UK scientists are developing a new form of contraceptive pill that could avoid the increased risk of breast cancer and blood clots seen with current products.
The team, led by Prof David Baird of the University of Edinburgh, are working on a prototype contraceptive that is based on progesterone receptor modulators, which include the controversial ‘abortion pill’ mifepristone (RU-486), although for contraception the compound would be used at much lower doses.
Current oral contraceptives tend to contain a combination of oestrogen and progesterone, with the latter included to offset an increased risk of breast, endometrial and ovarian cancers with oestrogen-only products.
Many women elect to take the so-called ‘mini pill’ which contains lower amounts of oestrogen, to reduce the risk of cancer and thrombosis. But these products are less effective at providing contraceptive cover than the combined pill.
The new pill would contain no oestrogen component, so should avoid these risks, according to Prof Baird.
It would also stop women having periods and could be of benefit for women who suffer from premenstrual syndrome, he suggested. And because one of the risk factors for breast cancer is a woman’s natural hormonal cycle, it is conceivable that PRMs could reduce the risk of breast cancer, aside from providing contraception, although long-term clinical studies would be need to prove that conclusively.
Baird and his team are hoping to get the pharmaceutical industry interested in the approach, and have already completed Phase II trials of low-dose mifepristone carried out in Nigeria, South Africa and Hong Kong.
However, mifepristone’s use to include abortion has made it politically-sensitive, so drugmakers may be reluctant to develop a product based on this PRM. And media coverage of its safety record could be an issue, even though a contraceptive would use only 1% of the dose used to cause an abortion.
Earlier this month, the US Food and Drug Administration disclosed that two more American women had died after taking mifepristone, bringing the total number of deaths among users of the drug to seven since it was approved in 2000.