Colchicine is used for acute gout attacks. Question 47 A patient is prescribed colchicine for an acute gout attack. Which adverse effect should the nurse practitioner monitor? A. GI upset (nausea, vomiting, diarrhea) B. Hyperglycemia C. Hypertension D. Tachycardia ANSWER: A. GI upset (nausea, vomiting, diarrhea). RATIONALE: Colchicine is used for acute gout attacks. Common adverse effects include GI upset. It has a narrow therapeutic range, and GI symptoms can be dose-limiting. Question 48 A patient is prescribed ibuprofen for osteoarthritis. The nurse practitioner should monitor for which adverse effect? A. GI bleeding B. Hyperkalemia C. Dry cough D. Tachycardia ANSWER: A. GI bleeding. RATIONALE: Ibuprofen is an NSAID that can cause GI bleeding, renal impairment, and cardiovascular events. Patients at risk include those over 65, those with a history of GI ulcers, and those taking anticoagulants. Question 49 A patient is prescribed celecoxib for osteoarthritis. The nurse practitioner understands that this medication: A. Is a non-selective NSAID with high GI bleeding risk B. Is a COX-2 inhibitor with lower GI bleeding risk but increased cardiovascular risk C. Is an opioid analgesic D. Is a corticosteroid ANSWER: B. Is a COX-2 inhibitor with lower GI bleeding risk but increased cardiovascular risk. RATIONALE: Celecoxib is a COX-2 inhibitor that selectively inhibits COX-2, reducing prostaglandin synthesis. It has lower GI bleeding risk but increased cardiovascular risk compared to non-selective NSAIDs. Question 50 A patient is prescribed tramadol for moderate pain. The nurse practitioner should monitor for which adverse effect? A. Seizures B. GI bleeding C. Hyperkalemia D. Dry cough ANSWER: A. Seizures. RATIONALE: Tramadol is a weak opioid agonist with serotonin and norepinephrine reuptake inhibition. It can lower the seizure threshold, especially at high doses or in patients on SSRIs. Question 51 A patient is prescribed morphine for severe pain. Which adverse effect should the nurse practitioner monitor? A. Respiratory depression B. GI bleeding C. Hyperkalemia D. Tachycardia ANSWER: A. Respiratory depression. RATIONALE: Morphine is an opioid agonist that can cause respiratory depression, constipation, sedation, and nausea. Respiratory depression is the most serious adverse effect. Naloxone is the antidote. Question 52 A patient is prescribed naloxone for opioid overdose. The nurse practitioner understands that this medication works by: A. Stimulating opioid receptors B. Blocking opioid receptors C. Increasing opioid metabolism D. Decreasing opioid absorption ANSWER: B. Blocking opioid receptors. RATIONALE: Naloxone is an opioid receptor antagonist that reverses opioid effects (respiratory depression, sedation). It is given IV, IM, or intranasally for opioid overdose. Question 53 A patient is prescribed buprenorphine for opioid use disorder. The nurse practitioner understands that this medication: A. Is a full opioid agonist B. Is a partial opioid agonist C. Is an opioid antagonist D. Is a non-opioid analgesic ANSWER: B. Is a partial opioid agonist. RATIONALE: Buprenorphine is a partial opioid agonist used for opioid use disorder. It has a ceiling effect for respiratory depression and reduces withdrawal symptoms. Methadone is a full agonist, and naloxone is an antagonist. Question 54 A patient is prescribed methadone for opioid use disorder. The nurse practitioner understands that this medication: A. Is a partial opioid agonist B. Is a full opioid agonist C. Is an opioid antagonist D. Is a non-opioid analgesic ANSWER: B. Is a full opioid agonist. RATIONALE: Methadone is a full opioid agonist used for opioid use disorder. It prevents withdrawal and reduces craving. It has a long half-life and requires daily dosing. Question 55 A patient is prescribed disulfiram for alcohol use disorder. The nurse practitioner should teach the patient to avoid: A. Alcohol-containing products B. High-fat foods C. Tyramine-rich foods D. Grapefruit juice ANSWER: A. Alcohol-containing products. RATIONALE: Disulfiram causes a reaction (flushing, nausea, vomiting, palpitations) when alcohol is consumed. Patients must avoid alcohol in beverages, foods, and products (mouthwash, cough syrup). Question 56 A patient is prescribed naltrexone for alcohol use disorder. The nurse practitioner understands that this medication: A. Is a full opioid agonist B. Is an opioid antagonist that reduces alcohol craving C. Causes a reaction when alcohol is consumed D. Is a partial opioid agonist ANSWER: B. Is an opioid antagonist that reduces alcohol craving. RATIONALE: Naltrexone is an opioid receptor antagonist that reduces alcohol craving and pleasure from alcohol. It does not cause a reaction with alcohol (unlike disulfiram). It is also used for opioid use disorder. Question 57 A patient is prescribed varenicline for smoking cessation. The nurse practitioner should monitor for which adverse effect? A. Suicidal ideation B. GI bleeding C. Hyperkalemia D. Tachycardia ANSWER: A. Suicidal ideation. RATIONALE: Varenicline is a partial nicotine agonist used for smoking cessation. It has a black box warning for suicidal ideation and neuropsychiatric symptoms. Patients should be monitored for mood changes. Question 58 A patient is prescribed bupropion for depression and smoking cessation. Which adverse effect should the nurse practitioner monitor? A. Seizures B. GI bleeding C. Hyperkalemia D. Dry cough ANSWER: A. Seizures. RATIONALE: Bupropion is an aminoketone antidepressant used for depression and smoking cessation. It lowers the seizure threshold, especially at high doses. It is also used for seasonal affective disorder. Question 59 A patient is prescribed rifampin for tuberculosis. The nurse practitioner should teach the patient that this medication may cause: A. Red-orange discoloration of body fluids B. Gray discoloration of teeth C. Green discoloration of urine D. Blue discoloration of skin ANSWER: A. Red-orange discoloration of body fluids. RATIONALE: Rifampin causes red-orange discoloration of urine, sweat, tears, and saliva. Patients should be warned about this benign effect. Gray discoloration is associated with tetracycline. Question 60 A patient is prescribed isoniazid (INH) for tuberculosis. Which adverse effect should the nurse practitioner monitor? A. Peripheral neuropathy B. Hepatotoxicity C. Both A and B D. Ototoxicity ANSWER: C. Both A and B. RATIONALE: Isoniazid (INH) can cause peripheral neuropathy (due to vitamin B6 deficiency) and hepatotoxicity. Pyridoxine (vitamin B6) is often given to prevent neuropathy. Liver function tests should be monitored. Question 61 A patient is prescribed pyridoxine (vitamin B6) with isoniazid. The nurse practitioner explains that this is to prevent: A. Hepatotoxicity B. Peripheral neuropathy C. Nephrotoxicity D. Ototoxicity ANSWER: B. Peripheral