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Prevacid (Lansoprazole) Against Gastric Acid

Prevacid (Lansoprazole) Against Gastric AcidLansoprazole (Prevacid / Takeda-Abbott Pharmaceutical) has received marketing approval for short-term treatment of active duodenal ulcers and esophagitis and for long-term treatment of gastric hypersecretory conditions such as Zollinger-Ellison syndrome. The drug is the second proton-pump inhibitor, following omeprazole (Prilosec / Astra Merck), approved in 1989. Like omeprazole, lansoprazole inhibits gastric acid production by the parietal cells of the stomach. It relieves symptoms and promotes healing of ulcers and esophageal erosion.

Prevacid is administered as capsules containing enteric-coated granules of lansoprazole. It is absorbed rapidly, reaching peak plasma concentrations within about 1.7 hours. Bioavailability exceeds 80%. In healthy subjects, mean plasma half-life is 1.5 hours. Food diminishes peak plasma concentration and the area under the concentration-time curve (AUC). Lansoprazole is 97% bound to plasma proteins. The drug undergoes extensive hepatic metabolism. Despite a short plasma half-life, the inhibitory effect of the drug on gastric acid secretion lasts about 24 hours.

In a clinical trial involving 284 patients, healing rates after 2 weeks for duodenal ulcers were 42.4% with 15 mg lansoprazole/day, 35.6% with 30 mg/day, and 39.1% with 60 mg/day, compared with 11.3% for placebo. After 4 weeks, the respective healing rates with lansoprazole were 89.4%, 91.7%, and 89.9%, compared with 46.1% for placebo. In a second trial with 280 patients, the healing rates at 4 weeks with lansoprazole were 92.3% with 15 mg/day and 80.3% with 30 mg/day, compared with 70.5% for 300 mg ranitidine and 47.5% for placebo. (Lanza F et al. Am J Gastroenterol. 1994; 89: 1191-1200.)

In a trial of lansoprazole in 269 patients with erosive esophagitis, the healing rate at 8 weeks ranged from 90.9% with 15 mg/day to 95.4% with 30 mg/day, compared with 52.5% for placebo. In another trial the healing rate was 92.1% with 30 mg/day, compared with 69.9% for ranitidine 150 mg twice a day. Lansoprazole has been found to promote healing in more than 80% of patients in whom initial treatment with H2-receptor antagonists had failed.

Lansoprazole has been well-tolerated in clinical use. Adverse events occurring in more than 1% of patients have included abdominal pain (1.8%), diarrhea (3.6%), and nausea (1.4%). Lansoprazole does not interact with other drugs, but coadministration with sucralfate can slow and reduce absorption of lansoprazole.

Prevacid is supplied as 15-mg pink-and-green capsules and 30-mg pink-and-black capsules. The recommended adult dosage for duodenal ulcers is 15 mg daily before eating, for 4 weeks. The recommended dosage for erosive esophagitis is 30 mg daily before eating, for up to 8 weeks. If healing does not occur, or if erosive esophagitis recurs, an additional 8 weeks of treatment may be helpful. For hypersecretory conditions, an initial dosage of 60 mg a day is recommended, with adjustments to suit individual patient needs. Doses greater than 120 mg a day should be given in divided doses.

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