The Effect of Rifampicin on the Pharmacokinetics of Intracellular Tenofovir-diphosphate and Tenofovir When Coadministered With Tenofovir Alafenamide Fumarate During the Maintenance Phase of Tuberculosis Treatment in TB/HIV-1 Coinfected Participants

This is a pharmacokinetic study investigating the effect of rifampicin on the pharmacokinetics of intracellular tenofovir-diphosphate and plasma tenofovir when coadministered with tenofovir alafenamide fumarate during the maintenance phase of tuberculosis treatment in TB/HIV-1 coinfected participants (EpiTAF)

This is an open-label, sequential, single centre pharmacokinetic (PK) study investigating the effect of rifampicin on the pharmacokinetics of intracellular tenofovir-diphosphate and plasma tenofovir when coadministered with tenofovir alafenamide fumarate during the maintenance phase of tuberculosis treatment in TB/HIV-1 coinfected participants (EpiTAF).

An open-label, sequential, pharmacokinetic (PK) drug-drug interaction study will be conducted in medically stable virologically suppressed HIV-1 infected adults coinfected with TB, who are in the maintenance phase of their TB treatment. After intensive PK evaluation of IC TFV-DP and pTFV, participants will be switched from their standard-of-care tenofovir disoproxil fumarate (TDF)/FTC/EFV regimen, to TAF + 3TC + EFV at the start of the study treatment period. After 28 days each participant will have intensive PK evaluation of IC TFV-DP and pTFV on TAF + 3TC + EFV with rifampicin (RIF). After the second intensive PK assessment is completed, participants will be switched back to TDF/FTC/EFV, with a final intensive PK evaluation of IC TFV-DP and pTFV 8 days after completion of TB treatment, at the final study visit. Eighteen volunteers will be enrolled for a target of 13 participants completing the study.

The study includes screening and enrolment visits, 1 visit on day 28 and an end of study visit 28 days after the end of TB treatment.