neuropathy. RATIONALE: Pyridoxine (vitamin B6) is given with isoniazid to prevent peripheral neuropathy caused by INH-induced vitamin B6 deficiency. It does not prevent hepatotoxicity, nephrotoxicity, or ototoxicity. Question 62 A patient is prescribed ethambutol for tuberculosis. Which adverse effect should the nurse practitioner monitor? A. Optic neuritis (visual changes) B. Hepatotoxicity C. Peripheral neuropathy D. Ototoxicity ANSWER: A. Optic neuritis (visual changes). RATIONALE: Ethambutol can cause optic neuritis, resulting in visual changes (blurred vision, red-green color blindness). Visual acuity should be monitored. Hepatotoxicity is associated with INH and rifampin, peripheral neuropathy with INH. Question 63 A patient is prescribed acyclovir for herpes simplex. The nurse practitioner understands that this medication works by: A. Inhibiting viral DNA polymerase B. Blocking viral entry into cells C. Inhibiting viral reverse transcriptase D. Stimulating the immune system ANSWER: A. Inhibiting viral DNA polymerase. RATIONALE: Acyclovir is a nucleoside analogue that inhibits viral DNA polymerase, preventing viral replication. It is used for herpes simplex and varicella-zoster. Question 64 A patient is prescribed oseltamivir for influenza. The nurse practitioner understands that this medication: A. Is a neuraminidase inhibitor that must be started within 48 hours of symptoms B. Is a DNA polymerase inhibitor C. Is an antiviral for herpes D. Is a vaccine ANSWER: A. Is a neuraminidase inhibitor that must be started within 48 hours of symptoms. RATIONALE: Oseltamivir (Tamiflu) is a neuraminidase inhibitor used for influenza A and B. It must be started within 48 hours of symptom onset for maximum effectiveness. Question 65 A patient is prescribed amphotericin B for a systemic fungal infection. Which adverse effect should the nurse practitioner monitor? A. Nephrotoxicity B. Hepatotoxicity C. Ototoxicity D. Cardiotoxicity ANSWER: A. Nephrotoxicity. RATIONALE: Amphotericin B is a potent antifungal that can cause nephrotoxicity. Patients should be pre-hydrated and monitored for renal function. Hepatotoxicity is associated with azoles. Question 66 A patient is prescribed fluconazole for a fungal infection. The nurse practitioner understands that this medication: A. Is a polyene antifungal (like amphotericin B) B. Is an azole antifungal that inhibits ergosterol synthesis C. Is an echinocandin antifungal D. Is an antifungal for topical use only ANSWER: B. Is an azole antifungal that inhibits ergosterol synthesis. RATIONALE: Fluconazole is an azole antifungal that inhibits ergosterol synthesis in the fungal cell membrane. It is used for candidiasis and cryptococcosis. Question 67 A patient is prescribed metronidazole for a bacterial infection. The nurse practitioner should teach the patient to avoid: A. Alcohol B. Grapefruit juice C. Tyramine-rich foods D. High-fat foods ANSWER: A. Alcohol. RATIONALE: Metronidazole causes a disulfiram-like reaction when combined with alcohol (flushing, nausea, vomiting, tachycardia). Patients should avoid alcohol during treatment and for 48 hours after. Question 68 A patient is prescribed vancomycin for a severe bacterial infection. Which adverse effect should the nurse practitioner monitor? A. Red man syndrome B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. Red man syndrome. RATIONALE: Vancomycin can cause red man syndrome (flushing, rash, hypotension) if infused too rapidly. It should be infused over at least 60 minutes. Nephrotoxicity and ototoxicity are also risks. Question 69 A patient is prescribed gentamicin for a serious infection. Which adverse effect should the nurse practitioner monitor? A. Nephrotoxicity and ototoxicity B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. Nephrotoxicity and ototoxicity. RATIONALE: Gentamicin is an aminoglycoside that can cause nephrotoxicity and ototoxicity (hearing loss, balance issues). Serum peak and trough levels should be monitored. Question 70 A patient is prescribed doxycycline for a bacterial infection. The nurse practitioner should teach the patient to: A. Take the medication with food to prevent GI upset B. Take the medication on an empty stomach C. Avoid sunlight (photosensitivity) D. Take the medication with milk ANSWER: C. Avoid sunlight (photosensitivity). RATIONALE: Doxycycline is a tetracycline that causes photosensitivity. Patients should avoid prolonged sun exposure and use sunscreen. It should be taken with food, but not with calcium-containing products. Question 71 A patient is prescribed ciprofloxacin for a urinary tract infection. Which adverse effect should the nurse practitioner monitor? A. Tendon rupture B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. Tendon rupture. RATIONALE: Ciprofloxacin is a fluoroquinolone that increases the risk of tendon rupture, especially in older adults and those on corticosteroids. It also causes QT prolongation. Question 72 A patient is prescribed azithromycin for a respiratory infection. The nurse practitioner should monitor for which adverse effect? A. QT prolongation B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. QT prolongation. RATIONALE: Azithromycin is a macrolide that can cause QT prolongation, increasing the risk of cardiac dysrhythmias. Patients on other QT-prolonging drugs are at higher risk. Question 73 A patient is prescribed amoxicillin for a bacterial infection. Which adverse effect should the nurse practitioner monitor? A. Allergic reaction (rash, anaphylaxis) B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. Allergic reaction (rash, anaphylaxis). RATIONALE: Amoxicillin is a penicillin that can cause allergic reactions, ranging from rash to anaphylaxis. Patients with penicillin allergy should avoid it. Question 74 A patient is prescribed clindamycin for a bacterial infection. Which adverse effect should the nurse practitioner monitor? A. Clostridium difficile infection (pseudomembranous colitis) B. Hepatotoxicity C. Peripheral neuropathy D. GI bleeding ANSWER: A. Clostridium difficile infection (pseudomembranous colitis). RATIONALE: Clindamycin is associated with Clostridium difficile infection, which causes severe diarrhea and colitis. Patients should report watery diarrhea. Question 75 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would increase the levels of this substrate by inhibiting CYP2D6? A. Fluoxetine B. Carbamazepine C. Rifampin D. Phenytoin ANSWER: A. Fluoxetine. RATIONALE: Fluoxetine (and paroxetine) are potent CYP2D6 inhibitors. They increase levels of CYP2D6 substrates (e.g., codeine, tamoxifen, metoprolol). Carbamazepine, rifampin, and phenytoin are CYP inducers. Question 76 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would decrease the levels of this substrate by inducing CYP3A4? A. Ketoconazole B. Erythromycin C. Carbamazepine D. Grapefruit juice ANSWER: