Prostaglandins as abortifacients.

Abstract

Clinical trials have demonstrated the use of prostaglandins as effective abortifacients. Continuous intravenous infusion of the drugs however has been associated with certain side effects at therapeutically effective doses, such as nausea, vomiting, diarrhea and a local erythematous reaction at the site of venepuncture. Higher doses result in more serious side effects such as vasovagal symptoms, pyrexia and tachycardia. Direct application of prostaglandins E2 or F2a into the uterine cavity has been shown to minimize the side effects. Appropriate doses of prostaglandins every one or 2 hours administered at the site of action between the fetal membrane and uterine wall (via the cervix) produce the strong and frequent uterine contractions necessary for the expulsion of the products of conception. A drawback of this method is the need for the uterine cavity to be continuously monitored as dosage is determined by the uterine response. Another effective method of terminating 1st and 2nd trimester pregnacy with minimal side effects is vaginal administration (into the posterior fornix) of 50 mg PGF2a or 20 mg PGE2 every 2 or 3 hours. Single injection of prostaglandins into the amniotic sac usually results in complete abortion. The method is simple but should be used only in pregnancies of over 12 weeks' gestation as the amniotic sac is inaccessible in the 1st trimester. The prostaglandin method, compared with other methods of abortion in the 1st trimester of pregnancy (e.g., suction or dilatation and curettage) is inferior in terms of time, expense and convenience. Incomplete abortion is quite common in the 1st trimester when prostaglandins are used. With respect to 2nd trimester methods (hypertonic saline and hysterotomy) however, prostaglandins given by intravaginal, intrauterine, or intraamniotic routes offer clear advantages.