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?
It binds to different types of receptors in the body
It can cause constipation in toxic doses
It is selective to receptors that regulate more than one body process
It causes only one type of response, and the constipation is coincidental
The Correct Answer is A
Choice A reason: Morphine, an opioid, binds to mu, kappa, and delta receptors in the brain, spinal cord, and gastrointestinal tract. Mu receptors in the gut slow peristalsis, causing constipation, while central receptors relieve pain. This multi-receptor binding explains both therapeutic and side effects, making this the correct choice.
Choice B reason: Constipation from morphine occurs at therapeutic, not just toxic, doses due to mu receptor activation in the gastrointestinal tract, which reduces motility. Toxicity may worsen side effects, but constipation is a common effect at standard doses, making this choice inaccurate for explaining morphine’s mechanism.
Choice C reason: Morphine’s receptors (e.g., mu) regulate multiple processes, but the drug itself isn’t selective to multifunctional receptors. It binds broadly to opioid receptors, causing both analgesia and side effects like constipation. This choice misrepresents morphine’s non-selective binding, making it less accurate than choice A.
Choice D reason: Morphine’s effects, including analgesia and constipation, result from specific receptor binding, not coincidental processes. It activates opioid receptors in the brain for pain relief and in the gut for reduced motility. This choice incorrectly suggests constipation is unrelated to morphine’s pharmacological action, making it incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason: Furosemide, a loop diuretic, promotes potassium excretion, risking hypokalemia. The patient’s potassium level (3.1 mEq/L) is below normal (3.5-5.0 mEq/L), indicating hypokalemia, which can cause arrhythmias. Administering Lasix without addressing this could worsen the electrolyte imbalance, making this choice unsafe and incorrect.
Choice B reason: Oxygen administration addresses respiratory issues, not electrolyte imbalances like hypokalemia (3.1 mEq/L) caused by furosemide. There’s no indication of hypoxia in the lab results or scenario. This action doesn’t correct the potassium deficit or prevent further depletion, making it irrelevant and incorrect.
Choice C reason: Furosemide exacerbates hypokalemia (patient’s potassium: 3.1 mEq/L), risking cardiac arrhythmias or muscle weakness. Holding the dose prevents further potassium loss, and notifying the physician allows for correction (e.g., potassium supplements) and reassessment of therapy, making this the safest and most appropriate action.
Choice D reason: A 24-hour urine collection assesses renal function or output but doesn’t address the immediate concern of hypokalemia (3.1 mEq/L) caused by furosemide. This test is irrelevant to correcting the electrolyte imbalance or preventing further depletion, making it an inappropriate action in this scenario.
Correct Answer is C
Explanation
Choice A reason: Pentazocine is less effective for severe, chronic pain and has mixed agonist-antagonist effects. Fentanyl is stronger for opioid-tolerant patients, so this is incorrect.
Choice B reason: Hydrocodone is weaker than oxycodone and inadequate for severe, resistant pain. Fentanyl’s potency suits chronic cancer pain, so this is incorrect.
Choice C reason: Fentanyl transdermal is potent, long-acting, and ideal for severe, chronic cancer pain in opioid-tolerant patients. It’s appropriate here, making it the correct choice.
Choice D reason: Meperidine is not recommended for chronic pain due to neurotoxic metabolites. Fentanyl is safer and more effective, so this is incorrect.
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