C. Carbamazepine. RATIONALE: Carbamazepine is a potent CYP3A4 inducer that decreases levels of CYP3A4 substrates. Ketoconazole, erythromycin, and grapefruit juice are CYP3A4 inhibitors. Question 77 A patient is prescribed a medication that is highly protein-bound. Which condition would increase the free fraction of the drug? A. Hypoalbuminemia B. Renal failure C. Hepatic failure D. Dehydration ANSWER: A. Hypoalbuminemia. RATIONALE: Hypoalbuminemia reduces protein binding sites, increasing the free fraction of highly protein-bound drugs. This increases the risk of toxicity. Question 78 A patient is prescribed a medication that is eliminated by the kidneys. Which age-related change would most significantly affect this drug's clearance? A. Decreased hepatic blood flow B. Decreased glomerular filtration rate C. Decreased GI motility D. Increased body fat ANSWER: B. Decreased glomerular filtration rate. RATIONALE: Aging is associated with decreased glomerular filtration rate (GFR), which reduces renal clearance of renally eliminated drugs. Doses should be adjusted for renal function. Question 79 A patient is prescribed a medication that is eliminated by the liver. Which age-related change would most significantly affect this drug's clearance? A. Decreased hepatic blood flow and liver mass B. Decreased glomerular filtration rate C. Decreased GI motility D. Increased body fat ANSWER: A. Decreased hepatic blood flow and liver mass. RATIONALE: Aging is associated with decreased hepatic blood flow and liver mass, which can reduce the clearance of hepatically metabolized drugs. Phase I metabolism is more affected than Phase II. Question 80 A patient is prescribed a medication that is a P-glycoprotein substrate. Which drug would inhibit P-glycoprotein and increase the substrate's levels? A. Verapamil B. Carbamazepine C. Rifampin D. Phenytoin ANSWER: A. Verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that can increase levels of Pglycoprotein substrates (e.g., digoxin). Carbamazepine, rifampin, and phenytoin are Pglycoprotein inducers. Question 81 A patient is prescribed a medication that is a UGT substrate. Which condition would reduce the metabolism of this drug? A. Gilbert's syndrome B. Crigler-Najjar syndrome C. Liver cirrhosis D. Renal failure ANSWER: C. Liver cirrhosis. RATIONALE: UGT enzymes are primarily located in the liver. Liver cirrhosis reduces UGT activity, increasing levels of UGT substrates. Gilbert's and Crigler-Najjar syndromes are specific genetic deficiencies affecting bilirubin conjugation. Question 82 A patient is prescribed a medication that undergoes extensive first-pass metabolism. Which route of administration would increase bioavailability? A. Oral B. Sublingual C. Rectal D. Topical ANSWER: B. Sublingual. RATIONALE: Sublingual administration bypasses first-pass metabolism because the drug is absorbed directly into the systemic circulation, avoiding the portal circulation and liver. Question 83 A patient is prescribed a medication that is a prodrug. Which statement is true regarding prodrugs? A. They are active in their administered form B. They require metabolic activation to become active C. They are always inactive D. They are renally excreted unchanged ANSWER: B. They require metabolic activation to become active. RATIONALE: Prodrugs are inactive in their administered form and require metabolic conversion to become pharmacologically active. Examples include codeine, tamoxifen, and clopidogrel. Question 84 A patient is prescribed a medication with a half-life of 24 hours. How many days will it take to reach steady state? A. 2 days B. 3 days C. 4 days D. 5 days ANSWER: D. 5 days. RATIONALE: Steady state is reached after approximately 5 half-lives. For a drug with a 24hour half-life, steady state is reached in about 5 days (5 × 24 hours = 120 hours = 5 days). Question 85 A patient is prescribed a medication that is a CYP2C19 inhibitor. Which drug would be affected? A. Clopidogrel B. Warfarin C. Simvastatin D. Losartan ANSWER: A. Clopidogrel. RATIONALE: Clopidogrel is a prodrug that requires CYP2C19 activation. CYP2C19 inhibitors (e.g., omeprazole) reduce clopidogrel efficacy. Warfarin is metabolized by CYP2C9, simvastatin by CYP3A4, and losartan by CYP2C9 and CYP3A4. Question 86 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would increase the levels of this substrate by inhibiting CYP2C9? A. Fluconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Fluconazole. RATIONALE: Fluconazole is a CYP2C9 inhibitor that increases levels of CYP2C9 substrates (e.g., warfarin, phenytoin). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 87 A patient is prescribed a medication that is a CYP2D6 substrate. Which condition would reduce the metabolism of this drug? A. Poor metabolizer phenotype B. Extensive metabolizer phenotype C. Ultrarapid metabolizer phenotype D. Normal metabolizer phenotype ANSWER: A. Poor metabolizer phenotype. RATIONALE: Poor CYP2D6 metabolizers have reduced enzyme activity, leading to increased levels of CYP2D6 substrates and potential toxicity. Ultrarapid metabolizers have increased enzyme activity. Question 88 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would decrease the levels of this substrate by inducing CYP2D6? A. Fluoxetine B. Paroxetine C. Quinidine D. None of the above ANSWER: D. None of the above. RATIONALE: CYP2D6 is not significantly inducible. Fluoxetine, paroxetine, and quinidine are CYP2D6 inhibitors, not inducers. Genetic variation (poor vs. ultrarapid metabolizers) is the primary factor affecting CYP2D6 activity. Question 89 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would increase the levels of this substrate by inhibiting CYP3A4? A. Ketoconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ketoconazole. RATIONALE: Ketoconazole is a potent CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Rifampin, carbamazepine, and phenytoin are CYP3A4 inducers. Question 90 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would decrease the levels of this substrate by inducing CYP3A4? A. Erythromycin B. Grapefruit juice C. Rifampin D. Ketoconazole ANSWER: C. Rifampin. RATIONALE: Rifampin is a potent CYP3A4 inducer that decreases levels of CYP3A4 substrates. Erythromycin, grapefruit juice, and ketoconazole are CYP3A4 inhibitors. Question 91 A patient is prescribed a medication that is a UGT substrate. Which drug would inhibit UGT and increase the substrate's levels? A. Probenecid B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Probenecid. RATIONALE: Probenecid inhibits UGT enzymes and can increase levels of UGT substrates (e.g., morphine, lorazepam). Rifampin, carbamazepine, and phenytoin are UGT inducers. Question 92 A patient is prescribed a medication that is a P-glycoprotein substrate. Which drug would induce P-glycoprotein and decrease the substrate's levels? A. Rifampin