A new competitor to the only full-regimen pill on the market (Atripla) may emerge within another year or two with the continued development of the "quad pill". This combo pill includes three HIV drugs (the new integrase inhibitor elvitegravir + tenofovir + emtricitabine) and one non-HIV booster drug called cobicistat.
Two 48-week studies included about 150 people who had never been on HIV treatment. The first study compared the quad pill to Atripla, while the second evaluated cobicistat as a booster and compared cobicistat + Reyataz + Truvada to ritonavir + Reyataz + Truvada. CD4 counts ranged 341-436, viral loads were around 45,000, and no one had resistance to NRTIs, NNRTIs or protease inhibitors. Average age was about 35, and 9 out of 10 participants were men.
In the quad vs. Atripla study, higher CD4 count increases occurred with the quad pill (240 vs. 162). Also, side effects occurred less often (about 10%) in those taking the quad pill, and included nausea, vomiting and rash. In the cobicistat vs. ritonavir study, higher CD4 count increases occurred with cobicistat (230 vs. 206). Side effects also occurred less often with the cobicistat regimen, although more severe ones occurred with that regimen. Similar decreases in viral load to below 50 copies were seen in all four groups.
It appears that the new quad pill able to suppress HIV to undetectable levels equally as Atripla, perhaps without the side effects that many experience on Atripla due to Sustiva. It also appears that cobicistat is equal to ritonavir in boosting the protease inhibitor Reyataz.
However, an ongoing concern with cobicistat is its effect on kidney function. At 24 weeks, the drug caused a higher rate of abnormal kidney function in the quad pill study. Over the next 24 weeks, that change in function appeared to level off. Phase 3 study will help to distinguish this concern further.