NEW YORK (Reuters) -- The "abortion pill," RU 486, is safe and effective when used in combination with a prostaglandin to terminate pregnancies of 49 days duration or less, according to the results of a US clinical trial.
A report on the regimen, the first US data to be published, appears in the April 30th issue of The New England Journal of Medicine.
RU 486, also known as mifepristone is available to women in Europe and China as a medical means of terminating pregnancy. The drug stops cellular growth in the embryo or fetus. Mifepristone is usually taken in conjunction with misoprostol, a prostaglandin that induces uterine contraction and subsequent abortion.
The US trial was conducted by researchers from the Population Council, a nonprofit, private research institution devoted to reproductive health issues based in New York City. They tested the mifepristone-misoprostol combination therapy on 2,015 volunteers seeking termination of pregnancy at various US hospitals, Planned Parenthood clinics, and independent abortion clinics. All of the women had been pregnant for less than 63 days when they received the drug regimen.
Each patient was administered mifepristone, followed by misoprostol 2 days later. The patients remained under clinical observation for 4 hours after receiving misoprostol, since abortion and/or medication side effects are most likely to occur within the first few hours after administration of this drug.
The investigators discovered that the drug combination was less effective in inducing abortion among women with a previous history of abortion, compared with women seeking abortion for the first time.
They also discovered that the therapy's effectiveness fell with increasing duration of pregnancy. For example, the study authors found that rates of successful pregnancy termination were 92% among those women whose pregnancies were at or below 49 days of gestation at time of therapy, 83% among women whose pregnancies were placed at between 50 to 56 days, and 77% in pregnancies advanced to 57 to 63 days.
The researchers also report that "the incidence of adverse events rose with the duration of pregnancy." Two percent of women with pregnancies at or under 49 days required hospitalization or surgical intervention due to complications after mifepristone-misoprostol therapy, compared with 4% of women with a pregnancy duration between 50-63 days. Side effects included abdominal pain (experienced by nearly all the women), vaginal bleeding, nausea, and vomiting. "Excessive (vaginal) bleeding necessitated blood transfusions in four women and accounted for 25 of (the study total of) 27 hospitalizations," according to the researchers.
The Population Council holds the US patent for mifepristone. In September 1996, a US Food and Drug Administration (FDA) advisory committee submitted its recommendation that mifepristone be approved for use in medical abortion. Advisory committee recommendations are usually considered a precursor to full FDA approval.
"The method was highly acceptable to the women who used it and the physicians and staff who provided it," according to a statement issued by the Population Council.
At a press conference held Wednesday in New York, Heather O'Neill, public affairs director for the Danco Group, the Council's licensee for the manufacture and marketing of mifepristone, said the group was working with "...manufacturers and tableters towards production of mifepristone."
"We do expect to make the product available to (American) women sometime next year," she added.
"Many American women do not have access to abortion, and in developing countries up to 200,000 women die annually of complications after illegal abortions," write the study authors. "The availability of medical abortion in the United States and elsewhere could lead to greater access to safer abortion services."
The availability of RU 486 in the US would make abortion "more accessible in some areas," according to the Population Council statement. "We do not anticipate an increase in the number of abortions," the Council says. "In France, for example, the total number of abortions per year has not increased since the method was introduced in 1989."
SOURCE: The New England Journal of Medicine (1998;338:1241-1247)
