Incidence and predictors of adverse drug events in an African cohort of HIV-infected adults treated with efavirenz

Variation of adverse drug events in different settings in Africa: a systematic review

BACKGROUND

Adverse drug events (ADEs) represent challenges affecting Africa's healthcare systems owing to the increased healthcare expenditure and negative health outcomes of ADEs.

OBJECTIVES

We aimed to systematically review published studies on ADEs and synthesize the existing evidence of ADE prevalence in Africa.

METHODS

Studies reporting on ADE occurrence in African settings and published from Jan 1, 2000 to Oct 1, 2023 were identified by searching PubMed, EBSCO, Science Direct, and Web of Science. Studies that either articulately investigated ADEs caused by clinical condition (such as HIV patients) or ADEs caused by exposure to specific drug(s) (such as antibiotics) were considered specific and the remaining were general. Grouped ADE prevalence rates were described using median and interquartile range (IQR). PROSPERO registration (CRD42022374095).

RESULTS

We included 78 observational studies from 15 African countries that investigated the prevalence of ADEs leading to hospital admissions (17 studies), developed during hospitalizations (30 studies), and captured in the outpatient departments (38 studies) or communities (4 studies). Twelve studies included multiple settings. The median prevalence of ADE during hospitalization was 7.8% (IQR: 4.2-21.4%) and 74.2% (IQR: 54.1-90.7%) in general and specific patients, respectively. The ADE-related fatality rate was 0.1% and 1.3% in general and specific patients. The overall median prevalence of ADEs leading to hospital admissions was 6.0% (IQR: 1.5-9.0%); in general, patients and the median prevalence of ADEs in the outpatient and community settings were 22.9% (IQR: 14.6-56.1%) and 32.6% (IQR: 26.0-41.3%), respectively, with a median of 43.5% (IQR: 16.3-59.0%) and 12.4% (IQR: 7.1-28.1%) of ADEs being preventable in general and specific patients, respectively.

CONCLUSIONS

The prevalence of ADEs was significant in both hospital and community settings in Africa. A high ADE prevalence was observed in specific patients, emphasizing important areas for improvement, particularly in at-risk patient groups (e.g., pediatrics, HIV, and TB patients) in various settings. Due to limited studies conducted in the community setting, future research in this setting is encouraged.

Neuropsychiatric Adverse Events Following Antiretroviral Therapy in People Living with HIV: A Real-World Study of Dynamic Trends and Risk Factors in Hangzhou, China

Purpose

Neuropsychiatric adverse events (NPAEs) occur frequently in people living with human immunodeficiency virus (PLWH) receiving antiretroviral therapy (ART). This study aimed to assess the dynamic trends and risk factors of NPAEs among PLWH in Hangzhou taking efavirenz (EFV)- or dolutegravir (DTG)- or elvitegravir (EVG)-based regimens.

Patients and Methods

A total of 287 ART-naive PLWH were included in this study, EFV (400mg)- (n = 122), EFV (600mg)- (n = 37), DTG- (n = 73), EVG-based (n = 47) and other ART regimens (n = 8) as the initial ART regimen were administered for 12 months. All data were collected at five time points within a 12-month follow-up. The Pittsburgh Sleep Quality Index and Hospital Anxiety and Depression Scale were used to evaluate sleep disorders and anxiety and depression symptoms, respectively. The dynamic trends and potential risk factors of NPAEs were investigated using a generalized linear mixed model.

Results

Mean age was 29.4 (SD: 7.5) years with 97.2% males. After 12 months of ART, the prevalence of sleep disorders and anxiety decreased significantly, although only a slight improvement was observed for depression. In addition, there was a significant positive correlation between sleep disorders, anxiety, and depression. The risk factors for NPAEs differed slightly depending on the choice of ART regimen, but the seven factors most commonly associated with NPAEs were age, sex, marital status, education level, smoking status, body mass index, and WHO clinical stage. Treatment-induced changes in CD4-positive T-cell count and virological suppression did not depend on the particular choice of ART regimen.

Conclusion

The prevalence of sleep disorders and anxiety changed significantly over time on ART and the risks of these disorders were associated with seven common clinical and demographic factors.

Reversible Gynecomastia in HIV-Infected Man Treated With Triple Antiretroviral Therapy Containing Efavirenz: A Case Report

Gynecomastia is benign hypertrophy of male breast glandular tissue, either unilateral or bilateral, secondary to increased estrogen/testosterone ratio (elevated estrogen level, decreased testosterone levels, or both). The condition can be related to a medical disease or caused by some drugs.

Since the introduction of triple antiretroviral therapy (TAT), we have seen an improvement in the prognosis of human immunodeficiency virus (HIV) infection.

Here we report the case of a 53-year-old man receiving follow-up care in Internal Medicine for HIV infection receiving TAT (tenofovir/efavirenz/emtricitabine). After one year, the patient presented in the Department of Endocrinology, Diabetology, Metabolic Diseases, and Nutrition of Hassan II University Hospital Center, Fez, with bilateral gynecomastia. Hormonal exploration did not reveal any abnormality, so the gynecomastia was attributed to efavirenz use. The regimen was replaced by tenofovir, lamivudine, and dolutegravir. The gynecomastia was resolved within two months of discontinuing efavirenz.

In summary, we think that secondary gynecomastia should be suspected and screened in HIV patients receiving efavirenz-containing regimens.

Comparative incidence of adverse drug reaction during the first and subsequent year of antiretroviral therapy in a Nigerian HIV infected Cohort

Background

Despite close to two decades of antiretroviral therapy (ART) in Nigeria, data on late on-onset ART-associated adverse drug reactions (ADRs) are sparse.

Objectives

To describe early and late-onset ADRs and compare their incidence in an outpatient HIV positive Cohort on ART.

Method

We described the incidence of clinical ADRs identified and documented in an outpatient clinic cohort of HIV-positive patients treated between June 2004 and December 2015 at a tertiary health facility in Nigeria. Incidence rates of ADRs during the first and subsequent years of ART were compared.

Results

of the 13,983 patients' data analyzed, 9317 were females (66%), and those in the age bracket of 25 to 45 years made up 78% of the studied population. During 52,411 person-years (py) of ART, 1485 incident ADRs were recorded; Incidence rate (IR) 28.3 (95% confidence interval [CI] 26.9:29.8) ADRs per 1000 person-years (py) of ART. The IR of ADRs was about two times higher in the first year of ART compared to subsequent years of treatment; crude incidence rate ratio (IRR) 1.77 (95% CI 1.59:1.97). Anemia, hypersensitivity reactions, and nervous system disorders had 7, 23, and 5 times higher incidence, respectively, in the first year of therapy, compared to subsequent years.

Conclusion

The first year of ART is the period of highest risk of ADRs. Individual and programmatic treatment success in resource-limited settings requires strategies for early identification and management of ADR during the period of greatest risk of ADRs.

Incidence and predictors of Adverse Drug Reaction (ADR) among adult HIV positive patients on anti-retroviral treatment in Arba Minch town public health facilities, southern Ethiopia: A retrospective cohort study, 2020

Background

Besides its contribution in the treatment of Human Immunodeficiency Virus-infected patients, anti-retroviral drugs may also cause mild to serious adverse effects. It is the main causes for poor drug adherence, treatment discontinuation and changes in Anti-Retroviral Treatment (ART) regimens. Thus, the aim of this study was to assess the incidence and predictors of adverse drug reaction among adult Human Immunodeficiency Virus positive patients on anti-retroviral treatment from January 1, 2013 up to December 30, 2018 at Arba Minch town public health facilities, Southern Ethiopia.

Methods

An institution based retrospective cohort study was conducted on 456 charts. Secondary data was collected by structured questionnaire. Data were entered in Epi-data version 4.4.2 software and exported to STATA Version 14 for analysis. The Kaplan-Meier survival curve with Log-rank was used to estimate survival time. Bi-variable and multivariable Cox proportional hazard regression models were fitted to identify predictors of adverse drug reaction. In the bi-variable analysis, the variables with p-value < 0.25 were eligible for multivariable analysis. Finally, variables with p-values less than 0.05 in the multivariable Cox regression were considered as independent predictors. The statistical significance was declared at p-value<0.05.

Results

Out of 456 patients observed for 14,903 person-months (pm), 79 experienced adverse drug reactions and the overall incidence density rate was 0.53/100 pm, CI: 0.42–0.66/100 person’s month or 6.36 per 100 Pearson year of observation. Females were at higher risk of experiencing adverse drug reactions (ADRs) compared to males [AHR = 2.35; CI (1.18, 4.69)]. The risk of experiencing ADRs among patient with advanced WHO clinical stage (stage III and IV) was higher compared to stage I and II [AHR = 3.0, CI (1.22, 7.37)]. The risk of experiencing an ADR was at any given time higher among AZT and NVP containing regimens compared to TDF and EFV containing regimens. Finally, the risk of ADR among those patients from the health center was reduced by 59% compared to hospital patients, [AHR = 0.41, CI (0.17, 0.97)].

