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:
Synthesis of more receptor sites in response to the medication
Decreased selectivity of receptor sites, resulting in a variety of effects
Desensitization of receptor sites by continual exposure to the drug
Antagonists produced by the body that compete with the drug for receptor sites
The Correct Answer is C
Choice A reason: Synthesis of more receptor sites (upregulation) typically occurs with receptor antagonists, not agonists, as the body compensates for blocked receptors. This would increase drug sensitivity, not decrease effectiveness. For most medications, continuous exposure leads to desensitization, not receptor proliferation, making this choice incorrect for explaining tolerance.
Choice B reason: Decreased receptor selectivity implies a drug binding to unintended receptors, causing varied effects, not reduced efficacy. Tolerance results from receptor desensitization, not altered selectivity. This mechanism doesn’t explain the patient’s “immunity” to the drug’s therapeutic effects, making this choice scientifically inaccurate for the scenario.
Choice C reason: Desensitization occurs when continuous drug exposure reduces receptor responsiveness, leading to tolerance. For example, opioid receptors downregulate or internalize with prolonged agonist exposure, decreasing drug efficacy. This explains the patient’s perception of “immunity” as the drug’s effect diminishes over time, making this the correct choice.
Choice D reason: The body does not produce antagonists to compete with drugs for receptor sites. Tolerance arises from receptor desensitization or metabolic changes (e.g., enzyme induction), not endogenous antagonist production. This mechanism is not a recognized pharmacological process for reduced drug effectiveness, making this choice incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason: Bananas do not interact with acetaminophen. They are a potassium-rich food without impact on acetaminophen metabolism or hepatotoxicity. Acetaminophen’s primary risk is liver damage, especially with alcohol or overdose, making bananas irrelevant to its safe use, so this choice is incorrect.
Choice B reason: Leafy green foods, rich in vitamin K, may affect anticoagulants like warfarin but have no significant interaction with acetaminophen. They don’t influence acetaminophen’s metabolism or liver toxicity risk, making this choice irrelevant for patient instructions regarding safe acetaminophen use post-surgery.
Choice C reason: Alcohol increases acetaminophen’s hepatotoxicity by inducing CYP2E1 enzymes, which metabolize acetaminophen into toxic NAPQI, depleting liver glutathione and causing damage. Avoiding alcohol prevents severe liver injury, especially post-surgery when liver function is critical, making this the correct choice for patient safety.
Choice D reason: Dairy products do not interact with acetaminophen’s metabolism or toxicity. They may slow gastric emptying, slightly delaying absorption, but this isn’t a significant concern. Acetaminophen’s primary risk is hepatotoxicity, unaffected by dairy, making this choice incorrect for discharge instructions.
Correct Answer is ["B","C","E"]
Explanation
Choice A reason: Long-term proton pump inhibitor (PPI) use has a weak, controversial association with gastric cancer due to hypergastrinemia, but evidence is inconclusive. In older patients, risks like osteoporosis and nutrient deficiencies are more established and immediate concerns, making this choice less consistently worrisome compared to others.
Choice B reason: PPIs reduce gastric acid, impairing calcium absorption, which increases osteoporosis risk in older patients. Chronic use is linked to decreased bone density and higher fracture risk, particularly in the elderly, due to disrupted mineral homeostasis, making this a significant and correct adverse effect to monitor.
Choice C reason: PPIs inhibit acid production, reducing absorption of vitamin B12, magnesium, and iron, leading to deficiencies in older patients. These can cause anemia, neurological issues, or hypomagnesemia, which are particularly concerning in the elderly due to comorbidities, making this a correct and critical adverse effect.
Choice D reason: Headaches are a possible PPI side effect but are less common and less severe in older patients compared to osteoporosis, nutrient deficiencies, or drug interactions. They don’t pose a significant long-term risk or require specific monitoring, making this choice incorrect for major concerns.
Choice E reason: PPIs interact with drugs like clopidogrel, reducing its efficacy by inhibiting CYP2C19, and affect absorption of drugs requiring acidic environments. In older patients with polypharmacy, these interactions increase risks of adverse outcomes, making this a significant and correct concern for PPI use.
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