WASHINGTON -- In a controversial move, the Food and Drug Administration approved a new drug yesterday to combat the AIDS virus -- the first in almost five years -- before having determined conclusively that it is safe and effective.
Health officials and AIDS activists called the early approval of the anti-viral drug didanosine, or DDI, a landmark decision that signals what they called a new, more humane government response to the needs of desperately ill Americans.
"Today's action is a milestone," said Dr. David A. Kessler, head of the FDA. "It is the second major drug to be approved for AIDS. It is not a cure, but it does give patients a choice."
But critics said the move set a dangerous precedent that could flood the market with unproven or even dangerous drugs for acquired immune deficiency syndrome and other life-threatening illnesses such as cancer and Alzheimer's disease. Ordinarily, the FDA waits until it has the final results of clinical trials before allowing a new drug to be marketed.
The FDA approved DDI for treatment of adults and children with advanced AIDS who cannot tolerate or are not helped by AZT, which received approval in 1987. Until now, AZT was the only drug found to be effective in fighting human immunodeficiency virus -- or, HIV -- which causes AIDS and has killed some 122,000 Americans in 10 years.
Dr. Charles Moertel, a cancer specialist at the Mayo Clinic and a longtime FDA consultant, accused the agency of "abandoning the scientific basis for drug approval to yield to the shrill voices of the activist group du jour." AIDS activists have accused federal officials in often-noisy demonstrations of foot-dragging in the fight against AIDS.
Dr. Kessler defended the decision to approve the drug before clinical testing ends and said his agency would take similar steps for other new drugs that combat serious illnesses.
"If the science is there to allow a conclusion that a drug has a reasonable chance of clinical benefit in a life-threatening disease, this agency will move expeditiously," he said at a news conference.
In an interview later, he added, "Where there are life-threatening diseases and there is no alternative therapy, the patient, the public, is willing to take more risks."
The AIDS Action Council, a Washington lobbying group, said in a statement: "The FDA has sensitively balanced a strict scientific standard against the needs of people with no treatments for a life-threatening illness."
Critics have voiced deep misgivings about the relaxation of FDA's rigid guidelines that a drug must be proved safe and effective before it is allowed on the market.
"It's a mistake," said Dr. Deborah Cotton, one of two members of an FDA advisory committee who cast a minority vote against early approval of DDI last July. "There's uncertainty about DDI in two directions: whether or not it works and whether or not it's safe."
"The precedent we've set is a bad one," she said. "We will see more drugs approved on the basis of very little data and we will have less ability to know how to choose among them or how to use them in combination."
Bristol-Myers Squibb, which will market DDI under the name Videx, said it will help people with limited resources get the drug either through insurance or Medicaid coverage, or by providing it at no cost to those who have no third-party coverage.
Bruce Ross, a spokesman for the pharmaceutical company, also said DDI would be available at pharmacies within the next few days.
The company said its factory price for a year's supply of the most common dose, 400 milligrams a day, would be $1,745. After markups, the price from retail pharmacies would be $1,990.
A year's course of the most common dose of AZT, 500 milligrams a day, costs $2,190 wholesale. After a 14 percent markup, the retail price is close to $2,500, although some markups drive the cost up to more than $3,000.
Although DDI's FDA label will stipulate that it should be prescribed to AIDS patients who do not respond to AZT, once the FDA has approved a drug, doctors can prescribe it as they see fit.
Based on data from early clinical trials, DDI increases the number of white blood cells known as CD-4 cells. The depletion of those infection-fighting cells -- from counts of 1,000 in a healthy individual to 200 or less in patients with advanced AIDS -- signals the weakening of the immune system that makes people with AIDS susceptible to a wide range of infections.
"It seems to help people even after they've already been on AZT for several years. It gives them a boost for their immune system and a new attack on the virus, so that means it may help people live longer until we have better drugs," said Mark Harrington of ACT UP (AIDS Coalition to Unleash Power) in New York.
The Associated Press contributed to this article.