Pharmacology · Pharmacokinetics and Pharmacodynamics

A drug is administered as a 500 mg IV bolus and achieves an initial plasma concentration of 10 mg/L. Calculate the volume of distribution.

A 50 L ✓
B 5 L
C 25 L
D 100 L

Correct answer: A. 50 L

Explanation

Vd = Dose / C0 = 500 mg / 10 mg/L = 50 L. A Vd of 50 L exceeds total body water (~42 L), indicating significant tissue distribution beyond plasma. Drugs with Vd < 5 L are largely confined to plasma; Vd 5–15 L suggests extracellular distribution; Vd > 40 L indicates extensive tissue binding.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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