Vaginal pH influences the efficacy of misoprostol administered vaginally for the induction of midtrimester abortion. The presence of this relationship, despite premoistening misoprostol with an acidifying agent, suggests that the effect of vaginal pH might extend beyond affecting the pharmacokinetics of the drug.

A 3% acetic acid gel appears to be an effective and safe preparatory adjuvant to vaginal misoprostol treatment for midtrimester medical abortions, especially in women with a vaginal pH of 5 or higher. www.controlledtrials.com: ISRCTN75746444.