Pharmacokinetics of antiretroviral and tuberculosis drugs in children with HIV/TB co-infection: a systematic review

HIV-associated tuberculosis in infants, children, and adolescents younger than 15 years: an update on the epidemiology, diagnosis, prevention, and treatment

PURPOSE OF REVIEW

HIV-associated tuberculosis (TB) remains a major driver of morbidity and mortality in children and adolescents younger than 15 years (CLWH). The purpose of this review is to highlight recent findings in the areas of prevention, diagnosis, and treatment of HIV-associated TB in CLWH and to highlight knowledge and implementation gaps.

RECENT FINDINGS

We found that despite access to antiretroviral therapy (ART), high rates of HIV-associated TB are still reported, and with an unacceptably high mortality. There are no advances in screening for TB, but shorter courses of rifapentine-based TB preventive therapy are becoming available. The use of algorithms in TB diagnosis can potentially simplify the therapeutic decision making. There are more data supporting the use of dolutegravir (DTG) with rifampicin and a need to study unadjusted DTG especially in the youngest children. Short course therapy for nonsevere pulmonary TB is currently implemented and programmatic outcome should be studied in CLWH. Low uptake of ART and poor suppression remains an important driver of HIV-associated TB.

SUMMARY

Although screening and diagnosis remains challenging, there are several advances in the prevention and treatment of HIV-associated TB. Effective implementation of these strategies is needed to advance the outcomes of CLWH.

Twice-Daily Dosing of Dolutegravir in Infants on Rifampicin Treatment: A Pharmacokinetic Substudy of the EMPIRICAL Trial

BACKGROUND

We evaluated dolutegravir pharmacokinetics in infants with human immunodeficiency virus (HIV) receiving dolutegravir twice daily (BID) with rifampicin-based tuberculosis (TB) treatment compared with once daily (OD) without rifampicin.

METHODS

Infants with HIV aged 1-12 months, weighing ≥3 kg, and receiving dolutegravir BID with rifampicin or OD without rifampicin were eligible. Six blood samples were taken over 12 (BID) or 24 hours (OD). Dolutegravir pharmacokinetic parameters, HIV viral load (VL) data, and adverse events (AEs) were reported.

RESULTS

Twenty-seven of 30 enrolled infants had evaluable pharmacokinetic curves. The median (interquartile range) age was 7.1 months (6.1-9.9), weight was 6.3 kg (5.6-7.2), 21 (78%) received rifampicin, and 11 (41%) were female. Geometric mean ratios comparing dolutegravir BID with rifampicin versus OD without rifampicin were area under curve (AUC)0-24h 0.91 (95% confidence interval, .59-1.42), Ctrough 0.95 (0.57-1.59), Cmax 0.87 (0.57-1.33). One infant (5%) receiving rifampicin versus none without rifampicin had dolutegravir Ctrough <0.32 mg/L, and none had Ctrough <0.064 mg/L. The dolutegravir metabolic ratio (dolutegravir-glucuronide AUC/dolutegravir AUC) was 2.3-fold higher in combination with rifampicin versus without rifampicin. Five of 82 reported AEs were possibly related to rifampicin or dolutegravir and resolved without treatment discontinuation. Upon TB treatment completion, HIV viral load was <1000 copies/mL in 76% and 100% of infants and undetectable in 35% and 20% of infants with and without rifampicin, respectively.

CONCLUSIONS

Dolutegravir BID in infants receiving rifampicin resulted in adequate dolutegravir exposure, supporting this treatment approach for infants with HIV-TB coinfection.

First-Line Antituberculosis Drug Concentrations in Infants With HIV and a History of Recent Admission With Severe Pneumonia

Optimal antituberculosis therapy is essential for favorable clinical outcomes. Peak plasma concentrations of first-line antituberculosis drugs in infants with living HIV receiving WHO-recommended dosing were low compared with reference values for adults, supporting studies on increased doses of first-line TB drugs in infants.

Predicted Pharmacokinetic Interactions Between Hormonal Contraception and Single or Intermittently Dosed Rifampicin

The scale-up of rifampicin-based prevention regimens is an essential part of the global leprosy strategy. Daily rifampicin may reduce the effectiveness of the oral contraceptive pill (OCP), but little is known about the effects of rifampicin at the less frequent dosing intervals used for leprosy prophylaxis. As many women of reproductive age rely on OCP for family planning, evaluating the interaction with less-than-daily rifampicin regimens would enhance the scalability and acceptability of leprosy prophylaxis. Using a semi-mechanistic pharmacokinetic model of rifampicin induction, we simulated predicted changes in OCP clearance when coadministered with varying rifampicin dosing schedules. Rifampicin given as a single dose (600 or 1200 mg) or 600 mg every 4 weeks was not predicted to result in a clinically relevant interaction with OCP, defined as a >25% increase in clearance. Simulations of daily rifampicin were predicted to increase OCP clearance within the range of observed changes previously reported in the literature. Therefore, our findings suggest that OCP efficacy will be maintained when coadministered with rifampicin-based leprosy prophylaxis regimens of 600 mg once, 1200 mg once, and 600 mg every 4 weeks. This work provides reassurance to stakeholders that leprosy prophylaxis can be used with OCP without any additional recommendations for contraception prevention.

Global estimates and determinants of antituberculosis drug pharmacokinetics in children and adolescents: a systematic review and individual patient data meta-analysis

BACKGROUND

Suboptimal exposure to antituberculosis (anti-TB) drugs has been associated with unfavourable treatment outcomes. We aimed to investigate estimates and determinants of first-line anti-TB drug pharmacokinetics in children and adolescents at a global level.

METHODS

We systematically searched MEDLINE, Embase and Web of Science (1990-2021) for pharmacokinetic studies of first-line anti-TB drugs in children and adolescents. Individual patient data were obtained from authors of eligible studies. Summary estimates of total/extrapolated area under the plasma concentration-time curve from 0 to 24 h post-dose (AUC0-24) and peak plasma concentration (C max) were assessed with random-effects models, normalised with current World Health Organization-recommended paediatric doses. Determinants of AUC0-24 and C max were assessed with linear mixed-effects models.

RESULTS

Of 55 eligible studies, individual patient data were available for 39 (71%), including 1628 participants from 12 countries. Geometric means of steady-state AUC0-24 were summarised for isoniazid (18.7 (95% CI 15.5-22.6) h·mg·L-1), rifampicin (34.4 (95% CI 29.4-40.3) h·mg·L-1), pyrazinamide (375.0 (95% CI 339.9-413.7) h·mg·L-1) and ethambutol (8.0 (95% CI 6.4-10.0) h·mg·L-1). Our multivariate models indicated that younger age (especially <2 years) and HIV-positive status were associated with lower AUC0-24 for all first-line anti-TB drugs, while severe malnutrition was associated with lower AUC0-24 for isoniazid and pyrazinamide. N-acetyltransferase 2 rapid acetylators had lower isoniazid AUC0-24 and slow acetylators had higher isoniazid AUC0-24 than intermediate acetylators. Determinants of C max were generally similar to those for AUC0-24.

CONCLUSIONS

This study provides the most comprehensive estimates of plasma exposures to first-line anti-TB drugs in children and adolescents. Key determinants of drug exposures were identified. These may be relevant for population-specific dose adjustment or individualised therapeutic drug monitoring.

Adequacy of the 10 mg/kg Daily Dose of Antituberculosis Drug Isoniazid in Infants under 6 Months of Age

In 2010, the WHO recommended an increase in the daily doses of first-line anti-tuberculosis medicines in children. We aim to characterize the pharmacokinetics of the once-daily isoniazid (INH) dose at 10 mg/kg of body weight in infants <6 months of age. We performed a multicenter pharmacokinetic study in Spain. The N-acetyltransferase 2 gene was analyzed to determine the acetylation status. Samples were analyzed using a validated UPLC-UV assay. A non-compartmental pharmacokinetic analysis was performed. Twenty-three pharmacokinetic profiles were performed in 20 infants (8 females) at a median (IQR) age of 19.0 (12.6-23.3) weeks. The acetylator statuses were homozygous fast (n = 1), heterozygous intermediate (n = 12), and homozygous slow (n = 7). INH median (IQR) C_max and AUC_0-24h values were 4.8 (3.7-6.7) mg/L and 23.5 (13.4-36.7) h*mg/L and the adult targets (>3 mg/L and 11.6-26.3 h*mg/L) were not reached in three and five cases, respectively. The age at assessment or acetylator status had no impact on C_max values, but a larger INH AUC_0-24h (p = 0.025) and trends towards a longer half-life (p = 0.055) and slower clearance (p = 0.070) were observed in homozygous slow acetylators. Treatment was well tolerated; mildly elevated alanine aminotransferase levels were observed in three cases. In our series of young infants receiving isoniazid, no major safety concerns were raised, and the target adult levels were reached in most patients.

Integrase Strand Transfer Inhibitor Use in Children with Perinatal HIV-1 Infection: A Narrative Review

Integrase strand transfer inhibitors (INSTIs), including raltegravir (RAL), dolutegravir (DTG), elvitegravir (EVG), bictegravir (BIC), and cabotegravir (CAB), are increasingly used, given excellent data on their efficacy, effectiveness, and tolerability profile in adults, while data in children are accumulating. To review the most recent evidence on the efficacy, effectiveness, safety, and resistance of INSTIs in children, a quick narrative review of the available literature data was performed using the MEDLINE/PubMed and Scopus databases, including only English-language studies, published between 2009 and 2022. Six studies (259 children) on RAL use, 17 studies (3,448 children) on DTG, 2 studies (73 children) on EVG, and 1 study (102 children) on BIC were retrieved. Results on efficacy and effectiveness were close to those reported in adult studies, suggesting similarities between children and adult population. Resistance to RAL was detected in four studies, ranging between 5.0% to 35.3% of participants. In four studies resistance to DTG occurred in 12.4% to 22% of children. Adverse events to RAL have been uncommon reported. In studies on EVG, 8% to 74% of children developed uveitis, nausea, or abdominal pain. In DTG studies, the proportion of weight gain ranged from 10% to 87%, and neuropsychiatric effects ranged 1% to 16% of participants. One BIC study reported adverse events >10% of participants. The evidence supports high efficacy and low toxicity of INSTIs in pediatric and adolescent populations.

Tuberculosis in Children Living With HIV: Ongoing Progress and Challenges

There has been much recent progress on control of the tuberculosis (TB) and human immunodeficiency virus (HIV) epidemics globally. However, advances in children have lagged behind, and TB-HIV coinfection continues to be a major driver of pediatric mortality in many settings. This review highlights recent research findings in the areas of prevention, diagnosis, and treatment of HIV-associated childhood TB. Key areas for future research are defined. Current prevention efforts such as vaccination, TB symptom screening, and TB preventive treatment are demonstrated as beneficial but need to be optimized for children living with HIV (CLHIV). Diagnosis of HIV-associated TB in children remains a major challenge, depending heavily on clinicians' ability to judge an array of signs, symptoms, and imaging findings, but there are a growing number of promising diagnostic tools with improved accuracy and feasibility. Treatment of TB-HIV coinfection has also seen recent progress with more evidence demonstrating the safety and effectiveness of shorter regimens for treatment of TB infection and disease and improved understanding of interactions between antiretrovirals and TB medications. However, several evidence gaps on drug-drug interactions persist, especially for young children and those with drug-resistant TB. Accelerated efforts are needed in these areas to build upon current progress and reduce the burden of TB on CLHIV.

Dolutegravir twice-daily dosing in children with HIV-associated tuberculosis: a pharmacokinetic and safety study within the open-label, multicentre, randomised, non-inferiority ODYSSEY trial

BACKGROUND

Children with HIV-associated tuberculosis (TB) have few antiretroviral therapy (ART) options. We aimed to evaluate the safety and pharmacokinetics of dolutegravir twice-daily dosing in children receiving rifampicin for HIV-associated TB.

METHODS

We nested a two-period, fixed-order pharmacokinetic substudy within the open-label, multicentre, randomised, controlled, non-inferiority ODYSSEY trial at research centres in South Africa, Uganda, and Zimbabwe. Children (aged 4 weeks to <18 years) with HIV-associated TB who were receiving rifampicin and twice-daily dolutegravir were eligible for inclusion. We did a 12-h pharmacokinetic profile on rifampicin and twice-daily dolutegravir and a 24-h profile on once-daily dolutegravir. Geometric mean ratios for trough plasma concentration (Ctrough), area under the plasma concentration time curve from 0 h to 24 h after dosing (AUC0-24 h), and maximum plasma concentration (Cmax) were used to compare dolutegravir concentrations between substudy days. We assessed rifampicin Cmax on the first substudy day. All children within ODYSSEY with HIV-associated TB who received rifampicin and twice-daily dolutegravir were included in the safety analysis. We described adverse events reported from starting twice-daily dolutegravir to 30 days after returning to once-daily dolutegravir. This trial is registered with ClinicalTrials.gov (NCT02259127), EudraCT (2014-002632-14), and the ISRCTN registry (ISRCTN91737921).

FINDINGS

Between Sept 20, 2016, and June 28, 2021, 37 children with HIV-associated TB (median age 11·9 years [range 0·4-17·6], 19 [51%] were female and 18 [49%] were male, 36 [97%] in Africa and one [3%] in Thailand) received rifampicin with twice-daily dolutegravir and were included in the safety analysis. 20 (54%) of 37 children enrolled in the pharmacokinetic substudy, 14 of whom contributed at least one evaluable pharmacokinetic curve for dolutegravir, including 12 who had within-participant comparisons. Geometric mean ratios for rifampicin and twice-daily dolutegravir versus once-daily dolutegravir were 1·51 (90% CI 1·08-2·11) for Ctrough, 1·23 (0·99-1·53) for AUC0-24 h, and 0·94 (0·76-1·16) for Cmax. Individual dolutegravir Ctrough concentrations were higher than the 90% effective concentration (ie, 0·32 mg/L) in all children receiving rifampicin and twice-daily dolutegravir. Of 18 children with evaluable rifampicin concentrations, 15 (83%) had a Cmax of less than the optimal target concentration of 8 mg/L. Rifampicin geometric mean Cmax was 5·1 mg/L (coefficient of variation 71%). During a median follow-up of 31 weeks (IQR 30-40), 15 grade 3 or higher adverse events occurred among 11 (30%) of 37 children, ten serious adverse events occurred among eight (22%) children, including two deaths (one tuberculosis-related death, one death due to traumatic injury); no adverse events, including deaths, were considered related to dolutegravir.

INTERPRETATION

Twice-daily dolutegravir was shown to be safe and sufficient to overcome the rifampicin enzyme-inducing effect in children, and could provide a practical ART option for children with HIV-associated TB.

FUNDING

Penta Foundation, ViiV Healthcare, UK Medical Research Council.

Pharmacokinetic interaction between raltegravir and rifampicin in an infant with HIV exposed to active TB: a case report

We report a case of an infant with HIV receiving raltegravir granules for oral suspension and rifampicin-based TB prophylaxis. Raltegravir trough levels remained subtherapeutic and viral load increased during concurrent rifampicin therapy despite using double-dosed raltegravir. Even after rifampicin therapy, a higher dose was needed. This highlights the importance of therapeutic drug monitoring and dose adjustments of raltegravir in infants with rifampicin as comedication.

Two-year retention in care for adolescents on antiretroviral therapy in Ehlanzeni district, South Africa: a baseline cohort analysis

Adolescents living with HIV (ALHIV) struggle to remain engaged in HIV-related care and adhere to antiretroviral treatment (ART) due to a myriad of physical, psychological and cognitive-developmental challenges. We report on the profile of ALHIV aged 10-19 years on ART and the clinical factors associated with their retention in care. A retrospective cohort analysis was conducted with 16,108 ALHIV, aged 10-19 years, who were enrolled in 136 ART clinics in the Ehlanzeni district. Anonymised data were obtained from electronic medical records (Tier.net). Trends in retention in care among adolescents on ART was described using Kaplan-Meier survival estimates. Cox proportional analysis was performed to identify factors associated with retention in care over 2 years. More than half (53%) were females, and median duration on ART was 8 months. Retention in care among adolescents at months 6, 12, 18 and 24 was 90.5%, 85.4%, 80.8% and 76.2%, respectively. After controlling for confounders, risk of dying or lost to follow up increased for female adolescents (aHR = 1.28, 95% CI 1.10-1.49); being initiated on ART while pregnant (aHR = 2.72, 95% CI 1.99-3.69); history of TB infection (aHR = 1.71, 95% CI 1.10-2.65); and started ART at age 10-14 years (aHR = 2.45, 95% CI 1.96-3.05), and 15-19 years (aHR = 9.67, 95% CI 7.25-12.89). Retention in care among adolescents on ART over two-year period was considerably lower than the UNAIDS 2030 target of 95%. Of particular concern for intervention is the lower rates of retention in care among females and pregnant adolescents and starting ART between the ages of 10 and 19 years. Family or caregivers and peer support groups centred interventions designed to promote early initiation and retention in care through early case identification are needed.

Emerging data on rifampicin pharmacokinetics and approaches to optimal dosing in children with tuberculosis

INTRODUCTION

Despite its longstanding role in tuberculosis (TB) treatment, there continues to be emerging rifampicin research that has important implications for pediatric TB treatment and outstanding questions about its pharmacokinetics and optimal dose in children.

AREAS COVERED

This review aims to summarize and discuss emerging data on the use of rifampicin for: 1) routine treatment of drug-susceptible TB; 2) special subpopulations such as children with malnutrition, HIV, or TB meningitis; 3) treatment shortening. We also highlight the implications of these new data for child-friendly rifampicin formulations and identify future research priorities.

EXPERT OPINION

New data consistently show low rifampicin exposures across all pediatric populations with 10-20 mg/kg dosing. Although clinical outcomes in children are generally good, rifampicin dose optimization is needed, especially given a continued push to shorten treatment durations and for specific high-risk populations of children who have worse outcomes. A pooled analysis of existing data using applied pharmacometrics would answer many of the important questions remaining about rifampicin pharmacokinetics needed to optimize doses, especially in special populations. Targeted clinical studies in children with TB meningitis and treatment shortening with high-dose rifampicin are also priorities.

Dexamethasone is a dose-dependent perpetrator of drug-drug interactions: implications for use in people living with HIV

Global use of dexamethasone in COVID-19 patients has revealed a poor understanding of the drug-drug interaction (DDI) potential of dexamethasone, particularly with antiretroviral agents (ARVs). Dexamethasone is both a substrate and a dose-dependent inducer of cytochrome P450 3A4 (CYP3A4). As many ARVs are substrates and/or inhibitors or inducers of CYP3A4, there is concern about DDIs with dexamethasone either as a perpetrator or a victim. Assessment of DDIs that involve dexamethasone is complex as dexamethasone is used at a range of daily doses (generally 0.5 up to 40 mg) and a treatment course can be short, long, or intermittent. Moreover, DDIs with dexamethasone have been evaluated only for a limited number of drugs. Here, we summarize the available in vitro and in vivo data on the interaction potential of dexamethasone and provide recommendations for the management of DDIs with ARVs, considering various dexamethasone dosages and treatment durations.

Use of integrase inhibitors in HIV-associated tuberculosis in high-burden settings: implementation challenges and research gaps

People living with HIV have a higher risk of developing tuberculosis, and tuberculosis is one of the leading causes of death among people living with HIV globally. Treating HIV and tuberculosis concurrently has morbidity and mortality benefits. However, HIV and tuberculosis co-treatment is challenging due to drug-drug interactions, overlapping toxicities, tuberculosis-associated immune reconstitution syndrome, and concerns for treatment failure or drug resistance. Drug-drug interactions between antiretrovirals and tuberculosis drugs are driven mainly by the rifamycins (for example, the first-line tuberculosis drug rifampicin), and dose adjustments or drug switches during co-treatment are commonly required. Several implementation challenges and research gaps exist when combining the integrase strand transfer inhibitors (INSTIs), highly potent antiretroviral drugs recommended as first-line treatment of HIV, and drugs used for the treatment and prevention of tuberculosis. Ongoing and planned studies will address some critical questions on the use of INSTIs in settings with a high tuberculosis burden, including dosing of dolutegravir, bictegravir, and cabotegravir when used with the rifamycins for both tuberculosis treatment and prevention. Failure, in the past, to include people with tuberculosis in HIV clinical treatment trials has been responsible for some of the research gaps still evident for informing optimisation of HIV and tuberculosis co-treatment.

HIV-Associated Tuberculosis in Children and Adolescents: Evolving Epidemiology, Screening, Prevention and Management Strategies

Children and adolescents living with HIV continue to be impacted disproportionately by tuberculosis as compared to peers without HIV. HIV can impact TB screening and diagnosis by altering screening and diagnostic test performance and can complicate prevention and treatment strategies due to drug-drug interactions. Post-tuberculosis lung disease is an underappreciated phenomenon in children and adolescents, but is more commonly observed in children and adolescents with HIV-associated tuberculosis. This review presents new data related to HIV-associated TB in children and adolescents. Data on the epidemiology of HIV-associated TB suggests that an elevated risk of TB in children and adolescents with HIV persists even with broad implementation of ART. Recent guidance also indicates the need for new screening strategies for HIV-associated TB. There have been major advances in the availability of new antiretroviral medications and also TB prevention options for children, but these advances have come with additional questions surrounding drug-drug interactions and dosing in younger age groups. Finally, we review new approaches to manage post-TB lung disease in children living with HIV. Collectively, we present data on the rapidly evolving field of HIV-associated child tuberculosis. This evolution offers new management opportunities for children and adolescents living with HIV while also generating new questions for additional research.

The Impact of Tuberculosis on the Well-Being of Adolescents and Young Adults

The health needs of adolescents and young adults (AYAs) have been neglected in tuberculosis (TB) care, control, and research. AYAs, who are distinct from younger children and older adults, undergo dynamic physical, psychological, emotional, cognitive, and social development. Five domains of adolescent well-being are crucial to a successful transition between childhood and adulthood: (1) Good health; (2) connectedness and contribution to society; (3) safety and a supportive environment; (4) learning, competence, education, skills, and employability; and (5) agency and resilience. This review summarizes the evidence of the impact of TB disease and treatment on these five domains of AYA well-being.

No implication of HIV coinfection on the plasma exposure to rifampicin, pyrazinamide, and ethambutol in tuberculosis patients

There are contrasting findings regarding the effect of HIV on the pharmacokinetics of first‐line anti‐tubercular drugs (FLATDs) due to a lack of prospective controlled clinical studies, including patients with tuberculosis (TB) and patients with TB living with HIV. This study aims to assess the effect of HIV coinfection and antiviral therapy on the plasma exposure to FLATDs in patients with TB. HIV negative (TB‐HIV− group; n = 15) and HIV positive (TB‐HIV+ group; n = 18) adult patients with TB were enrolled during the second month of FLATDs treatment. All TB‐HIV+ patients were on treatment with lamivudine, tenofovir (or zidovudine), and raltegravir (or efavirenz). Serial blood sampling was collected over 24 h and FLATDs pharmacokinetic parameters were evaluated using noncompartmental methods. In the TB‐HIV+ patients, dose‐normalized plasma exposure area under the curve from zero to 24 h (nAUC_0–24; geometric mean and 95% confidence interval [CI]) values at steady‐state to rifampicin, pyrazinamide, and ethambutol were 18.38 (95% CI 13.74–24.59), 238.21 (95% CI 191.09–296.95), and 18.33 (95% CI 14.56–23.09) µg∙h/ml, respectively. Similar plasma exposure was found in the TB‐HIV− patients. The geometric mean and 90% CI of the ratios between TB‐HIV− and TB‐HIV+ groups suggest no significant pharmacokinetic interaction between the selected antivirals and FLATDs. Likewise, HIV coinfection itself does not appear to have any effect on the plasma exposure to FLATDs.

Tuberculosis preventive therapy for people living with HIV: A systematic review and network meta-analysis

BACKGROUND

Tuberculosis (TB) preventive therapy (TPT) is an essential component of care for people living with HIV (PLHIV). We compared efficacy, safety, completion, and drug-resistant TB risk for currently recommended TPT regimens through a systematic review and network meta-analysis (NMA) of randomized trials.

METHODS AND FINDINGS

We searched MEDLINE, Embase, and the Cochrane Library from inception through June 9, 2020 for randomized controlled trials (RCTs) comparing 2 or more TPT regimens (or placebo/no treatment) in PLHIV. Two independent reviewers evaluated eligibility, extracted data, and assessed the risk of bias. We grouped TPT strategies as follows: placebo/no treatment, 6 to 12 months of isoniazid, 24 to 72 months of isoniazid, and rifamycin-containing regimens. A frequentist NMA (using graph theory) was carried out for the outcomes of development of TB disease, all-cause mortality, and grade 3 or worse hepatotoxicity. For other outcomes, graphical descriptions or traditional pairwise meta-analyses were carried out as appropriate. The potential role of confounding variables for TB disease and all-cause mortality was assessed through stratified analyses. A total of 6,466 unique studies were screened, and 157 full texts were assessed for eligibility. Of these, 20 studies (reporting 16 randomized trials) were included. The median sample size was 616 (interquartile range [IQR], 317 to 1,892). Eight were conducted in Africa, 3 in Europe, 3 in the Americas, and 2 included sites in multiple continents. According to the NMA, 6 to 12 months of isoniazid were no more efficacious in preventing microbiologically confirmed TB than rifamycin-containing regimens (incidence rate ratio [IRR] 1.0, 95% CI 0.8 to 1.4, p = 0.8); however, 6 to 12 months of isoniazid were associated with a higher incidence of all-cause mortality (IRR 1.6, 95% CI 1.2 to 2.0, p = 0.02) and a higher risk of grade 3 or higher hepatotoxicity (risk difference [RD] 8.9, 95% CI 2.8 to 14.9, p = 0.004). Finally, shorter regimens were associated with higher completion rates relative to longer regimens, and we did not find statistically significant differences in the risk of drug-resistant TB between regimens. Study limitations include potential confounding due to differences in posttreatment follow-up time and TB incidence in the study setting on the estimates of incidence of TB or all-cause mortality, as well as an underrepresentation of pregnant women and children.

CONCLUSIONS

Rifamycin-containing regimens appear safer and at least as effective as isoniazid regimens in preventing TB and death and should be considered part of routine care in PLHIV. Knowledge gaps remain as to which specific rifamycin-containing regimen provides the optimal balance of efficacy, completion, and safety.

Pharmacokinetics of first-line drugs in children with tuberculosis using WHO-recommended weight band doses and formulations

Background

Dispersible pediatric fixed-dose combination (FDC) tablets delivering higher doses of first-line antituberculosis drugs in World Health Organization–recommended weight bands were introduced in 2015. We report the first pharmacokinetic data for these FDC tablets in Zambian and South African children in the treatment-shortening SHINE trial.

Methods

Children weighing 4.0–7.9, 8.0–11.9, 12.0–15.9, or 16.0–24.9 kg received 1, 2, 3, or 4 tablets daily, respectively (rifampicin/isoniazid/pyrazinamide [75/50/150 mg], with or without 100 mg ethambutol, or rifampicin/isoniazid [75/50 mg]). Children 25.0–36.9 kg received doses recommended for adults <37 kg (300, 150, 800, and 550 mg/d, respectively, for rifampicin, isoniazid, pyrazinamide, and ethambutol). Pharmacokinetics were evaluated after at least 2 weeks of treatment.

Results

In the 77 children evaluated, the median age (interquartile range) was 3.7 (1.4–6.6) years; 40 (52%) were male and 20 (26%) were human immunodeficiency virus positive. The median area under the concentration-time curve from 0 to 24 hours for rifampicin, isoniazid, pyrazinamide, and ethambutol was 32.5 (interquartile range, 20.1–45.1), 16.7 (9.2–25.9), 317 (263–399), and 9.5 (7.5–11.5) mg⋅h/L, respectively, and lower in children than in adults for rifampicin in the 4.0–7.9-, 8–11.9-, and ≥25-kg weight bands, isoniazid in the 4.0–7.9-kg and ≥25-kg weight bands, and ethambutol in all 5 weight bands. Pyrazinamide exposures were similar to those in adults.

Conclusions

Recommended weight band–based FDC doses result in lower drug exposures in children in lower weight bands and in those ≥25 kg (receiving adult doses). Further adjustments to current doses are needed to match current target exposures in adults. The use of ethambutol at the current World Health Organization–recommended doses requires further evaluation.