Uterine contractility and plasma levels of steroid hormones after intravaginal treatment of pregnant Japanese monkeys (Macaca fuscata fuscata) with 16,16-dimethyl-trans-delta2-prostaglandin E-1 methyl ester.

Intravaginal treatment with a PGE-1 analogue (ONO-802) resulted in strong uterine contractions with a high frequency which lasted for more than 3 h. When 20-50 microgram ONO-802/kg were administered intravaginally 5 times every 3 h in 5 pregnant animals, vaginal bleeding started by 6 h and abortion occurred by 26 h after the initial treatment. There were no significant side effects. Plasma levels of steroid hormones, especially progesterone and 20alpha-dihydroprogesterone, fluctuated initially and then finally dropped to undetectable levels within 24 h.