Coverage of CROI 2008 (Conference on Retroviruses and Opportunistic Infections)

February 4–6, 2008, Boston, MA

Truvada appears to improve limb fat loss

February 5, 2008

A poster presented at CROI shows that people switching from Combivir to Truvada had increases in limb fat and no changes in HIV levels, kidney function and bone mass. The SWEET study looked at 234 people on stable regimens of Sustiva (efavirenz) + Combivir (Retrovir/AZT + Epivir/lamivudine). Half were randomly switched from Combivir to Truvada (Viread/tenofovir + Emtriva/emtricitabine) while the other half stayed on Combivir. Participants were given DEXA scans, which look at bone and fat.

After 48 weeks, people on Truvada gained an average of 0.2kg of limb fat. Those who stayed on Combivir lost an average of just less than 0.2kg. The effects were greatest in people who had taken Retrovir for less than 3 years and with less limb fat at the start of the study. There are concerns with Truvada over kidney function and bone loss. In both cases there were trends toward more problems with Truvada than Combivir, but they were not significant.

These results confirm what has been known for some time. Combivir, which was the first fixed-dose combination pill, has a higher risk of limb fat loss than Truvada. This switch study showed that the loss of fat on Combivir could be somewhat reversed with a switch to Truvada. While there were no significant differences between the groups on measures of bone or kidney health, there were small trends that tend to confirm the concerns about Truvada. People who consider switching from one drug to another should consider all the pros and cons with their health providers.