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Government Warns Some Birth Control Pills May Cause Blood Clots

October 19, 1995 GMT

LONDON (AP) _ The government warned Thursday that a new type of birth control pill used by 1.5 million British women may cause blood clots, according to new, unpublished studies.

The Government’s Committee on Safety and Medicines advised doctors not to prescribe the pills, sold under several brand names, to women who are overweight, have varicose veins or have a history of blood clots.

It considered withdrawing the pills but decided not to, partly because some women cannot tolerate any other kind of pills.

Two contraceptives in the United States contain the same ingredients and account for 15 percent of the oral contraceptive market: Desogen by Organon and Ortho-Cept by Ortho Pharmaceuticals, the U.S. Food and Drug Administration said.

The FDA said it could not offer advice to American women until it finishes reviewing the studies. International health experts were debating their merits at a meeting in Canada Thursday and Friday, the FDA said.

The pills, which had been hailed as a major advance, all combine estrogen with one of two types of the hormone progesten, desogestrel or gestodene.

They are taken by half the 3 million British women using oral contraceptives and are sold under the brand names Femodene, Femodene ED, Minulet, Triadene, Tri-Minulet, Marvelon and Mercilon.

Manufacturers and some family planning experts criticized the government for acting on premature and potentially flawed data.

Professor Michael Rawlins, chairman of the British government committee, advised women taking the pills ``not to panic″ and to discuss the advisability of continuing with their doctors.

``The chance of a woman on the pill experiencing a thrombosis is small,″ he said. ``There is no need for anyone to suddenly stop taking the pill.″

Indications of a problem with the pills emerged in July from a still unpublished World Health Organization study, Rawlins said.

British health officials were sufficiently alarmed to urge that another study on the same subject under way in Europe be speeded up, he said. The research was concluded this month.

The Committee on Safety of Medicines then conducted a rapid study of its own using information from a database of general practitioners.

``The three studies all showed the same sort of thing and are very consistent,″ Rawlins said.


The new research indicates that the risk of thrombosis, or blood clots, in deep veins among women using the combined pill is six times the normal average and double that faced by women who use other types of pills, he said.

Blood clots forming in veins, usually in the legs, can cause major health problems if they break away and travel into the vessels of the lungs. In rare cases, they can lead to death.

However, experts stressed that the risk represents a ratio of only three in every 10,000 for healthy young women _ half the natural risk of thrombosis during pregnancy.

The Geneva-based World Health Organization issued a statement calling for its results to be ``confirmed by independent studies″ to rule out any element of chance or bias.

Dr. Anne Szarewski of the Margaret Pyke Centre in London, a leading family planning clinic, called the government’s reaction irresponsible and premature.

``The effect of this is going to be absolute chaos,″ she said. ``All these women who have been told this is the best pill to take are suddenly being thrown completely and told they are more dangerous.″

When the combination pills were introduced in Britain, they were hailed for preventing ovarian and uterine cancer and pelvic infections that can cause infertility. They were also said to have fewer side effects like weight gain, hair growth and acne.

The new formula was also believed to cut the risk of thrombosis in arteries, which can lead to strokes and heart attacks.

Schering Health Care, which manufactures Femodene, Triadene and Tri-Minulet, said the government warning was ``surprising since it is based on the preliminary evaluation of unpublished data.

Organon Laboratories of Cambridge, which produces Marvelon and Mercilon, disputed the conclusions and called the new data ``potentially flawed.″

Wyeth Laboratories, another manufacturer, called the results ``inconsistent with more than 10 years of substantial clinical trial data and spontaneous side-effect reports from around the world.″