Does an acidic medium enhance the efficacy of vaginal misoprostol for pre-abortion cervical priming?

Absorption pharmacokinetics reveal a relationship between plasma concentrat ions of misoprostol and its therapeutic effect. To achieve a constant plasm a profile and optimal efficacy, it is important to develop a medium that en sures complete dissolution of vaginal misoprostol tablets, Vaginal misopros tol is said to liquefy better in an acidic medium; thus, the aim of this st udy was to determine whether a 200 mu g misoprostol tablet dissolved in ace tic acid would be more efficacious than 200 mu g misoprostol dissolved in w ater for pre-abortion cervical priming. A total of 120 healthy nulliparous women requesting legal termination of pregnancy between 6-12 weeks gestatio n were allocated randomly to either of the study groups. Vacuum aspiration was performed 3-4 h after insertion of the misoprostol tablet. Using Hegar' s dilator, the degree of cervical dilatation before operation was measured. Of 60 women, 14 (23%) achieved a cervical dilatation of greater than or eq ual to 8 mm when the misoprostol dose was dissolved in acetic acid; 12 (20% ) achieved a similar cervical dilatation when the dose was dissolved in wat er. The mean cervical dilatation for the acid and water media used was 6.3 mm and 6.2 mm respectively; these differences were not statistically signif icant, neither were pre-operative and intra-operative blood losses statisti cally different between the two groups. Twenty-four (40%) and four (7%) res pectively of women in whom a water medium was used experienced vaginal blee ding and abdominal pain; 20 (33%) and 0 women respectively among those in w hom an acetic acid medium was used experienced vaginal bleeding and abdomin al pain. These differences in side effects were not statistically significa nt. Our study shows that the use of acetic acid to dissolve vaginal misopro stol does not improve the efficacy in achieving successful cervical dilatat ion for pre-abortion cervical priming.