There are also studies that have shown albumin to increase the intracellular activity of drugs, including protease inhibitors [28,29], perhaps by increasing intracellular concentrations. see more Although the effect of low albumin levels would be expected to be greater in the African population because of the frequency of malnutrition among patients with HIV/AIDS, this may not have clinical implications, as the effect was only observed at treatment baseline. Other parameters related to the severity of HIV disease,

including baseline CD4 cell count and viral load, did not influence efavirenz pharmacokinetics; however, these results should be treated with caution, given the narrow PLX3397 concentration range of CD4 counts of the participants. CD4 counts in this study did not vary widely because the study was conducted in a programme setting and all patients were initiating ART at CD4 cell counts <200 cells/µL, with the exception of those with CDC/WHO stage III or IV disease. The average half-life observed in this study (26 and 27 h on days 1 and 14, respectively) was lower than that reported in other studies [1], and this could largely be explained by the sampling schedule which, for ethical reasons, could not be extended beyond 24 h in these HIV-infected patients

on standard medication. The majority of studies that have reported long expected half-lives of 40–55 h or more were conducted in health volunteers with data collected over a longer time period [30]. The half-life obtained in this study is similar to that obtained

in a study by Ma et al., in which samples were collected over a 12-h period (t1/2 23–30.8 h) [31], although the protease inhibitor amprenavir was co-administered to the volunteers between days 10 and 14 of the study. The mean apparent oral clearance rate found in this study after 2 weeks of treatment (7.4 L/h) was similar to that reported by Kappelhoff et al. (7.9 L/h) [16] but lower than that reported by Zhu et al. (9.2 L/h) [8]. This could be explained by the much greater ethnic diversity among participants in the study of Kappelhoff et al. Masitinib (AB1010) compared with that of Zhu et al., in which the participants were largely White non-Hispanic; the former study also found the clearance rate of efavirenz to be 28% higher in White non-Hispanics than in Africans. The large range of oral clearance rates (1.6–20.6 L/h) observed in this study corresponds to previous findings in Zimbabwe and Uganda, where wide ranges of oral clearance rates were suggested to be largely caused by the high prevalence of CYP2B6 polymorphism in Africa [4,7], leading to the categorization of people as slow, intermediate and fast metabolizers. Mukonzo et al.