Chapter 4 Pharmacokinetics

Chapter 04: Pharmacokinetics Test Bank MULTIPLE CHOICE 1. A patient tells the nurse that the oral drug that has been prescribed has caused a lot of stomach discomfort in the past. What will the nurse ask the prescriber? a. Whether a sublingual form of the medication can be given b. Whether the medication can be given by a parenteral route instead c. Whether an enteric-coated form of the drug is available d. Whether the patient can receive a sustained-release preparation of the drug ANS: C Enteric-coated drugs are preparations that have been coated with a material that dissolves in the intestines, not the stomach. This coating is used either to protect the drug from stomach acid and pepsin or to protect the stomach from a drug that can cause gastric upset. Sublingual forms often are used for drugs that undergo rapid inactivation during the first pass through the hepatic circulation so that the drug can be absorbed directly into the systemic circulation. Parenteral routes are more costly and less safe than oral administration and should not be used unless necessary. A sustained-release preparation is used to release the drug into the body over a specific period to reduce the number of daily doses required to sustain therapeutic drug levels. PTS: 1 DIF: Cognitive Level: Application REF: p. 31 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 2. A patient claims to get better effects with a tablet of Brand X of a drug than with a tablet of Brand Y of the same drug. Both brands contain the same amount of the active ingredient. What does the nurse know to be most likely? a. Advertising by pharmaceutical companies can enhance patient expectations of one brand over another, leading to a placebo effect. b. Because the drug preparations are chemically equivalent, the effects of the two brands must be identical. c. Tablets can differ in composition and can have differing rates of disintegration and dissolution, which can alter the drug’s effects in the body. d. The bioavailability of a drug is determined by the amount of the drug in each dose. ANS: C Even if two brands of a drug are chemically equivalent (i.e., they have identical amounts of the same chemical compound), they can have different effects in the body if they differ in bioavailability. Tablets made by different manufacturers contain different binders and fillers, which disintegrate and dissolve at different rates and affect the bioavailability of the drug. Two brands may be chemically equivalent and still differ in bioavailability, which is not determined by the amount of drug in the dose. PTS: 1 DIF: Cognitive Level: Application REF: pp. 31-32 TOP: Nursing Process: Diagnosis MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 3. A patient receives a drug that has a narrow therapeutic range. The nurse administering this medication will expect to do what? a. Administer the drug at intervals longer than the drug half-life. b. Administer this medication intravenously. c. Monitor plasma drug levels. d. Teach the patient that maximum drug effects will occur within a short period. ANS: C A drug with a narrow therapeutic range is more difficult to administer safely, because the difference between the minimum effective concentration and the toxic concentration is small. Patients taking these medications must have their plasma drug levels monitored closely to ensure that they are getting an effective dose that is not toxic. Administering medications at longer intervals only increases the time required to reach effective plasma drug levels. Drugs that have a narrow therapeutic range may be given by any route and do not differ from other medications in the amount of time it takes for them to take effect, which is a function of a drug’s half-life and dosing frequency. PTS: 1 DIF: Cognitive Level: Application REF: pp. 39-40 TOP: Nursing Process: Evaluation MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential 4. A patient is given a prescription for azithromycin [Zithromax] and asks the nurse why the dose on the first day is twice the amount of the dose on the next 4 days. Which reply by the nurse is correct? a. “A large initial dose helps to get the drug to optimal levels in the body faster.” b. “The first dose is larger to minimize the first pass effect of the liver.” c. “The four smaller doses help the body taper the amount of drug more gradually.” d. “Tubular reabsorption is faster with initial doses, so more is needed at first.” ANS: A A large initial dose is often used as a loading dose to help get serum drug levels to plateau levels more quickly. Larger doses do not prevent first pass effects