Browsing by Author "Sinxadi, Phumla"

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    Association of lopinavir concentrations with plasma lipid or glucose concentrations in HIV-infected South Africans: a cross sectional study
    (BioMed Central Ltd, 2012) Sinxadi, Phumla; McIlleron, Helen; Dave, Joel; Smith, Peter; Levitt, Naomi; Maartens, Gary
    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) mug/mL. Regression analyses showed no significant association between lopinavir pre-dose concentrations and fasting cholesterol (beta-coefficient 0.04 (95% CI 0.07 to 0.00)), triglycerides (beta-coefficient 0.01 (95% CI 0.04 to 0.02)), fasting glucose (beta-coefficient 0.01 (95% CI 0.04 to 0.02)), or 2-hour glucose concentrations (beta-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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    Clinical, pharmacokinetic, and genetic determinants of change in serum creatinine among Southern Africans on dolutegravir based antiretroviral therapy
    (2023) Mpofu, Rephaim; Sinxadi, Phumla; Maartens Gary
    Introduction: Dolutegravir increases serum creatinine by inhibiting renal secretion of creatinine, potentially resulting in inappropriate regimen switches. We investigated determinants of early changes in serum creatinine in a Southern African cohort starting dolutegravir-based antiretroviral therapy. Methods: We conducted a secondary analysis of data from participants in a randomised controlled trial of dolutegravir with tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide fumarate (TAF) plus emtricitabine (ADVANCE, NCT03122262). We assessed clinical, pharmacokinetic, and genetic factors associated with the change in serum creatinine from baseline to week 4 using linear regression adjusting for age, sex, baseline serum creatinine, HIV-1 RNA viral load, CD4 T-cell count, total body weight, and co-trimoxazole use. Results: We included 689 participants, of whom 470 had pharmacokinetic data and 315 had genetic data. Mean change in serum creatinine was 11.3 µmol.L-1. Dolutegravir area under the 24-hour concentration-time curve (change in creatinine regression coefficient [β] = 2.78 [95% confidence interval 0.54, 5.01]) and male sex (β = 5.20 [2.92, 7.48]) were associated with an increased change in serum creatinine at week 4, while higher baseline serum creatinine (β = -0.22 [-0.31, -0.12]), use of TAF (β = -2.30 [-4.06, -0.53]) and Uridine glucuronosyltransferase 1A1 (UGT1A1) polymorphism rs929596 (β = -2.33 [-4.49, -0.17]; not significant after adjustment for multiple comparisons) were associated with a decreased change in serum creatinine. Conclusion: We identified clinical and pharmacokinetic determinants of change in serum creatinine in participants starting a dolutegravir-based regimen. UGT1A1 polymorphisms may play a role, but further research on genetic determinants is needed.
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    Lack of association between stavudine exposure and lipoatrophy, dysglycaemia, hyperlactataemia and hypertriglyceridaemia: a prospective cross sectional study
    (BioMed Central Ltd, 2010) Sinxadi, Phumla; van der Walt, Jan-Stefan; McIlleron, Helen; Badri, Motasim; Smith, Peter; Dave, Joel; Levitt, Naomi; Maartens, Gary
    BACKGROUND: Stavudine continues to be widely used in resource poor settings despite its toxicity. Our objective was to determine association between plasma stavudine concentrations and lipoatrophy, concentrations of glucose, lactate and triglycerides. METHODS: Participants were enrolled in a cross-sectional study with lipoatrophy assessment, oral glucose tolerance test, fasting triglycerides, finger prick lactate, and stavudine concentrations. Individual predictions of the area under the concentration curve (AUC) were obtained using a population pharmacokinetic approach. Logistic regression models were fitted to assess the association between stavudine geometric mean ratio > 1 and impaired fasting glucose, impaired glucose tolerance, hyperlactataemia, hypertriglyceridaemia, and lipoatrophy. RESULTS: There were 47 study participants with a median age of 34 years and 83% were women. The median body mass index and waist:hip ratio was 24.5 kg/m2 and 0.85 respectively. The median duration on stavudine treatment was 14.5 months. The prevalence of lipoatrophy, impaired fasting glucose, impaired glucose tolerance, hyperlactataemia, and hypertriglyceridaemia were 34%, 19%, 4%, 32%, and 23% respectively. Estimated median (interquartile range) stavudine AUC was 2191 (1957 to 2712) ng*h/mL. Twenty two participants had stavudine geometric mean ratio >1. Univariate logistic regression analysis showed no association between stavudine geometric mean ratio >1 and impaired fasting glucose (odds ratio (OR) 2.00, 95% CI 0.44 to 9.19), impaired glucose tolerance (OR 1.14, 95% CI 0.07 to 19.42), hyperlactataemia (OR 2.19, 95%CI 0.63 to 7.66), hypertriglyceridaemia (OR 1.75, 95%CI 0.44 to 7.04), and lipoatrophy (OR 0.83, 95% CI 0.25 to 2.79). CONCLUSIONS: There was a high prevalence of metabolic complications of stavudine, but these were not associated with plasma stavudine concentrations. Until there is universal access to safer antiretroviral drugs, there is a need for further studies examining the pathogenesis of stavudine-associated toxicities.
