Prazosin is used in a patient with benign prostatic hyperplasia. Unlike doxazosin, prazosin requires more frequent dosing because it lacks which pharmacokinetic property?
- A High first-pass metabolism requiring dose adjustment
- B Long elimination half-life due to extensive protein binding ✓
- C Sustained-release formulation enabling once-daily dosing
- D Glucuronide conjugation extending its duration of action
Correct answer: B. Long elimination half-life due to extensive protein binding
Explanation
Doxazosin has a much longer elimination half-life (~22 hours) compared to prazosin (~2–3 hours), largely due to doxazosin's greater lipophilicity and higher plasma protein binding, allowing once-daily dosing. Prazosin's shorter half-life requires 2–3 times daily administration. Both undergo first-pass hepatic metabolism, but this does not account for the dosing frequency difference.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.