A two-drug combination of AZT and 3TC blocks the ability of the AIDS virus to develop resistance to single-drug therapy and appears to be the most effective way of treating the disease, researchers said.
Scientists at the Wellcome Research Laboratories in Kent, England, said that when AZT is taken with 3TC, the combination overcomes the problem of viral resistance that reduces the ef-fective-ness of either drug taken alone.In 24-week-long tests on patients infected with the AIDS virus, the combination caused a drop in the amount of viral infection and a rise in the number of lymphocytes, called CD4 cells, that are the target of the virus.
CD4 cells protect the body from infection and it is their loss that causes AIDS patients to contract infection so easily.
"The combination of AZT and 3TC is the most efficacious pair of drugs tried to date with respect to the magnitude and duration of changes in CD4 cell number and viral load," researchers report this week in Science, the journal of the American Association for the Advancement of Science.
The study was co-authored by Brendan A. Larder, Sharon D. Kemp and P. Richard Harrigan of the Wellcome laboratories.
Both drugs act on the virus by stopping its reproduction, but a laboratory analysis of the combination found that 3TC prevented the AIDS virus from developing a resistance against AZT.