Which of the following is an adverse effect commonly associated with opioid analgesics?

Correct Answer: B

Rationale: The correct answer is B: Sedation. Opioid analgesics commonly cause sedation due to their central nervous system depressant effects. They act on opioid receptors in the brain, leading to drowsiness and sedation. Diarrhea (A) is more commonly associated with opioid-induced constipation. Hypertension (C) is not a common adverse effect of opioids; they are more likely to cause hypotension. Hypokalemia (D) is not directly linked to opioid use. Sedation is the most prevalent adverse effect of opioids, making it the correct choice here.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting sodium reabsorption in the kidneys. Hydrochlorothiazide is a thiazide diuretic that works by inhibiting the sodium-chloride symporter in the distal convoluted tubule of the kidneys, leading to increased excretion of sodium and water. This results in decreased blood volume and subsequently lowers blood pressure. Explanation of incorrect choices: B: Increasing sodium retention in the kidneys - This is the opposite effect of what hydrochlorothiazide does. C: Blocking calcium channels in the blood vessels - This is the mechanism of action for calcium channel blockers, not thiazide diuretics. D: Inhibiting ACE in the lungs - This is the mechanism of action for ACE inhibitors, not thiazide diuretics.

Correct Answer: B

Rationale: The correct answer is B: Non-competitive antagonist. This is because a non-competitive antagonist binds irreversibly to a different site on the receptor compared to the agonist (norepinephrine in this case) and prevents its activation, leading to a decrease in response. In the graph, the presence of Drug X shifts the concentration-response curve of norepinephrine downward without affecting the maximum response, indicating non-competitive antagonism. A: Silent antagonists do not affect the agonist's binding or activity on the receptor. C: Competitive antagonists compete with the agonist for the same binding site on the receptor, affecting potency but not the maximum response. D: Chemical antagonist is a broad term for any antagonist that binds to the agonist or receptor to prevent activation but does not specifically describe the mechanism like non-competitive antagonism does.

Correct Answer: A

Rationale: The correct answer is A: Constriction of cerebral vessels. Ergotamine is known to constrict cerebral blood vessels, which helps in preventing migraine attacks by reducing the dilation of these vessels that occurs during a migraine. This constriction helps to decrease the pulsatile headache pain associated with migraines. B: Extravasation of plasma into perivascular space is incorrect because it does not contribute to the therapeutic effect of ergotamine in treating migraines. C: Prostaglandin release from vascular endothelium is incorrect because ergotamine works by vasoconstriction rather than affecting prostaglandin release. D: Platelet aggregation in the cerebral vascular bed is incorrect because ergotamine does not target platelet aggregation as a mechanism of action in treating migraines.

Correct Answer: D

Rationale: The correct answer is D: Nausea and vomiting. Ergotamine is known to commonly cause gastrointestinal side effects such as nausea and vomiting. This is due to its vasoconstrictive effects on blood vessels in the gastrointestinal tract. Visual hallucinations (choice A) are more commonly associated with LSD use, not ergotamine. Postural hypotension (choice B) is more likely to occur with alpha-adrenergic blockers, not ergotamine. Facial flushing (choice C) is more commonly seen with niacin therapy, not ergotamine. Therefore, in this case, the most likely adverse effect for the patient taking ergotamine would be nausea and vomiting due to its vasoconstrictive effects on the gastrointestinal tract.