Abstract

Background: Antiretroviral drug combinations affect dolutegravir trough concentrations. Here, the authors focused on dolutegravir plus booster darunavir antiretroviral regimens to investigate the effect of the booster and/or timing of drug administration on dolutegravir and darunavir plasma trough concentrations. Methods: This retrospective observational study included consecutive people with HIV (PWH) receiving dolutegravir plus booster darunavir antiretroviral regimens for at least 3 months, with at least one assessment of dolutegravir and darunavir plasma trough concentrations. Results: A total of 200 drug therapeutic drug monitoring results from 116 PWH were included. Dolutegravir and darunavir trough concentrations ranged, respectively, from 70 to 3648 mcg/L and from 102 to 11,876 mcg/L. The antiretroviral drug combination associated with the highest dolutegravir trough concentration was dolutegravir plus darunavir/cobicistat, both once daily (1410 ± 788 mcg/L), whereas dolutegravir once daily plus darunavir/ritonavir twice daily had the lowest trough concentrations (686 ± 481 mcg/L). Doubling the dose of dolutegravir did not significantly increase drug trough concentrations compared with that of once-daily regimens. Instead, the highest darunavir trough concentrations were with ritonavir (2850 ± 1456 mcg/L, P < 0.05 versus cobicistat-based regimens). Doubling the drug dose resulted in a significant increase in the darunavir trough concentration (4445 ± 2926 mcg/L, P < 0.05). Conclusions: Dolutegravir trough concentrations were significantly reduced in PWH receiving darunavir/ritonavir twice daily. This evidence should be carefully considered in clinical conditions requiring higher dolutegravir exposure, such as in the presence of drug–drug interactions with drugs known to reduce dolutegravir bioavailability or in highly experienced PWH.