The Food and Drug Administration has approved new labeling for zidovudine, or AZT, to include people who are infected with the AIDS virus but have not yet developed the full-scale disease, HHS Secretary Louis W. Sullivan, M.D., announced today.
The expanded labeling reflects the results of two studies sponsored by the National Institute of Allergy and Infectious Diseases that indicate the drug slows the progression of the disease when used at early stages of infection.
HHS Secretary Sullivan said, "The studies and the change in labeling mean that better treatment can now be offered to thousands of people at earlier stages of infection with the AIDS virus before their health deteriorates critically."
HHS Assistant Secretary for Health James O. Mason, M.D., Dr.P.H., noted that today's action follows recent agency approval of a new lower dose for zidovudine, and the sanctioning of a Treatment IND protocol which allows widespread distribution of the drug to children at advanced stages of infection with the AIDS virus.
He said, "Today's action underscores the government's commitment to widen the treatment options available against AIDS. It also underscores the great deal of scientific cooperation between the government and the private sector in the efforts against this disease."
Zidovudine, the only drug proven effective against the AIDS virus, was approved by FDA in March 1987 for treating people with more advanced stages of infection. These are patients who have had either an episode of Pneumocystis carinii pneumonia -- an infection that commonly strikes people with AIDS -- or who are symptomatic and have CD4 helper cell counts of 200 or less. CD4 helper cells are white blood cells important in the immune system that are destroyed by the AIDS virus. Healthy individuals normally have CD4 helper cell counts of 1,000 or more.
Earlier this year FDA approved a labeling change for zidovudine which lowered the recommended dose for the long-term regimen to 600 milligrams a day -- half the previously recommended dose. The reduced dosage not only lowers the frequency of side effects, thereby allowing more patients to continue zidovudine therapy, but also dramatically reduces the cost of zidovudine treatment for many patients.
The expanded labeling approved today will include use of zidovudine in people with CD4 helper cell levels of 500 or less.
NIAID protocol 016 involved 713 patients with early AIDS-related complex including conditions such as oral thrush, chronic rash or intermittent diarrhea, as well as CD4 cell levels between 200 and 500. The other NIAID study, protocol 019, involved more than 1,500 people infected with the AIDS virus who had not yet developed any symptoms of AIDS. In both studies, zidovudine appeared to significantly slow the progression of the disease.
On Jan. 30, FDA's Antiviral Drug Products Advisory Committee reviewed data from both these studies and recommended that FDA approve expanded labeling indications. The committee, made up of outside experts, also considered evidence from animal studies that zidovudine is carcinogenic in rodents. The group recommended that the potential risk for cancer should be investigated further, including any possibly unique effects on women, fetuses and children. Nevertheless, the committee believed that on balance, the benefits of zidovudine's use in those at earlier stages of infection with the AIDS virus outweigh any potential risk.
Zidovudine can inhibit the production of red blood cells, requiring treatment for anemia. The drug can also reduce white blood cell counts to the extent that the drug's use has to be discontinued.
The supplemental application that was approved today was submitted by the drug's sponsor, Burroughs Wellcome of Research Triangle Park, N.C., Oct. 31. It applies to both the capsule and syrup forms of the drug.