The Effectiveness of Three Drug Combinations in HIV-Infected Patients Who Have Taken Zidovudine for More Than 12 Weeks

To compare the effect of stavudine (d4T) alone or with zidovudine (AZT) versus didanosine (ddI) alone or with AZT on CD4 counts, HIV RNA levels, and viral load in HIV-infected patients \[AS PER AMENDMENT 3/21/97: To compare the effects of d4T alone versus ddI alone versus AZT plus ddI\]. To compare the safety of d4T/AZT. AS PER AMENDMENT 3/21/97: To evaluate the pharmacokinetic interactions of AZT and d4T both at an extracellular and intracellular level. Although AZT and ddI can delay the advancement of HIV disease, the benefit of either of these drugs has proven to be only temporary. d4T, a new nucleoside analog with a favorable toxicity profile and demonstrated activity against HIV, offers an additional therapeutic option. It is reasonably assumed that the benefit of an antiretroviral agent in terms of delaying clinical disease progression is directly related to its ability to achieve and sustain viral suppression; thus, this study measures effects on viral load and CD4 count.

Although AZT and ddI can delay the advancement of HIV disease, the benefit of either of these drugs has proven to be only temporary. d4T, a new nucleoside analog with a favorable toxicity profile and demonstrated activity against HIV, offers an additional therapeutic option. It is reasonably assumed that the benefit of an antiretroviral agent in terms of delaying clinical disease progression is directly related to its ability to achieve and sustain viral suppression; thus, this study measures effects on viral load and CD4 count. Patients are randomized in a blinded fashion to receive AZT or placebo in combination with open-label d4T or ddI for up to 48 weeks. AS PER AMENDMENT 3/21/97: The study is now composed of three arms: open-label d4T versus open-label ddI plus blinded AZT placebo versus blinded AZT plus open-label ddI. Patients originally assigned to the d4T + AZT arm, which was closed 10/96, will be given the option of discontinuing AZT and remaining on d4T monotherapy or discontinuing all study drugs. In addition, all study participants will be asked to participate in a pharmacology substudy.