A comparison of two stable prostaglandin E analogues for termination of early pregnancy and for cervical dilatation.

Termination of pregnancy with prostaglandin E analogues is in general associated with a lower frequency of gastrointestinal side effects than if corresponding F analogues are used. Their clinical use has, however, been limited by stability problems. In the present study the efficacy of different dose schedules of two new stable E analogues for termination of early pregnancy and for preoperative dilatation of the cervical canal was evaluated in 389 women. In early pregnant patients, vaginal administration of 75 mg of 9-deoxo-16, 16-dimethyl-9-methylene PGE2 repeated after six hours or three intramuscular injections of 0.5 mg 16-phenoxy-omega-17, 18, 19, 20-tetranor PGE2 methyl sulfonylamide administered in three-hour intervals resulted in a complete abortion in 94 to 100 per cent of the patients. Both treatments were associated with a low frequency of side effects. The 9-methylene analogue had the advantage of causing less uterine pain than 16-phenoxy-omega-17, 18, 19, 20-tetranor PGE2 methyl sulfonylamide with the dose schedules used. Single vaginal administration of 30 mg of 9-deoxo-16, 16-dimethyl-9-methylene PGE2 and one intramuscular injection of 0.5 mg of the methyl sulfonylamide analogue 12 hours prior to vacuum aspiration were equally effective in dilating the cervix in late first trimester pregnant patients. For both compounds, the frequency of side effects were lower than that previously reported for different PGF analogues administered by non-invasive routes.