Conclusion and recommendation

The incidence rate of ADRs was reduced among patients on ARVs compared to previous studies and it was high during the early years of ART initiation. HIV patients should be closely followed in the early years of ART initiation, since this is the time of highest risk ADRs and emphasis should be given for female and clinically advanced patients.

Predictors of Discontinuation of Efavirenz as Treatment for HIV, Due to Neuropsychiatric Side Effects, in a Multi-Ethnic Sample in the United Kingdom

Efavirenz (EFV) is one of the most commonly prescribed antiretroviral therapy (ART) medications for human immunodeficiency virus-infected adults because of its favorable pharmacokinetic profile and well-documented efficacy. Nonetheless, neuropsychiatric adverse events (AE) occur in almost half of the EFV users and it is the main reason for treatment discontinuation. To identify the sociodemographic characteristics and reported neuropsychiatric side effects that placed EFV users at an increased risk of discontinuation in a multi-ethnic sample in the United Kingdom. A retrospective medical records analysis of patients prescribed EFV-containing ART in an outpatient sexual health clinic between 2010 and 2016. One hundred forty-nine medical records were reviewed. Fifty-five patients discontinued EFV within the study period. About 55.7% of patients suffered from at least one neuropsychiatric AE, the most commonly recorded symptoms were depression, vivid dreams, dizziness, and sleep disturbance. There was an inverse relationship between number of AE and EFV continuation [adjust odds ratio (OR) = 0.12; confidence interval (95% CI) = 0.03-0.44, p < .05]. Furthermore, neuropsychiatric symptoms, including depression (adjust OR = 3.01; 95% CI = 1.30-6.96, p < .05), sleep disturbance (adjust OR = 3.00; 95% CI = 1.10-8.19, p < .05), and vivid dreams (adjust OR = 2.51; 95% CI = 1.05-6.00, p < .05), were independent predictors of EFV discontinuation. The findings revealed that patients who did not experience any neuropsychiatric side effects were eight times more likely to stay on an EFV-containing regimen than those who suffered from more than three symptoms. Additionally, patients who experienced depression or sleep disturbance were at threefold elevated risk of discontinuing an EFV-based regimen. The implications for clinical practice are discussed.

Adverse events in Chinese human immunodeficiency virus (HIV) patients receiving first line antiretroviral therapy

BACKGROUND

Although the global human immunodeficiency virus (HIV) epidemic has improved significantly due to antiretroviral treatment (ART), ART-related adverse events (AEs) remain an issue. Therefore, investigating the factors associated with ART-related AEs may provide vital information for monitoring risks.

METHODS

A prospective cohort study was conducted among adult patients (aged 18 years or older) with HIV who received Tenofovir (TDF) + Lamivudine (3TC) + Efavirenz (EFV) as first-line ART regimens. All AEs during the first 12 months of therapy were recorded. Logistic regression analysis was used to identify variables associated with AEs.

RESULTS

Four hundred seventy-four patients receiving TDF+ 3TC+ EFV ART regimens between March 2017 and October 2017 were included in the study analysis. Among them, 472 (99.6%) experienced at least one AE, 436 (92.0%) patients experienced at least one AE within 1 month of treatment, 33 (7.0%) between one and 3 months of treatment, and three (0.6%) patients after 3 months of treatment. The most commonly reported AE was nervous system (95.6%) related, followed by dyslipidemia (79.3%), and impaired liver function (48.1%). Patients with baseline body mass index (BMI) greater than 24 kg/m2 (adjusted OR 1.77, 95%CI 1.03-3.02), pre-existing multiple AEs (adjusted OR 2.72, 95%CI 1.59-4.64), and pre-existing severe AEs (adjusted OR 5.58, 95%CI 2.65-11.73) were at increased odds of developing a severe AE. Patients with baseline BMI greater than 24 kg/m2 (adjusted OR 2.72, 95%CI 1.25-5.89) were more likely to develop multiple AEs.

CONCLUSION

The incidence of ART-related adverse events over a 12-month period in China was high. Baseline BMI greater than 24 kg/m2, pre-existing multiple AEs, and pre-existing severe AEs were shown to be independent risk factors for developing a severe AE.

