what is the active part of the molecule in famotidine
DRUG DESCRIPTION. The active ingredient in PEPCIDÂ® (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 C 8 H 15 N 7 O 2 S 3 and its molecular weight is 337.43.Its structural formula is:top using famotidine and call your doctor at once if you have a serious side effect such as: 1  easy bruising or bleeding; 2  fast or pounding heartbeat; 3  confusion, hallucinations, seizure; 4  numbness or tingly feeling; or. 5  jaundice (yellowing of the skin or eyes).