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    Pharmacogenetics of Tenofovir (Alafenamide or Disoproxil Fumarate Prodrug) Renal Toxicity in HIV positive Black Southern Africans
    (2022) Mateza, Somila; Sinxadi, Phumla; Haas, David W; Maartens, Gary
    Background: Among individuals treated for HIV-1 infection, renal toxicity is more likely with tenofovir disoproxil fumarate (TDF) than with tenofovir alafenamide (TAF). Limited previous studies suggest potential genetic associations with TDF-associated renal toxicity. We hypothesized that polymorphisms in genes of potential relevance to tenofovir, TDF and TAF disposition are associated with renal toxicity in people living with HIV in Southern Africa. Material and Methods: Adult participants randomized to initiate TAF or TDF (each given with emtricitabine) in the dolutegravir arms of the ADVANCE trial had the option to co-enrol in a pharmacogenetic sub-study. We assessed changes from week 4 (to minimize impact of early dolutegravir-induced increases in creatinine) to week 48 in estimated glomerular filtration rate (eGFRCKD-EPI), and log-transformed changes from baseline to week 48 in urine retinol binding protein and urine β2-microglobulin, each adjusted for urinary creatinine (uRBP/Cr and uB2M/Cr, respectively). Genotyping was done using Illumina MEGAEX, followed by imputation with TOPMed. Genetic associations with each renal outcome (eGFR, uRBP/Cr and uB2M/Cr) were assessed using multivariable linear regression models adjusting for age, sex, treatment group, and screening body mass index, CD4 count, and log10 HIV-1 RNA. Primary analyses prioritized 14 polymorphisms previously reported to be associated with tenofovir disposition or renal tubular dysfunction, and all polymorphisms (+/- 50 kB) in selected genes of interest: ABCB1, ABCC2, ABCC4, ABCC10, ABCG2, AK2, AK3, CES1, CYP3A4, NME1, SLC22A2, SLC22A6, SLC22A8 and SLC22A11. We also explored associations genome-wide. Results: In ADVANCE, 336 participants randomized to either TAF or TDF consented to genetic testing. All were Black-African, 63% were female, median age was 32 years, CD4 count 292 cells/μL, and log10 HIV-1 RNA 4.4 copies/mL. Among the 14 polymorphisms of primary interest, the lowest Pvalues for change in eGFR, uRBP/Cr and uB2M/Cr were ABCC4 rs899494 (P = 0.021), ABCC10 rs2125739 (P = 0.07), and ABCC4 rs1059751 (P = 0.0087), respectively. Among genes of interest, the lowest P-values for change in eGFR, uRBP/Cr and uB2M/Cr were ABCC4 rs4148481 (P = 1.5x10-4 ), rs691857 (P = 3.2x10-4 ), and PKD2 rs72659631 (P = 8.6x10-4 ), respectively. In genome-wide analyses, the lowest P-values for change in eGFR, uRBP/Cr, and uB2M/Cr were COL27A1 rs1687402 (P = 3.2x10-9 ), CDH4 rs66494466 (P = 3.4 x 10-8 ), and ITGA4 rs3770126 (P = 4.5 x10-7 ), respectively. Conclusions: Among Southern African participants in a randomized trial of dolutegravir plus either TAF/emtricitabine or TDF/emtricitabine, two polymorphisms previously associated with TDF renal toxicity, ABCC4 rs899494 and ABCC4 rs1059751, were nominally associated with change in eGFR and uB2M/Cr, respectively, but did not withstand correction for multiple testing (nor did associations in genes of interest). A polymorphism in COL27A1, which encodes collagen type XXVII alpha 1 chain, was genome-wide associated with change in eGFR. These findings enhance our understanding of the impact of human genetics on tenofovir-associated renal toxicity.
