Chapter 5 Pharmacodynamics

Chapter 05: Pharmacodynamics Test Bank MULTIPLE CHOICE A patient is receiving digoxin twice daily. When assessing the patient before giving a dose, the nursecounts a pulse of 60 beats per minute and learns that the patient is experiencing nausea. The nurseconsults a drug manual and verifies that the ordered dose is correct. What should the nurse do? a. Contact the prescriber to report the symptoms. b. Delay the dose so the drug can clear from receptor sites. c. Give the medication as ordered, because the dose is correct. d. Request an antinausea medication from the prescriber. ANS: A The symptoms indicate toxicity, and even though the dose is safe and effective in most cases, an individual patient may have toxic effects with a standard dose. The nurse should contact the prescriber to discuss the next steps. Delaying a dose without a change in order is not within the scope of practice for a nurse. The nurse should not give a dose of a medication when toxicity is suspected, because additional drug will compound the symptoms. Antiemetics are useful for counteracting drug side effects, but they should not be used when the patient’s symptoms indicate toxicity. PTS: 1 DIF: Cognitive Level: Application REF: pp. 51-52 TOP: Nursing Process: Evaluation MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential 2. A patient reports becoming “immune” to a medication because it no longer works to alleviate symptoms. The nurse recognizes that this decreased effectiveness is likely caused by: a. antagonists produced by the body that compete with the drug for receptor sites. b. decreased selectivity of receptor sites, resulting in a variety of effects. c. desensitization of receptor sites by continual exposure to the drug. d. synthesis of more receptor sites in response to the medication. ANS: C Continual exposure to an agonist would cause the cell to become less responsive or desensitized. The body does not produce antagonists as a response to a medication. Receptor site selectivity is determined by physiologic factors and not by the substances that bind to them. Medications do not cause more receptors to be produced. PTS: 1 DIF: Cognitive Level: Analysis REF: p. 51 TOP: Nursing Process: Diagnosis MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 3. A patient has been receiving an antibiotic with a small therapeutic index for 10 days. Upon assessment, the nurse notes an increase in the drug’s side effects. What would be the nurse’s priority action? a. Call the prescriber and have the antibiotic changed. b. Suspect an allergic reaction and administer a PRN antihistamine. c. Ask the prescriber to order a plasma drug level test. d. Set up oxygen and obtain an order for an antagonist. ANS: C A narrow therapeutic index indicates that a drug is relatively unsafe and should be monitored closely. The nurse should have a blood level drawn to confirm suspicions of toxicity. The nurse would not have the antibiotic changed, because there is no cause at this time. The patient is unlikely to be experiencing an allergic reaction, because the antibiotic has been in the system for 10 days. The patient shows no signs of anaphylaxis, so oxygen and an antagonist are not indicated. PTS: 1 DIF: Cognitive Level: Application REF: p. 53 TOP: Nursing Process: Evaluation MSC: NCLEX Client Needs Category: Physiologic Integrity: Reduction of Risk Potential 4. A patient who is taking morphine for pain asks the nurse how a pain medication can also cause constipation. What does the nurse know about morphine? a. It binds to different types of receptors in the body. b. It can cause constipation in toxic doses. c. It causes only one type of response, and the constipation is coincidental. d. It is selective to receptors that regulate more than one body process. ANS: D Morphine is a medication that is selective to receptor type that regulates more than one process. Because it is selective to receptor type, it does not bind to different types of receptors. Constipation is a normal side effect and is not significant for toxicity. PTS: 1 DIF: Cognitive Level: Analysis REF: pp. 48-49 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 5. What occurs when a drug binds to a receptor in the body? a. It alters the receptor to become nonresponsive to its usual endogenous molecules. b. It increases or decreases the activity of that receptor. c. It gives the receptor a new function. d. It prevents the action of the receptor by altering its response to chemical mediators. ANS: B When a drug binds to a receptor, it mimics or blocks the actions of the usual endogenous regulatory molecules, either increasing or decreasing the rate of the physiologic activity normally controlled by that receptor. It does not alter the activity of the receptor and does not give the receptor a new function. PTS: 1 DIF: Cognitive Level: Analysis REF: pp. 46-47 TOP: Nursing Process: Assessment MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 6. The nurse administers naloxone [Narcan] to a patient who has received a toxic dose of morphine sulfate. The nurse understands that the naloxone is effective because of which action? a. Countering the effects of morphine sulfate by agonist actions b. Increasing the excretion of morphine sulfate by altering serum pH c. Preventing activation of opioid receptors through antagonist actions d. Regulating the sensitivity of opioid receptors by neurochemical alterations ANS: C Naloxone acts by blocking the action of opioids at opioid receptors. An opioid agonist would increase the effects of morphine. Naloxone does not affect serum pH or excretion of opioids. Naloxone does not alter the sensitivity of opioid receptors. PTS: 1 DIF: Cognitive Level: Analysis REF: pp. 48-49 TOP: Nursing Process: Implementation MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies MULTIPLE RESPONSE 1. Two nurses are discussing theories of drug-receptor interaction. Which statements are true regarding the affinity of a drug and its receptor? (Select all that apply.) a. Affinity and intrinsic activity are dependent properties. b. Affinity refers to the strength of the attraction between a drug and its receptor. c. Drugs with high affinity are strongly attracted to their receptors. d. Drugs with low affinity are strongly attracted to their receptors. e. The affinity of a drug for its receptors is reflected in its potency. ANS: B, C, E Affinity refers to the strength of the attraction between a drug and its receptor. Drugs with high affinity are strongly attracted to their receptors, and the affinity of a drug and its receptors is reflected in its potency. Affinity and intrinsic activity are independent properties. Drugs with low affinity are weakly attracted to their receptors. PTS: 1 DIF: Cognitive Level: Comprehension REF: pp. 48-49 TOP: Nursing Process: Diagnosis MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies 2. Which drugs will not be affected by interpatient variability? (Select all that apply.) a. Antiseptics applied to the skin to slow bacterial growth b. Antacids to help with the discomfort of heartburn c. Broad-spectrum antibiotics that are effective against many organisms d. Chelating agents that remove metal compounds from the body e. Topical analgesics used to treat localized pain ANS: A, B, D Antiseptics, antacids, and chelating agents are all receptorless drugs that do not depend on the body’s processes for effects; these agents react with other molecules. Broad-spectrum antibiotics and topical analgesics bind with receptors to produce desired effects, and these processes can be influenced by individual patient variables. PTS: 1 DIF: Cognitive Level: Comprehension REF: p. 51 TOP: Nursing Process: Diagnosis MSC: NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies