Pregnancy interception with a combination of prostaglandins: studies in monkeys

Treatment with combinations of synthetic prostaglandins, one with an ovarian site of action and one with a uterine site of action, terminated pregnancy in all rhesus monkeys given the injection on day 28 of fertile menstrual cycles. Single prostaglandins, even at higher doses, interrupted pregnancy in only one-third of the monkeys. The most effective treatment, 5-oxa-17-phenyl-18,19,20-trinor prostaglandin F1 alpha methyl ester plus 9-deoxo-16,16-dimethyl-9-methylene prostaglandin E2, promptly intercepted early pregnancy after a single administration and without side effects.