Androgen is secreted by

Correct Answer: C

Rationale: Androgens, primarily testosterone, are secreted by the testes' Leydig cells, stimulated by luteinizing hormone (LH) from the pituitary, making the testes the direct source. Follicle-stimulating hormone (FSH) from the pituitary regulates sperm production, not androgen secretion. Gonadotropin-releasing hormone (GnRH) from the hypothalamus triggers pituitary LH and FSH release, indirectly influencing androgen production, not secreting it. The pituitary releases LH and FSH, not androgens itself. The testes' role as the endocrine organ producing androgens is clear, driven by LH, and is fundamental to male reproductive and secondary sexual characteristics, setting it apart from regulatory hormones in the hypothalamic-pituitary-gonadal axis.

Correct Answer: B

Rationale: Aging reduces liver/renal clearance, raising plasma levels (e.g., digoxin), heightening response and toxicity risk, per pharmacokinetics. Body water drops, concentrating drugs, not diluting. Doses decrease, not increase-metabolism slows. Absorption may slow, but pH rises, not falls. Plasma increase drives effects, key in elders.

Correct Answer: B

Rationale: Calcium absorbs best with food-e.g., fat aids uptake, per pharmacokinetics-unlike empty stomach. Insomnia isn't typical-constipation is. Vitamin D matters-enhances absorption. Meal timing optimizes use, per guidance.

Correct Answer: D

Rationale: Procainamide can induce a lupus-like syndrome . Symptoms (malaise, fever, nausea) and malar rash mimic SLE, a known side effect due to drug-induced autoantibodies. Contact dermatitis lacks systemic features. Sun reaction or discoid lupus don't fit the drug link. Collagen disease (E) is vague. This reversible syndrome resolves with discontinuation, distinguishing it from primary lupus.

Correct Answer: A

Rationale: Azathioprine, metabolized by xanthine oxidase, interacts with allopurinol , which inhibits this enzyme. This raises azathioprine levels, risking toxicity. Colchicine , Indomethacin , and Prednisolone don't affect this pathway. Probenecid (E) is safe. Avoiding allopurinol prevents immunosuppression complications.