Question

The i.v. bolus dosage is 500mg and the plasma drug concentration is 0.8 mg/ml. What should be the volume of distribution?

(a) 625 mg/ml

(b) 625 l

(c) 625 ml

(d) 0.0016 mg/ml

The question was posed to me in an interview for job.

Enquiry is from One & Two Compartment Open Model topic in chapter Compartment Modelling, Non Linear Pharmacokinetics, Bioavailability and Bioequivalence of Drug Biotechnology

Answer 1

Right choice is (c) 625 ml

Easiest explanation: The apparent volume of distribution Vd is given by Amount of drug in the body (X) / plasma drug concentration (C). Vd is expressed in liters or milliliters. Thus 500/0.8=625.