Question

Which class of drugs has these common structural features?

(a) 1^st generation antihistamines

(b) 2^nd generation antihistamines

(c) 3^rd generation antihistamines

(d) 4^th generation antihistamines

I have been asked this question in semester exam.

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

Answer 1

Right choice is (a) 1^st generation antihistamines

To elaborate: 1^st generation antihistamines has 2 aromatic rings, connected to a central carbon, nitrogen, or oxygen. Spacer between central atom and the amine, usually 2-3 carbons in length. (Can be linear, ring, branched, saturated or unsaturated). The amine is substituted with small alkyl groups. Chirality at X and having the rings in different planes increases potency of the drug.