A 65-year-old female is prescribed hydrochlorothiazide for hypertension. The primary mechanism of action of hydrochlorothiazide is:

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: 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.

Correct Answer: A

Rationale: The correct answer is A: Relaxation of the detrusor muscle. Diphenhydramine, an anticholinergic drug, causes relaxation of the detrusor muscle, leading to urinary retention. In benign prostatic hyperplasia, the enlarged prostate already causes obstruction, exacerbating the urinary retention. Therefore, the relaxation of the detrusor muscle due to diphenhydramine worsens the situation by further impairing bladder emptying. Explanation for other choices: B: Constriction of the bladder external sphincter - This would lead to urinary retention, not relieve it. C: Constriction of the prostate capsule - Constriction of the prostate capsule would not relieve urinary retention in benign prostatic hyperplasia. D: Relaxation of the bladder internal sphincter - Relaxation of the bladder internal sphincter would promote bladder emptying, which is opposite to the clinical presentation of urinary retention in this case.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.