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    Pharmacogenomics and pharmacokinetics of dolutegravir and tenofovir in Southern Africans living with HIV
    (2023) Cindi, Zinhle Andile; Sinxadi, Phumla
    Background The World Health Organization (WHO) recommends dolutegravir in combination with a nucleos(t)ide reverse transcriptase inhibitor (NRTI) backbone as the preferred first-line regimen for people living with HIV (PLWHIV) initiating antiretroviral therapy (ART). Tenofovir alafenamide (TAF) and tenofovir disoproxil fumarate (TDF) are both prodrugs of tenofovir. However, plasma tenofovir exposure is higher when given as TDF, and TAF yields lower plasma but higher intracellular tenofovir concentrations. Although generally well tolerated, excessive weight gain has been associated with dolutegravir and (TAF) in PLWHIV initiating ART or those switching from efavirenz- or TDF-containing ART. Interindividual variability in dolutegravir and tenofovir pharmacokinetics or the interindividual differences in host response may, in part, be explained by host genetics. We characterized associations between genetic polymorphisms and dolutegravir exposure, tenofovir clearance and magnitude of weight gain in Southern Africans initiating ART. Methods We collected clinical and laboratory data in adults randomized to initiate TAF or TDF in dolutegravir-containing arms of the ADVANCE trial (NCT03122262). We measured dolutegravir and tenofovir concentrations and developed population pharmacokinetic models for dolutegravir and tenofovir using non-linear mixed-effects modelling. Genome-wide genotyping followed by imputation was performed. Linear regression models examined associations between genetic polymorphisms and unexplained variability in dolutegravir area under the concentration-time curve (AUCVAR), unexplained variability in tenofovir clearance, and percentage weight gain from baseline to week 48. Results Considering genetic associations with unexplained variability in dolutegravir area under the concentration-time curve (AUCVAR), the lowest P-value with AUCVAR was UGT1A1 rs887829 (P = 1.8 x 10-4 ), which was also associated with log10 bilirubin (P = 8.6 x 10-13). After adjusting for rs887829, AUCVAR was independently associated with rs28899168 in the UGT1A locus (P = 0.02), as were bilirubin concentrations (P = 7.7 x 10-8 ). In the population pharmacokinetic model, compared to C/C, rs887829 T/T and C/T were associated with 25.9% and 10.8% decreases in dolutegravir clearance, respectively. There were no significant genome-wide associations. Considering genetic associations with unexplained variability in tenofovir clearance, we found no significant associations with tenofovir clearance for either TAF or TDF among 5 polymorphisms previously associated with tenofovir pharmacokinetics (lowest P-value > 0.3 for each drug). Among 11 polymorphisms selected based on both prior strong association with any drug phenotype in PharmGKB and any genome-wide association with any trait in the GWAS catalog, IFNL4 rs12979860 T>C was significantly associated with increased tenofovir clearance (TAF: P = 0.003; TDF: P = 0.003). In genome-wide analyses, the lowest P-values for tenofovir clearance in the TAF and TDF arms were with LINC01684 rs9305223 (P = 3.0 x 10-8 ) and intergenic rs142693425 (P = 1.4 x 10-8 ), respectively. Four additional polymorphisms were genome-wide significant. In genome-wide multivariate linear regression analyses adjusting for baseline age, sex, concomitant NRTI, and population stratification, there were no significant associations between 59 polymorphisms relevant to dolutegravir and tenofovir disposition and the percentage weight gain. We found a genome-wide significant association between TMEM163 rs7590091 and percentage weight gain from baseline to week 48 (P = 3.7 x 10-8 ). Conclusion Among Southern African people living with HIV randomized to TAF or TDF, we identified several potential genetic associations with dolutegravir exposure, tenofovir clearance and weight gain. The novel associations between dolutegravir AUCVAR and rs28899168, tenofovir clearance and IFNL4 rs12979860, and weight gain and TMEM163 rs7590091 require independent replication. These findings enhance our understanding of dolutegravir and tenofovir pharmacogenetics among Southern Africans living with HIV.
