A proton-pump inhibitor expedition: The case histories of omeprazole and esomeprazole

Thirty years ago, disorders associated with inappropriate levels of gastric acid were a major problem for which treatment options were limited, and approaches to the control of gastric acid secretion were thus the focus of considerable drug discovery efforts. Here, we summarize how one such programme led to the development of the proton-pump inhibitor omeprazole (Losec, Prilosec), a conceptually new drug that proved clinically superior to previous antisecretory drugs in the treatment of acid-related disorders, and which became the world's best-selling drug in the late 1990s. We then describe how the antisecretory and clinical effects were further improved by the development of esomeprazole (Nexium), a single enantiomer of omeprazole, which was launched in 2000.