Prevacid

[Lansoprazole]

Hepatic Insufficiency

In patients with various degrees of chronic hepatic disease, the mean plasma half-life of the drug was prolonged from 1. 5 hours to 3. 2-7. 2 hours. An increase in mean AUC of up to 500% was observed at steady state in hepatically-impaired patients compared to healthy subjects. Dose reduction in patients with severe hepatic disease should be considered.

PREVACID

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Race

The pooled mean pharmacokinetic parameters of lansoprazole from twelve U. S. Phase 1 studies (N= 513) were compared to the mean pharmacokinetic parameters from two Asian studies (N= 20). The mean AUCs of lansoprazole in Asian subjects were approximately twice those seen in pooled U. S. data; however, the inter-individual variability was high. The Cmax values were comparable.

Pharmacodynamics

Mechanism of Action Lansoprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or histamine H2-receptor antagonist properties, but that suppress gastric acid secretion by specific inhibition of the (H + ,K + )-ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid (proton) pump within the parietal cell, lansoprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated gastric acid secretion irrespective of the stimulus.

Antisecretory Activity

After oral administration, lansoprazole was shown to significantly decrease the basal acid output and significantly increase the mean gastric pH and percent of time the gastric pH was >3 and >4. Lansoprazole also significantly reduced meal-stimulated gastric acid output and secretion volume, as well as pentagastrin-stimulated acid output. In patients with hypersecretion of acid, lansoprazole significantly reduced basal and pentagastrin-stimulated gastric acid secretion.

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