Question

Another name of diphenhydramine is :

• A. Benzhydramine
• B. Dimenhydrinate
• C. Mecloprodin
• D. Neohetramine

Hint:

Diphenhydramine belongs to the ethanolamine ether class of antihistamines. The presence of two phenyl rings linked to a single carbon forms the benzhydryl group, which gives the drug its alternative chemical name: Benzhydramine.

Answer 1

The Correct Option is A

Concept: Diphenhydramine is a widely used first-generation \(\text{H}_1\)-antihistamine that also possesses significant central sedative and anticholinergic properties. In chemical nomenclature, drugs often have synonyms based directly on their core structural components. Analyzing the structural formula of diphenhydramine reveals its chemical synonyms.

Step 1: Dissecting the Chemical Structure of Diphenhydramine.
The systematic chemical name of diphenhydramine is \(2\)-(diphenylmethoxy)-\(N,N\)-dimethylethanamine. Its chemical structure consists of:
• Two benzene rings attached to a central carbon atom. This specific radical, \((\text{C}_6\text{H}_5)_2\text{CH}-\), is known as a benzhydryl core or moiety.
• An ether linkage connecting this benzhydryl core to a \(2\)-(dimethylamino)ethyl side chain. Because it consists of a benzhydryl core attached to an amino-ether framework, it is chemically known as Benzhydramine.

Step 2: Evaluating the other options.

• Option (B) Dimenhydrinate: Dimenhydrinate is not an alternative chemical name for pure diphenhydramine. Rather, it is a combination salt consisting of diphenhydramine paired with a chlorinated xanthine derivative, 8-chlorotheophylline, used to mitigate motion sickness. It contains only about \(53\%\) to \(55\%\) of pure diphenhydramine by weight.
• Option (C) Mecloprodin: This represents a completely different chemical compound belonging to a separate structural class.
• Option (D) Neohetramine: Neohetramine is an old trade name for Thonzylamine, an antihistamine belonging to the ethylenediamine structural class rather than the ethanolamine ether class. Conclusion: Diphenhydramine is chemically synonymous with Benzhydramine due to its foundational benzhydryl structural backbone.