Question

Famotidine contains:

• A. Thiazole ring
• B. Imidazole ring
• C. Pyrrole ring
• D. Furane ring

Answer 1

The Correct Option is A

Understanding the Question:
The question asks which heterocyclic ring is part of famotidine's chemical structure.

Key Concept:
The H2-receptor antagonists are usually remembered by the ring each one carries: cimetidine has an imidazole ring, ranitidine has a furan ring, and famotidine has a thiazole ring fused to a guanidine group.

Checking Each Option:
Imidazole is cimetidine's signature ring, not famotidine's, so this option names the wrong drug in the family.
Pyrrole rings do not appear in any of the standard H2 blockers used in practice.
Furane, the furan ring, belongs to ranitidine's structure rather than famotidine's.
Thiazole is the ring actually present in famotidine, forming the guanidinothiazole core that is joined through a side chain to the drug's sulfamoyl-amidine end.

Final Answer:
Famotidine contains a thiazole ring.