Effectiveness and Pharmacokinetic Exposures of First-Line Drugs Used to Treat Drug-Susceptible Tuberculosis in Children: A Systematic Review and Meta-Analysis.

BACKGROUND: Optimal doses of first-line drugs for treatment of drug-susceptible tuberculosis in children and young adolescents remain uncertain. We aimed to determine whether children treated using World Health Organization-recommended or higher doses of first-line drugs achieve successful outcomes and sufficient pharmacokinetic (PK) exposures. METHODS: Titles, abstracts, and full-text articles were screened. We searched PubMed, EMBASE, CENTRAL, and trial registries from 2010 to 2021. We included studies in children aged <18 years being treated for drug-susceptible tuberculosis with rifampicin (RIF), pyrazinamide, isoniazid, and ethambutol. Outcomes were treatment success rates and drug exposures. The protocol for the systematic review was preregistered in PROSPERO (no. CRD42021274222). RESULTS: Of 304 studies identified, 46 were eligible for full-text review, and 12 and 18 articles were included for the efficacy and PK analyses, respectively. Of 1830 children included in the efficacy analysis, 82% had favorable outcomes (range, 25%-95%). At World Health Organization-recommended doses, exposures to RIF, pyrazinamide, and ethambutol were lower in children than in adults. Children ≤6 years old have 35% lower areas under the concentration-time curve (AUCs) than older children (mean of 14.4 [95% CI 9.9-18.8] vs 22.0 [13.8-30.1] µg·h/mL) and children with human immunodeficiency virus (HIV) had 35% lower RIF AUCs than HIV-negative children (17.3 [11.4-23.2] vs 26.5 [21.3-31.7] µg·h/mL). Heterogeneity and small sample sizes were major limitations. CONCLUSIONS: There is large variability in outcomes, with an average of 82% favorable outcomes. Drug exposures are lower in children than in adults. Younger children and/or those with HIV are underexposed to RIF. Standardization of PK pediatric studies and individual patient data analysis with safety assessment are needed to inform optimal dosing.

Pharmacokinetics and Safety of Bedaquiline in Human Immunodeficiency Virus (HIV)-Positive and Negative Older Children and Adolescents With Rifampicin-Resistant Tuberculosis.

BACKGROUND: Pharmacokinetic data for bedaquiline in children are limited. We described the pharmacokinetics and safety of bedaquiline in South African children and adolescents receiving treatment for multidrug/rifampicin-resistant tuberculosis (MDR/RR-TB) in routine care. METHODS: In this observational cohort study, children aged 6-17 years receiving bedaquiline at recommended doses as part of MDR/RR-TB treatment underwent semi-intensive pharmacokinetic sampling. Bedaquiline and the M2 metabolite plasma concentrations were quantified, and nonlinear mixed-effects modeling performed. Pediatric data were described using a pre-established model of bedaquiline pharmacokinetics in adults. The exposure reference was 187 µg ⋅ h/mL, the median weekly area under the curve (AUC) of adults at week 24 of treatment with bedaquiline. Safety was assessed through monthly clinical, blood and electrocardiogram monitoring, and treatment outcomes described. RESULTS: Fifteen children (3 human immunodeficiency virus [HIV]-positive) with median age 13.3 years (range 6.5-16.3) were included. A bedaquiline pharmacokinetic model was adapted to be allometrically scaled in clearance and volume, centered in the median child population weight. Bedaquiline bioavailability was 57% of that in adults. Overall bedaquiline exposures were below target, and AUC reference attainment was achieved in only 3 (20%) children. Ten children experienced 27 adverse events at least possibly related to bedaquiline; no adverse events led to bedaquiline withdrawal. Two adverse events (arthritis and arthralgia) were considered severe, and 2 children had mild QT interval corrected for heart rate using Fridericia's formula (QT) prolongation. CONCLUSIONS: The evaluated doses of bedaquiline in children ≥ 6 years of age were safe but achieved slightly lower plasma concentrations compared to adults receiving the recommended dose, possibly due to delayed food intake relative to bedaquiline administration.

Polypharmacy Is Associated With Falls in Women With and Without HIV.

BACKGROUND: Aging in people with HIV is associated with increased risk of developing synergistic conditions such as neurocognitive impairment, polypharmacy, and falls. We assessed associations between polypharmacy (use of 5 or more non-ART medications), use of neurocognitive adverse effects (NCAE) medications, and odds of falls in women with HIV (WWH) and without HIV (HIV-). METHODS: Self-reported falls and medication use data were contributed semiannually by 1872 (1315 WWH and 557 HIV-) Women's Interagency HIV Study participants between 2014 and 2016. Polypharmacy and NCAE medication use were evaluated separately and jointly in multivariable models to assess their independent contributions to single and multiple falls risk. RESULTS: The proportion of women who reported any fall was similar by HIV status (19%). WWH reported both greater polypharmacy (51% vs. 41%; P < 0.001) and NCAE medication use (44% vs. 37%; P = 0.01) than HIV- women. Polypharmacy conferred elevated odds of single fall [adjusted odds ratio (aOR) 1.67, 95% CI: 1.36 to 2.06; P < 0.001] and multiple falls (aOR 2.31, 95% CI: 1.83 to 2.93; P < 0.001); the results for NCAE medications and falls were similar. Both polypharmacy and number of NCAE medications remained strongly and independently associated with falls in multivariable models adjusted for HIV serostatus, study site, sociodemographics, clinical characteristics, and substance use. CONCLUSIONS: Polypharmacy and NCAE medication use were greater among WWH compared with HIV-, and both were independently and incrementally related to falls. Deprescribing and avoidance of medications with NCAEs may be an important consideration for reducing fall risk among WWH and sociodemographically similar women without HIV.

Interaction of N-acetylcysteine and cysteine in human plasma.

N-acetyl-L-cysteine (NAC), a well-known antioxidant, has been successfully used as adjuvant therapy for late-stage childhood cerebral adrenoleukodystrophy (c-ALD); however, the mechanisms of NAC action are poorly understood. Previous research indicates that NAC serves as a precursor to L-cysteine (Cys), the rate-limiting substrate in the biosynthesis of glutathione (GSH), a potent, endogenous antioxidant. We hypothesized that NAC acts by liberating protein-bound Cys in plasma in an NAC concentration-dependent manner, which increases unbound Cys available for GSH biosynthesis. Human plasma was incubated for 1 h with varying, clinically relevant concentrations of NAC (0-1000 µg/mL). The effect of this interaction over time was evaluated by incubating plasma for 5-90 min with 100 µg/mL NAC. Unbound and bound Cys and NAC were separated by ultrafiltration, and concentrations were measured using high-performance liquid chromatography-mass spectrometry. Significant increases in unbound Cys were observed with increasing NAC concentrations. Also, Cys plasma protein binding decreased from 85% (10 µg/mL NAC) to approximately 0% (1000 µg/mL). Total endogenous Cys was 66% unbound at 5 min after incubation. These results demonstrate that NAC liberates endogenous, protein-bound Cys in human plasma at clinically relevant NAC concentrations. A greater understanding of NAC actions will aid in the optimization of NAC therapy including its use in c-ALD.