B. Verapamil C. Amiodarone D. Cyclosporine ANSWER: A. Rifampin. RATIONALE: Rifampin induces P-glycoprotein, decreasing levels of P-glycoprotein substrates (e.g., digoxin). Verapamil, amiodarone, and cyclosporine are P-glycoprotein inhibitors. Question 93 A patient is prescribed a medication that is a CYP2C9 substrate. Which condition would increase the risk of bleeding if the patient is also on warfarin? A. CYP2C92 or *3 polymorphism B. CYP2C9*1/1 genotype C. Extensive metabolizer phenotype D. Normal CYP2C9 function **ANSWER: A. CYP2C92 or 3 polymorphism. RATIONALE: CYP2C92 and *3 polymorphisms result in reduced enzyme activity, leading to increased warfarin levels and bleeding risk. CYP2C9*1/1 is the normal genotype with normal enzyme activity. Question 94 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would inhibit CYP2C19 and increase the substrate's levels? A. Omeprazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Omeprazole. RATIONALE: Omeprazole is a CYP2C19 inhibitor that increases levels of CYP2C19 substrates (e.g., clopidogrel, diazepam). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 95 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would induce CYP2C19 and decrease the substrate's levels? A. Omeprazole B. Rifampin C. Fluoxetine D. Ketoconazole ANSWER: B. Rifampin. RATIONALE: Rifampin is a CYP2C19 inducer that decreases levels of CYP2C19 substrates. Omeprazole, fluoxetine, and ketoconazole are CYP2C19 inhibitors. Question 96 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would inhibit CYP1A2 and increase the substrate's levels? A. Ciprofloxacin B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ciprofloxacin. RATIONALE: Ciprofloxacin is a CYP1A2 inhibitor that increases levels of CYP1A2 substrates (e.g., theophylline, caffeine). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 97 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would induce CYP1A2 and decrease the substrate's levels? A. Ciprofloxacin B. Fluvoxamine C. Smoking D. Erythromycin ANSWER: C. Smoking. RATIONALE: Smoking induces CYP1A2, decreasing levels of CYP1A2 substrates. Ciprofloxacin and fluvoxamine are CYP1A2 inhibitors, and erythromycin is a CYP3A4 inhibitor. Question 98 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would inhibit CYP2B6 and increase the substrate's levels? A. Ticlopidine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ticlopidine. RATIONALE: Ticlopidine is a CYP2B6 inhibitor that increases levels of CYP2B6 substrates (e.g., bupropion, efavirenz). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 99 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would induce CYP2B6 and decrease the substrate's levels? A. Ticlopidine B. Rifampin C. Fluoxetine D. Ketoconazole ANSWER: B. Rifampin. RATIONALE: Rifampin is a CYP2B6 inducer that decreases levels of CYP2B6 substrates. Ticlopidine is a CYP2B6 inhibitor, and fluoxetine and ketoconazole are CYP2D6 and CYP3A4 inhibitors, respectively. Question 100 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would inhibit CYP2C8 and increase the substrate's levels? A. Gemfibrozil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Gemfibrozil. RATIONALE: Gemfibrozil is a CYP2C8 inhibitor that increases levels of CYP2C8 substrates (e.g., repaglinide, paclitaxel). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 101 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would induce CYP2C8 and decrease the substrate's levels? A. Gemfibrozil B. Rifampin C. Fluoxetine D. Ketoconazole ANSWER: B. Rifampin. RATIONALE: Rifampin is a CYP2C8 inducer that decreases levels of CYP2C8 substrates. Gemfibrozil is a CYP2C8 inhibitor. Question 102 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of ketoconazole D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of ketoconazole. RATIONALE: Ketoconazole is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. St. John's wort, rifampin, and carbamazepine are CYP3A4 inducers that decrease levels. Question 103 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of erythromycin B. Concurrent use of grapefruit juice C. Concurrent use of carbamazepine D. Concurrent use of ketoconazole ANSWER: C. Concurrent use of carbamazepine. RATIONALE: Carbamazepine is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Erythromycin, grapefruit juice, and ketoconazole are CYP3A4 inhibitors. Question 104 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of verapamil D. Concurrent use of phenytoin ANSWER: C. Concurrent use of verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Rifampin, carbamazepine, and phenytoin are P-glycoprotein inducers. Question 105 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of rifampin D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a P-glycoprotein inducer that decreases levels of P-glycoprotein substrates. Verapamil, amiodarone, and cyclosporine are P-glycoprotein inhibitors. Question 106 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of probenecid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates. Rifampin, carbamazepine, and phenytoin are UGT inducers. Question 107 A patient is prescribed a medication that is a UGT substrate. Which condition would decrease the levels of this drug? A. Concurrent use of probenecid B. Concurrent use of valproic acid C. Concurrent use of rifampin D. Concurrent use of ibuprofen ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a UGT inducer that decreases levels of UGT substrates. Probenecid and valproic acid are UGT inhibitors. Question 108 A patient is prescribed a medication that is a CYP2D6 substrate. Which condition would increase the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype C. Extensive metabolizer phenotype D. Normal metabolizer phenotype ANSWER: A. Poor metabolizer phenotype. RATIONALE: Poor CYP2D6 metabolizers have reduced enzyme activity, leading to increased levels of CYP2D6 substrates. Ultrarapid metabolizers have increased enzyme activity and lower drug levels. Question 109 A patient is prescribed a medication that is a CYP2D6 substrate. Which condition would decrease the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype C. Extensive metabolizer phenotype D. Intermediate metabolizer phenotype ANSWER: B. Ultrarapid metabolizer phenotype. RATIONALE: Ultrarapid CYP2D6 metabolizers have increased enzyme activity, leading to decreased levels of CYP2D6 substrates. This can result in therapeutic failure for prodrugs like codeine. Question 110 A patient is prescribed a medication that is a CYP2C9 substrate. Which condition would increase the levels of this drug? A. CYP2C9*1/*1 genotype B. CYP2C9*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C9 function **ANSWER: B. CYP2C92 or 3 polymorphism. RATIONALE: CYP2C9*2 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C9 substrates (e.g., warfarin, phenytoin) and increased risk