Question

Which of the following antihistamines contains the -CN group?

• A. Dimetapp
• B. Cimetidine
• C. Terfenadine
• D. Ranitidine

Hint:

Cimetidine is an H\(_2\)-receptor antagonist that contains a cyano (-CN) group, which distinguishes it from other similar drugs like ranitidine.

Answer 1

The Correct Option is B

Step 1: Identifying the -CN Group.
The -CN group (cyano group) is an organic functional group consisting of a carbon triple-bonded to a nitrogen atom. Among the listed antihistamines, cimetidine contains the -CN group. Cimetidine is a H\(_2\)-receptor antagonist used for the treatment of ulcers and gastroesophageal reflux disease (GERD).

Step 2: Analyzing the options.
(A) Dimetapp: Incorrect. Dimetapp does not contain a -CN group. It is primarily used for treating allergies and cold symptoms.
(B) Cimetidine: Correct. Cimetidine contains a -CN group in its chemical structure.
(C) Terfenadine: Incorrect. Terfenadine does not contain a -CN group. It is an antihistamine used for allergic conditions.
(D) Ranitidine: Incorrect. Ranitidine does not contain a -CN group. It is similar to cimetidine but lacks the cyano group.

Step 3: Conclusion.
The antihistamine that contains the -CN group is Cimetidine, corresponding to option (B).