1281. Rifampicin and Tenofovir Alafenamide Containing Regimen Drug Interaction in People Living with HIV: Case Series Report

Abstract Background Owing to the excellent safety and efficacy profile of the tenofovir alafenamide (TAF) over tenofovir disoproxil fumarate (TDF), it is the preferred prodrug of tenofovir (TFV) implicated in the management of people living with HIV (PLWH). PLWH are more susceptible to having tuberculosis (TB) and therefore, rifampicin (RIF) use as a key component of antituberculosis therapy is frequently indicated. However, since TAF is a substrate for drug transporters such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) and RIF being an inducer for these transporters, the concomitant use of RIF and TAF is not recommended. The magnitude of this drug-drug interaction in PLWH is not known. Hence, the objective of this study was to Methods We retrospectively reviewed the charts of PLWH (≥ 18 years old) seen in our center and who received the TAF-containing regimens and RIF together for ≥ 4 weeks. Demographic data were described using descriptive statistics. We defined the clinical impact as the following: 1- maintaining viral suppression (< 20 copies/mL) for those with suppressed viral load at baseline, 2- the attainment of the viral load suppression (< 20 copies/mL) for those with unsuppressed viral load at baseline. The clinical impact was assessed from the RIF initiation to the end of the therapy. Results A total of 6 PLWH were identified, 5 (83.3%) of them were males. The median (IQR) age was 41.5 years old (49.25 to 36). All patients received dolutegravir 50 mg twice daily (DTG) plus the combination of TAF 25 mg and emtricitabine 200 mg (FTC) once daily as their antiretroviral regimen. Pulmonary tuberculosis was the indication for RIF in all the cases. The RIF dose of 600 mg was the most frequently prescribed (83.3%). The mean (±SD) duration of RIF-TAF co-administration was 30 weeks (2.8). Four patients had suppressed viral load levels at baseline, which was maintained throughout the course of TB treatment. Two patients had unsuppressed viral load levels at baseline and attained viral load suppression throughout the treatment course. Conclusion This case series study demonstrated the possibility of RIF-TAF co-administration, without attenuation the efficacy of TAF, however further work on a large sample is needed to confirm our findings. Disclosures All Authors: No reported disclosures.