Factors associated to modification of first-line antiretroviral therapy due to adverse events in people living with HIV/AIDS

Antiretroviral therapy (ART) has modified the outcome of patients with HIV infection, providing virological control and reducing mortality. However, there are several reasons as to why patients may discontinue their antiretroviral therapy, with adverse events being one of the main reasons reported in the literature. This is a case-control nested in a cohort of people living with HIV/AIDS, conducted to identify the incidence of ART modification due to adverse events and the associated factors, in two referral services in Recife, Brazil, between 2011 and 2014. Of the modifications occurred in the first year of ART, 25.7% were driven by adverse events. The median time elapsed between initiating ART and the first modification due to adverse events was 70.5 days (95% CI: 26-161 days). The main adverse events were dermatological, neuropsychiatric and gastrointestinal. Dermatological events were the earliest to appear after initiating ART. Efavirenz was the most prescribed and most modified drug during the study period. The group of participants who used zidovudine, lamivudine, and efavirenz had a 2-fold greater chance (adjusted OR: 2.16 95% CI: 1.28-3.65) of switching ART due to adverse events when compared to the group that used tenofovir with lamivudine and efavirenz.

Gynecomastia in HIV-positive adult men receiving efavirenz-based antiretroviral therapy at Newlands clinic, Harare, Zimbabwe

Background

Gynecomastia is known to occur in some men taking an efavirenz-based antiretroviral therapy (ART) regimen. However, the incidence and outcomes of gynecomastia are not known in Zimbabwe. We described the characteristics and outcomes of gynecomastia among male patients on an efavirenz-based ART regimen.

Methods

We conducted a retrospective cohort review of data of all male patients aged ≥18 years taking an efavirenz-based regimen at Newlands Clinic, Harare, Zimbabwe before 31 March 2017. The primary outcome was gynecomastia as defined by breast/nipple enlargement reported by patient and confirmed by clinical palpation. Routinely collected data on demographics, baseline CD4, body mass index, duration on efavirenz, clinical presentation and outcomes were extracted from the clinic database and analysed using STATA 12.1. We investigated for any associations with concomitant medicines using cox regression.

Results

We analysed data for 1432 men with a median age of 40 years (IQR: 33–48). Half of the patients were in WHO stage 1 at ART commencement. Median body mass index and CD4 count at efavirenz commencement was 21 (IQR: 19–23) and 260 cells/mm³ (IQR: 126–412) respectively. The incidence of gynecomastia was 22/1000 person-years (IQR: 17.3–27.8). Over half of the cases (58%) were bilateral and 75% of all cases developed within two years of starting efavirenz. There were no significant associations with concomitant use of isoniazid (HR: 0.95, p = 0.87) or amlodipine (HR: 0.43, p = 0.24). Gynecomastia resolved in 83.5% of cases following withdrawal of efavirenz with a median time to resolution of 3 months (IQR: 2–9).

Conclusion

The incidence of gynecomastia among patients taking efavirenz-based ART was low with most cases developing early on during treatment. Most cases resolved completely after withdrawing efavirenz.

Incidence and predictors of major adverse drug events among drug-resistant tuberculosis patients on second-line anti-tuberculosis treatment in Amhara regional state public hospitals; Ethiopia: a retrospective cohort study

Background

Second line anti-tuberculosis drugs are substantially complex, long term, more costly, and more toxic than first line anti-tuberculosis drugs. In Ethiopia, evidence on the incidence and predictors of adverse drug events has been limited. Thus, this study aimed at assessing incidence and predictors of major adverse drug events among drug resistant tuberculosis patients on second line tuberculosis treatment in Amhara Regional State public hospitals, Ethiopia.

Methods

A multi-center retrospective cohort study was conducted on 570 drug resistant tuberculosis Patients. Data were entered in to EPI-Data version 4.2.0.0 and exported to Stata version 14 for analysis. Proportional hazard assumption was checked. The univariate Weibull regression gamma frailty model was fitted. Cox-Snell residual was used to test goodness of fit and Akaike Information Criteria (AIC) for model selection. Hazard ratio with 95% CI was computed and variables with P-value < 0.05 in the multivariable analysis were taken as significant predictors for adverse drug event.

