A prospective study to evaluate the efficacy and safety of vitamin E and levocarnitine prophylaxis against doxorubicin-induced cardiotoxicity in adult breast cancer patients.

BACKGROUND: Doxorubicin induces acute and chronic cardiotoxicity. This study is aimed to evaluate the efficacy and safety of vitamin E and levocarnitine (EL) as cardioprotective agents against acute doxorubicin cardiotoxicity in female adult breast cancer patients. METHODS: A prospective, randomized controlled study was conducted in patients treated with doxorubicin and cyclophosphamide (AC). Patients were randomly assigned to EL plus AC or AC alone for the duration of 4 cycles. Cardiac enzymes (B-type natriuretic peptide, creatine kinase, troponin I (Trop)) and cardiac events were monitored during treatment to evaluate the cardioprotective efficacy of EL. RESULTS: Seventy-four patients were recruited and received four cycles of chemotherapy. The intervention group (n = 35) showed a significant reduction in both the B-type natriuretic peptide and creatine kinase cardiac enzymes compared to the control group (n = 39). The median (IQR) change for BNP was 0.80 (0.00-4.00) for IG versus 1.80 (0.40-3.60) for CG groups (p < 0.001); creatine kinase was -0.08 (-0.25-0.05) for IG versus 0.20 (0.05-0.50) for CG (p < 0.001). The addition of EL decreased the cardiac events by 24.2% (p = 0.02). All adverse events were tolerable and manageable. CONCLUSION: This study supports the addition of EL as prophylaxis against acute doxorubicin cardiotoxicity and it was also very well tolerated by a majority of the patients. The co-administration of EL at higher doxorubicin (240 mg/m2) dose should be further investigated.

The Impact of Certain Pharmacogenetic Differences on the Metabolism of Antiretroviral Drugs Used in A Black South African Population.

BACKGROUND: Genetic polymorphism of drug-metabolising enzymes and transporters may influence the effect and toxicity of antiretroviral drugs. OBJECTIVES: To determine and compare the minimum allele frequency of 20 single nucleotide polymorphisms (SNPs) with possible involvement in the metabolism of the antiretroviral drugs with other populations. To investigate the influence of these variants on Reverse transcriptase, Protease and Integrase strand transfer inhibitor drugs. METHOD: DNA samples were collected from 1489 subjects. All SNPs with a gene call score of > 0.6 were selected for genotyping. The R package calculated call rates, MAF and Hardy-Weinberg equilibrium (HWE), test p-values, and Chi-squared analysis were performed on the data. The Fisher's exact test compared the allele frequencies between the populations. RESULTS: The highest similarities in minimum allele frequency (MAF) were between the Prospective Urban and Rural Epidemiological group (PURE), a Black population in South Africa, and the Yoruba and Luhya populations in Africa. The following SNPs were identified with a possible effect on metabolism: CYP2B6 rs28399494 (MAF 11%) is indicated in the toxicity of Efavirenz and Nevirapine. CYP3A5 rs776746 (MAF 17%) and CYP3A4 rs2749674 (MAF 23%) both cause an increase in the metabolism of the protease inhibitors. The very low MAF values for both SCL01B1 rs4149056 (MAF 0.6%) and ABCC rs717620 (MAF 2.8%) are indications that OATP1B1 transport function and glomerular filtration tempo will not be compromised. The high MAF value of 30% for UGTA1 rs10929302 can result in hyperbilirubinemia, which can decrease the clearance of Dolutegravir. CONCLUSION: These results show a possibility of kidney protection and an increase in bilirubin in this population.

Critical appraisal of clinical guidelines for prevention and management of doxorubicin-induced cardiotoxicity.

OBJECTIVE: Doxorubicin is a valuable chemotherapeutic drug; however, it is associated with a high risk of cardiotoxicity. Several institutions and organizations have developed guidelines for risk factor assessment, monitoring and prevention strategies against chemotherapy-induced cardiotoxicity. This review aimed to assess the quality of current practice guidelines, using the Appraisal of Guidelines for Research and Evaluation II (AGREE II). This tool was used to compare the recommendations with regards to their strength and evidence recommendations were based on. DATA SOURCES: This review identified guidelines in literature from January 1960 to February 6, 2022, through a systematic search that included PubMed, EMBASE, MEDLINE, Cochrane Database and Google Scholar. The quality, consistency and the strength of supporting evidence was evaluated using the AGREE II method. DATA SUMMARY: Eight guidelines met the inclusion criteria and 144 recommendations were extracted from these guidelines. The results from the AGREE II evaluation showed that the total assessment scores of guidelines ranged from 2 to 5, indicating the guidelines need modifications. The recommendations were evaluated according to the references used, and it was found that 12 (11%) recommendations had high evidence, 36 (33%) had moderate evidence, 38 (35.19%) had low and 22 (20.37%) had insufficient evidence. Recommendations for risk factors assessment, prophylaxis of cardiotoxicity, management of cardiotoxicity and monitoring of cardiotoxicity were quite varied amongst the different guidelines evaluated. CONCLUSIONS: All studied guidelines need modifications as per the AGREE II evaluating tool. Several shortcomings were identified, including a lack of evidence-based studies supporting the recommendations in the guidelines.

