Intracervical release of ST-1435 for contraception

Seven women used an ST-1435-releasing intracervical contraceptive device (ST-ICD), inserted immediately after the cessation of menstrual bleeding. Patterns of bleeding and clinical performance were evaluated and plasma concentrations of ST-1435, estradiol, progesterone and gonadotropins were measured by radioimmunoassays. The results of ten months of treatment are presented. There were no uniform patterns of bleeding. No hormonal side-effects were registered. The plasma concentration of ST-1435 reached 100 pg/ml within two hours after insertion of an ST-ICD. No ovulations occurred during the initial three months of treatment. A rapid decline in the plasma concentrations of ST-1435 was observed; during the tenth month the concentration of ST-1435 was under the sensitivity of the radioimmunoassay of ST-1435. Hence, the release of ST-1435 from Silastic was too rapid for long-acting contraceptive purposes.