Lansoprazole-d₄is intended for use as an internal standard for the quantification of lansoprazole by GC- or LC-MS. Lansoprazole is a proton pump inhibitor that inhibits the H⁺/K⁺-ATPase.¹It inhibits K⁺and H⁺accumulation in gastric microsomes in a concentration-dependent manner (IC₅₀s = 6.3 and 7 µM, respectively) and inhibits H⁺/K⁺-ATPase activity by approximately 60% when used at a concentration of 10 µM. Lansoprazole inhibits the H⁺/K⁺-ATPase in parietal cells, thus inhibiting gastric acid secretion and increasing intragastric pH.²It is a substituted benzimidazole that binds covalently to proton pumps, providing complete and prolonged inhibition of acid secretion.^3,4Formulations containing lansoprazole have been used as a proton pump inhibitor and in combination with antibiotics in the treatment ofH. pyloriinfections and duodenal ulcer disease.

1.Nagaya, H., Satoh, H., Kubo, K., et al.Possible mechanism for the inhibition of gastric (H+ + K+)-adenosine triphosphatase by the proton pump inhibitor AG-1749J. Pharmacol. Exp. Ther.248(2)799-805(1989) 2.Schubert, M.L.Pharmacotherapy for acid/peptic disordersYale J. Biol. Med.69(2)197-201(1996) 3.Richardson, P., Hawkey, C.J., and Stack, W.A.Proton pump inhibitors. Pharmacology and rationale for use in gastrointestinal disordersDrugs56(3)307-335(1998) 4.Klotz, U.Pharmacokinetic considerations in the eradication of Helicobacter pyloriClin. Pharmacokinet.38(3)243-270(2000)