New boosting agent equivalent to Ritonavir

The new boosting drug cobicistat is equivalent to ritonavir (Norvir) when used to enhance levels of atazanavir (Reyataz), results of a study presented to the Washington conference show.

The potency of several anti-HIV drugs, including most protease inhibitors, is enhanced by taking a small boosting dose of the protease inhibitor ritonavir.

Until recently, ritonavir was the only available boosting agent.

However, a new drug called cobicistat has now been developed. Unlike ritonavir it has no activity against HIV.

Researchers compared the outcomes of people taking first-line HIV treatment based on atazanavir according to whether the protease inhibitor was taken in combination with cobicistat or ritonavir.

After 48 weeks of treatment, study participants taking the cobicistat booster were just as likely as those treated with ritonavir to have an undetectable viral load (85 vs 87%).

CD4 cell count increases were also comparable for the two agents, as was the frequency of side-effects.