Vitamin E and levocarnitine as prophylaxis against doxorubicin-induced cardio toxicity in the adult cancer patient: A review.

OBJECTIVE: Doxorubicin, a component of the anthracycline group, is a highly effective in the treatment of hematologic and solid malignancies. Because of the cardiotoxic adverse effects, use is limited. Antioxidants may negate this anthracycline-induced cardiotoxicity, although the literature is not conclusive with regards to the cardioprotective benefits of antioxidants. This review assessed and mapped evidence of the efficacy of vitamin E and levocarnitine against doxorubicin-induced cardiotoxicity in adult cancer patients. DATA SOURCES: This review was based on the Arksey and O'Malley methodology. Potentially relevant literature in English published between January 1960 and April 2021 was identified through a database search. Oxford Quality Scoring System and AMSTR2 were used to assess the quality of trials and systematic reviews respectively, as well as the risks of potential bias. DATA SUMMARY: Nineteen of the 10 268 (0.2%) articles from the initial search were included in the final analysis (12 clinical trials and 7 systematic reviews). Vitamin E was included in seven prospective clinical trials. Levocarnitine was included in five clinical trials as an individual agent and a single trial as a combination treatment. No trials could be found investigating the combination of vitamin E and levocarnitine in humans. CONCLUSIONS: This review found that levocarnitine trials showed some cardioprotective effects but the results from vitamin E trials were controversial and inconclusive. Most of the trials reviewed had some shortcomings. Further investigations are therefore needed to determine the efficacy of vitamin E and levocarnitine in preventing doxorubicin-induced cardiotoxicity in adult cancer patients.

Parental reporting of adverse drug reactions in South Africa: An online survey.

BACKGROUND: The high incidence of adverse drug reactions (ADRs) in children is of global concern. Enhancing the reporting of ADRs could contribute to making safer medicines available to children. AIM: To assess parents' awareness of reporting ADRs and their knowledge on the reporting procedures in South Africa. SETTING: South African parents with online access. METHOD: A quantitative descriptive study was conducted based on an anonymous voluntarily web-based self-administered questionnaire that was distributed through Facebook® and LinkedIn™ to parents in South Africa. RESULTS: The questionnaire was completed voluntarily by 206 respondents. The majority of participants (70.9%) were aware of the term ADR. Significant associations between not being aware of the term ADR and single marital status, lower education level, not having private medical aid and accessing public clinics for medical services were found. The majority (66.5%) of participants did report an ADR to a healthcare professional whilst only 15% reported it to a product manufacturer. More than half of the participants (58.7%) knew how to report ADRs whilst 72.8% knew what type of ADRs to report. Almost a third (32.5%) did not know where more information on ADR reporting could be found or how ADRs could be reported (31.5%). CONCLUSION: The majority of the respondents were aware of the term ADR, indicative of a good knowledge basis on which ADRs to report and the importance of reporting ADRs. However, gaps in the respondents' knowledge were identified which highlighted specific groups of individuals to be targeted to increase ADR awareness and improve the knowledge on the reporting process.

Factors Associated with Bone Mineral Density and Bone Resorption Markers in Postmenopausal HIV-Infected Women on Antiretroviral Therapy: A Prospective Cohort Study.