in drugs susceptible to this type of metabolism. Tapering of doses sometimes is used to prevent rebound or withdrawal effects and is done by stepping down the amount of drug with each dose. Tubular reabsorption is a process that allows drugs to be reabsorbed from the urine into the blood. PTS: 1 DIF: Cognitive Level: Application REF: p. 41 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 5. A nurse is giving an enteral medication. The patient asks why this method is preferable for this drug. How will the nurse reply? a. “This route allows more rapid absorption of the drug.” b. “This route is safer, less expensive, and more convenient.” c. “This route is the best way to control serum drug levels.” d. “This route prevents inactivation of the drug by digestive enzymes.” ANS: B Parenteral routes include the intravenous, intramuscular, and subcutaneous routes. Enteral routes include oral administration, including pills and liquid suspensions. Enteral routes are safer, cheaper, and easier to use. Parenteral routes are used when rapid absorption, precise control of plasma drug levels, and prevention of digestive inactivation are important. PTS: 1 DIF: Cognitive Level: Comprehension REF: pp. 31-32 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 6. The nurse is preparing to administer penicillin G intramuscularly to a child. The child’s parents ask why the drug cannot be given in an oral liquid form. What is the nurse’s reply? a. “This drug causes severe gastric upset if given orally.” b. “This drug has a narrow therapeutic range, and the dose must be tightly controlled.” c. “This drug is absorbed much too quickly in an oral form.” d. “This drug would be inactivated by enzymes in the stomach.” ANS: D Penicillin G is inactivated by digestive enzymes in the stomach and cannot be given orally. It does not have a narrow therapeutic range. PTS: 1 DIF: Cognitive Level: Application REF: pp. 27-28 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 7. A provider has written an order for a medication: drug × 100 mg PO every 6 hours. The half-life for the drug is approximately 6 hours. The nurse is preparing to administer the first dose at 8:00 AM on Tuesday. On Wednesday, when will the serum drug level reach plateau? a. 2:00 AM b. 8:00 AM c. 2:00 PM d. 8:00 PM ANS: B It takes four half-lives for a drug to reach plateau. Total body stores reach their peak at the beginning of the fifth dose of a drug if all doses are equal in amount; in this case, this will be at 8:00 AM the following day. PTS: 1 DIF: Cognitive Level: Application REF: pp. 40-41 TOP: Nursing Process: Planning MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 8. An adult male patient is 1 day postoperative from a total hip replacement. On a pain scale of 0 to 10, with 10 being the greatest pain, the patient reports a pain level of 10. Which medication would be most appropriate for the nurse to administer to this patient? a. 60 mg morphine sulfate PO b. 75 mg meperidine [Demerol] intramuscularly c. 6 mg morphine sulfate intravenously d. Fentanyl [Duragesic] patch 50 mcg transdermally ANS: C The intravenous route is the fastest route of absorption and the one most appropriate for a patient in extreme pain. With the oral route, the medication would take at least 45 minutes to be effective, too long for a patient in extreme pain. With the intramuscular route, the medication would take at least 15 minutes to be effective; although faster than the oral route, this is not as fast as the intravenous route. A Duragesic patch would be the most inappropriate route because of the long drug half-life. This is a more appropriate route for long-term use. PTS: 1 DIF: Cognitive Level: Application REF: pp. 31-32 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 9. A nurse is explaining drug metabolism to a nursing student who asks about glucuronidation. The nurse knows that this is a process that allows drugs to be: a. excreted in hydrolyzed form in the feces to reduce drug toxicity. b. reabsorbed from the urine into the renal circulation to minimize drug loss. c. recycled via the enterohepatic recirculation to remain in the body longer. d. transported across the renal tubules to be excreted in the urine. ANS: C Glucuronidation of some drugs in the liver allows drugs to enter the bile, pass into the duodenum, and then be hydrolyzed to release the free drug. This is a repeating cycle of enterohepatic recirculation, which allows drugs to remain in the body longer. Glucuronidated drugs that are more resistant to hydrolysis are excreted in the feces. Glucuronidation occurs in the enterohepatic circulation and not in the renal