Question

Which drugs cannot pass the Capillary endothelial Barrier?

(a) Molecular size less than 600 Dalton

(b) Drugs bound to blood components

(c) Drugs bound to a chemical moiety

(d) All drugs can pass

This question was addressed to me during an interview.

My doubt is from Drug Distribution topic in division Distribution of Drugs of Drug Biotechnology

Answer 1

Correct answer is (b) Drugs bound to blood components

The explanation: All drugs ionized, unionized but with a molecular size less than 600 Dalton can pass through the capillary endothelial into the interstitial fluid. Only drugs bound to the blood components are restricted because the molecular size becomes large.