Dose Escalation Study to Determine the Pharmacokinetics of Atazanavir Administered With RIfampicin to HIV Positive Adults on sEcond-line ART Regimen With Suppressed HIV-1 Viral Load

The trial will enrol virologically suppressed HIV infected volunteers who are stable on ATV/r and 2 NRTI containing ART following stringent screening to rule out evidence of renal, hepatic or gastrointestinal dysfunction which may affect the PK evaluation. A steady-state PK (PK1) sample collection shall be done on day 7 (+/-3) after enrolment. RIF will be added at standard dose (600 mg once daily) with a further PK evaluation 14 days later (PK2); due to the potential risk of sub therapeutic PI concentrations and emergence of HIV drug resistant strains, these individuals will be given DTG 50 mg twice daily for the duration of the dose-escalation study. ATV/r dose will be increased in a single step to the total modelled dose (PK3), given as twice daily doses. Once at maximum ATV/r dose, RIF will be increased to 1200 mg once a day for a further seven days (PK4). RIF will then be stopped, ATV/r stepped down to 300/100mg once a day and DTG continued for a further one week.