Which of the following drugs characteristically obeys zero-order kinetics over its entire clinically relevant concentration range?

• A Warfarin
• B Metformin
• C Digoxin
• D Ethanol ✓

Explanation

Ethanol is metabolized mainly by alcohol dehydrogenase, an enzyme with very limited capacity that is saturated at concentrations produced by even small amounts of alcohol, so it is eliminated at a roughly constant rate irrespective of blood level. Phenytoin, the other classic example tested in exams, follows first-order kinetics at low concentrations and becomes zero-order only near therapeutic doses.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.