A meta-analysis of the relative effects of both pill burden (the number of pills taken per day) and dosing frequency of antiretroviral (ARV) regimens has found that cocktails with fewer pills are linked to better drug adherence and virologic suppression, and that adherence is better among those on once- versus twice-daily regimens, but only modestly.

Publishing their findings in Clinical Infectious Diseases, researchers compiled 19 randomized controlled trials, including 6,312 participants, that compared once-daily with twice-daily ARV dosing and had information about adherence and virologic suppression.

The researchers found that, on average, adherence was modestly improved for those taking once-daily ARV regimens when compared with those taking twice-daily regimens. There was no difference in virologic suppression rates between the two groups, however. Adherence and virologic suppression rates both tapered among those taking once- or twice-daily regimens as time passed. However, these decreases were greater among those taking twice-daily doses.

Having to take a larger number of pills each day, regardless of whether the dosing schedule was once- or twice-daily, was linked with lower adherence and worse virologic suppression rates. But for those taking once-daily regimens, this difference was not statistically significant, meaning it could have happened by chance.

To read the study abstract, click here.