Question

Which second generation antihistaminic does NOT produce an active metabolite?

• A. Loratadine
• B. Terfenadine
• C. Cetirizine
• D. None

Hint:

It is the active metabolite of hydroxyzine and is not converted further.

Answer 1

The Correct Option is C

Step 1: Many second generation antihistaminics are actually prodrugs or are converted in the body to an active form. Terfenadine is metabolised to fexofenadine, and loratadine is metabolised to desloratadine. Both of these metabolites are pharmacologically active.

Step 2: Cetirizine is itself the active carboxylic acid metabolite of hydroxyzine. It is not further converted to an active product, so it does not generate a new active metabolite. This makes option (c) correct.

Step 3: Among the second generation agents, all are metabolised to active products EXCEPT cetirizine and mizolastine. Loratadine (a) and terfenadine (b) both have active metabolites, so they are wrong, and option (d) None is also wrong because cetirizine fits.