The pharmacokinetics and different regimens of misoprostol in early first-trimester medical abortion.

Misoprostol is a synthetic prostaglandin E(1) analogue that is commonly used for medical abortion. It can be given orally, vaginally and sublingually. A pharmacokinetic study has shown that sublingual misoprostol has the shortest onset of action, the highest peak concentration and the greatest bioavailability among the three routes of administration. Earlier clinical trials have shown that vaginal misoprostol is superior to oral misoprostol when combined with mifepristone for early first-trimester medical abortion. Recent studies on the clinical efficacy of sublingual misoprostol have demonstrated that it is as effective as vaginal misoprostol. Further studies are required to determine the optimal dose and route of administration of misoprostol that can give the highest complete abortion rate, lowest ongoing pregnancy rate and least side effects.