of toxicity. Question 111 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would increase the levels of this drug? A. CYP2C19*1/*1 genotype B. CYP2C19*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C19 function **ANSWER: B. CYP2C192 or 3 polymorphism. RATIONALE: CYP2C192 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C19 substrates (e.g., clopidogrel, omeprazole). CYP2C19*1/1 is the normal genotype. Question 112 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would decrease the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype (CYP2C19*17) C. Intermediate metabolizer phenotype D. Normal metabolizer phenotype ANSWER: B. Ultrarapid metabolizer phenotype (CYP2C19*17). RATIONALE: CYP2C19*17 is a gain-of-function polymorphism resulting in increased enzyme activity, leading to decreased levels of CYP2C19 substrates. This can result in therapeutic failure for drugs like clopidogrel. Question 113 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of erythromycin D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of erythromycin. RATIONALE: Erythromycin is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. St. John's wort, rifampin, and carbamazepine are CYP3A4 inducers. Question 114 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of ketoconazole B. Concurrent use of itraconazole C. Concurrent use of St. John's wort D. Concurrent use of verapamil ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Ketoconazole, itraconazole, and verapamil are CYP3A4 inhibitors. Question 115 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of cyclosporine D. Concurrent use of phenytoin ANSWER: C. Concurrent use of cyclosporine. RATIONALE: Cyclosporine is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates (e.g., digoxin). Rifampin, carbamazepine, and phenytoin are P-glycoprotein inducers. Question 116 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of St. John's wort D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a P-glycoprotein inducer that decreases levels of Pglycoprotein substrates. Verapamil, amiodarone, and cyclosporine are P-glycoprotein inhibitors. Question 117 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of valproic acid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of valproic acid. RATIONALE: Valproic acid is a UGT inhibitor that increases levels of UGT substrates (e.g., lamotrigine, lorazepam). Rifampin, carbamazepine, and phenytoin are UGT inducers. Question 118 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would inhibit CYP2D6 and increase the substrate's levels? A. Paroxetine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Paroxetine. RATIONALE: Paroxetine is a potent CYP2D6 inhibitor that increases levels of CYP2D6 substrates. Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 119 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would inhibit CYP2C9 and increase the substrate's levels? A. Fluconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Fluconazole. RATIONALE: Fluconazole is a CYP2C9 inhibitor that increases levels of CYP2C9 substrates (e.g., warfarin, phenytoin). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 120 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would inhibit CYP2C19 and increase the substrate's levels? A. Omeprazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Omeprazole. RATIONALE: Omeprazole is a CYP2C19 inhibitor that increases levels of CYP2C19 substrates (e.g., clopidogrel, diazepam). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 121 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would inhibit CYP1A2 and increase the substrate's levels? A. Ciprofloxacin B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ciprofloxacin. RATIONALE: Ciprofloxacin is a CYP1A2 inhibitor that increases levels of CYP1A2 substrates (e.g., theophylline, caffeine). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 122 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would inhibit CYP2B6 and increase the substrate's levels? A. Ticlopidine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ticlopidine. RATIONALE: Ticlopidine is a CYP2B6 inhibitor that increases levels of CYP2B6 substrates (e.g., bupropion, efavirenz). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 123 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would inhibit CYP2C8 and increase the substrate's levels? A. Gemfibrozil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Gemfibrozil. RATIONALE: Gemfibrozil is a CYP2C8 inhibitor that increases levels of CYP2C8 substrates (e.g., repaglinide, paclitaxel). Rifampin, carbamazepine, and phenytoin are CYP inducers. Question 124 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would inhibit CYP3A4 and increase the substrate's levels? A. Ketoconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ketoconazole. RATIONALE: Ketoconazole is a potent CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Rifampin, carbamazepine, and phenytoin are CYP3A4 inducers. Question 125 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would induce CYP3A4 and decrease the substrate's levels? A. Erythromycin B. Grapefruit juice C. Rifampin D. Ketoconazole ANSWER: C. Rifampin. RATIONALE: Rifampin is a potent CYP3A4 inducer that decreases levels of CYP3A4 substrates. Erythromycin, grapefruit juice, and ketoconazole are CYP3A4 inhibitors. Question 126 A patient is prescribed a medication that is a P-glycoprotein substrate. Which drug would inhibit P-glycoprotein and increase the substrate's levels? A. Verapamil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates (e.g., digoxin). Rifampin, carbamazepine, and phenytoin are P-glycoprotein inducers. Question 127 A patient is prescribed a medication that is a UGT substrate. Which drug would inhibit UGT and increase the substrate's levels? A. Probenecid B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates (e.g., morphine, lorazepam). Rifampin, carbamazepine, and phenytoin are UGT inducers. Question 128 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would induce CYP2D6 and decrease the substrate's levels? A. Fluoxetine B. Paroxetine C. Quinidine D. None of the above ANSWER: D. None of the above. RATIONALE: CYP2D6 is not significantly inducible. Fluoxetine, paroxetine, and quinidine are CYP2D6 inhibitors. Question 129 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would induce CYP2C9 and decrease the substrate's levels? A. Rifampin B. Fluconazole C. Amiodarone D. Metronidazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C9 inducer that decreases levels of CYP2C9 substrates (e.g., warfarin, phenytoin). Fluconazole, amiodarone, and metronidazole are CYP2C9 inhibitors. Question 130 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would induce CYP2C19 and decrease the substrate's levels? A. Rifampin B. Omeprazole C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C19 