The study aimed to determine factors associated with changes in bone mineral density (BMD) and bone resorption markers over two years in black postmenopausal women living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART). Women (n = 120) aged > 45 years were recruited from Potchefstroom, South Africa. Total lumbar spine and left femoral neck (LFN) BMD were measured with dual energy X-ray absorptiometry. Fasting serum C-Telopeptide of Type I collagen (CTx), vitamin D and parathyroid hormone were measured. Vitamin D insufficiency levels increased from 23% at baseline to 39% at follow up. In mixed linear models serum CTx showed no change from baseline to end (p = 0.363, effect size = 0.09). Total and LFN BMD increased significantly over two years, but effect sizes were small. No significant change in spine BMD over time was detected (p = 0.19, effect size = 0.02). Age was significantly positively associated with CTx over time, and negatively with total and LFN BMD. Physical activity (PA) was positively associated with LFN BMD (p = 0.008). Despite a decrease in serum vitamin D, BMD and CTx showed small or no changes over 2 years. Future studies should investigate PA interventions to maintain BMD in women living with HIV.

A retrospective descriptive investigation of adult patients receiving third-line antiretroviral therapy in the North West province, South Africa.

BACKGROUND: Greater access and prolonged exposure to ART may inevitably lead to more treatment failure and increase the need for third-line ART (TLART) in a resource-limited setting. OBJECTIVE: To describe characteristics and resistance patterns of adult patients initiated on TLART in three districts of the North West province. METHOD: All-inclusive retrospective descriptive investigation. Demographics and clinical variables were recorded from adult patient health records (2002-2017) and analysed. RESULTS: 21 Patients (17 females, 4 males) with median (IQR) age of 34 years (30.2-37.8) at HIV diagnosis and 45 years (39.5-47) at TLART initiation were included. Median duration (days) from HIV diagnosis to first-line ART initiation was 101 (37-367), treatment duration on first-line, second-line and between second-line failure and TLART initiation were: 1 269 (765-2 343); 1 512 (706-2096) and 71 (58-126) days respectively.High-level resistance most prevalent were: nelfinavir/r (85.7%), indinavir/r (80.9%), lopinavir/r (76.2%), emtricitabine and lamivudine (95.2%), nevirapine (76.2%) and efavirenz (71.4%). Resistance to 3 major PI mutations in 95% of patients and cross resistance were documented extensively. CONCLUSION: This study support the need for earlier resistance testing. It firstly reported on time duration post diagnosis on various ART regimens and secondly resistance patterns of adults before TLART was initiated in these districts.

Health students' experiences of the process of interprofessional education: a pilot project.

The need for interprofessional education (IPE) in health science disciplines is a current global trend. However, despite international support and demand, IPE is still new to many health professions curricula in South Africa. Furthermore, while ample existing academic literature addresses commonly encountered barriers to IPE, there is still a need to investigate the dynamics and challenges associated with the process of implementing IPE at universities. IPE is not yet part of the formal curriculum at a faculty of health sciences at a South African Higher Education Institute, so a pilot project was conducted to investigate the experiences of an IPE process by students from different health professions toward informing the planning and implementation of IPE in the formal curriculum. To this effect, a multi-layered IPE project was piloted across pharmacy, nursing, social work, psychology, dietetics, and human movement sciences within this Faculty of Health Sciences. The aim of this research was to determine the dynamics between the different health professions by exploring and describing the students' experiences of the IPE process. Theoretical case studies were presented to third-year students, who were grouped into interprofessional teams from the six different health professions at the Higher Education Institute's health sciences faculty. Data were gathered from reflective journals over a five-week period and a questionnaire was administered at the end of the project. Data were analysed and evaluated based on the interprofessional learning domains listed in the IPE framework of the World Health Organization. All participating health professions students felt positive about the project and agreed that it provided them with valuable IPE experiences. However, their long-term participation and commitment presented difficulty in an already demanding curriculum. The interprofessional dynamics were influenced by the relevance of the scenarios presented in the case studies to the different professions, the students' personalities and their previous experiences. Although the nursing students took initial leadership, contributions from the other professions became more prominent as the case studies unfolded. The findings indicated that the inclusion of different health professions in an interprofessional team should be guided by the specific scenarios incorporated to simulate interprofessional cooperation. The availability of the students and their scope of practice at third-year level should also be taken into account.

Hypertriglyceridaemia and the risk of pancreatitis six months post lopinavir/ritonavir initiation.

