Aspirin may be safer than you think. Two Harvard researchers have found it to be an effective contraceptive in female rats. Indomethacin, a common anti-inflammatory drug used to treat arthritis, was found to be twenty to thirty times as effective as aspirin as a rat contraceptive.
Harold R. Behrman, assistant professor of Physiology at the Laboratory for Human Reproduction and Reproductive Biology at Harvard and Gayle P. Orczyk, a post-doctoral research fellow at Harvard Medical School discovered that the two drugs provide contraception by preventing ovulation.
The contraceptive effect could be produced by injections of 10 milligrams of aspirin or one-half milligram of indomethacin per rat for two days. These dosages are approximately equivalent to one and one-half times the maximum prescribed human dosage.
Larger single dosages could also prevent the rats from ovulating.
Behrman and Orczyk linked the striking effect of aspirin and indomethacin to luteinizing hormone and prostaglandins. LH stimulates the final ripening and rupture of the ovary follicles to release the eggs and is essential for ovulation. Prostaglandins are natural hormones which help to regulate various bodily functions including ovulation.
The ovulation blocking effect of a single drug injection could be reversed by LH injections, so Behrman and Orczyk suggested that a single drug treatment prevented the secretion of LH.
To determine the effect of aspirin and indomethacin on human ovulation, Behrman and Orczyk are beginning preliminary studies with women who take large amounts of aspirin and indomethacin for the treatment of rheumatoid arthritis.
A report on the research with rats appeared in the initial (Feb. 1) issue of the new journal Prostaglandins.