A biodegradable long-term contraceptive implant developed in China

The paper describes a biodegradable long-acting contraceptive capsule-type implant-CaproF. A well know biodegradable polyester, poly(ε-caprolactone) (PCL) was used as the principle matrix and a water-leachable polyether, Pluronic F68 (F68), was used as drug releasing enhancer. The levonorgestrel (LNG) containing capsules showed an average LNG release rate of 7.0 μg/day·cm length for a period of 2 years in rats. A stable serum LNG level of around 350 pg/ml was maintained during the 2 year implantation. The contraceptive effect of the implants was verified in animal test. A 6 months preliminary clinical trial in 9 volunteer women was carried out. Average serum levels of LNG from the 9 women were around 300 pg/ml for the whole testing periods. Implantation of 2 pieces of 3.0 cm length of the capsule has been recognized as effective dosage for contraception in humans. A series of toxicological studies demonstrated that the LNG-containing PCL/F68 capsule has no toxic effects