Results from a study presented at the joint 2008 ICAAC/IDSA meeting in Washington, DC found that people on a stable, suppressive HIV regimen can maintain control of their HIV if they switch to the fixed-dose combination pill Atripla (efavirenz + tenofovir + emtricitabine/FTC). The same study also found a somewhat higher risk of side effects for those who switched.

In this study, 300 people with undetectable HIV on a stable regimen were randomly assigned (2:1) to either switch to Atripla or stay on their same regimen. In all, 207 people were picked to switch, and 97 stayed on their current regimen. The study evaluated HIV levels as well as the frequency and type of side effects experienced.

Both strategies worked quite well in the study. After 48 weeks, 87% of people who switched to Atripla had HIV levels below 50, compared to 85% of people who stayed on their regimen -- a difference not considered to be statistically significant. CD4 counts stayed stable, raising only a small amount in both groups.

People who had taken an NNRTI before were somewhat more likely to stay undetectable if they switched, while those who had taken protease inhibitors were somewhat more likely to stay undetectable if they stayed on their old regimen. The differences between these groups were small and appeared to be due mostly to people who were lost to follow up during the study.

There were significantly more side effects reported by people who switched. This is not surprising for two reasons. First, people had been on their old regimens for at least 3 months, with an average time on their pre-study regimen of 2.5?3 years. Side effects are always more likely when switching from a well tolerated regimen to any new regimen.

Secondly, most of the side effects reported were typical of efavirenz, including dizziness and sleep disturbances. Few people stopped their regimens due to side effects -- a fairly reliable measure of tolerability.

Over 90% of people in the study said they would prefer to take a regimen that was one pill taken once a day. 97% of people switched to Atripla said their regimen was easy to take, compared to 81% of people who didn't switch. Adherence was high in both groups, with no meaningful difference.

Atripla is the most commonly used HIV drug combination for people taking their first regimen. This study suggests it can also be used safely by people who have taken other drug regimens and who are looking for a simpler regimen.