Question

Which of the following drugs get distributed to the same extent in both lean and adipose tissue?

(a) Phenytoin

(b) Caffeine

(c) Digoxin

(d) Antibiotics

The question was posed to me during an online interview.

My enquiry is from Pharmacokinetic Principles Applications topic in chapter Applications of Pharmacokinetic Principles, Diuretics, Drug Concentration and Pharmacologic Response of Drug Biotechnology

Answer 1

Right answer is (b) Caffeine

For explanation I would say: Drugs such as caffeine, theophylline, lidocaine and lorazepam gets distributed in same extent in both lean and adipose tissues, the volume of distribution is larger in the obese patient but same when we calculate for per kg total body weight basis, hence dose should be administered n total weight basis. For polar drugs for e.g. antibiotics which distribute in excess body space of obese patients to an extent less than that in lean tissues.