BACKGROUND: Hypertriglyceridaemia (HTG) is an important risk factor for pancreatitis and cardiovascular disease (CVD), depending on severity. Hypertriglyceridaemia is common in human immunodeficiency virus (HIV) infection and is also a common complication of lopinavir/ritonavir (LPV/r). OBJECTIVES: To evaluate the risk of pancreatitis associated with HTG in patients six months post initiation of LPV/r-based therapy in a regional public hospital. METHODS: Triglyceride (TG), serum amylase (s-amylase) and CD4+ count values were retrospectively investigated six months post LPV/r-based initiation. Age, gender, previous antiretroviral regimen and period since HIV diagnosis were also recorded. RESULTS: The final sample consisted of 194 patients, 50 males and 144 females; mean (± standard deviation [s.d.]) age was 39.52 (± 9.98) years, and the mean (± s.d.) period since HIV diagnosis was 91.32 (± 25.18) months. Normal TG levels (< 1.70 mmol/L) were detected in only 55% of patients and the rest presented with some degree of HTG. The mean (± s.d.) TG for the entire sample was elevated at 1.94 (± 1.30) mmol/L with the mean (± s.d.) of the males at 2.36 (± 1.74) - statistically higher compared to the females at 1.79 (± 1.08) mmol/L (p = 0.034). No cases of pancreatitis were recorded and the time since HIV diagnosis did not indicate any statistically significant differences in the means of the TG, serum amylase or CD4 count values. CONCLUSION: Triglyceride levels were not substantially elevated to induce pancreatitis at six months post initiation of LPV/r, but were elevated above the accepted upper normal limit of 1.70 mmol/L which may have implications for cardiovascular risk.

Adverse Neuropsychiatric Events and Recreational Use of Efavirenz and Other HIV-1 Antiretroviral Drugs.

Efavirenz is a highly effective HIV-1 antiretroviral; however, it is also frequently associated with neuropsychiatric adverse events (NPAE) that include abnormal dreams, sleep disturbances, nervousness, anxiety, depression, and dizziness. The incidence of NPAEs upon initiation of treatment with efavirenz-containing medications is high, exceeding 50% in most studies. Although the NPAEs tend to decrease after the first month in many patients, they persist for long periods of time in others. Efavirenz-based treatment is generally well-tolerated in children, although some experience persistent concentration problems, as well as sleep disturbances, psychotic reactions, and seizures. In an effort to link basic with clinical research, parameters associated with efavirenz brain exposure are discussed, and factors that increase efavirenz levels are explored in depth as they are expected to contribute to NPAE risk. These include the role of modifiable and nonmodifiable risk factors such as diet, weight, and drug-drug interactions and sex, age, and ethnicity/pharmacogenetics. In addition to NPAEs, this review explores what is known about antiretroviral (ARV) drugs being used for recreational purposes. Although multiple ARV drugs are covered, special attention is devoted to efavirenz given that the majority of reports of NPAEs and illicit use of ARV drugs concern efavirenz. The evolving molecular mechanistic basis of NPAEs and abuse of efavirenz point to a complex and polymodal receptor pharmacology. Animal studies to date primarily point to a serotonergic mechanism of action. Recently emerging associations between HIV-associated neurocognitive disorder and efavirenz use, and possible contributions of the mitochondrial-immune-inflammatory-redox cascade are explored in the context of the signaling mechanisms that appear to be involved.

CYP2B6 Haplotype Predicts Efavirenz Plasma Concentration in Black South African HIV-1-Infected Children: A Longitudinal Pediatric Pharmacogenomic Study.

South Africa has the highest burden of the human immunodeficiency virus (HIV) infection globally. Efavirenz (EFV), a frequently used drug against HIV infection, displays a relationship between drug concentration and pharmacodynamics effects clinically. However, haplotype-based genetic variation in drug metabolism in a pediatric sample has been little considered in a longitudinal long-term context. CYP2B6 plays a key role in variation of EFV plasma concentration through altered drug metabolism. We report here on a prospective clinical pharmacogenomics/pharmacokinetic study of Bantu-speaking children, importantly, over a period of 24 months post-initiation of EFV-based treatment in South Africa. We characterized the HIV-1-infected children (n = 60) for the CYP2B6 c.516G>T, c.785A>G, c.983T>C, and c.1459C>T single nucleotide polymorphisms (SNPs). These SNPs were determined using polymerase chain reaction/restricted fragment length polymorphism and SNaPshot genotyping. Longitudinal mid-dose EFV plasma concentrations were determined by LC-MS/MS and association analyses with genotypes and haplotypes at 1, 3, and 24 months were performed. The CYP2B6 c.516T/T genotype showed significantly higher EFV plasma concentrations (p < 0.001) compared to non 516T-allele carriers at all three time points. The minor allele frequencies (MAF) for CYP2B6 c.516T, c.785G, c.983C, and c.1459T were 0.410, 0.408, 0.110, and 0.000 respectively. Haplotypes were constructed using CYP2B6 c.516G>T,-c.785A>G and c.983T>C. The haplotype T-G-T presented with significantly increased EFV plasma concentrations compared to the reference G-A-T haplotype at 1, 3, and 24 months (p = 0.009; p = 0.003; p = 0.001), suggesting that the T-G-T haplotype predisposes a risk of EFV plasma concentrations >4 µg/mL. The clinical implications of these pharmacogenomics observations for EFV toxicity and treatment resistance warrant further future research.

