Efficacy of testosterone-filled polydimethylsiloxane implants in maintaining plasma testosterone in rabbits.

Experiments were designed to examine the release of testosterone through polydimethylsiloxane (PDS) capsules in vitro and in situ and to test the efficacy of PDS capsules in maintaining testosterone in the peripheral circulation of castrate male rabbits for several months. The results demonstrate that (1) tritiated testosterone passed through PDS capsules suspended in water, (2) the tritiated material released into water had the same chromatographic mobility as authentic testosterone when subjected to thin-layer chromatography, (3) the rate of release of testosterone into water was dependent upon capsule surface area, (4) the release of testosterone from implants in situ was dependent upon surface