A drug is 98% bound to plasma albumin. It is administered with another drug that displaces it from albumin binding sites. Which pharmacokinetic parameter is most directly affected by this displacement interaction?

• A Total body clearance
• B Elimination half-life
• C Volume of distribution ✓
• D Oral bioavailability

Explanation

Displacement from albumin increases the free (unbound) drug fraction. The unbound drug can distribute more widely into tissues, increasing the volume of distribution. Clearance of a low-extraction drug is affected, but Vd changes most directly. For high-extraction drugs, clearance depends on blood flow, not binding. Half-life depends on both clearance and Vd. Bioavailability is a function of absorption and first-pass metabolism, not protein binding displacement.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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