The European Commission has granted marketing approval for Bristol-Myers Squibb’s protease inhibitor Reyataz, administered with ritonavir, as a once-daily option for first-line therapy in treatment-naive HIV-1 infected adults.

Reyataz (atazanavir) is already approved in Europe for use after the failure of first-line treatment in combination with other antiretrovirals, and has been approved for first-line use in the USA since May 2003. The EU green light is based on the CASTLE study which showed that atazanavir, boosted with ritonavir, was non-inferior to Abbott Laboratories’ Kaletra (lopinavir/ritonavir). The study revealed that 78% who started treatment with once-daily Reyataz had a viral load below 50 copies/ml at week 48, compared to 76% who started treatment with twice-daily Kaletra.

Reyataz was also better tolerated in the main, with a trend towards less diarrhoea and fewer cholesterol and triglyceride increases among those who received the drug. However 34% of those who received atazanavir developed hyperbilirubinemia, an elevation of bilirubin levels in the blood that can lead to jaundice.

Jean-Michel Molina of the Hopital Saint Louis in Paris, France, said that Reyataz is a “very potent and convenient, once-daily protease inhibitor that offers the benefit of good tolerability” and it is the first time that a boosted PI with a once-daily regimen has got the thumbs-up in Europe. “This offers an additional therapy option for both naïve and treatment-experienced patients," he added.