In this study, 78% of the 440 patients in the Reyataz /r arm met the primary endpoint of achieving undetectable viral load (defined as HIV-1 RNA less than 50 copies/mL) at 48 weeks, compared with 76% of the 443 patients in the lopinavir/r arm. The Reyataz /r arm was associated with significantly lower increases from baseline compared to the lopinavir/r arm in total cholesterol, triglycerides and non-HDL cholesterol at 48 weeks (p<0.0001). Two percent of patients in the Reyataz /r arm and seven percent of patients in the lopinavir/r arm required initiation of lipid-lowering therapy in the study. Nine percent of patients in the Reyataz /r arm and 13% of patients in the lopinavir/r arm discontinued the study therapy before week 48. Castle is the first large-scale, open-label, randomized study designed to demonstrate the non-inferiority of Reyataz /r to lopinavir/r in previously untreated HIV-1 infected adult patients.