inducer that decreases levels of CYP2C19 substrates. Omeprazole, fluoxetine, and ketoconazole are CYP2C19 inhibitors. Question 131 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would induce CYP1A2 and decrease the substrate's levels? A. Smoking B. Ciprofloxacin C. Fluvoxamine D. Erythromycin ANSWER: A. Smoking. RATIONALE: Smoking induces CYP1A2, decreasing levels of CYP1A2 substrates (e.g., theophylline, caffeine). Ciprofloxacin and fluvoxamine are CYP1A2 inhibitors. Question 132 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would induce CYP2B6 and decrease the substrate's levels? A. Rifampin B. Ticlopidine C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2B6 inducer that decreases levels of CYP2B6 substrates. Ticlopidine is a CYP2B6 inhibitor. Question 133 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would induce CYP2C8 and decrease the substrate's levels? A. Rifampin B. Gemfibrozil C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C8 inducer that decreases levels of CYP2C8 substrates. Gemfibrozil is a CYP2C8 inhibitor. Question 134 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of ketoconazole D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of ketoconazole. RATIONALE: Ketoconazole is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. St. John's wort, rifampin, and carbamazepine are CYP3A4 inducers. Question 135 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of erythromycin B. Concurrent use of grapefruit juice C. Concurrent use of carbamazepine D. Concurrent use of ketoconazole ANSWER: C. Concurrent use of carbamazepine. RATIONALE: Carbamazepine is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Erythromycin, grapefruit juice, and ketoconazole are CYP3A4 inhibitors. Question 136 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of verapamil D. Concurrent use of phenytoin ANSWER: C. Concurrent use of verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Rifampin, carbamazepine, and phenytoin are P-glycoprotein inducers. Question 137 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of rifampin D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a P-glycoprotein inducer that decreases levels of P-glycoprotein substrates. Verapamil, amiodarone, and cyclosporine are P-glycoprotein inhibitors. Question 138 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of probenecid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates. Rifampin, carbamazepine, and phenytoin are UGT inducers. Question 139 A patient is prescribed a medication that is a UGT substrate. Which condition would decrease the levels of this drug? A. Concurrent use of probenecid B. Concurrent use of valproic acid C. Concurrent use of rifampin D. Concurrent use of ibuprofen ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a UGT inducer that decreases levels of UGT substrates. Probenecid and valproic acid are UGT inhibitors. Question 140 A patient is prescribed a medication that is a CYP2D6 substrate. Which condition would increase the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype C. Extensive metabolizer phenotype D. Normal metabolizer phenotype ANSWER: A. Poor metabolizer phenotype. RATIONALE: Poor CYP2D6 metabolizers have reduced enzyme activity, leading to increased levels of CYP2D6 substrates. Question 141 A patient is prescribed a medication that is a CYP2C9 substrate. Which condition would increase the levels of this drug? A. CYP2C9*1/*1 genotype B. CYP2C9*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C9 function **ANSWER: B. CYP2C92 or 3 polymorphism. RATIONALE: CYP2C9*2 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C9 substrates. Question 142 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would increase the levels of this drug? A. CYP2C19*1/*1 genotype B. CYP2C19*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C19 function **ANSWER: B. CYP2C192 or 3 polymorphism. RATIONALE: CYP2C19*2 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C19 substrates. Question 143 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would decrease the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype (CYP2C19*17) C. Intermediate metabolizer phenotype D. Normal metabolizer phenotype ANSWER: B. Ultrarapid metabolizer phenotype (CYP2C19*17). RATIONALE: CYP2C19*17 is a gain-of-function polymorphism resulting in increased enzyme activity, leading to decreased levels of CYP2C19 substrates. Question 144 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of erythromycin D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of erythromycin. RATIONALE: Erythromycin is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 145 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of ketoconazole B. Concurrent use of itraconazole C. Concurrent use of St. John's wort D. Concurrent use of verapamil ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 146 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of cyclosporine D. Concurrent use of phenytoin ANSWER: C. Concurrent use of cyclosporine. RATIONALE: Cyclosporine is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 147 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of St. John's wort D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a P-glycoprotein inducer that decreases levels of Pglycoprotein substrates. Question 148 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of valproic acid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of valproic acid. RATIONALE: Valproic acid is a UGT inhibitor that increases levels of UGT substrates. Question 149 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would inhibit CYP2D6 and increase the substrate's levels? A. Paroxetine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Paroxetine. RATIONALE: Paroxetine is a potent CYP2D6 inhibitor that increases levels of CYP2D6 substrates. Question 150 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would inhibit CYP2C9 and increase the substrate's levels? A. Fluconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Fluconazole. RATIONALE: Fluconazole is a CYP2C9 inhibitor that increases levels of CYP2C9 substrates. Question 151 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would inhibit CYP2C19 and increase the substrate's levels? A. Omeprazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Omeprazole. RATIONALE: Omeprazole is a CYP2C19 inhibitor that increases levels of CYP2C19 substrates. Question 152 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would inhibit CYP1A2 and increase the substrate's levels? A. Ciprofloxacin B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ciprofloxacin. RATIONALE: Ciprofloxacin is a CYP1A2 inhibitor that increases levels of CYP1A2 substrates. Question 153 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would inhibit CYP2B6 and increase the substrate's