A46-year-old woman recently diagnosed with classic migraine had a headache attack at least once a week. Ergotamine was prescribed to prevent the impending attacks. Which of the following actions most likely contributed to the therapeutic effect of the drug in the patient's disorder?

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: 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.

Correct Answer: C

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

Correct Answer: C

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