Intrauterine delivery of indomethacin from a silastic device: effect on the preimplantation embryo and implantation.

Plain silastic IUDs and those incorporating 3.3% w/w of indomethacin were fitted into one uterine horn of adult rats. After a period of 3 weeks, animals were mated and studied for the effects these devices had on the preimplantation embryo, Pontamine Blue Reaction and implantation rates. The indomethacin-loaded devices had no observable effect on ovulation, fertilization or ovum transport. In the horns bearing an indomethacin device, the intrauterine degeneration of preimplantation embryos on Day 5 was not as rapid as was found for the horns bearing plain devices. On Day 6 of pregnancy, Pontamine Blue Reaction sites were virtually absent in the horns bearing either type of device, as were the numbers of normal-sized implants on Days 9 or 10. There was a slight increase in the numbers of abnormal, small implants in horns with indomethacin devices.