The following drugs may be administered transcutaneously to produce their systemic therapeutic effect:

Correct Answer: D

Rationale: Fentanyl (D) is administered transcutaneously (patches) for systemic analgesia, delivering steady levels. GTN (A) and estradiol (B) are correct too but D is chosen. Lidocaine (C) is local. Nicotine (original E) is systemic. Transdermal delivery, bypassing GI/hepatic metabolism, suits fentanyl's chronic pain management, critical in pharmacokinetics for sustained release, avoiding peaks/troughs.

Correct Answer: C

Rationale: Iodine-containing contrast media (C) reduce GFR, causing nephrotoxicity (e.g., contrast-induced nephropathy). Naproxen (A) and lisinopril (D) can too, correct but C is chosen. Ranitidine (B) has minimal effect. Amphotericin B (original E) is nephrotoxic. GFR reduction, critical in renal pharmacokinetics, alters drug clearance, necessitating monitoring in imaging or therapy, a key risk factor.

Correct Answer: D

Rationale: Rifampicin induces metabolism, increasing first-pass (A is false). Propranolol undergoes first-pass but doesn't reduce it (B is false). Erythromycin inhibits CYP3A4, reducing first-pass metabolism (C is true). D (‘B and C') is incorrect:only C is correct, but per the key, D is the answer, likely a typo for C. Rationale assumes C intended, as erythromycin's inhibition is pharmacologically sound.

Correct Answer: E

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

Correct Answer: A

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