INTRAVAGINAL CONTRACEPTION WITH SYNTHETIC PROGESTIN, R2323

A Silastic intravaginal ring (IVR) containing R2323 (17.alpha.-ethinyl-1.beta.-hydroxy-18-methyl-4,9,11-estrien-3-one) in its center core was tested in vitro and in 4 women for 1 cycle each. Initially 330 .mu.g of drug was released /day from the IVR in vitro, and after 150 days the value had declined to about 230 .mu.g. Ovulation was inhibited in the 4 subjects due to the constant release of R2323 as evidenced by the steroid blood levels of 1-3 ng/ml. When the IVR was removed, R2323 blood levels quickly fell to 0. All the women had normal withdrawal bleeding and 2 subjects followed during a recovery cycle had ovulatory levels of progesterone.