The extremely high prevalence of HIV/AIDS in sub-Saharan Africa and limitations of current antiretroviral medicines demand new tools to optimize therapy such as pharmacogenomics for person-toperson variations. African populations exhibit greater genetic diversity than other world populations, thus making it difficult to extrapolate findings from one population to another. Nevirapine, an antiretroviral medicine, displays large plasma concentration variability which adversely impacts therapeutic virological response. This study, therefore, aimed to identify sources of variability in nevirapine pharmacokinetics and pharmacodynamics, focusing on genetic variation in CYP2B6 and CYP1A2. Using a cross-sectional study design, 118 HIV-infected adult Zimbabwean patients on nevirapine-containing highly active antiretroviral therapy (HAART) were characterized for three key functional single nucleotide polymorphisms (SNPs), CYP2B6 c.516G>T (rs3745274), CYP2B6 c.983T>C (rs28399499), and CYP1A2 g.-163C>A (rs762551). We investigated whether genotypes at these loci were associated with nevirapine plasma concentration, a therapeutic biomarker, and CD4 cell count, a biomarker of disease progression. CYP2B6 and CYP1A2 were chosen as the candidate genes based on reports in literature, as well as their prominence in the metabolism of efavirenz, a drug in the same class with nevirapine. Nevirapine plasma concentration was determined using LC-MS/MS. The mean nevirapine concentration for CYP2B6 c.516T/T genotype differed significantly from that of 516G/G ( p < 0.001) and 516G/T ( p < 0.01) genotypes, respectively. There were also significant differences in mean nevirapine concentration between CYP2B6 c.983T > C genotypes ( p = 0.04). Importantly, the CYP1A2 g.-163C>A SNP was significantly associated with the pharmacodynamics endpoint, the CD4 cell count ( p = 0.012). Variant allele frequencies for the three SNPs observed in this Zimbabwean group were similar to other African population groups but different to observations among Caucasian and Asian populations. We conclude that CYP2B6 c.516G>T and CYP2B6 c.983T>C could be important sources of nevirapine pharmacokinetic variability that could be considered for dosage optimization, while CYP1A2 g.-163C>A seems to be associated with HIV disease progression. These inter-and intra-population pharmacokinetic and pharmacodynamics differences suggest that a single prescribed dosage may not be appropriate for the treatment of disease. Further research into a personalized nevirapine regimen is required.

Background:Antiretroviral therapy (ART) to suppress HIV replication has reduced morbidity and mortality yet effectiveness of current HIV drugs is threatened by HIV drug resistance (HIVDR) mutations.Objective:To determine HIVDR mutations using proviral DNA from specimens of patients presenting to an HIV treatment clinic.Methods:DNA from 103 patients, 86 treatment-experienced, 17 treatment-naïve, were genotyped for the HIV-1C reverse transcriptase gene (RT; codons 21-304) using Sanger sequencing and sequences analyzed using Sequencher software. Resistance mutations were interpreted using Stanford HIVDR reference database.Results:Median age was 39 (IQR, 33-46) years and 80% of patients were female. Six-percent (n=6) had at least one HIVDR mutation, comprising NRTI-associated mutations, (M184V, T69D, T69N and V75I); NNRTI-associated mutations (G190A, K103N, V106M, Y181C) and thymidine analogue associated mutations (D67N, K70R, K219Q, L210W, M41L, T215Y). Of the six participants, with at least one HIVDR mutation, all were treatment experienced, five were on tenofovir, lamivudine and nevirapine and one was on tenofovir, lamivudine and atazanavir. There was no difference in median CD4 count and viral loads when patients were compared by presence of HIVDR mutations.Conclusion:We demonstrated the use of proviral DNA in HIVDR testing in adult patients and present that all the patients with various kinds of HIVDR mutations were treatment experienced, pointing to the role of drug regimens in driving viral mutations. Thus, the use of proviral DNA has potential to help provide surveillance on risk of HIVDR in HIV-infected individuals who are on treatment, which may assist in corrective treatment.