By 1979, Tagamet was being sold in more than 100 countries and became the top-selling prescription product in the U.S., Canada, and several other countries.
Njegovo odkritje je plod sodelovanja podjetja Smith, Kline and French (SK&F; danes GlaxoSmithKline) ter raziskovalcev Jamesa W. Blacka, C. Robina Ganellina in drugih v projektu iskanja zaviralca histaminskih receptorjev, ki bi zavrl izločanje želodčne kisline.