Misoprostol is rapidly absorbed after oral administration and then is rapidly and extensively de-esterified to form misoprostol acid, the principal and active metabolite of the drug. Some of this conversion may occur in the parietal cells. A single dose inhibits acid production within 30 minutes; the therapeutic effect peaks at 60—90 minutes and lasts for up to 3 hours. Food and antacids decrease the rate of misoprostol absorption, resulting in delayed and decreased peak plasma concentrations of the active metabolite. The free acid is excreted mainly in the urine, with an elimination t/2 of about 20-40 minutes.
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