The Pharmacokinetics and Safety of IDV/r With NRTIs in HIV/TB Co-infected Patients Receiving Rifampicin

We believe that there is a strong rationale for the study of IDV/r 600/100 bid as a boosted-PI combination that, in the presence of RMP, is able to produce a satisfactory PK profile associated with adequate antiretroviral potency, tolerability and efficacy.

The fixed-dose combination of d4T+3TC+NVP (GPOvir) has been widely used in Thailand since June 2002. The prevalence of NNRTI resistance has increased since 2005. Efavirenz-based antiretroviral therapy (ART) is preferred in patients with TB/HIV receiving rifampin-containing TB regimens. However, efavirenz cannot be used in the context of NNRTI failure, intolerance or toxicity. The optimal ART in populations receiving rifampicin remains unknown. Rifabutin, which is recommended in combination with a boosted protease inhibitor (PI/r) is expensive and not available in Thailand and other developing countries. Ritonavir-boosted indinavir (IDV/r) is potent and the cheapest boosted PI available in Thailand. If IDV/r in combination with rifampin demonstrates suitable pharmacokinetics and is well tolerated, this regimen might prove useful and could be widely implemented. However, high rates of gastrointestinal and renal toxicity have been demonstrated in Thai patients receiving standard doses of IDV/r 800/100 BID. We believe that there is a strong rationale to study if IDV/r 600/100 BID in combination with rifampin is able to produce a satisfactory pharmacokinetic profile, with antiretroviral potency, tolerability and efficacy.