A contraceptive vaginal ring releasing ethinyl estradiol and the progestin ST-1435: bleeding control, serum steroid concentrations, serum lipids and serum chemistry.

Four women used vaginal rings releasing the synthetic progestin ST-1435 and ethinyl estradiol for at least three 21-day cycles with a 7-day treatment-free period between intervals of use. Patterns of bleeding were evaluated and serum concentrations of ST-1435, estradiol, progesterone and ethinyl estradiol were measured by radioimmunoassay. Total serum cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides and serum chemistry were determined before ring use and during the first and third treatment cycles. The women experienced no difficulties in using the vaginal ring and all continued to use the ring after the first three cycles. Bleeding control was good and hormonal side effects were minimal. Serum steroid concentrations were: ST-1435, 289 +/- 117 pmol/l (mean +/- SD); ethinyl estradiol, 172 +/- 108 pmol/l; and estradiol, 184 +/- 107 pmol/l. Concentrations of serum progesterone were low, indicating complete suppression of ovulation during treatment. Total serum cholesterol increased slightly during use of ring. However, this increase could be accounted for by an increase in serum HDL-cholesterol. Liver function tests were in the normal range during ring use and values of serum chemistry showed no significant changes. This contraceptive vaginal ring presents a good method of contraception, showing good bleeding control and no harmful metabolic effects.