Induction of abortion by different prostaglandin analogues

The clinical advantages and disadvantages of intra amniotic administration of PGF2alpha in comparison with hypertonic saline has recently been summarized by the Prostaglandin Task Force within the World Health Organization Expanded program. The investigation comprised approximately 1,500 patients treated randomly with the two methods. The main advantage of the PG method was a significantly shorter induction-abortion interval and a lesser risk for serious complications and the significant disadvantage a slight increase in the mean frequency of minor complaints in terms of diarrhoea and vomiting. With PGF2alpha it seems difficult to obtain a "one shot" method to terminate second trimester pregnancy even with the intra-amniotic route of administration. The 15-methyl analogues seem more promising in this respect. The uterine response following administration of this compound is characterized by a more gradual initiation of uterine stimulation and a sustained effect, One intraamniotic injection of 2.5 mg 15-methyl-PGF2alpha induced abortion in nearly 100% of the cases and the incidence of side effects was low. Promising results with this compound have also been obtained following a single extra-amniotic instillation or by repeated intramuscular injections. Vaginal administration of 15-methyl PGF2alpha or its methyl ester can also be used for termination of pregnancy. Recently orally active PG analogues have become available for clinical testing. One of these compounds, 16,16-dimethyl-PGE2 may in some cases stimulate uterine contractility sufficiently to induce a second trimester abortion following repeated oral administration.