The following drugs are effectively administered by the rectal route to produce their systemic effect:

Correct Answer: C

Rationale: Metronidazole (C) is effective rectally for systemic effects (e.g., anaerobic infections), partially avoiding first-pass metabolism. Indometacin (A) is correct too but C is chosen. Sulfasalazine (B) acts locally. Glycerin (D) is local (laxative). Diazepam (original E) is systemic via rectum. Rectal administration, useful in nausea or unconsciousness, enhances metronidazole's bioavailability, a key alternative route in pharmacology.

Correct Answer: D

Rationale: Metformin (D) must be avoided in severe renal failure (GFR <10 mL/min), risking lactic acidosis due to reduced clearance. Prednisolone (A) and amoxicillin (B) are safe with adjustment. Bumetanide (C) is usable. Oxytetracycline (original E) needs caution but not avoidance. Metformin's renal excretion, critical in diabetes, demands strict contraindication, a key safety concern in renal impairment pharmacology.

Correct Answer: B

Rationale: A is false:acetylation is phase II. B is true:theophylline follows zero-order kinetics at high doses with a narrow index. C is false:first-order eliminates a constant fraction, not amount. D is false:zero-order kinetics doesn't reach steady state predictably. B is correct, reflecting theophylline's clinical monitoring needs.

Correct Answer: D

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

Correct Answer: B

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