A 2,2,2-trifluoroethoxypyridyl derivative of timoprazole that is used in the therapy of stomach ULCERS and zollinger-ellison syndrome. The drug inhibits H(+)-K(+)-EXCHANGING ATPASE which is found in GASTRIC PARIETAL cells. lansoprazole is a racemic mixture of (R)- and (S)-isomers.