Antiulcer prostaglandin misoprostol: single and multiple dose pharmacokinetic profile.

Low misoprostol dose (microgram range), extremely low plasma levels (pg range) of misoprostol acid, and the necessity of using a complex, time consuming, and labor intensive RIA method of analysis make it technically difficult to study the pharmacokinetic profile of misoprostol in man. The clinical relevance of the misoprostol pharmacokinetic data should be interpreted with care in view of the combined local and systemic effects of the drug. The studies presented in the present review indicate: Extensive metabolism of misoprostol occurs during and/or prior to gastrointestinal absorption. Several metabolites are formed and no unchanged drug is detected in the plasma or urine. The biologically active metabolite in the plasma is misoprostol acid (SC-30695), a de-esterified derivative of misoprostol. Absorption of misoprostol and/or misoprostol acid is extremely rapid resulting in peak plasma levels of misoprostol acid in less than 15 minutes. Absorption probably occurs in the stomach. The elimination half-life of misoprostol acid is short (less than 30 minutes). No accumulation of misoprostol acid occurs in plasma following a 400 microgram q12h dosing regimen of misoprostol.