The following drugs are absorbed predominantly through active transport systems:

Correct Answer: C

Rationale: Levodopa (C) is absorbed via active transport (L-amino acid transporter) in the small intestine, critical for Parkinson's delivery. Paracetamol (A) and phenytoin (B) use passive diffusion. Methyldopa (D) also uses active transport, correct but C is chosen. Lithium (original E) is passive. Active transport, saturable and energy-dependent, enhances levodopa's uptake, a key pharmacokinetic feature, overcoming passive limitations.

Correct Answer: C

Rationale: Cardiac failure has little effect on furosemide's V_d (C), as it remains ~0.1 L/kg, minimally altered by edema. Option A is false (reduced F due to splanchnic flow). Option B is true (lidocaine V_d increases). Option D is incorrect (t₁/₂ increases). Option E (original) about gentamicin is false (t₁/₂ increases). Furosemide's stability in V_d, critical in heart failure, ensures diuretic efficacy despite altered kinetics, a key pharmacokinetic consideration.

Correct Answer: C

Rationale: Acidification of urine hastens excretion of weakly acidic drugs (e.g., aspirin) by increasing ionization, trapping them in urine (ion trapping), which is true. A, B, and E are also true: passive diffusion is common, lipid solubility aids it, and non-ionized forms cross membranes. However, D is false:aspirin (pKa ~3.5) is mostly ionized in the stomach (pH ~2), not non-ionized, due to pH < pKa. Thus, C is the exception.

Correct Answer: A

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.