In April 2010, the FDA approved the once-a-day dosing of Kaletra (lopinavir + ritonavir) for adults who have taken HIV therapy before but with two or less lopinavir mutations. This new dose is not recommended for those with 3 or more of the following mutations: L10F/I/R/V, K20M/N/R, L24I, L33F, M36I, I47V, G48V, I54L/T/V, V82A/C/F/S/T, and I84V.
Results from the M06-802 study of nearly 600 people compared Kaletra taken once a day to twice a day. All participants had never taken lopinavir before, and all had viral loads of at least 1,000 before starting Kaletra. (Viral loads of 1,000 or more are necessary to run resistance tests to identify mutations.) About 1/3 were women. All took two NRTIs in addition to Kaletra.
However, taking Kaletra twice a day may still be a better choice for some individuals. Results from another study, ACTG 5076, followed 321 people who took Kaletra either once or twice a day with 2 NRTIs. Although adherence was better in those taking Kaletra once a day, for those with viral loads above 100,000, their HIV levels weren't as well controlled. 89% on twice a day Kaletra were undetectable at 48 weeks, while only 76% of those on once a day were undetectable.
In the end, once a day dosing can improve adherence rates in general, and once-a-day Kaletra seems to be safe and effective in people with lower viral loads. However, for those whose viral loads are above 100,000, they may want to take Kaletra twice a day to more fully control HIV.