The clinical indications for Prostin E2 (dinoprostone, a synthetic prostaglandin) are enumerated. In obstetrics and gynecology, the smooth muscle properties, similar to those of oxytocin, make Prostin E2 a viable alternative to oxytocin for similar indications. For labor induction, Prostin E2 is 90% effective in late pregnancy when infused intravenously. A final concentration of 1.5 mcgm/ml is sufficient for labor induction, except in the case of fetal death in utero where higher drug concentrations are required to expel the fetus. Prostin E2 is preferable to oxytocin for labor induction because of its narrower dose range and lack of serious side effects. Prostin E2 is also indicated for medical termination of pregnancy, So far clinical experience indicates that Prostin E2 administered by the intrauterine, extraamniotic route is more effective and better tolerated than the intravenous route. In second trimester abortions, the drug, administered extraamniotically, has been effective in 90% of cases vs. 70% effectiveness with intravenous infusion. The initial extraamniotic instillation should be 1 ml, and subsequent instillations can range from 1-2 ml. The initial intravenous infusion should be 2.5 mcgm for 30 minutes increased stepwise to 5 mcgm/minute. Side effects are the same but of greater severity via intravenous infusion. The use of Prostin E2 as a morning after contraceptive is discussed.
The results of 3 British and 1 American investigation of the risk of thromboembolism among women using oral contraceptives are reviewed. 1 British study conducted among general practitioners found the risk of developing superficial thrombophlebitis about 3 times greater among pill users. Neither of 2 other studies, in which hospital admissions and fatalities were analyzed, found any significant link between oral contraceptives and coronary thrombosis, but both indicated a 6 to 8-fold increase in risks of venous thromboembolism and of cerebral thrombosis. The findings of the American study were similar. None of the 4 studies discovered any evidence that the thromboembolic risk is greater early in the course of medication or, that it increases with duration of use. The American study obtained some evidence that sequential preparations might be more harmful than combined ones. The British Committee on Safety of Drugs has since determined, on the basis of analysis of routinely submitted reports of suspected adverse reactions, that the thromboembolic risk is higher with pills containing 75 mcg or more of estrogen than among those containing only 50 mcg. For the woman, who for any reason finds oral contraception to be the only satisfactory method of birth control, the risks may be considered acceptable provided medical supervision is adequate. Use of the pill entails other known major hazards (jaundice, hypertension) and knowledge of the longterm effects is very incomplete. Substantial evidence suggests that the estrogenic component of combined and sequential pills is responsible for the thromboembolic risks. The greater risks of pregnancy and menstrual disturbances accompanying progestogen-only oral contraceptives may limit their advantages.
