Tenofovir diphosphate intracellular concentration following tenofovir alafenamide administration in bictegravir-containing vs. dolutegravir-containing antiretroviral regimens

: This study investigates intracellular (IC) exposure of tenofovir alafenamide (TAF) and its clinical determinants in experienced people living with HIV. We conducted a monocentric retrospective analysis of 86 adults treated with either bictegravir (BIC)- or dolutegravir (DTG)-containing regimen. Plasma and IC trough concentrations (Ctrough) of tenofovir diphosphate (TFV-DP) were examined in relation to demographic and renal parameters. A significant correlation emerged between plasma and IC TFV-DP Ctrough. Higher plasma TFV levels were associated with older age and reduced estimated glomerular filtration rate. Adherence calculated as proportion of days covered (PDC) did not differ between regimens. These findings provide novel real-world insights into IC TFV-DP pharmacokinetics and suggest that BIC-containing regimens may enhance IC drug accumulation, although the impact of this observation on virological outcomes requires further studies.