levels? A. Ticlopidine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ticlopidine. RATIONALE: Ticlopidine is a CYP2B6 inhibitor that increases levels of CYP2B6 substrates. Question 154 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would inhibit CYP2C8 and increase the substrate's levels? A. Gemfibrozil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Gemfibrozil. RATIONALE: Gemfibrozil is a CYP2C8 inhibitor that increases levels of CYP2C8 substrates. Question 155 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would inhibit CYP3A4 and increase the substrate's levels? A. Ketoconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ketoconazole. RATIONALE: Ketoconazole is a potent CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 156 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would induce CYP3A4 and decrease the substrate's levels? A. Erythromycin B. Grapefruit juice C. Rifampin D. Ketoconazole ANSWER: C. Rifampin. RATIONALE: Rifampin is a potent CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 157 A patient is prescribed a medication that is a P-glycoprotein substrate. Which drug would inhibit P-glycoprotein and increase the substrate's levels? A. Verapamil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 158 A patient is prescribed a medication that is a UGT substrate. Which drug would inhibit UGT and increase the substrate's levels? A. Probenecid B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates. Question 159 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would induce CYP2D6 and decrease the substrate's levels? A. Fluoxetine B. Paroxetine C. Quinidine D. None of the above ANSWER: D. None of the above. RATIONALE: CYP2D6 is not significantly inducible. Question 160 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would induce CYP2C9 and decrease the substrate's levels? A. Rifampin B. Fluconazole C. Amiodarone D. Metronidazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C9 inducer that decreases levels of CYP2C9 substrates. Question 161 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would induce CYP2C19 and decrease the substrate's levels? A. Rifampin B. Omeprazole C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C19 inducer that decreases levels of CYP2C19 substrates. Question 162 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would induce CYP1A2 and decrease the substrate's levels? A. Smoking B. Ciprofloxacin C. Fluvoxamine D. Erythromycin ANSWER: A. Smoking. RATIONALE: Smoking induces CYP1A2, decreasing levels of CYP1A2 substrates. Question 163 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would induce CYP2B6 and decrease the substrate's levels? A. Rifampin B. Ticlopidine C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2B6 inducer that decreases levels of CYP2B6 substrates. Question 164 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would induce CYP2C8 and decrease the substrate's levels? A. Rifampin B. Gemfibrozil C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C8 inducer that decreases levels of CYP2C8 substrates. Question 165 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of ketoconazole D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of ketoconazole. RATIONALE: Ketoconazole is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 166 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of erythromycin B. Concurrent use of grapefruit juice C. Concurrent use of carbamazepine D. Concurrent use of ketoconazole ANSWER: C. Concurrent use of carbamazepine. RATIONALE: Carbamazepine is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 167 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of verapamil D. Concurrent use of phenytoin ANSWER: C. Concurrent use of verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 168 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of rifampin D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a P-glycoprotein inducer that decreases levels of P-glycoprotein substrates. Question 169 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of probenecid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates. Question 170 A patient is prescribed a medication that is a UGT substrate. Which condition would decrease the levels of this drug? A. Concurrent use of probenecid B. Concurrent use of valproic acid C. Concurrent use of rifampin D. Concurrent use of ibuprofen ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a UGT inducer that decreases levels of UGT substrates. Question 171 A patient is prescribed a medication that is a CYP2D6 substrate. Which condition would increase the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype C. Extensive metabolizer phenotype D. Normal metabolizer phenotype ANSWER: A. Poor metabolizer phenotype. RATIONALE: Poor CYP2D6 metabolizers have reduced enzyme activity, leading to increased levels of CYP2D6 substrates. Question 172 A patient is prescribed a medication that is a CYP2C9 substrate. Which condition would increase the levels of this drug? A. CYP2C9*1/*1 genotype B. CYP2C9*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C9 function **ANSWER: B. CYP2C92 or 3 polymorphism. RATIONALE: CYP2C9*2 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C9 substrates. Question 173 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would increase the levels of this drug? A. CYP2C19*1/*1 genotype B. CYP2C19*2 or *3 polymorphism C. Extensive metabolizer phenotype D. Normal CYP2C19 function **ANSWER: B. CYP2C192 or 3 polymorphism. RATIONALE: CYP2C19*2 and *3 polymorphisms result in reduced enzyme activity, leading to increased levels of CYP2C19 substrates. Question 174 A patient is prescribed a medication that is a CYP2C19 substrate. Which condition would decrease the levels of this drug? A. Poor metabolizer phenotype B. Ultrarapid metabolizer phenotype (CYP2C19*17) C. Intermediate metabolizer phenotype D. Normal metabolizer phenotype ANSWER: B. Ultrarapid metabolizer phenotype (CYP2C19*17). RATIONALE: CYP2C19*17 is a gain-of-function polymorphism resulting in increased enzyme activity, leading to decreased levels of CYP2C19 substrates. Question 175 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of erythromycin D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of erythromycin. RATIONALE: Erythromycin is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 176 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of ketoconazole B. Concurrent use of itraconazole C. Concurrent use of St. John's wort D. Concurrent use of verapamil ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 177 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of cyclosporine D. Concurrent use of phenytoin ANSWER: C. Concurrent use of cyclosporine. RATIONALE: Cyclosporine is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 178 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of