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    Pharmacokinetic-Pharmacogenetic-and-Pharmacodynamic Adherence Relationships in Cohort South African HIV Infected Children on Lopinavir-and Nevirapine-Based Regimens
    (2019) Moholisa, Retsilisitsoe R; McIlleron, Helen; Maartens, Gary; Sinxadi, Phumla
    Background: Antiretroviral therapy (ART), notably lopinavir and nevirapine substantially reduces Human immune-deficiency virus (HIV) associated morbidity and mortality in HIVinfected children. Low concentrations of nevirapine and lopinavir have been linked to inferior virological outcomes; it is recommended that lopinavir and nevirapine concentrations are maintained above 1 mg/L and 3 mg/L, respectively, in order to maintain viral suppression. Adherence to both lopinavir and nevirapine ART, respectively has long known to be a crucial contributor to HIV treatment success. Lopinavir and nevirapine pharmacokinetics demonstrate considerable inter-individual variability, which may affect treatment outcomes. At least part of this variability may be explained by host genetic factors. Associations between human genetic variants and exposure to lopinavir and nevirapine are incompletely understood, and have not been studied in a South African paediatric population. Data in this thesis were from a clinical trial conducted at Rahima Moosa Mother and Child Hospital in Johannesburg to assess whether NVP can be re-used (Post-randomization Phase) among 323 children exposed to NVP for PMTCT if they are first suppressed on ritonavir-boosted lopinavir based regimen (Pre-randomization Phase). This thesis assessed the relationship between serial clinic visits lopinavir (Pre-and-Post-randomization) and nevirapine (Postrandomization) concentrations and/or percentage adherence(Pre-and-Post-randomization) and virological outcomes in children. Moreover, population pharmacokinetics models were used to characterise lopinavir and nevirapine parameters. From the final models parameters were derived and were used to assess the relationship between lopinavir and nevirapine pharmacokinetics and genetic polymorphism relevant to both drugs Methods: Cox proportional hazard regression modelling for multiple failure events was used to estimate the crude and adjusted hazard effect of lopinavir (Pre-and Post-randomization) and nevirapine(Post-randomization) concentrations and/or percent adherence(Pre-and Post-randomization) of viral load>400 copies/mL (Pre-randomization) and >50 copies/mL (Post-randomization), respectively. The population means and variances of lopinavir and nevirapine pharmacokinetic parameters at steady state were estimated using non-linear mixed-effects regression. The final models of lopinavir and nevirapine were used to derive individual clearances (CL/F), minimum concentrations (Cmin) and area under the concentration time curves (AUC). The associations between model-derived pharmacokinetic parameters and genotypes in selected genes relevant to lopinavir or nevirapine were explored. Results: In 237 children pre-randomization with viral loads and lopinavir concentrations, the crude and adjusted Cox models revealed significant associations between virologic failure (viral load>400 copies/mL) and both lopinavir plasma concentrations (<1/mg/L) and pretreatment height-for-age z-scores but not percent adherence. In 99 children postrandomization, lopinavir concentrations >1 mg/L reduced the risk of viremia (viral load >50 copies/mL) with about 40%, compared to children with LPV <1 mg/L. No association was found with percent adherence in this group. In 95 children on nevirapine post-randomization, nevirapine concentrations were not significantly associated with increased hazard of viremia (viral load >50 copies/mL). Similarly, there was no significant association with percent adherence in this group. Lopinavir and nevirapine pharmacokinetics were both separately best described with a one compartment models with absorption lag time and transit compartment absorption models, respectively. There was an age driven effect on lopinavir and nevirapine relative bioavailability, respectively. After adjusting for multiple testing, there was no significant association between lopinavir CL/F, Cmin and AUC and genetic polymorphisms in the ABCB1, CYP3A4, CYP3A5 and SLCO1B1. CYP2B6 516G→T and CYP2B6 983T→C were associated with NVP CL/F. CYP2B6 983T→C was associated with NVP Cmin and AUC. Additionally, polymorphisms in the ABCB1 and CYP3A5 were independently associated with NVP CL/F, Cmin and AUC. Conclusions: Lopinavir concentrations <1mg/L were associated with the increased hazard of viremia (viral load >400 copies/mL or >50 copies/mL). The results suggest that lopinavir plasma concentration monitoring at a routine clinic visit may be a useful tool in identifying sub-therapeutic antiretroviral concentrations in children, and this could be used as a guide to therapeutic drug monitoring in children. There was no statistically significant association between polymorphisms in the ABCB1, CYP3A4, CYP3A5 and SLCO1B1 and lopinavir pharmacokinetics. Polymorphisms in the ABCB1, CYP2B6 CYP3A4 and CYP3A5 predicted nevirapine pharmacokinetics.
