About The Study

This study compared AZT combined with ddI vs AZT combined with ddC.

Study Approach

This was an open-label trial (both investigators and volunteers knew which treatment was being given). Participants were divided according to AZT exposure and CD4 counts, and were randomly assigned to receive one of the two treatment regimens. Clinical and lab assessments, including viral load, were done monthly for the first three months, and at the fifth and seventh months.

Study population

One hundred and thirty-six HIV-positive volunteers were randomized. The participants had not taken ddI or ddC in the past. They had CD4 counts between 50 and 300. Of the 136 participants, 67 were randomly assigned to ddI and 69 to ddC. The average age was 38, 93% were male, 74% were gay or bisexual and 1.5% had AIDS. The median CD4 count was 230 and viral load was 3.6 logs at enrollment.


There were no significant differences in CD4 counts or viral load over time between the two groups. Participants in both groups experienced a one log drop in viral load by week two which was sustained for the seven months of the study. Both drugs were well-tolerated.


The use of AZT with either ddI or ddC is associated with an increase in CD4 counts and a decrease in viral load. The short-term safety of the two regimens was considered similar.