St. John's wort D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of St. John's wort. RATIONALE: St. John's wort is a P-glycoprotein inducer that decreases levels of Pglycoprotein substrates. Question 179 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of valproic acid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of valproic acid. RATIONALE: Valproic acid is a UGT inhibitor that increases levels of UGT substrates. Question 180 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would inhibit CYP2D6 and increase the substrate's levels? A. Paroxetine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Paroxetine. RATIONALE: Paroxetine is a potent CYP2D6 inhibitor that increases levels of CYP2D6 substrates. Question 181 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would inhibit CYP2C9 and increase the substrate's levels? A. Fluconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Fluconazole. RATIONALE: Fluconazole is a CYP2C9 inhibitor that increases levels of CYP2C9 substrates. Question 182 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would inhibit CYP2C19 and increase the substrate's levels? A. Omeprazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Omeprazole. RATIONALE: Omeprazole is a CYP2C19 inhibitor that increases levels of CYP2C19 substrates. Question 183 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would inhibit CYP1A2 and increase the substrate's levels? A. Ciprofloxacin B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ciprofloxacin. RATIONALE: Ciprofloxacin is a CYP1A2 inhibitor that increases levels of CYP1A2 substrates. Question 184 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would inhibit CYP2B6 and increase the substrate's levels? A. Ticlopidine B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ticlopidine. RATIONALE: Ticlopidine is a CYP2B6 inhibitor that increases levels of CYP2B6 substrates. Question 185 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would inhibit CYP2C8 and increase the substrate's levels? A. Gemfibrozil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Gemfibrozil. RATIONALE: Gemfibrozil is a CYP2C8 inhibitor that increases levels of CYP2C8 substrates. Question 186 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would inhibit CYP3A4 and increase the substrate's levels? A. Ketoconazole B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Ketoconazole. RATIONALE: Ketoconazole is a potent CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 187 A patient is prescribed a medication that is a CYP3A4 substrate. Which drug would induce CYP3A4 and decrease the substrate's levels? A. Erythromycin B. Grapefruit juice C. Rifampin D. Ketoconazole ANSWER: C. Rifampin. RATIONALE: Rifampin is a potent CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 188 A patient is prescribed a medication that is a P-glycoprotein substrate. Which drug would inhibit P-glycoprotein and increase the substrate's levels? A. Verapamil B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 189 A patient is prescribed a medication that is a UGT substrate. Which drug would inhibit UGT and increase the substrate's levels? A. Probenecid B. Rifampin C. Carbamazepine D. Phenytoin ANSWER: A. Probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates. Question 190 A patient is prescribed a medication that is a CYP2D6 substrate. Which drug would induce CYP2D6 and decrease the substrate's levels? A. Fluoxetine B. Paroxetine C. Quinidine D. None of the above ANSWER: D. None of the above. RATIONALE: CYP2D6 is not significantly inducible. Question 191 A patient is prescribed a medication that is a CYP2C9 substrate. Which drug would induce CYP2C9 and decrease the substrate's levels? A. Rifampin B. Fluconazole C. Amiodarone D. Metronidazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C9 inducer that decreases levels of CYP2C9 substrates. Question 192 A patient is prescribed a medication that is a CYP2C19 substrate. Which drug would induce CYP2C19 and decrease the substrate's levels? A. Rifampin B. Omeprazole C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C19 inducer that decreases levels of CYP2C19 substrates. Question 193 A patient is prescribed a medication that is a CYP1A2 substrate. Which drug would induce CYP1A2 and decrease the substrate's levels? A. Smoking B. Ciprofloxacin C. Fluvoxamine D. Erythromycin ANSWER: A. Smoking. RATIONALE: Smoking induces CYP1A2, decreasing levels of CYP1A2 substrates. Question 194 A patient is prescribed a medication that is a CYP2B6 substrate. Which drug would induce CYP2B6 and decrease the substrate's levels? A. Rifampin B. Ticlopidine C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2B6 inducer that decreases levels of CYP2B6 substrates. Question 195 A patient is prescribed a medication that is a CYP2C8 substrate. Which drug would induce CYP2C8 and decrease the substrate's levels? A. Rifampin B. Gemfibrozil C. Fluoxetine D. Ketoconazole ANSWER: A. Rifampin. RATIONALE: Rifampin is a CYP2C8 inducer that decreases levels of CYP2C8 substrates. Question 196 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would increase the levels of this drug? A. Concurrent use of St. John's wort B. Concurrent use of rifampin C. Concurrent use of ketoconazole D. Concurrent use of carbamazepine ANSWER: C. Concurrent use of ketoconazole. RATIONALE: Ketoconazole is a CYP3A4 inhibitor that increases levels of CYP3A4 substrates. Question 197 A patient is prescribed a medication that is a CYP3A4 substrate. Which condition would decrease the levels of this drug? A. Concurrent use of erythromycin B. Concurrent use of grapefruit juice C. Concurrent use of carbamazepine D. Concurrent use of ketoconazole ANSWER: C. Concurrent use of carbamazepine. RATIONALE: Carbamazepine is a CYP3A4 inducer that decreases levels of CYP3A4 substrates. Question 198 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of verapamil D. Concurrent use of phenytoin ANSWER: C. Concurrent use of verapamil. RATIONALE: Verapamil is a P-glycoprotein inhibitor that increases levels of P-glycoprotein substrates. Question 199 A patient is prescribed a medication that is a P-glycoprotein substrate. Which condition would decrease the levels of this drug? A. Concurrent use of verapamil B. Concurrent use of amiodarone C. Concurrent use of rifampin D. Concurrent use of cyclosporine ANSWER: C. Concurrent use of rifampin. RATIONALE: Rifampin is a P-glycoprotein inducer that decreases levels of P-glycoprotein substrates. Question 200 A patient is prescribed a medication that is a UGT substrate. Which condition would increase the levels of this drug? A. Concurrent use of rifampin B. Concurrent use of carbamazepine C. Concurrent use of probenecid D. Concurrent use of phenytoin ANSWER: C. Concurrent use of probenecid. RATIONALE: Probenecid is a UGT inhibitor that increases levels of UGT substrates.