The active ingredient in PEPCIDŽ (famotidine) is a histamine H2-receptor antagonist. Famotidine is N'(aminosulfonyl)-3-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]propanimidamide. The empirical formula of famotidine is C8H15N7O2S3 and its molecular weight is 337.43. Its structural formula is:

The active ingredient in PEPCID* (famotidine) Injection Premixed and PEPCID (famotidine) Injection is a histamine H2-receptor antagonist. Famotidine is N'-(aminosulfonyl)-3-[[[2-[(diaminomethylene)amino]-4- thiazolyl]methyl]thio]propanimidamide. The empirical formula of famotidine is C8H15N7O2S3 and its molecular weight is 337.43. Its structural formula is: