Concentrations of Efavirenz, Tenofovir, and Emtricitabine in Obesity: A Cross-Sectional Study

BACKGROUND

Obesity is increasing worldwide including in people living with HIV (PLWH). Antiretroviral pharmacokinetic data in obesity are limited.

OBJECTIVES

To measure antiretroviral drug concentrations in obese and nonobese PLWH treated with the fixed-dose combination of efavirenz-tenofovir-emtricitabine. To determine pharmacokinetic differences across indicators of obesity and their associated immunovirological outcomes.

METHODS

We conducted a cross-sectional sample analysis of 2 cohort studies. We measured mid-dose efavirenz, 8-hydroxy-efavirenz, tenofovir, and emtricitabine concentrations. Antiretroviral drug concentrations were analyzed by body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR).

RESULTS

We performed a study of 213 participants: General obesity was detected in 20.4% using BMI and abdominal obesity in 53.6% using WC and 62.4% using WHR, respectively. The median concentrations of all antiretroviral drugs were lower among obese participants determined by BMI and WC, with efavirenz showing greater differences than tenofovir or emtricitabine. For BMI, results were most striking for efavirenz (1752.3 vs 2342.9 ng/mL, P = 0.002) with lower concentrations in obese participants. Using WC, efavirenz (1845.8 vs 2571.2 ng/mL, P < 0.001), tenofovir (65.8 vs 73.2 ng/mL, P = 0.036), and emtricitabine (159.5 vs 221.0 ng/mL, P = 0.005) concentrations were lower in obese participants. Eight-hydroxyefavirenz concentrations were similar in nonobese and obese participants for WC. Using WHR, the concentrations of all antiretroviral drugs were lower in the obese population, most strikingly for emtricitabine (173.5 vs 229.0 ng/mL, P = 0.015). There were no immunovirological associations.

CONCLUSION

We found lower antiretroviral concentrations in all obese groups, most strikingly in participants with abdominal obesity determined by WC. Lower drug concentrations had no immunovirological associations.

Prevalence and Characteristics of HIV-Associated Stroke in a Tertiary Hospital Setting in South Africa

BACKGROUND AND OBJECTIVES

Antiretroviral treatment (ART) era HIV-associated stroke data from sub-Saharan Africa are limited. We determined the prevalence of HIV in patients presenting with acute symptomatic stroke and compared risk factors, clinical characteristics, and brain imaging with age-matched stroke patients without HIV.

METHODS

We conducted a retrospective study of adults presenting with any type of stroke to Tygerberg Hospital in a 12-month period. Patients living with HIV (PLWH) and HIV-uninfected (HIV-) patients were matched based on age group (1:2 ratio). Patients were identified by keyword search, while HIV status was ascertained from laboratory data. Clinical and imaging data were extracted from medical records.

RESULTS

Among 884 patients presenting with acute strokes, the minimum prevalence of HIV infection was 9.3% (95% CI: 7.4%-11.2%), with 496 patients (56.1%) with negative HIV status and 306 patients with unknown HIV status (34.6%). The mean age at presentation in PLWH was 46 (±11) years compared with 55 (±14) years in HIV- patients (p < 0.001). Smoking was less prevalent in PLWH with an adjusted relative risk ratio of RR = 0.58 (95% CI: 0.39-0.86). Concurrent infection was more prevalent in PLWH (25.6% vs 4.9%, p ≤ 0.001) with an adjusted relative risk ratio of RR = 2.07 (95% CI: 1.49-2.84), largely in patients with a CD4 count <200 cells/μL. PLWH with higher CD4 counts (≥200 cells/μL, 51.3%) had more traditional risk factors and less concurrent infection. Among PLWH, 68.3% were on ART, and 39.3% of them had been started or restarted on ART within the past 6 months. Basal ganglia infarcts (35.6% vs 18.3%, p = 0.014) and multiple vascular territory involvement (25.4% vs 7.7%, p = 0.002) were more common in PLWH. Clinical presentation, ischemic stroke type, and in-hospital outcomes did not differ between the groups.

DISCUSSION

Stroke patients with HIV were younger, had less traditional cardiovascular risk factors, and more concurrent infections than patients without HIV, especially those with a lower CD4 count. Recent ART initiation or reinitiation rates were high. Significant differences in CT brain imaging findings were seen. Understanding the multifactorial mechanisms underlying increased stroke risk, including associated infections and potential ART-associated immune reconstitution, is crucial and needs further study.

Bleeding and thrombosis outcomes in hospitalised COVID-19 patients on low-molecular-weight heparin and antiplatelet therapy

BACKGROUND

An increased incidence of thromboembolic events in hospitalised COVID‑19 patients has been demonstrated despite the use of low-molecular-weight heparin (LMWH). Antiplatelet therapy prior to admission and early in the disease course has been hypothesised to be protective against thrombosis.

OBJECTIVES

To describe the bleeding and thrombosis outcomes in hospitalised patients with confirmed COVID‑19 receiving LMWH, with and without concomitant antiplatelet therapy. Secondary objectives were to explore predictors of bleeding and thrombosis outcomes, and dosing practices of antiplatelet therapy and LMWH.

METHODS

We conducted a descriptive, cross-sectional study of bleeding and thrombosis outcomes at Tygerberg Academic Hospital, Cape Town, South Africa, during the first COVID‑19 wave, in 808 hospitalised patients with confirmed COVID‑19 receiving LMWH with and without concomitant antiplatelet therapy. Multivariate logistic regression analysis was performed if predictors were deemed statistically and clinically significant.

RESULTS

Patients receiving both LMWH and antiplatelet therapy had similar bleeding outcomes compared with patients only receiving LMWH (odds ratio (OR) 1.5; 95% confidence interval (CI) 0.6 - 4.0). Patients receiving both LMWH and antiplatelet therapy had increased odds of developing thrombosis compared with patients only receiving LMWH (OR 4.8; 95% CI 2.1 - 10.7).

CONCLUSION

The bleeding risk in COVID‑19 patients receiving both LMWH and antiplatelet therapy was not significantly increased. A potentially higher risk of thrombosis in patients receiving LMWH and antiplatelet therapy was observed. However, this could reflect confounding by indication. Randomised studies are required to further evaluate the use of antiplatelet therapy to treat hospitalised patients with COVID‑19.

Drug concentration at the site of disease in children with pulmonary tuberculosis

BACKGROUND

Current TB treatment for children is not optimized to provide adequate drug levels in TB lesions. Dose optimization of first-line antituberculosis drugs to increase exposure at the site of disease could facilitate more optimal treatment and future treatment-shortening strategies across the disease spectrum in children with pulmonary TB.

OBJECTIVES

To determine the concentrations of first-line antituberculosis drugs at the site of disease in children with intrathoracic TB.

METHODS

We quantified drug concentrations in tissue samples from 13 children, median age 8.6 months, with complicated forms of pulmonary TB requiring bronchoscopy or transthoracic surgical lymph node decompression in a tertiary hospital in Cape Town, South Africa. Pharmacokinetic models were used to describe drug penetration characteristics and to simulate concentration profiles for bronchoalveolar lavage, homogenized lymph nodes, and cellular and necrotic lymph node lesions.

RESULTS

Isoniazid, rifampicin and pyrazinamide showed lower penetration in most lymph node areas compared with plasma, while ethambutol accumulated in tissue. None of the drugs studied was able to reach target concentration in necrotic lesions.

CONCLUSIONS

Despite similar penetration characteristics compared with adults, low plasma exposures in children led to low site of disease exposures for all drugs except for isoniazid.

Population pharmacokinetics of esomeprazole in patients with preterm preeclampsia

Esomeprazole is a proton pump inhibitor being investigated for treatment of preeclampsia. Esomeprazole pharmacokinetics during pregnancy are unknown. We used data from 10 pregnant participants with preterm preeclampsia, and 49 non-pregnant participants to develop a population pharmacokinetic model of esomeprazole. A two-compartment model described the data well. In pregnant participants after single dose, clearance was 42.2% (14.9% - 61.6%) lower compared to non-pregnant, most likely due to inhibition of CYP2C19. In non-pregnant after repeated dosing, clearance was 54.9% (48.2% - 63.5%) lower in extensive metabolizers and bioavailability was 33% (10.0% - 52.0%) higher compared to single dosing, which could be due to autoinhibition of CYP2C19. During pregnancy, the CYP2C19 autoinhibition effect with repeated dosing is expected to lead to much lower increase in exposure compared to non-pregnant, since CYP2C19 is already inhibited due to pregnancy.

Comparison of patients with severe COVID-19 admitted to an intensive care unit in South Africa during the first and second wave of the COVID-19 pandemic

Background

The second wave of coronavirus disease 2019 (COVID-19), dominated by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Beta variant, has been reported to be associated with increased severity in South Africa (SA).

Objectives

To describe and compare clinical characteristics, management and outcomes of COVID-19 patients admitted to an intensive care unit (ICU) in SA during the first and second waves.

Methods

In a prospective, single-centre, descriptive study, we compared all patients with severe COVID-19 admitted to ICU during the first and second waves. The primary outcomes assessed were ICU mortality and ICU length of stay (LOS).

Results

In 490 patients with comparable ages and comorbidities, no difference in mortality was demonstrated during the second compared with the first wave (65.9% v. 62.5%, p=0.57). ICU LOS was longer in the second wave (10 v. 6 days, p<0.001). More female admissions (67.1% v. 44.6%, p<0.001) and a greater proportion of patients were managed with invasive mechanical ventilation than with non-invasive respiratory support (39.0% v. 14%, p<0.001) in the second wave.

Conclusion

While clinical characteristics were comparable between the two waves, a higher proportion of patients was invasively ventilated and ICU stay was longer in the second. ICU mortality was unchanged.

Opportunities to enhance antibiotic stewardship: colistin use and outcomes in a low-resource setting

Background

Colistin use is increasing with the rise in MDR Gram-negative infections globally. Effective antibiotic stewardship is essential to preserve this antibiotic of last resort.

Objectives

This study investigated stewardship and safety errors related to colistin use to identify opportunities for improvement.

Patients and methods

A prospective descriptive study involving all patients 13 years and older treated with colistin at a tertiary hospital in Cape Town, South Africa, between August 2018 and June 2019. We collected clinical, laboratory and outcome data and assessed provided treatment for stewardship and safety errors.

Results

We included 44 patients. Treatment errors were identified for 34 (77%) patients (median = 1), most commonly inadequate monitoring of renal function (N = 16, 32%). We also identified no rational indication for colistin (N = 9, 20%), loading dose error (N = 12, 27%); maintenance dose error (N = 10, 23%); no prior culture (N = 11, 25%); and failure to de-escalate (2 of 9) or adjust dose to changes in renal function (6 of 15). All cause in-hospital mortality was 47%. Amongst survivors, median ICU stay was 6 days and hospital stay more than 30 days. Eight (18%) patients developed renal injury or failure during treatment. Three (7%) patients in this study were found to have colistin-resistant organisms including two prior to colistin exposure.

Conclusions

This study has identified opportunities to enhance colistin stewardship and improve efficacy and safety of prescription. The appearance of colistin-resistant organisms reinforces the urgent need to ensure effective and appropriate use of colistin.

Pharmacogenetics of the Late-Onset Efavirenz Neurotoxicity Syndrome (LENS)

BACKGROUND

The late-onset efavirenz neurotoxicity syndrome (LENS) presents as ataxia and/or encephalopathy with supratherapeutic efavirenz plasma concentrations (>4 µg/mL). Efavirenz is primarily metabolized by cytochrome P450 2B6 (CYP2B6), with CYP2A6 as an accessory pathway. We hypothesized that participants with LENS would predominantly be CYP2B6 slow metabolizers. The aim of our study was to determine the frequency of CYP2B6 slow metabolizers in participants with LENS.

METHODS

Adult HIV-positive participants on efavirenz-based antiretroviral therapy presenting with LENS were prospectively enrolled. Genetic polymorphisms known to be associated with increased efavirenz plasma concentrations in CYP2B6 (rs3745274, rs28399499, rs4803419) and CYP2A6 (rs28399433) were selected and used to determine proportions of slow metabolizers. Pharmacokinetic analyses were performed using liquid chromatography-tandem mass spectrometry. Median (IQR) plasma efavirenz and 8-hydroxyefavirenz were described.

RESULTS

Fifteen participants were enrolled. Thirteen (13/15) were Black-African and 13 were female. Median weight was 49.9kg with a median duration on efavirenz of 2.2 years. All 15 participants were successfully genotyped as slow CYP2B6 metabolizers, with 6 participants additionally having CYP2A6 heterozygous genotype. Thirteen were receiving the CYP2A6 enzyme inhibitor isoniazid, and all 15 were genotypic NAT2 slow or intermediate acetylators. Efavirenz plasma concentration was markedly increased at 50.5 (47.0-65.4) µg/mL; 8-hydroxyefavirenz concentration was markedly decreased at 0.10 (0.07-0.15) µg/mL.

CONCLUSIONS

Our cohort provides definitive evidence that LENS is associated with the CYP2B6 slow metabolizer genotype, with a median efavirenz plasma concentration >12-fold higher than the defined upper limit of the therapeutic range. Isoniazid and low body weight are important contributors to LENS development.

Use of metformin to prolong gestation in preterm pre-eclampsia: randomised, double blind, placebo controlled trial

OBJECTIVE

To evaluate whether extended release metformin could be used to prolong gestation in women being expectantly managed for preterm pre-eclampsia.

DESIGN

Randomised, double blind, placebo controlled trial.

SETTING

Referral hospital in Cape Town, South Africa.

PARTICIPANTS

180 women with preterm pre-eclampsia between 26+0 to 31+6 weeks' gestation undergoing expectant management: 90 were randomised to extended release metformin and 90 to placebo.

INTERVENTION

3 g of oral extended release metformin or placebo daily, in divided doses, until delivery.

MAIN OUTCOME MEASURE

The primary outcome was prolongation of gestation.

RESULTS

Of 180 participants, one woman delivered before taking any trial drug. The median time from randomisation to delivery was 17.7 days (interquartile range 5.4-29.4 days; n=89) in the metformin arm and 10.1 (3.7-24.1; n=90) days in the placebo arm, a median difference of 7.6 days (geometric mean ratio 1.39, 95% confidence interval 0.99 to 1.95; P=0.057). Among those who continued to take the trial drug at any dose, the median prolongation of gestation in the metformin arm was 17.5 (interquartile range 5.4-28.7; n=76) days compared with 7.9 (3.0-22.2; n=74) days in the placebo arm, a median difference of 9.6 days (geometric mean ratio 1.67, 95% confidence interval 1.16 to 2.42). Among those who took the full dosage, the median prolongation of gestation in the metformin arm was 16.3 (interquartile range 4.8-28.8; n=40) days compared with 4.8 (2.5-15.4; n=61) days in the placebo arm, a median difference of 11.5 days (geometric mean ratio 1.85, 95% confidence interval 1.14 to 2.88). Composite maternal, fetal, and neonatal outcomes and circulating concentrations of soluble fms-like tyrosine kinase-1, placental growth factor, and soluble endoglin did not differ. In the metformin arm, birth weight increased non-significantly and length of stay decreased in the neonatal nursery. No serious adverse events related to trial drugs were observed, although diarrhoea was more common in the metformin arm.

CONCLUSIONS

This trial suggests that extended release metformin can prolong gestation in women with preterm pre-eclampsia, although further trials are needed. It provides proof of concept that treatment of preterm pre-eclampsia is possible.

TRIAL REGISTRATION

Pan African Clinical Trial Registry PACTR201608001752102 https://pactr.samrc.ac.za/.

The 12-month period prevalence and cardiac manifestations of HIV in patients with acute coronary syndrome at a tertiary hospital in Cape Town, South Africa: a retrospective cross-sectional study

Background

HIV-positive patients are increasingly being affected by non-communicable diseases such as coronary artery disease (CAD). Data from high-income countries (HICs) indicate that HIV-positive patients have different risk-factor profiles for acute coronary syndrome (ACS) as well as different cardiac manifestations of this syndrome compared to HIV-negative patients. There is limited data from Sub-Saharan Africa (SSA), and particularly from South Africa with the biggest HIV epidemic in the world. The objective of this study was to determine the 12-month period prevalence of HIV in patients with ACS and to compare the risk-factor profile, ACS presentation and management between HIV-positive and HIV-negative adults.

Methods

We included all patients hospitalised with ACS from 01 January to 31 December 2018 in a tertiary hospital, Tygerberg Hospital, in Cape Town, South Africa. The HIV-status of all patients was determined using routine clinical records. We performed multiple conditional logistic regression on HIV-positive and HIV-negative patients (1:3 ratio) to compare the risk factor profile, ACS presentation and management between the groups.

Results

Among 889 patients, 30 (3.4%) were HIV-positive (95% confidence interval (CI): 2.3–4.8). HIV-positive patients were younger, more frequently men, and had a lower prevalence of medical comorbidities and a family history of CAD. They were more likely to present with ST-elevation myocardial infarction (STEMI) [odd’s ratio (OR) (95% CI): 3.12 (1.2–8.4)], and have single-vessel disease [OR (95% CI): 3.03 (1.2–8.0)]. Angiographic and echocardiographic data, as well as management, did not differ between the groups. Among HIV-positive patients, 17 (65%) were virally suppressed (HIV viral load < 200 copies/mL) with a median CD4⁺ count of 271 cells/mm³. The majority (20, 67%) of HIV-positive patients were receiving antiretroviral therapy at the time of the ACS.

Conclusions

We found an HIV-prevalence of 3.4% (95% CI 2.3–4.8) in adults with ACS in a high endemic HIV region. HIV-positive patients were younger and more likely to present with STEMIs and single-vessel disease, but had fewer CAD risk factors, suggesting additional mechanisms for the development of ACS.

Single Dose Abacavir Pharmacokinetics and Safety in Neonates Exposed to Human Immunodeficiency Virus (HIV)

Abacavir is a potential option for prophylaxis and early treatment of human immunodeficiency virus (HIV), but no data are available in neonates. Ten neonates administered a single abacavir dose of 8 mg/kg before 15 days of life had substantially higher exposures than those reported in infants and children, with no reported adverse events.

The Pharmacokinetics of Crushed Levetiracetam Tablets Administered to Neonates

BACKGROUND

Intravenous phenobarbital remains the first-line therapy in the management of neonatal seizures. Shortages of intravenous phenobarbital in South Africa necessitated the addition of oral levetiracetam as part of management of neonatal seizures.

OBJECTIVE

We evaluated the pharmacokinetics of crushed immediate-release levetiracetam tablets administered to neonates to terminate seizures.

METHODS

A prospective, observational study of neonates admitted with seizures to Tygerberg Hospital. Participants received crushed levetiracetam (diluted in saline) given orally or via naso-/orogastric tube. At steady-state, pharmacokinetic sampling was performed at pre-dose, 1.5, 2.5 and 4 h post-dose. Maximum concentration (Cmax), time to Cmax (Tmax), trough concentrations (Ctrough) and area under the concentration-time curve (AUC0-12) were calculated using non-compartmental analysis. Seizure termination and safety profiles were documented.

RESULTS

Nineteen participants were grouped into three dosing ranges: (i) 5-15 mg/kg/12-hourly, (ii) 15-25 mg/kg/12-hourly and (iii) 25-35 mg/kg/12-hourly. Range 1 demonstrated AUC0-12 167.0 ± 45.6 h*μg/mL, Cmax 19.19 ± 4.12 μg/mL and Ctrough 9.99 ± 3.86 µg/mL. Range 2, AUC0-12 316.5 ± 108.4 h*μg/mL, Cmax 35.12 ± 10.54 µg/mL and Ctrough 19.25 ± 8.48 µg/mL. Range 3, AUC0-12 290.9 (range 176.14-405.59) h*μg/mL, Cmax 36.11 (range 27.58-44.64) µg/mL and Ctrough 13.03 (2.98-23.07) µg/mL. Seizures terminated in 17/19 (90%) neonates by day 3 and 19/19 (100%) by day 4 post-levetiracetam initiation.

CONCLUSION

Crushed levetiracetam has comparable pharmacokinetics to historical data. No pharmacokinetic differences were observed between oral vs. naso-/orogastric administration. Crushed levetiracetam tablets can be considered for neonates in low-resource settings where intravenous and syrup access is limited.

LAY SUMMARY

Intravenous preparations of antiepileptic medications are used in the management of neonatal seizures. Various established standard of care intravenous antiepileptic medicines are unavailable nationally and internationally due to reasons outside our control. This stock shortage included intravenous phenobarbitone which is the first-line treatment for paediatric seizures. Due to phenobarbital shortage, levetiracetam has been identified by the neonatologists at Tygerberg Hospital, Cape Town, South Africa, as a suitable treatment option due to its efficacy and safety profile. However, intravenous levetiracetam and oral syrup is not registered in South Africa. Levetiracetam tablets are being crushed, dissolved and administered to neonates. There are no data available on the absorption of crushed levetiracetam tablets administered to neonates via a nasogastric tube. This study characterized the pharmacokinetic profile of crushed levetiracetam administered to neonates. We selected neonates receiving levetiracetam from the neonatal wards at Tygerberg hospital and drew blood to analyse the levetiracetam concentrations at 4 different time points. We found that the overall exposure of crushed levetiracetam tablets were comparable to the exposures achieved in historical data of the unaltered formulations. We concluded that crushed levetiracetam tablets can be considered for neonates in low resource settings where intravenous and syrup access is limited.

How COVID-19 has fundamentally changed clinical research in global health

COVID-19 has had negative repercussions on the entire global population. Despite there being a common goal that should have unified resources and efforts, there have been an overwhelmingly large number of clinical trials that have been registered that are of questionable methodological quality. As the final paper of this Series, we discuss how the medical research community has responded to COVID-19. We recognise the incredible pressure that this pandemic has put on researchers, regulators, and policy makers, all of whom were doing their best to move quickly but safely in a time of tremendous uncertainty. However, the research community's response to the COVID-19 pandemic has prominently highlighted many fundamental issues that exist in clinical trial research under the current system and its incentive structures. The COVID-19 pandemic has not only re-emphasised the importance of well designed randomised clinical trials but also highlighted the need for large-scale clinical trials structured according to a master protocol in a coordinated and collaborative manner. There is also a need for structures and incentives to enable faster data sharing of anonymised datasets, and a need to provide similar opportunities to those in high-income countries for clinical trial research in low-resource regions where clinical trial research receives considerably less research funding.

Pharmacogenetics of tenofovir and emtricitabine penetration into cerebrospinal fluid

Background

Blood-cerebrospinal fluid (CSF) barrier transporters affect the influx and efflux of drugs. The antiretrovirals tenofovir and emtricitabine may be substrates of blood-brain barrier (BBB) and blood-CSF barrier transporters, but data are limited regarding the pharmacogenetics and pharmacokinetics of their central nervous system (CNS) penetration.

Objectives

We investigated genetic polymorphisms associated with CSF disposition of tenofovir and emtricitabine.

Method

We collected paired plasma and CSF samples from 47 HIV-positive black South African adults who were virologically suppressed on efavirenz, tenofovir and emtricitabine. We considered 1846 single-nucleotide polymorphisms from seven relevant transporter genes (ABCC5, ABCG2, ABCB1, SLCO2B1, SCLO1A2, SLCO1B1 and ABCC4) and 782 met a linkage disequilibrium (LD)-pruning threshold.

Results

The geometric mean (95% confidence interval [CI]) values for tenofovir and emtricitabine CSF-to-plasma concentration ratios were 0.023 (0.021-0.026) and 0.528 (0.460-0.605), respectively. In linear regression models, the lowest p-value for association with the tenofovir CSF-to-plasma ratio was ABCB1 rs1989830 (p = 1.2 × 10^-3) and for emtricitabine, it was ABCC5 rs11921035 (p = 1.4 × 10^-3). None withstood correction for multiple testing.

Conclusion

No genetic polymorphisms were associated with plasma, CSF concentrations or CSF-to-plasma ratios for either tenofovir or emtricitabine.

Minimizing the impact of the triple burden of COVID-19, tuberculosis and HIV on health services in sub-Saharan Africa

In this perspective, we discuss the impact of COVID-19 on tuberculosis (TB)/HIV health services and approaches to mitigating the growing burden of these three colliding epidemics in sub-Saharan Africa (SSA). SSA countries bear significantly high proportions of TB and HIV cases reported worldwide, compared to countries in the West. Whilst COVID-19 epidemiology appears to vary across Africa, most countries in this region have reported relatively lower-case counts compared to the West. Nevertheless, the COVID-19 pandemic has added an additional burden to already overstretched health systems in SSA, which, among other things, have been focused on the longstanding dual epidemics of TB and HIV. As with these dual epidemics, inadequate resources and poor case identification and reporting may be contributing to underestimations of the COVID-19 case burden in SSA. Modelling studies predict that the pandemic-related disruptions in TB and HIV services will result in significant increases in associated morbidity and mortality over the next five years. Furthermore, limited empirical evidence suggests that SARS-CoV-2 coinfections with TB and HIV are associated with increased mortality risk in SSA. However, predictive models require a better evidence-base to accurately define the impact of COVID-19, not only on communicable diseases such as TB and HIV, but on non-communicable disease comorbidities. Further research is needed to assess morbidity and mortality data among both adults and children across the African continent, paying attention to geographic disparities, as well as the clinical and socio-economic determinants of COVID-19 in the setting of TB and/or HIV.

Incident tuberculosis disease in patients receiving biologic therapies in the Western Cape, South Africa from 2007 to 2018

BACKGROUND

South Africa has one of the highest tuberculosis incidence rates. Biologic disease-modifying anti-rheumatic drugs are associated with an increased risk of tuberculosis. The objective of this study was to describe the tuberculosis disease incidence rate among public sector patients receiving biologic therapies in the Western Cape Province.

METHODS

A retrospective, descriptive analysis was undertaken using routine health data collated by the Provincial Health Data Centre from January 2007 (first use of biologic therapy in the Western Cape) to September 2018.

RESULTS

We identified 609 patients treated with tumour necrosis factor-alpha (TNF-α) or non-TNF-α biologic therapies. Thirty-seven (37) patients developed tuberculosis after biologic therapy exposure, of whom the majority (78%) had an immune mediated inflammatory disease and the remainder (22%) a haematologic malignancy. The incidence rate of tuberculosis per 100,000 person-years was 2227 overall [95% confidence interval (CI): 1591, 3037]. Patients treated with TNF-α inhibitors and non-TNF-α inhibitors had estimated incidence rates of 2819 [95% CI: 1669, 4480] and 1825 [95% CI: 1131, 2797], respectively (p = 0.10).

CONCLUSION

Patients exposed to both TNF-α and non-TNF-α biologic therapies may have a higher incidence of tuberculosis disease compared to the background risk of 681 cases per 100,000 per year in the Western Cape.

Accelerating Clinical Evaluation of Repurposed Combination Therapies for COVID-19

As the global COVID-19 pandemic continues, unabated and clinical trials demonstrate limited effective pharmaceutical interventions, there is a pressing need to accelerate treatment evaluations. Among options for accelerated development is the evaluation of drug combinations in the absence of prior monotherapy data. This approach is appealing for a number of reasons. First, combining two or more drugs with related or complementary therapeutic effects permits a multipronged approach addressing the variable pathways of the disease. Second, if an individual component of a combination offers a therapeutic effect, then in the absence of antagonism, a trial of combination therapy should still detect individual efficacy. Third, this strategy is time saving. Rather than taking a stepwise approach to evaluating monotherapies, this strategy begins with testing all relevant therapeutic options. Finally, given the severity of the current pandemic and the absence of treatment options, the likelihood of detecting a treatment effect with combination therapy maintains scientific enthusiasm for evaluating repurposed treatments. Antiviral combination selection can be facilitated by insights regarding SARS-CoV-2 pathophysiology and cell cycle dynamics, supported by infectious disease and clinical pharmacology expert advice. We describe a clinical evaluation strategy using adaptive combination platform trials to rapidly test combination therapies to treat COVID-19.

Clinical Pharmacokinetics and Pharmacodynamics of Rifampicin in Human Tuberculosis

The introduction of rifampicin (rifampin) into tuberculosis (TB) treatment five decades ago was critical for shortening the treatment duration for patients with pulmonary TB to 6 months when combined with pyrazinamide in the first 2 months. Resistance or hypersensitivity to rifampicin effectively condemns a patient to prolonged, less effective, more toxic, and expensive regimens. Because of cost and fears of toxicity, rifampicin was introduced at an oral daily dose of 600 mg (8-12 mg/kg body weight). At this dose, clinical trials in 1970s found cure rates of ≥ 95% and relapse rates of < 5%. However, recent papers report lower cure rates that might be the consequence of increased emergence of resistance. Several lines of evidence suggest that higher rifampicin doses, if tolerated and safe, could shorten treatment duration even further. We conducted a narrative review of rifampicin pharmacokinetics and pharmacodynamics in adults across a range of doses and highlight variables that influence its pharmacokinetics/pharmacodynamics. Rifampicin exposure has considerable inter- and intra-individual variability that could be reduced by administration during fasting. Several factors including malnutrition, HIV infection, diabetes mellitus, dose size, pharmacogenetic polymorphisms, hepatic cirrhosis, and substandard medicinal products alter rifampicin exposure and/or efficacy. Renal impairment has no influence on rifampicin pharmacokinetics when dosed at 600 mg. Rifampicin maximum (peak) concentration (C_max) > 8.2 μg/mL is an independent predictor of sterilizing activity and therapeutic drug monitoring at 2, 4, and 6 h post-dose may aid in optimizing dosing to achieve the recommended rifampicin concentration of ≥ 8 µg/mL. A higher rifampicin C_max is required for severe forms TB such as TB meningitis, with C_max ≥ 22 μg/mL and area under the concentration-time curve (AUC) from time zero to 6 h (AUC₆) ≥ 70 μg·h/mL associated with reduced mortality. More studies are needed to confirm whether doses achieving exposures higher than the current standard dosage could translate into faster sputum conversion, higher cure rates, lower relapse rates, and less mortality. It is encouraging that daily rifampicin doses up to 35 mg/kg were found to be safe and well-tolerated over a period of 12 weeks. High-dose rifampicin should thus be considered in future studies when constructing potentially shorter regimens. The studies should be adequately powered to determine treatment outcomes and should include surrogate markers of efficacy such as C_max/MIC (minimum inhibitory concentration) and AUC/MIC.

Pediatric Antiretroviral Therapeutic Drug Monitoring: A Five and a Half Year Experience from a South African Tertiary Hospital

INTRODUCTION

Antiretroviral therapeutic drug monitoring (TDM) is not routinely used in the management of human immunodeficiency virus, but may be useful in pediatric patients who are prone to altered pharmacokinetics. Data on the routine use of antiretroviral TDM in pediatrics are sparse especially data from sub-Saharan Africa.

METHODS

We retrospectively reviewed the antiretroviral TDM indications at Tygerberg Children's Hospital, identified pediatric patients who had antiretroviral TDM requests from January 2012 until June 2017 and reviewed their clinical records.

RESULTS

Fifty-nine patients were identified who presented with 64 clinical problems for which TDM was requested. TDM was requested for lopinavir, efavirenz and nevirapine in 83% (53/64), 14% (9/64) and 3% (2/64) of clinical problems, respectively. Lopinavir was mostly requested in patients when adherence measures did not correlate with the clinical picture, suspected non-adherence, lopinavir-rifampicin interactions and for neonatal safety monitoring. Efavirenz was requested when toxicity was suspected and nevirapine in patients receiving rifampicin. Lopinavir TDM confirmed non-adherence in 25% (4/16) of cases when adherence measures did not correlate with the clinical picture and in 43% (3/7) of cases when non-adherence was suspected by the clinician. Efavirenz TDM confirmed toxicity in 100% (6/6) of patients.

CONCLUSIONS

Lopinavir TDM was mostly requested when adherence measures did not correlate with the clinical picture, when rifampicin was co-administered and for perinatal safety monitoring. Lopinavir TDM excluded pharmacokinetic reasons for failure in patients failing treatment when lopinavir dosing was supervised. Efavirenz TDM was requested for suspected toxicity with a 100% positive predictive value.

Pharmacogenetics and pharmacokinetics of CNS penetration of efavirenz and its metabolites

BACKGROUND

There are limited data on the pharmacogenetics and pharmacokinetics of the CNS penetration of efavirenz.

OBJECTIVES

We investigated genetic polymorphisms associated with CSF concentrations of efavirenz and its metabolites and explored the relationships with neurocognitive performance.

METHODS

We included 47 HIV-infected South African black adults with and without HIV-associated neurocognitive disorder on efavirenz/tenofovir/emtricitabine and collected paired plasma-CSF samples. We considered 2049 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.

RESULTS

We identified 9 slow, 21 intermediate and 17 extensive metabolizers. The CYP2B6 983 genotype in multivariate analyses predicted log10-transformed concentrations of plasma efavirenz (β = 0.38, P = 2.7 × 10-03), plasma 7-hydroxy-efavirenz (β = 0.59, P = 3.7 × 10-03), plasma 8-hydroxy-efavirenz:efavirenz ratio (β = -0.31, P = 1.8 × 10-04) and CSF efavirenz (β = 0.36, P = 0.01). Lower plasma 7-hydroxy-efavirenz concentrations were independently associated with CYP2A6 rs10853742 (β = -0.55, P = 3.5 × 10-05), ABCB1 rs115780656 (β = -0.65, P = 4.1 × 10-05) and CYP2A6 -48A→C (β = -0.59, P = 0.01). CYP2A6 -48A→C was independently associated with higher CSF 8-hydroxy-efavirenz:efavirenz ratio (β = 0.54, P = 0.048). CYP2B6 rs2279345 polymorphism was associated with lower plasma 7-hydroxy-efavirenz:efavirenz ratio in multivariate analyses (P < 0.05). No polymorphisms were associated with CSF:plasma ratios of efavirenz, plasma or CSF concentrations of 8-hydroxy-efavirenz or neurocognitive performance.

CONCLUSIONS

We identified novel genetic associations with plasma efavirenz, plasma 7-hydroxy-efavirenz, plasma 7-hydroxy-efavirenz:efavirenz ratio, plasma 8-hydroxy-efavirenz:efavirenz ratio, CSF efavirenz and CSF 8-hydroxy-efavirenz:efavirenz ratio.

Chloroquine and Hydroxychloroquine for the Prevention or Treatment of COVID-19 in Africa: Caution for Inappropriate Off-label Use in Healthcare Settings

The novel severe acute respiratory syndrome-coronavirus-2 pandemic has spread to Africa, where nearly all countries have reported laboratory-confirmed cases of novel coronavirus disease (COVID-19). Although there are ongoing clinical trials of repurposed and investigational antiviral and immune-based therapies, there are as yet no scientifically proven, clinically effective pharmacological treatments for COVID-19. Among the repurposed drugs, the commonly used antimalarials chloroquine (CQ) and hydroxychloroquine (HCQ) have become the focus of global scientific, media, and political attention despite a lack of randomized clinical trials supporting their efficacy. Chloroquine has been used worldwide for about 75 years and is listed by the WHO as an essential medicine to treat malaria. Hydroxychloroquine is mainly used as a therapy for autoimmune diseases. However, the efficacy and safety of CQ/HCQ for the treatment of COVID-19 remains to be defined. Indiscriminate promotion and widespread use of CQ/HCQ have led to extensive shortages, self-treatment, and fatal overdoses. Shortages and increased market prices leave all countries vulnerable to substandard and falsified medical products, and safety issues are especially concerning for Africa because of its healthcare system limitations. Much needed in Africa is a cross-continental collaborative network for coordinated production, distribution, and post-marketing surveillance aligned to low-cost distribution of any approved COVID-19 drug; this would ideally be piggybacked on existing global aid efforts. Meanwhile, African countries should strongly consider implementing prescription monitoring schemes to ensure that any off-label CQ/HCQ use is appropriate and beneficial during this pandemic.

Current evidence for directed and supportive investigational therapies against COVID-19

Coronavirus disease 2019 (COVID-19) is a global health crisis. There is currently a great need for effective and safe therapies directed at the disease, but no drugs are presently registered for use in COVID-19. Several directed therapies have been proposed, and most are still in clinical trials. Currently available published, peer-reviewed results mostly involve small sample sizes with study limitations restricting the interpretation of the findings. Many trials currently published also do not have a control group, limiting the interpretation of the effect of the intervention. Investigational directed therapies as well as investigational supportive therapies against COVID-19 are reviewed here. Chloroquine and hydroxychloroquine show promise as directed therapies, but current trial results are conflicting. Lopinavir/ritonavir also shows potential, but was started late in the disease course in most trials. No randomised controlled evidence is currently available for remdesivir and favipiravir. Corticosteroid use is not recommended for directed therapy against COVID-19, and the role of tocilizumab is currently unclear, based on limited evidence. Early initiation of investigational directed therapies may provide benefit in selected patients. The results from larger randomised controlled trials will clarify the place of these therapies in COVID-19 treatment.

The neurologic phenotype of South African patients with HIV-associated neurocognitive impairment

Background

The neurologic manifestations of HIV include a spectrum of HIV-associated neurocognitive disorders, as well as a cluster of neurologic symptoms and signs. The neurologic manifestations have been modified but not eradicated by antiretroviral therapy (ART). We describe the neurologic phenotype in South African patients with predominant HIV-1 subtype C infection on ART and its association with neurocognitive impairment and efavirenz and 8-hydroxy-efavirenz concentrations.

Methods

We conducted a cross-sectional analysis of the neurologic examination findings of HIV+ patients with neurocognitive impairment and used multiple linear regression to explore associations with neurocognitive impairment, efavirenz, and 8-hydroxy-efavirenz pharmacokinetics (plasma and CSF).

Results

We included 80 participants established on ART (median 40 months) of which 72 (90%) were female. The median age was 35 (interquartile range [IQR], 32-42) and the median Global Deficit Score was 0.94 (IQR 0.63-1.36). We found associations between neurocognitive impairment and neurologic signs: gait (slow walking speed [p = 0.03; R² = 0.06], gait ataxia [p < 0.01; R² = 0.21], and abnormal gait appearance [p < 0.01; R² = 0.18]); coordination (upper limb bradykinesia [p < 0.01; R² = 0.10] and lower limb bradykinesia [p = 0.01; R² = 0.10]); reflexes (jaw jerk [p = 0.04; R² = 0.05] and palmomental response [p = 0.03; R² = 0.06]); ocular signs (impaired smooth pursuit [p = 0.01; R² = 0.09] and impaired saccades [p < 0.01; R² = 0.15]); and motor signs (spasticity [p ≤ 0.01; R² = 0.15] and muscle weakness [p = 0.01; R² = 0.08]). No significant associations were found between plasma and CSF efavirenz or 8-hydroxy efavirenz concentrations and any neurologic sign.

Conclusion

We found that individual neurologic signs were associated with neurocognitive impairment in South African HIV+ patients with predominant HIV-1 subtype C infection on ART and could be used in clinical practice to assess severity.

Registration number

PACTR201310000635418.

An Approach to the Pharmacotherapy of Neuroleptic Malignant Syndrome

Neuroleptic malignant syndrome is a rare, idiosyncratic emergency associated with exposure to dopamine antagonists, commonly antipsychotic drugs. The typical clinical picture consists of altered consciousness, muscular rigidity, fever, and autonomic instability. While the condition has generally been well described, the pathophysiology is still poorly understood. The importance of this case report is to highlight the lack of robust evidence-based treatment for this emergency. We submit an approach to the pharmacotherapy of neuroleptic malignant syndrome based on the available evidence.

Esomeprazole to treat women with preterm preeclampsia: a randomized placebo controlled trial

BACKGROUND

Preterm preeclampsia has a high rate of fetal death or disability. There is no treatment to slow the disease, except delivery. Preclinical studies have identified proton pump inhibitors as a possible treatment.

OBJECTIVE

The purpose of this study was to examine whether esomeprazole could prolong pregnancy in women who have received a diagnosis of preterm preeclampsia.

STUDY DESIGN

We performed a double-blind, randomized controlled trial at Tygerberg Hospital in South Africa. Women with preterm preeclampsia (gestational age 26 weeks+0 days to 31 weeks+6 days) were assigned randomly to 40-mg daily esomeprazole or placebo. The primary outcome was a prolongation of gestation of 5 days. Secondary outcomes were maternal and neonatal outcomes. We compared circulating markers of endothelial dysfunction that was associated with preeclampsia and performed pharmacokinetic studies.

RESULTS

Between January 2016 and April 2017, we recruited 120 participants. One participant was excluded because of incorrect randomization, which left 59 participants in the esomeprazole and 60 participants in the placebo group. Median gestational age at enrolment was 29+4 weeks gestation. There were no between-group differences in median time from randomization to delivery: 11.4 days (interquartile range, 3.6-19.7 days) in the esomeprazole group and 8.3 days (interquartile range, 3.8-19.6 days) in the placebo group (3 days longer in the esomeprazole arm; 95% confidence interval, -2.9-8.8; P=.31). There were no placental abruptions in the esomeprazole group and 6 (10%) in the placebo group (P=.01, P=.14 adjusted). There were no differences in other maternal or neonatal outcomes or markers of endothelial dysfunction. Esomeprazole and its metabolites were detected in maternal blood among those treated with esomeprazole, but only trace amounts in the umbilical cord blood.

CONCLUSION

Daily esomeprazole (40 mg) did not prolong gestation in pregnancies with preterm preeclampsia or decrease circulating soluble fms-like tyrosine kinase 1 concentrations. Higher levels in the maternal circulation may be needed for clinical effect.

Paediatric antimicrobial use at a South African hospital

BACKGROUND

Data on antimicrobial use among hospitalized children in Africa are very limited due to the absence of electronic prescription tracking.

METHODS

This study evaluated antimicrobial consumption rates, the antimicrobial spectrum used, and the indications for therapy on a paediatric ward and in the paediatric intensive care unit (PICU) at Tygerberg Hospital, Cape Town, South Africa. Antimicrobial prescription and patient demographic data were collected prospectively from May 10, 2015 to November 11, 2015. For the same period, data on antimicrobials dispensed and costs were extracted from the pharmacy electronic medicine management system. The volume of antimicrobials dispensed (dispensing data) was compared with observed antimicrobial use (prescription data).

RESULTS

Of the 703 patients admitted, 415/451 (92%) paediatric ward admissions and 233/252 (92%) PICU admissions received ≥1 antimicrobials. On the ward, 89% of prescriptions were for community-acquired infections; 29% of PICU antimicrobials were prescribed for healthcare-associated infections. Ampicillin and third-generation cephalosporins were the most commonly prescribed agents. Antimicrobial costs were 67541 South African Rand (ZAR) (5680 United States Dollars (USD)) on the ward and 210484 ZAR (17702 USD) in the PICU. Ertapenem and meropenem were the single largest contributors to antimicrobial costs on the ward (43%) and PICU (30%), respectively. The volume of antimicrobials dispensed by the pharmacy (dispensing data) differed considerably from observed antimicrobial use (prescription data).

CONCLUSIONS

High rates of antimicrobial consumption were documented. Community-acquired infections were the main indication for prescription. Although pharmacy dispensing data did not closely approximate observed use, this represents a promising method for antimicrobial usage tracking in the future.

Adding a brief self-report cognitive tool to the IHDS improves effectiveness of identifying patients with HIV-associated dementia in South Africa

We compared the diagnostic accuracy of two brief screening tools (the International HIV Dementia Scale (IHDS), and the IHDS combined with a novel self-report instrument, the HIV Cognitive Symptom Questionnaire (HCSQ)) with that of three brief neuropsychological screening batteries (a 2-, a 3-, and a 4-test battery, each consisting of standardized cognitive tests) in discriminating individuals with HIV-associated dementia (HAD) from those with milder forms of cognitive impairment. We analyzed data from 94 isiXhosa-speaking South African HIV-infected participants who were screened as part of a clinical trial evaluating adjunctive treatment in patients with moderate to severe HIV-associated cognitive impairment. A comprehensive neuropsychological battery diagnosed 53% (50/94) of the participants with HAD. We evaluated the sensitivity and specificity for the screening tools and screening batteries. The brief screening tool performed better compared to the brief neuropsychology battery. The IHDS-HCSQ combination delivered 94% sensitivity and 63% specificity for HAD compared to the IHDS (74 and 70% at a cutoff of ≤8) which offers a viable and quick way to screen for HAD in people living with HIV. It is easy to administer, is time- and cost-efficient, and it appears to be a better option, for these purposes, than brief neuropsychology batteries. It is viable for use in clinical, research, and workplace settings when identification of HIV-infected people with severe cognitive impairment is required.

A preliminary review of warfarin toxicity in a tertiary hospital in Cape Town, South Africa

AIM

Warfarin is a widely used anticoagulant for the prevention and treatment of thromboembolism. We conducted a retrospective review to determine the causes and management of warfarin toxicity of patients admitted to Tygerberg hospital between June 2014 and June 2015.

RESULTS

We identified and evaluated 126 patients who met the inclusion criteria. The cause of warfarin toxicity was identified and addressed in only 14.3% (18/126) of patients. Where the cause was identified, 56% (10/18) was due to dosing errors and 17% (3/18) drug-drug interaction (DDI). However, 77% (97/126) of patients were retrospectively identified as receiving concomitant medicines known to interact with warfarin at the time of admission. Twenty-eight percent (35/126) of patients presented with major bleeding, which included seven cases of intracranial haemorrhage. Patients were admitted for a median of eight days at an average treatment cost of R10 578.

CONCLUSION

We found that warfarin toxicity carries significant mortality and cost, but little attention is paid to the causes of toxicity.

Antiretroviral treatment in HIV-infected children who require a rifamycin-containing regimen for tuberculosis

INTRODUCTION

In high prevalence settings, tuberculosis and HIV dual infection and co-treatment is frequent. Rifamycins, especially rifampicin, in combination with isoniazid, ethambutol and pyrazinamide are key components of short-course antituberculosis therapy. Areas covered: We reviewed available data, for which articles were identified by a Pubmed search, on rifamycin-antiretroviral interactions in HIV-infected children. Rifamycins have potent inducing effects on phase I and II drug metabolising enzymes and transporters. Antiretroviral medications are often metabolised by the enzymes induced by rifamycins or may suppress specific enzyme activity leading to drug-drug interactions with rifamycins. These may cause significant alterations in their phamacokinetic and pharmacodynamic properties, and sometimes that of the rifamycin. Recommended strategies to adapt to these interactions include avoidance and dose adjustment. Expert opinion: Despite the importance and frequency of tuberculosis as an opportunistic disease in HIV-infected children, current data on the management of co-treated children is based on few studies. We need new strategies to rapidly assess the use of rifamycins, new anti-tuberculosis drugs and antiretroviral drugs together as information on safety and dosing of individual drugs becomes available.

Renal safety of lithium in HIV-infected patients established on tenofovir disoproxil fumarate containing antiretroviral therapy: analysis from a randomized placebo-controlled trial

Background

The prevalence of bipolar disorder in HIV-infected patients is higher than the general population. Lithium is the most effective mood stabiliser, while tenofovir disoproxil fumarate (TDF) is frequently used as part of combination antiretroviral therapy (ART). Both TDF and lithium are associated with renal tubular toxicity, which could be additive, or a pharmacokinetic interaction may occur at renal transporters with a decrease in TDF elimination.

Objective

We report on the change in estimated glomerular filtration rate (eGFR) using the modification of diet in renal disease formula in participants who received ART including TDF and were enrolled in a 24 week randomised trial of lithium versus placebo in patients with HIV-associated neurocognitive impairment.

Methods

We included HIV-infected adults with cognitive impairment established on ART for at least 6 months with a suppressed viral load attending public sector ART clinics in Cape Town, South Africa. We excluded participants with an eGFR <60 mL/min and treated with medications predisposing to lithium toxicity. We reviewed participants weekly for the first month for adverse events followed by 4 weekly visits for renal function assessment, adverse event monitoring and adherence. Lithium dose was titrated to achieve the maintenance target plasma concentration of between 0.6 and 1.0 mmol/L. Sham lithium concentrations were generated for participants receiving placebo.

Results

We included 23 participants allocated to the lithium arm and 30 participants allocated to the placebo arm. Baseline characteristics were not statistically different with a mean age of 37.7 and 40.8 years, a median time on ART of 33 and 40 months and an eGFR of 139.3 and 131.0 mL/min in the lithium and placebo arms respectively. There was no statistical significant difference in the reduction in eGFR or increase in potassium between the two arms during the 24 weeks.

Conclusions

We found that 24-week treatment of HIV-infected patients with lithium and TDF did not result in increased nephrotoxicity.

Trial registration The study was registered on the Pan African Clinical Trials Registry (PACTR) with the identifier number PACTR201310000635418. Registered 11 October 2013 before the first participant was enrolled

Moderate to severe HIV-associated neurocognitive impairment: A randomized placebo-controlled trial of lithium

BACKGROUND

HIV-associated neurocognitive disorder (HAND) remains highly prevalent despite effective anti-retroviral therapy (ART). A number of adjunctive pharmacotherapies for HAND have been studied with disappointing results, but preliminary data suggest that lithium may provide clinical benefit. In addition, the low cost of lithium would facilitate access in low- and middle-income countries which carry the greatest burden of HIV.

METHODS

Our objective was to evaluate the 24-week efficacy and safety of lithium in patients with moderate to severe HAND. Our primary efficacy endpoint was the change in Global Deficit Score (GDS) from baseline to 24 weeks, whereas our secondary endpoint was the change in proton magnetic resonance spectroscopy (H-MRS) brain metabolite concentrations. We conducted a 24-week randomized placebo-controlled trial of lithium as adjunctive pharmacotherapy. We enrolled participants with moderate to severe HAND, on ART for at least 6 months, with suppressed viral loads and attending public sector primary care clinics in Cape Town, South Africa. We randomized 66 participants to lithium (n = 32) or placebo (n = 34). Lithium or placebo was dosed 12-hourly and titrated to achieve the maintenance target plasma concentration of 0.6 to 1.0 mmol/L. Sham lithium concentrations were generated for participants receiving placebo.

RESULTS

Totally 61 participants completed the study (lithium arm = 30; placebo arm = 31). Participants at enrolment had a mean age of 40 years and a median CD4+ T-cell count of 500 cells/μL. 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 analyzed according to age, severity of impairment, CD4+ count, time on ART, and ART regimen. Standard H-MRS metabolite concentrations were similar between the treatment arms. The study drug was well tolerated in both study arms. Six serious adverse events occurred, but none were considered related to the study drug.

CONCLUSION

Adjunctive lithium pharmacotherapy in patients on ART with HAND was well tolerated but had no additional benefit on neurocognitive impairment.

The pharmacokinetics of lopinavir/ritonavir when given with isoniazid in South African HIV-infected individuals

Isoniazid preventive therapy is recommended in patients on antiretroviral treatment (ART) with latent tuberculous infection to prevent progression to active tuberculosis disease. Isoniazid (INH) inhibits cytochrome (CY) P3A4, which metabolises lopinavir (LPV). The administration of INH may cause higher LPV concentrations, which may increase LPV toxicity. LPV bioavailability is increased by co-formulated ritonavir (r), which may enhance the interaction of INH on LPV. We studied the effect of INH on LPV concentrations by administering INH for 7 days and performing intensive pharmacokinetic sampling in 16 human immunodeficiency virus infected patients established on LPV/r-based ART. INH did not significantly increase steady-state LPV area under the plasma concentration-time curve calculated for the 12 h-dosing interval.

Model-based evaluation of the pharmacokinetic differences between adults and children for lopinavir and ritonavir in combination with rifampicin

AIMS

Rifampicin profoundly reduces lopinavir concentrations. Doubled doses of lopinavir/ritonavir compensate for the effect of rifampicin in adults, but fail to provide adequate lopinavir concentrations in young children on rifampicin-based antituberculosis therapy. The objective of this study was to develop a population pharmacokinetic model describing the pharmacokinetic differences of lopinavir and ritonavir, with and without rifampicin, between children and adults.

METHODS

An integrated population pharmacokinetic model developed in nonmem 7 was used to describe the pharmacokinetics of lopinavir and ritonavir in 21 HIV infected adults, 39 HIV infected children and 35 HIV infected children with tuberculosis, who were established on lopinavir/ritonavir-based antiretroviral therapy with and without rifampicin-containing antituberculosis therapy.

RESULTS

The bioavailability of lopinavir was reduced by 25% in adults whereas children on antituberculosis treatment experienced a 59% reduction, an effect that was moderated by the dose of ritonavir. Conversely, rifampicin increased oral clearance of both lopinavir and ritonavir to a lesser extent in children than in adults. Rifampicin therapy in administered doses increased CL of lopinavir by 58% in adults and 48% in children, and CL of ritonavir by 34% and 22% for adults and children, respectively. In children, the absorption half-life of lopinavir and the mean transit time of ritonavir were lengthened, compared with those in adults.

CONCLUSIONS

The model characterized important differences between adults and children in the effect of rifampicin on the pharmacokinetics of lopinavir and ritonavir. As adult studies cannot reliably predict their magnitude in children, drug-drug interactions should be evaluated in paediatric patient populations.

Neuronal toxicity of efavirenz: a systematic review

INTRODUCTION

Efavirenz commonly causes early neuropsychiatric side effects, but tolerance develops in most patients. There is emerging evidence that efavirenz use may damage neurons, which could result in impaired neurocognitive performance.

AREAS COVERED

The authors conducted a systematic review using the PubMed database, references cited by other articles and conference web sites to determine if there is evidence that efavirenz may contribute to cognitive impairment by damaging nerve cells.

EXPERT OPINION

There is weak clinical evidence suggesting that efavirenz use may worsen neurocognitive impairment or be associated with less improvement in neurocognitive impairment than other antiretrovirals. Efavirenz, especially its major metabolite 8-hydroxy-efavirenz, is toxic in neuron cultures at concentrations found in the cerebrospinal fluid. Extensive metabolizers of efavirenz may therefore be more likely to develop efavirenz toxicity by forming more 8-hydroxy-efavirenz. Several potential mechanisms exist to explain the observed efavirenz neurotoxicity, including altered calcium hemostasis, decreases in brain creatine kinase, mitochondrial damage, increases in brain proinflammatory cytokines and involvement of the cannabinoid system. There is a need for large randomized controlled trials to determine if the neuronal toxicity induced by efavirenz results in clinically significant neurological impairment.

The pharmacokinetics of nevirapine when given with isoniazid in South African HIV-infected individuals

Isoniazid preventive therapy (IPT) is recommended in patients on antiretroviral treatment. Isoniazid (INH) inhibits CYP3A4, which metabolises nevirapine (NVP). Administration of INH may cause higher NVP concentrations and toxicity. We studied the effect of INH on NVP concentrations in 21 patients randomised to either placebo (n = 13) or INH (n = 8) in an ongoing trial of IPT in patients on ART. INH was associated with a 24% increase in median NVP area under the plasma concentration-time curve for the 12 h dosing interval, which was not statistically significant (P = 0.66).

The safety, effectiveness and concentrations of adjusted lopinavir/ritonavir in HIV-infected adults on rifampicin-based antitubercular therapy

Objective

Rifampicin co-administration dramatically reduces plasma lopinavir concentrations. Studies in healthy volunteers and HIV-infected patients showed that doubling the dose of lopinavir/ritonavir (LPV/r) or adding additional ritonavir offsets this interaction. However, high rates of hepatotoxicity were observed in healthy volunteers. We evaluated the safety, effectiveness and pre-dose concentrations of adjusted doses of LPV/r in HIV infected adults treated with rifampicin-based tuberculosis treatment.

Methods

Adult patients on a LPV/r-based antiretroviral regimen and rifampicin-based tuberculosis therapy were enrolled. Doubled doses of LPV/r or an additional 300 mg of ritonavir were used to overcome the inducing effect of rifampicin. Steady-state lopinavir pre-dose concentrations were evaluated every second month.

Results

18 patients were enrolled with a total of 79 patient months of observation. 11/18 patients were followed up until tuberculosis treatment completion. During tuberculosis treatment, the median (IQR) pre-dose lopinavir concentration was 6.8 (1.1–9.2) mg/L and 36/47 (77%) were above the recommended trough concentration of 1 mg/L. Treatment was generally well tolerated with no grade 3 or 4 toxicity: 8 patients developed grade 1 or 2 transaminase elevation, 1 patient defaulted additional ritonavir due to nausea and 1 patient developed diarrhea requiring dose reduction. Viral loads after tuberculosis treatment were available for 11 patients and 10 were undetectable.

Conclusion

Once established on treatment, adjusted doses of LPV/r co-administered with rifampicin-based tuberculosis treatment were tolerated and LPV pre-dose concentrations were adequate.

Current trends in drug treatment of obsessive-compulsive disorder

This article aims to highlight current trends in the pharmacologic management of obsessive-compulsive disorder (OCD). A systematic search of the electronic database MEDLINE was conducted. The first case report of clomipramine efficacy in the management OCD more than 40 years ago gave new hope for the treatment of this debilitating disorder. Selective serotonin reuptake inhibitors (SSRIs) proved to have a similar efficacy profile compared with clomipramine but had a superior tolerability profile. While many patients with OCD respond to SSRIs or clomipramine, the treatment of those with refractory OCD remains challenging. Different augmentation agents in treatment-resistant OCD have been explored, with antipsychotic agents having the largest supporting evidence base. Nevertheless, new pharmacologic treatment options are required and are under investigation.