Raltegravir Pharmacokinetics in Treatment-Naive Patients Is Not Influenced by Race: Results from the Raltegravir Early Therapy in African-Americans Living with HIV (REAL) Study

Racial differences in antiretroviral treatment responses remain incompletely explained and may be a consequence of differential pharmacokinetics (PK) associated with race. Raltegravir, an inhibitor of HIV-1 integrase, is commonly used in the treatment of HIV-infected patients, many of whom are African-American. However, there are few data regarding the PK of raltegravir in African-Americans. HIV-infected men and women, self-described as African-American and naive to antiretroviral therapy were treated with raltegravir (RAL) at 400 mg twice a day, plus a fixed dose of tenofovir-emtricitabine (TDF/FTC) at 300 mg/200 mg once daily. Intensive PK sampling was conducted over 24 h at week 4. Drug concentrations at two trough values of 12 and 24 h after dosing (C(12) and C(24)), area under the concentration-curve values (AUC), maximum drug concentration (C(max)), and the time at which this concentration occurred (T(max)) in plasma were estimated with noncompartmental pharmacokinetic methods and compared to data from a subset of white subjects randomized to the RAL twice a day (plus TDF/FTC) arm of the QDMRK study, a phase III study of the safety and efficacy of once daily versus twice daily RAL in treatment naive patients. A total of 38 African-American participants were enrolled (90% male) into the REAL cohort with the following median baseline characteristics: age of 36 years, body mass index (BMI) of 23 kg/m(2), and a CD4 cell count of 339/ml. Plasma HIV RNA levels were below 200 copies/ml in 95% of participants at week 4. The characteristics of the 16 white QDMRK study participants were similar, although fewer (69%) were male, the median age was higher (45 years), and BMI was lower (19 kg/m(2)). There was considerable interindividual variability in RAL concentrations in both cohorts. Median C(12) in REAL was 91 ng/ml (range, 10 to 1,386) and in QDMRK participants was 128 ng/ml (range, 15 to 1,074). The C(max) median concentration was 1,042 ng/ml (range, 196 to 10,092) for REAL and 1,360 ng/ml (range, 218 to 9,701) for QDMRK. There were no significant differences in any RAL PK parameter between these cohorts of African-American and white individuals. Based on plasma PK, and with similar adherence rates, the performance of RAL among HIV-infected African-Americans should be no different than that of infected patients who are white.