Drug Groups

approved; investigational

Description

Lansoprazole is a proton pump inhibitor which prevents the stomach from producing acid. It is manufactured by TAP Pharmaceutical Products. Lansoprazole has been marketed for many years and is one of several PPI's available.

Indication

For the treatment of acid-reflux disorders (GERD), peptic ulcer disease, H. pylori eradication, and prevention of gastroinetestinal bleeds with NSAID use.

Pharmacology

Lansoprazole, an acid proton-pump inhibitor similar to omeprazole, is used as an untiulcer drug in the treatment and maintenance of healing of duodenal or gastric ulcers, erosive and reflux esophagitis, NSAID-induced ulcer, Zollinger-Ellison syndrome, and Barrett's esophagus. Lansoprozole is active against Helicobacter pylori. The plasma elimination half-life of lansoprazole does not reflect its duration of suppression of gastric acid secretion. Thus, the plasma elimination half-life is less than two hours, while the acid inhibitory effect lasts more than 24 hours.

Toxicity

Symptoms of overdose include abdominal pain, nausea and diarrhea.

Affected Organisms

Biotransformation

Hepatic. Two metabolites have been identified in measurable quantities in plasma (the hydroxylated sulfinyl and sulfone derivatives of lansoprazole). These metabolites have very little or no antisecretory activity. Lansoprazole is thought to be transformed into two active species which inhibit acid secretion by (H⁺,K⁺)-ATPase within the parietal cell canaliculus, but are not present in the systemic circulation.

Absorption

The absorption of lansoprazole is rapid, with mean C_max occurring approximately 1.7 hours after oral dosing, and relatively complete with absolute bioavailability over 80%.

Half Life

1.5 (± 1.0) hours

Protein Binding

97%

Elimination

Following single-dose oral administration of PREVACID, virtually no unchanged lansoprazole was excreted in the urine. In one study, after a single oral dose of 14C-lansoprazole, approximately one-third of the administered radiation was excreted in the urine and two-thirds was recovered in the feces. This implies a significant biliary excretion of the lansoprazole metabolites.

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