Results

A total of 570 patients were followed for 5045.09 person-month (PM) observation with a median follow-uptime of 8.23 months (Inter Quartile Range (IQR) =2.66–23.33). The overall incidence rate of major adverse drug events was 5.79 per 100 PM (95% CI: 5.16, 6.49). Incidence rate at the end of 2nd, 4th, and 6th months was 13.73, 9.25, 5.97 events per 100 PM observations, respectively. Age at 25–49 (Adjusted Hazard Ratio (AHR) = 3.36, 95% CI: 1.36, 8.28), and above 50 years (AHR = 5.60, 95% CI: 1.65, 19.05), co-morbid conditions (AHR = 2.74 CI: 1.12, 6.68), and anemia (AHR = 3.25 CI: 1.40, 7.53) were significant predictors of major adverse drug events.

Conclusion

The incidence rate of major adverse drug events in the early 6 months of treatment was higher than that of the subsequent months. Age above 25 years, base line anemia, and co-morbid conditions were independent predictors of adverse drug events. Thus, addressing significant predictors and strengthening continuous follow-ups are highly recommended in the study setting.

Cases of antiretroviral-associated gynaecomastia reported to the National HIV & Tuberculosis Health Care Worker Hotline in South Africa

BACKGROUND

Gynaecomastia is associated with exposure to antiretroviral therapy (ART), in particular efavirenz. There is limited data on clinical characteristics of patients with ART-associated gynaecomastia in resource-limited settings and little guidance on the optimal management of this adverse drug reaction (ADR). We describe the clinical characteristics, management and outcomes of gynaecomastia cases reported to the National HIV & Tuberculosis Health Care Worker Hotline in South Africa.

METHODS

We identified all gynaecomastia cases in adolescent boys and men on ART reported to the hotline between June 2013 and July 2014. We collected follow up data telephonically at monthly intervals to document clinical management and outcomes.

RESULTS

We received 51 reports of gynaecomastia between June 2013 and July 2014; 11% of the 475 patient-specific ADR queries to the hotline. All patients were on efavirenz-based ART. Mean age was 34 years (standard deviation 12) and seven were adolescents. The median onset of gynaecomastia was 15 months after efavirenz initiation (interquartile range 6-42). Gynaecomastia was bilateral in 29 patients (57%) and unilateral in 16 (31%). Serum testosterone was quantified in 25 of 35 patients with follow up data, and was low in 2 (8%). Efavirenz was replaced with an alternative antiretroviral in 29/35 patients (83%) and gynaecomastia improved in 20/29 (69%).

CONCLUSIONS

Gynaecomastia was a frequently reported ADR in our setting, occurring with prolonged efavirenz exposure. Testosterone was low in the minority of tested cases. Most clinicians elected to switch patients off efavirenz, and gynaecomastia improved in the majority.

Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals

Neurological complications associated with the human immunodeficiency virus (HIV) are a matter of great concern. While antiretroviral (ARV) drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity.

Pharmacogenomics and Global Precision Medicine in the Context of Adverse Drug Reactions: Top 10 Opportunities and Challenges for the Next Decade

In a move indicative of the enthusiastic support of precision medicine, the U.S. President Barack Obama announced the Precision Medicine Initiative in January 2015. The global precision medicine ecosystem is, thus, receiving generous support from the United States ($215 million), and numerous other governments have followed suit. In the context of precision medicine, drug treatment and prediction of its outcomes have been important for nearly six decades in the field of pharmacogenomics. The field offers an elegant solution for minimizing the effects and occurrence of adverse drug reactions (ADRs). The Clinical Pharmacogenetics Implementation Consortium (CPIC) plays an important role in this context, and it aims at specifically guiding the translation of clinically relevant and evidence-based pharmacogenomics research. In this forward-looking analysis, we make particular reference to several of the CPIC guidelines and their role in guiding the treatment of highly relevant diseases, namely cardiovascular disease, major depressive disorder, cancer, and human immunodeficiency virus, with a view to predicting and managing ADRs. In addition, we provide a list of the top 10 crosscutting opportunities and challenges facing the fields of precision medicine and pharmacogenomics, which have broad applicability independent of the drug class involved. Many of these opportunities and challenges pertain to infrastructure, study design, policy, and science culture in the early 21st century. Ultimately, rational pharmacogenomics study design and the acquisition of comprehensive phenotypic data that proportionately match the genomics data should be an imperative as we move forward toward global precision medicine.