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    Towards Evidence-Based Implementation of Pharmacogenomics in Southern Africa: Comorbidities and Polypharmacy Profiles across Diseases
    (Multidisciplinary Digital Publishing Institute, 2023-07-26) Soko, Nyarai Desiree; Muyambo, Sarudzai; Dandara, Michelle T. L.; Kampira, Elizabeth; Blom, Dirk; Jones, Erika S. W.; Rayner, Brian; Shamley, Delva; Sinxadi, Phumla; Dandara, Collet
    Pharmacogenomics may improve patient care by guiding drug selection and dosing; however, this requires prior knowledge of the pharmacogenomics of drugs commonly used in a specific setting. The aim of this study was to identify a preliminary set of pharmacogenetic variants important in Southern Africa. We describe comorbidities in 3997 patients from Malawi, South Africa, and Zimbabwe. These patient cohorts were included in pharmacogenomic studies of anticoagulation, dyslipidemia, hypertension, HIV and breast cancer. The 20 topmost prescribed drugs in this population were identified. Using the literature, a list of pharmacogenes vital in the response to the top 20 drugs was constructed leading to drug–gene pairs potentially informative in translation of pharmacogenomics. The most reported morbidity was hypertension (58.4%), making antihypertensives the most prescribed drugs, particularly amlodipine. Dyslipidemia occurred in 31.5% of the participants, and statins were the most frequently prescribed as cholesterol-lowering drugs. HIV was reported in 20.3% of the study participants, with lamivudine/stavudine/efavirenz being the most prescribed antiretroviral combination. Based on these data, pharmacogenes of immediate interest in Southern African populations include ABCB1, CYP2B6, CYP2C9, CYP2C19, CYP2D6 CYP3A4, CYP3A5, SLC22A1, SLCO1B1 and UGT1A1. Variants in these genes are a good starting point for pharmacogenomic translation programs in Southern Africa.
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    Treatment of HIV associated neurocognitive disorders
    (2018) Decloedt, Eric Hermann; Maartens, Gary; Joska, John; Sinxadi, Phumla
    Background Human immunodeficiency virus (HIV) invades the central nervous system (CNS) as early as 8 days after HIV infection, causing a wide spectrum of neuropathological changes including HIV associated neurocognitive disorders (HAND). HAND is a spectrum of cognitive impairment, which in its most severe form cause marked interference with day-to-day functioning (HIV-associated dementia). Antiretroviral therapy (ART) has substantially reduced the incidence of HIV-associated dementia, but has not had an impact on the overall prevalence of HAND. The prevalence of milder stages of HAND in ART experienced individuals varies from 15 - 50%. Transporters expressed in the blood brain barrier and blood cerebrospinal fluid (CSF) barrier affect influx and efflux of drugs including antiretrovirals. Antiretrovirals that have better penetration into the CNS may result in improved cognitive function in patients with HAND, however this has not yet been conclusively shown. On the other hand, prolonged CNS exposure to high antiretroviral concentrations has been proposed as a cause of secondary decline in cognitive function as several antiretrovirals are neurotoxic. Efavirenz in particular, but also tenofovir and emtricitabine, have been shown to have direct neurotoxicity in preclinical models. Polymorphisms in genes that encode these enzymes or transporters may therefore affect antiretroviral CSF concentrations. Africans are the most genetically diverse population worldwide and South Africa has the world’s largest ART programme, with most of patients currently receiving efavirenz-tenofovir-emtricitabine. The impact of pharmacogenetic polymorphisms on the pharmacokinetics of efavirenz-tenofovir-emtricitabine CNS penetration are lacking. A number of adjunctive pharmacotherapies for HAND have been studied, including lithium. Multiple mechanisms have been suggested for the