Browsing by Author "Sinxadi, Phumla Z"

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    Open Access
    Association of lopinavir concentrations with plasma lipid or glucose concentrations in HIV-infected South Africans: a cross sectional study
    (BioMed Central Ltd, 2012-10-26) Sinxadi, Phumla Z; McIlleron, Helen M; Dave, Joel A; Smith, Peter J; Levitt, Naomi S; Maartens, Gary
    Abstract Background Dyslipidaemia and dysglycaemia have been associated with exposure to ritonavir-boosted protease inhibitors. Lopinavir/ritonavir, the most commonly used protease inhibitor in resource-limited settings, often causes dyslipidaemia. There are contradictory data regarding the association between lopinavir concentrations and changes in lipids. Aim To investigate associations between plasma lopinavir concentrations and lipid and glucose concentrations in HIV-infected South African adults. Methods Participants stable on lopinavir-based antiretroviral therapy were enrolled into a cross-sectional study. After an overnight fast, total cholesterol, triglycerides, and lopinavir concentrations were measured and an oral glucose tolerance test was performed. Regression analyses were used to determine associations between plasma lopinavir concentrations and fasting and 2 hour plasma glucose, fasting cholesterol, and triglycerides concentrations. Results There were 84 participants (72 women) with a median age of 36 years. The median blood pressure, body mass index and waist: hip ratio were 108/72 mmHg, 26 kg/m2 and 0.89 respectively. The median CD4 count was 478 cells/mm3. Median duration on lopinavir was 18.5 months. The median (interquartile range) lopinavir concentration was 8.0 (5.2 to 12.8) μg/mL. Regression analyses showed no significant association between lopinavir pre-dose concentrations and fasting cholesterol (β-coefficient −0.04 (95% CI −0.07 to 0.00)), triglycerides (β-coefficient −0.01 (95% CI −0.04 to 0.02)), fasting glucose (β-coefficient −0.01 (95% CI −0.04 to 0.02)), or 2-hour glucose concentrations (β-coefficient −0.02 (95% CI −0.09 to 0.06)). Lopinavir concentrations above the median were not associated with presence of dyslipidaemia or dysglycaemia. Conclusions There was no association between lopinavir plasma concentrations and plasma lipid and glucose concentrations.
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    Open Access
    Efavirenz pharmacogenetics and metabolic toxicity in black South Africans
    (2022) Makgai, Lesiba Meshack; Sinxadi, Phumla Z; Maartens, Gary
    Background: Efavirenz is associated with hepatotoxicity, dyslipidaemia and dysglycaemia. We aimed to determine if CYP2B6 composite metaboliser genotypes influence lipids, glucose and ALT concentrations. Methods: Data and DNA from South African antiretroviral therapy (ART)-naïve participants initiating efavirenz with emtricitabine plus tenofovir disoproxil fumarate (TDF) were used to characterise associations between CYP2B6 metaboliser genotypes and the percentage difference in metabolic parameters from baseline to week 48 using univariate and multivariate linear regression models. Results: A total of 171 participants were successfully genotyped. Median baseline age was 32 years, CD4 count was 292 cells/mm3 and log10 viral load was 4.42 copies/ml. Univariate analyses showed significant associations between CYP2B6 slow metaboliser genotype and total cholesterol (β = 13.78, p = 0.003), LDL cholesterol (β = 15.89, p = 0.008) and HDL cholesterol (β = 24.78, p = 0.002). These associations remained significant in multivariate analyses adjusting for age, sex, weight, baseline CD4 cell count and viral load [total cholesterol (β = 14.93, p< 0.001), LDL cholesterol (β = 15.57, p = 0.014), and HDL cholesterol (β = 24.22, p< 0.001)]. No associations were found between CYP2B6 metaboliser genotype and triglycerides, glucose or ALT. Conclusion: Among Black South African participants on efavirenz-based ART, CYP2B6 slow metaboliser genotype was associated with high cholesterol concentrations. In an African population with high prevalence of CYP2B6 slow metabolisers, close monitoring of lipids is needed.
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    Pharmacogenomics and pharmacokinetics of antiretroviral drugs and their associations with metabolic complications in HIV-infected Black South Africans
    (2016) Sinxadi, Phumla Z; Maartens, Gary; Haas, David W
    BACKGROUND: Antiretroviral therapy (ART), notably efavirenz and lopinavir, have been associated with metabolic abnormalities known to increase cardiovascular risk. Efavirenz and lopinavir pharmacokinetics demonstrate considerable interindividual variability, which in part, may be explained by host genetic factors. Mitochondrial DNA (mtDNA) variation influences ART related metabolic complications. However, the associations between genetic polymorphisms and pharmacokinetics of antiretroviral drugs, and their associations with metabolic complications, are incompletely understood. We explored associations of mitochondrial DNA (mtDNA) haplogroups and ART related metabolic complications, characterized relationships between genetic polymorphisms and plasma efavirenz concentrations, and investigated associations between plasma efavirenz/lopinavir concentrations and lipid and glucose concentrations in HIVinfected Black South Africans. METHODS: We collected clinical and laboratory data from HIV infected patients on ART from Cape Town. We sequenced the mitochondrial genome and determined African mtDNA haplogroups. We genotyped 241 polymorphisms in genes potentially relevant to efavirenz metabolism and transport. We measured steady state efavirenz and lopinavir concentrations and used regression analyses to determine associations with metabolic parameters.