Mifepristone, the controversial "abortion pill" also known as RU-486, is safe and effective and should be made available to American women, an advisory panel of the Food and Drug Administration concluded yesterday.

Seven of eight voting members of the FDA's Reproductive Health Drugs Advisory Committee voted that the medical abortion method was safe for use in the United States, although they warned that "safe" is not the same as "risk-free."

The FDA is not bound by the recommendations of its advisory committees but usually follows them. FDA Commissioner David Kessler said after the meeting that the panel had given him "a very strong signal" that the drug should be approved and added, "We take that advice very, very seriously."

Mifepristone is an antiprogestin, one of a family of drugs that blocks the action of the hormone progesterone, needed to maintain pregnancy. If approved, it would be administered in two stages. Patients who have been pregnant for less than 49 days would take a 600-milligram oral dose of mifepristone one day, and return two days later for a 200-microgram dose of misoprostol, a "prostaglandin" drug already approved by the agency that triggers uterine contractions. The combination induces an abortion without surgery.

Most abortions occur within four hours of taking misoprostol. The regimen outlined in the application calls for the patient to spend those four hours in the clinic or doctor's office, and also includes monitoring after the fact. The treatment is expected to cost several hundred dollars.

In French and American studies, the drug combination is successful in 95 percent of cases. Women in whom it fails should have a surgical abortion, because the drugs might cause birth defects, said representatives of the Population Council, the New York-based research organization that applied for the drug's approval.

Mifepristone was developed by French researchers in 1980 and approved in France in 1988. Nearly 200,000 women have had medical abortions using the drug in France, the United Kingdom and Sweden and other countries. Twenty-one births have been reported after unsuccessful medical abortion attempts. Three of those children were born with birth defects: one with a club foot, one with "abnormal fingernails," and one with an immune system deficiency that proved fatal.

Because mifepristone could constitute an advance over existing therapy, the FDA considers it a "priority drug" and has a statutory goal of acting on the application within six months.

The panel reviewed data from two French clinical trials that enrolled 2,480 women, and an American trial in 2,121 women, conducted as part of the application for U.S. approval. The American data, however, were preliminary and have not been thoroughly verified or reviewed.

"I don't know why this meeting is being held at this time when the data are not finalized," complained panel member Mary Jo O'Sullivan, professor and director of obstetrics at the University of Miami School of Medicine.

In all three studies, the drug combination produced abortions in at least 95 percent of cases. Patients experienced side effects including cramps, nausea, and vomiting -- symptoms also common to miscarriage and abortion. As many as 82 percent of patients reported painful contractions; as many as 30 percent reported that their symptoms were "severe." More infrequent side effects included headache, dizziness and, very rarely, heart palpitations and toothache.

Most women required no medication for pain. Twenty-six women in the American study required hospitalization after the procedure. Thirty-two women in the American trial, or 1.5 percent of the study population, underwent suction abortion to stop bleeding following the procedure. That figure was roughly twice the percentage in the French studies, which some panelists suggested might be attributable to differences in medical culture between the two countries.

Members of the panel focused on whether women would comply with the two-drug, three-visit regimen. Cassandra E. Henderson of New York's Albert Einstein College of Medicine, said more study was needed in populations less likely to follow the full medical regimen than the initial study groups. Without such studies, Henderson said, there is "a great risk for harming a very large, vulnerable population" of patients.

The committee voted unanimously to meet again if final analysis of U.S. data was substantially different from the French results, and recommended clearly worded warnings about the risks of the procedure and the need for monitoring. When members of the group were asked to vote on whether the drug's benefits outweighed its risks, O'Sullivan said, "if you're talking about the woman, it may be beneficial to her -- but it's of no benefit to the baby whatsoever."

More than 30 people spoke before the panel, illuminating the vast rift that separates those who would protect the right to have abortions from those who would restrict the practice to protect the unborn.

Wanda Franz, president of the National Right to Life Committee, expressed disappointment in the advisory panel vote. "Unfortunately, the committee, which was stacked with abortion supporters, brushed aside serious health concerns for women who take this drug," Franz said.

Opponents of the drug's approval said that those favoring it understated the risks. Mark Louviere, a Waterloo, Iowa physician who cared for a woman who experienced life-threatening bleeding after taking mifepristone, told the panel that he was later outraged to hear that Iowa Planned Parenthood had claimed there were no unexpected complications. FDA officials, however, confirmed that the agency received a full report of the incident. The woman did not visit her doctor when her bleeding persisted.

Proponents of the drug's approval said that surgical abortion is safe, but insisted the medical alternative could be safer still -- and not just in medical terms. Susan Hill of the National Women's Health Organization, recounted working with colleague David Gunn, the abortion doctor shot and killed in 1993 for his work. Approval of a medical option, she said, could "stop the ghettoization of abortion providers" and provide greater privacy for patients.

Atlanta resident Marie Head compared her experience with an RU-486 abortion to a surgical abortion that she had undergone years earlier. "The medical procedure was safer and much less traumatic for me," she said.

Security for the day-long meeting was tight, and was held at a new, out-of-the-way FDA facility in Gaithersburg. The agency maintained a checkpoint for cars, as well as metal detectors and scanners for packages and briefcases. An overflow crowd watched the meeting via a video feed at a nearby hotel.

If approved by the FDA, the drug would be sold by Advances in Health Technology, a nonprofit organization created late last year to market this and future reproductive drugs. A representative of AHT said the drug could be available next year. CAPTION: FDA Commissioner David Kessler, right, and advisory committee member Mary Pendergast listen to testimony yesterday about approval of RU-486.