circulation. PTS: 1 DIF: Cognitive Level: Comprehension REF: p. 37 TOP: Nursing Process: Planning MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 10. A patient is receiving intravenous gentamicin. A serum drug test reveals toxic levels. The dosing is correct, and this medication has been tolerated by this patient in the past. Which could be a probable cause of the test result? a. A loading dose was not given. b. The drug was not completely dissolved in the IV solution. c. The patient is taking another medication that binds to serum albumin. d. The medication is being given at a frequency that is longer than its half-life. ANS: C Gentamicin binds to albumin, but only weakly, and in the presence of another drug that binds to albumin, it can rise to toxic levels in blood serum. A loading dose increases the initial amount of a drug and is used to bring drug levels to the desired plateau more quickly. A drug that is not completely dissolved carries a risk of causing embolism. A drug given at a frequency longer than the drug half-life will likely be at subtherapeutic levels and not at toxic levels. PTS: 1 DIF: Cognitive Level: Analysis REF: p. 34 TOP: Nursing Process: Evaluation MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential 11. The nurse is caring for a child who has ingested a toxic amount of aspirin. The provider orders an intravenous drug that will increase pH in the blood and urine. The nurse understands that this effect is necessary to: a. decrease the gastric absorption of aspirin. b. decrease the lipid solubility of aspirin. c. increase the serum protein binding of aspirin. d. increase the urinary excretion of aspirin. ANS: D The phenomenon of pH-dependent ionization can be used to accelerate renal excretion of drugs. When children have been exposed to toxic amounts of aspirin, they can be treated, in part, by giving an agent that elevates urinary pH, leading to less passive reabsorption of the now ionized molecules of aspirin and, hence, more excretion. Elevating the pH of the blood and urine does not affect absorption in the stomach. Ionization of aspirin does not affect lipid solubility or protein binding. PTS: 1 DIF: Cognitive Level: Analysis REF: pp. 25-26 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential 12. A patient is taking a drug that does not bind to albumin. Which aspect of renal drug excretion is affected by this characteristic? a. Active tubular secretion b. Glomerular filtration c. Passive tubular reabsorption d. pH-dependent ionization ANS: B As blood flows through the glomerular capillaries, fluids and small molecules are forced through the pores of the capillary wall. Large molecules, such as drugs bound to albumin, remain behind in the blood. Active tubular secretion requires active transport systems to pump molecules from one side of the membrane to another. Passive tubular reabsorption allows substances in high concentrations in the tubule to be reabsorbed into the blood, and lipid-soluble drugs readily cross this membrane by passive reabsorption. pH-dependent ionization affects drugs that ionize in either acid or alkaline environments. PTS: 1 DIF: Cognitive Level: Analysis REF: p. 37 TOP: Nursing Process: Evaluation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies MULTIPLE RESPONSE 1. When administering medications to infants, it is important to remember which of the following? (Select all that apply.) a. Breast-feeding infants are more likely to develop toxicity when given lipid-soluble drugs. b. Immaturity of renal function in infancy causes infants to excrete drugs less efficiently. c. Infants have immature livers, which slows drug metabolism. d. Infants are more sensitive to medications that act on the central nervous system (CNS). e. Oral medications are contraindicated in infants, because PO administration requires a cooperative patient. ANS: B, C, D Immature renal function causes infants to excrete drugs more slowly, and infants are at risk for toxicity until renal function is well developed. Infants’ livers are not completely developed, and they are less able to metabolize drugs efficiently. Because the blood-brain barrier is not well developed in infants, caution must be used when administering CNS drugs. Lipid-soluble drugs may be excreted in breast milk if the mother is taking them, but breast-feeding does not affect medications given directly to the infant. Oral medications may be given safely to infants as long as they are awake and can swallow the drug. PTS: 1 DIF: Cognitive Level: Comprehension REF: pp. 32-33 TOP: Nursing Process: Assessment MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential