Cyanoguanidines

Cimetidine, sold under the brand name Tagamet among others, is a histamine H2 receptor antagonist that inhibits stomach acid production. It is mainly used in the treatment of heartburn and peptic ulcers.

2-Cyanoguanidine is a nitrile derived from guanidine. It is a dimer of cyanamide, from which it can be prepared.