potential beneficial cognitive effect of lithium, including the inhibition of glycogen synthase kinase-3- beta, which mediates inflammation signaling pathways and neuronal apoptosis. Lithium has been used in mood disorders and other neuropsychiatric conditions for more than 40 years. In addition, lithium is a low-cost drug and widely available in public service settings in low and middle-income countries. There is a need for controlled data to evaluate the efficacy of lithium as adjunctive therapy for HAND. Finally, it is unknown whether lithium causes additive nephrotoxicity in combination with tenofovir. Methods We conducted a 24-week randomised placebo-controlled trial of lithium as adjunctive pharmacotherapy in participants with moderate to severe HAND established on ART for at least 6 months, with suppressed viral loads. We randomised 66 participants to lithium (n=32) or placebo (n= 34). Our primary efficacy endpoint was the change in Global Deficit Score (GDS) from baseline to 24 weeks, while our secondary endpoint was the change in proton magnetic resonance spectroscopy (1 H-MRS) brain metabolite concentrations. We collected paired plasma-CSF samples in 47 adult participants with and without HAND treated with efavirenz-tenofovir-emtricitabine. We considered 2049 single-nucleotide polymorphisms (SNPs), including SNPs known to affect plasma efavirenz exposure, from potentially relevant genes (ABCC5, ABCG2, ABCB1, SLCO2B1, SCLO1A2, ABCC4, CYP2B6 and CYP2A6) and 880 met a linkage disequilibrium (LD)-pruning threshold. We investigated genetic polymorphisms associated with CSF exposure of efavirenz and its metabolites, tenofovir and emtricitabine. The secondary objective was to explore the pharmacokineticpharmacodynamic relationships with neurocognitive performance. Finally, we investigated the change in estimated glomerular filtration rate (eGFR) in participants who received concomitant tenofovir and lithium. Results The median change in GDS between baseline and week 24 for the lithium and placebo arms were -0.57 (95% confidence interval [CI] -0.77, -0.32) and -0.56 (-0.69, -0.34) respectively, with a mean difference of -0.054 (95% CI -0.26, 0.15); p = 0.716. The improvement remained similar when analysed according to age, severity of impairment, CD4+ count, time on ART and ART regimen. Standard 1 H-MRS metabolite concentrations were similar between the treatment arms. The study drug was well tolerated in both study arms. There was no statistically significant difference in the reduction in eGFR or in potassium between the two arms during the 24 weeks. A model that included the composite CYP2B6 15582/516/983 genotype in univariate analyses best predicted the log10-transformed concentrations of plasma efavirenz, plasma 7-hydroxy-efavirenz, plasma 8-hydroxyefavirenz-to-efavirenz ratio and CSF efavirenz. Lower plasma 7-hydroxy-efavirenz concentrations were independently associated with CYP2A6 rs10853742, ABCB1 rs115780656 and CYP2A6 -48A→C. The CYP2A6 -48A→C polymorphism was independently associated with higher CSF 8-hydroxy-efavirenz-to-efavirenz ratio. The CYP2B6 rs2279345 polymorphism was associated with lower plasma 7-hydroxy-efavirenzto-efavirenz ratio in univariate on multivariate analyses adjusting for CYP2B6 516G→T and 983T→C. No polymorphisms were associated with CSF-to-plasma ratios of all 3 drugs, plasma or CSF 8-hydroxy-efavirenz, tenofovir or emtricitabine concentrations, or neurocognitive performance. Conclusion Adjunctive lithium pharmacotherapy in patients on ART with HAND was well tolerated but had no additional benefit on neurocognitive impairment. We found that 24-week treatment of HIV-infected patients with lithium and tenofovir did not result in increased nephrotoxicity. We identified novel genetic associations with plasma efavirenz, plasma 7-hydroxy-efavirenz, plasma 7-hydroxy-efavirenz-to-efavirenz ratio, plasma 8-hydroxy-efavirenz-to-efavirenz ratio, CSF 8-hydroxy-efavirenz-to-efavirenz ratio and CSF efavirenz.