New AIDS Drug OKd for Use With AZT
The Food and Drug Administration Monday approved 3TC--a new anti-viral AIDS drug--to be used with the frequently prescribed AZT, further bolstering the growing belief that using combinations of powerful drugs is the most effective way to fight the infection.
The drug was licensed less than five months after its manufacturer first submitted its application to the agency, and two weeks after an FDA advisory committee recommended that it be approved.
Both drugs are manufactured by Glaxo Wellcome Inc. of Research Triangle Park, N.C.
It is the fifth in a family of anti-viral AIDS drugs called nucleoside analogs to receive FDA approval since 1987. In addition to AZT and 3TC, these include DDI, DDC and D4T, all of which attack the underlying infection. Many other drugs have been approved to treat the symptoms of AIDS--such as pneumocystis carinii pneumonia--which result from the underlying condition.
The agency is expected to soon approve saquinavir, the first in a new generation of AIDS drugs called protease inhibitors. These are regarded as far more potent than nucleoside analogs.
The 3TC/AZT drug combination “marks the beginning of the realization of the synergistic effects of combination therapy,” said Dr. Joseph J. Eron Jr., assistant professor of medicine at the University of North Carolina School of Medicine in Chapel Hill. The 3TC/AZT therapy is a new first-line choice for patients. The other existing AIDS drugs are approved for use only after AZT alone has failed.
“The real significance of this combination lies in its potent and sustained anti-viral effect, and its boost to the immune system,” added Eron, who was the lead U.S. researcher investigating the 3TC/AZT combination in patients who had never been treated before with anti-viral AIDS drugs.
The 3TC/AZT combination is not the first such combination therapy to be sanctioned by the FDA. In 1992, the agency approved DDC only for use with AZT.
The 3TC/AZT approval was based on data from four clinical trials that showed the combination was more effective in boosting CD4 immune system cells than 3TC alone, AZT alone or AZT in combination with DDC.
The trials showed that patients treated with the combination experienced higher increases of CD4 cells than patients on the other three regimens.
Such an increase in CD4 cells does not necessarily translate into longer life or fewer symptoms, but the FDA--under its so called “fast-track” approach--has agreed to use these signs as preliminary indications of how well a drug works.
On average, CD4 cell counts for those taking the new combination of drugs increased by 30 to 50 cells per cubic milliliter of blood above the levels at the start of the 24-week study.
Side effects of the combination are similar to those of other nucleoside analogs, including nausea, diarrhea, anemia, low white blood cells, inflammation of the pancreas--particularly in children who have taken earlier nucleoside analog therapy--and neuropathy, which is pain and numbness in the extremities.