A drug is administered in a dose of 200 mg and its plasma concentration is 40 micro gram/ml. What is the volume of distribution -

Ans. is 'a' i.e., 5 litre The volume of distribution = Dose administered iv ------------------ Plasma concentration o So, to contain all the administered drug (200 mg), the required fluid will be 200 mg -------- 40 m/ml = 200 x 10-3 gm -------------- 40 x 10-6 gm/ml = 5 x 103 ml = 5000 ml (5L)