Associations between plasma tenofovir concentration and renal function markers in HIV-infected women.

BACKGROUND: Tenofovir disoproxil fumarate (TDF) has been associated with kidney tubular dysfunction and reduced renal function. Limited studies were performed in Europe and Asia that related plasma tenofovir (TFV) concentration with renal function; no such studies to date have been performed on Africans. OBJECTIVE: To investigate the correlation between plasma tenofovir (TFV) concentration and certain renal function markers in HIV-infected women on TDF antiretroviral therapy (ART). These markers were also compared to a HIV-uninfected control group. METHODS: HIV-infected women (n = 30) on TDF-based ART were matched with 30 controls for age and body mass index. Renal markers analysed were estimated glomerular filtration rate (eGFR), creatinine clearance (CrCl), serum creatinine, albuminuria, glucosuria, serum urea, serum uric acid, urine sodium and maximum tubular reabsorption of phosphate. Baseline eGFR and CrCl data were obtained retrospectively for the HIV-infected women. Plasma TFV was assayed using a validated HPLC-MS/MS method. Stepwise regression, Mann-Whitney test, unpaired and paired t-tests were applied in the statistical analyses. RESULTS: TFV concentration was independently associated with albuminuria (adjusted r2 = 0.339; p = 0.001) in HIV-infected women. In the adjusted (weight) analysis, eGFR (p = 0.038), CrCl (p = 0.032) and albuminuria (p = 0.048) were significantly higher in HIV-infected compared to the uninfected women, but eGFR was abnormally high in HIV-infected women. Both eGFR (p < 0.001) and CrCl (p = 0.008) increased from baseline to follow-up in HIV-infected women. CONCLUSION: Plasma TFV concentration was associated with increased albuminuria in HIV-infected women in this sub-study. Both eGFR and CrCl were increased in HIV-infected women from baseline. These findings should be confirmed in larger studies, and hyperfiltration in HIV-infected women warrants further investigation.

Positive association between dietary iron intake and iron status in HIV-infected children in Johannesburg, South Africa.

Anemia is a common complication of pediatric HIV infection and is associated with suboptimal cognitive performance and growth failure. Routine iron supplementation is not provided to South African HIV-infected children. We hypothesized that dietary iron intake without supplementation is sufficient to protect against iron deficiency (ID) in HIV-infected children receiving highly active antiretroviral therapy. In this prospective study, the difference between dietary intakes of iron-deficient children (soluble transferrin receptor >9.4 mg/L) and iron-sufficient children after 18 months on highly active antiretroviral therapy was examined. The association between iron intake and hemoglobin (Hb) concentration was also assessed. Longitudinal data collected for 18 months from 58 HIV-infected African children were assessed by generalized estimation equations, with adjustment for demographic information, dietary intakes, growth parameters, and CD4%. After adjustment for covariates, the longitudinal association between dietary iron intake and Hb concentration remained significant. This association shows that for every 1-mg increase in iron intake per day, Hb increases by 1.1 g/L (P < .001). Mean Hb increased significantly after 18 months of follow-up (106 ± 14 to 129 ± 14 g/L, P < .01), but soluble transferrin receptor also increased (7.7 ± 2.7 to 8.9 ± 3.0 mg/L, P < .01). The incidence of ID increased from 15.2% at baseline to 37.2% after 18 months. Children with animal protein intakes greater than >20 g/d had significantly lower odds for ID at 18 months than did children with lower intakes (odds ratio, 0.40; 95% confidence interval, 0.21-0.77). Dietary iron intake was insufficient to protect against ID, pointing to a need for low-dose iron supplementation for iron-deficient HIV-infected children and interventions to increase the consumption of animal protein.

Evidence for time-dependent interactions between ritonavir and lopinavir/ritonavir plasma levels following P-glycoprotein inhibition in Sprague-Dawley rats.