Incidence and risk factors for neuropsychiatric events among Ghanaian HIV patients on long-term non-nucleoside reverse transcriptase inhibitor-based therapy

Background

Non-nucleoside reverse transcriptase inhibitor (NNRTI)-based antiretroviral therapy (ART) is associated with neuropsychiatric toxicity. Little is known about the risk of short- and long-term neuropsychiatric toxicity in sub-Saharan Africa, where NNRTIs are widely used in first-line combination ART. This observational study assessed the risk of neuropsychiatric toxicity in Ghanaian patients starting first-line ART between 2004 and 2010 at a single centre.

Methods

In this retrospective observational study, frequencies of documented neuropsychiatric toxicity events were assessed and time to events calculated using a Kaplan–Meier analysis. Associations of neuropsychiatric toxicity with specific NNRTIs and other explanatory variables were examined using Cox proportional hazards modelling.

Results

Of 3999 patients initiating NNRTI-based ART, who were followed for a median of 30 (0.25–90) months (11,237 person years), 218 (5.5%) reported symptoms of neuropsychiatric toxicity at a rate of 21.4 events per 1000 person-years (95% CI, 18.8–24.2/1000 py). Events were more common with efavirenz than nevirapine (7.6% versus 2.4%), were usually reported within the first 2 months of ART initiation and persisted up to 84 months in a few patients. The most commonly reported neuropsychiatric adverse drug reactions were insomnia (50%), headaches (8%), dizziness (7%) and abnormal dreams (6%). The factors independently associated with neuropsychiatric toxicity were BMI < 16 kg/m² (aHR of 1.44 [95% CI, 1.02–2.03]) and use of efavirenz (aHR 3.29 [95% CI, 2.32–4.69]). Substitution of NNRTI on account of toxicity was reported in up to 17% of patients experiencing neuropsychiatric events.

Conclusions

NNRTI-related neuropsychiatric toxicity, mainly due to efavirenz, was infrequently documented in this Ghanaian cohort under routine clinical care settings. Regimens with more favourable tolerability will be needed as first-line agents in sub-Saharan Africa in the coming years.

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Millions of patients living with HIV AIDS in sub-Saharan Africa are initiated on an efavirenz-based combination antiretroviral therapy which is frequently associated with neuropsychiatric toxicity.

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In this retrospective study involving 3999 Ghanaian HIV-infected patients initiating therapy between 2004 and 2010, neuropsychiatric toxicity was documented in 5.5% with a higher incidence among efavirenz recipients (7.6%) compared with nevirapine recipients (2.4%).

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Peak neuropsychiatric adverse events occurred within the first two months upon initiating therapy with some few further events occurring as later on during 90 months of follow-up.

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Up to 17% of patients reporting neuropsychiatric toxicity had treatment modifications as a result.

An Expanded Analysis of Pharmacogenetics Determinants of Efavirenz Response that Includes 3'-UTR Single Nucleotide Polymorphisms among Black South African HIV/AIDS Patients

Introduction: Efavirenz (EFV) is a non-nucleoside reverse transcriptase inhibitor prescribed as part of first-line highly active antiretroviral therapy (HAART) in South Africa. Despite administration of fixed doses of EFV, inter-individual variability in plasma concentrations has been reported. Poor treatment outcomes such as development of adverse drug reactions or treatment failure have been linked to EFV plasma concentrations outside the therapeutic range (1–4 μg/mL) in some studies. The drug metabolizing enzyme (DME), CYP2B6, is primarily responsible for EFV metabolism with minor contributions by CYP1A2, CYP2A6, CYP3A4, CYP3A5, and UGT2B7. DME coding genes are also regulated by microRNAs through targeting the 3′-untranslated region. Expanded analysis of 30 single nucleotide polymorphisms (SNPs), including those in the 3′-UTR, was performed to identify pharmacogenetics determinants of EFV plasma concentrations in addition to CYP2B6 c.516G>T and c.983T>C SNPs.

Methods: SNPs in CYP1A2, CYP2B6, UGT2B7, and NR1I2 (PXR) were selected for genotyping among 222 Bantu-speaking South African HIV-infected patients receiving EFV-containing HAART. This study is a continuation of earlier pharmacogenetics studies emphasizing the role of genetic variation in the 3′-UTR of genes which products are either pharmacokinetic or pharmacodynamic targets of EFV.

Results: Despite evaluating thirty SNPs, CYP2B6 c.516G>T and c.983T>C SNPs remain the most prominent predictors of EFV plasma concentration.

Conclusion: We have shown that CYP2B6 c.516G>T and c.983T>C SNPs are the most important predictors of EFV plasma concentration after taking into account all other SNPs, including genetic variation in the 3′-UTR, and variables affecting EFV metabolism.