The interaction between verapamil, a P-glycoprotein (P-gp) inhibitor, with ritonavir and lopinavir/ritonavir (LPV/r) after acute and chronic treatment was investigated in rats. Rats were divided into 4 groups, viz. Group 1: ritonavir, 20 mg/kg/d (n=18), group 2: ritonavir, 20 mg/kg/d plus verapamil 5 mg/kg/d (n=18), group 3: LPV/r, 80 and 20 mg/kg/d (n=17) and group 4: LPV/r, 80 and 20 mg/kg/d plus verapamil 5 mg/kg/d (n=18). Blood samples were collected after decapitation on days 1, 7 and 21. Lopinavir and ritonavir plasma levels were simultaneous determined by a validated LC/MS/MS method. The lower limit of quantification for both ritonavir and lopinavir was 0.078 µg/ml. Verapamil significantly increased ritonavir plasma levels, administered as monotherapy, following acute (p<0.005) and chronic treatment (day 21) (p<0.005). During acute (but not chronic) LPV/r treatment, verapamil also increased the lopinavir levels (p<0.05). A time or exposure dependent pharmacokinetic interaction was thus observed between verapamil and ritonavir whether administered alone or after the lopinavir-ritonavir combination (LPV/r). This interaction occurred most prominently after acute treatment, and became less pronounced over time. This study indicates the importance of a longer time frame to investigate enzyme based drug interactions in rat models.

Determination of salivary efavirenz by liquid chromatography coupled with tandem mass spectrometry.

A novel and robust screening method for the determination of the non-nucleoside reverse transcriptase inhibitor, efavirenz (EFV), in human saliva has been developed and validated based on high performance liquid chromatography tandem mass spectrometry (LC-MS/MS). Sample preparation of the saliva involved solid-phase extraction (SPE) on C18 cartridges. The analytes were separated by high performance liquid chromatography (Phenomenex Kinetex C18, 150mm×3mm internal diameter, 2.6µm particle size) and detected with tandem mass spectrometry in electrospray positive ionization mode with multiple reaction monitoring. Gradient elution with increasing methanol (MeOH) concentration was used to elute the analytes, at a flow-rate of 0.4mL/min. The total run time was 8.4min and the retention times for the internal standard (reserpine) was 5.4min and for EFV was 6.5min. The calibration curves showed linearity (r(2), 0.989-0.992) over the concentration range of 3.125-100µg/L. Mean intra- and inter-assay relative standard deviation, accuracy, mean extraction recovery, limit of detection (LOD) and limit of quantification (LOQ) were 0.46-9.43%, 80-120%, 60% (±7.95), 1.84 and 6.11µg/L respectively. The working range was defined as 6.25-100µg/L. This novel LC-MS/MS assay is suitable for reliable detection of low EFV concentrations in saliva and can be used as a screening tool for monitoring EFV compliance.

Efavirenz plasma concentrations at 1, 3, and 6 months post-antiretroviral therapy initiation in HIV type 1-infected South African children.

The aim of this study was to quantify the plasma efavirenz concentrations over 6 months in black HIV-1-infected South African children (3-14 years), from resource-limited households, attending an outpatient clinic. The children were antiretroviral treatment (ART) naive and received efavirenz in combination with two nucleoside reverse transcriptase inhibitors according to South African national guidelines. Two blood samples were taken between 12 and 20 h after the last efavirenz dose at 1 (n = 58), 3 (n = 54), and 6 (n = 54) months post-ART initiation. A total of 328 efavirenz mid-dose plasma samples from 58 patients was determined with a validated liquid chromatography tandem mass spectrometry method. Viral suppression (<25 copies/ml) was achieved in 95% of the children after 6 months on ART. The median (range) plasma concentration at time points 1 and 2 were 2.06 (0.10-11.14) and 1.80 (0.14-10.70) microg/ml with respective mean (+/-SD) blood sampling times of 15.24 (2.03) and 16.91 (2.03) h post-evening dose. Efavirenz plasma samples within the therapeutic range of 1-4 microg/ml accounted for 58%; 17% were <1 microg/ml and 25% were >4 microg/ml over the 6 months. Efavirenz levels persistently >4 microg/ml were recorded for 13 (23%) children and 3 (5%) children had persistent efavirenz levels <1 microg/ml. Possible reasons for efavirenz plasma levels outside the accepted therapeutic range include genetic variation in drug metabolism, incorrect dosing, drug-drug interactions, and nonadherence. However, these need to be further explored and the importance of sequential plasma levels has been highlighted in this study.