Pharmacokinetics of Levofloxacin in Children Treated for Exposure to Drug-Resistant Tuberculosis

Pharmacokinetics and Optimal Dosing of Levofloxacin in Children for Drug-Resistant Tuberculosis: An Individual Patient Data Meta-Analysis

BACKGROUND

Each year 25 000-32 000 children develop rifampicin- or multidrug-resistant tuberculosis (RR/MDR-TB), and many more require preventive treatment. Levofloxacin is a key component of RR/MDR-TB treatment and prevention, but the existing pharmacokinetic data in children have not yet been comprehensively summarized. We aimed to characterize levofloxacin pharmacokinetics through an individual patient data meta-analysis of available studies and to determine optimal dosing in children.

METHODS

Levofloxacin concentration and demographic data were pooled from 5 studies and analyzed using nonlinear mixed effects modeling. Simulations were performed using current World Health Organization (WHO)-recommended and model-informed optimized doses. Optimal levofloxacin doses were identified to target median adult area under the time-concentration curve (AUC)24 of 101 mg·h/L given current standard adult doses.

RESULTS

Data from 242 children (2.8 years [0.2-16.8] was used). Apparent clearance was 3.16 L/h for a 13-kg child. Age affected clearance, reaching 50% maturation at birth and 90% maturation at 8 months. Nondispersible tablets had 29% lower apparent oral bioavailability compared to dispersible tablets. Median exposures at current WHO-recommended doses were below the AUC target for children weighing <24 kg and under <10 years, resulting in approximately half of the exposure in adults. Model-informed doses of 16-33 mg/kg for dispersible tablets or 16-50 mg/kg for nondispersible tablets were required to meet the AUC target without significantly exceeding the median adult Cmax.

CONCLUSIONS

Revised weight-band dosing guidelines with doses of >20 mg/kg are required to ensure adequate exposure. Further studies are needed to determine safety and tolerability of these higher doses.

Pharmacokinetics and Safety of WHO-Recommended Dosage and Higher Dosage of Levofloxacin for Tuberculosis Treatment in Children: a Pilot Study

OBJECTIVES

To evaluate the pharmacokinetic parameters of the 2020 World Health Organization (WHO)-recommended pediatric dosage of levofloxacin and the higher-than-WHO dosage.

METHODS

Children aged 1-15 years with tuberculosis who received levofloxacin-based treatment for at least 7 days were enrolled. First, five children were enrolled to receive the WHO-recommended dosage (15-20 mg/kg/day), then an additional five children received a dosage higher than the WHO-recommended dosage (20-30 mg/kg/day). Blood samples were collected at predose and postdose 1, 2, 4, 6, 8, and 12 hours. A target of the ratio of the free area under the concentration-time curve to minimum inhibitory concentration (fAUC/MIC) was 100.

RESULTS

The median (interquartile range) age was 9.6 (4.9-10.5) and 12.0 (10.1-12.3) years in the WHO dosage and higher-than-WHO dosage groups, respectively. The median (interquartile range) duration of antituberculosis treatment was 24 (8-24) weeks. The geometric mean (95% confidence interval) of fAUC/MIC was 60.4 (43.5-84.0) and 103.2 (70.1-151.8) in the WHO and higher-than-WHO dosage groups, respectively. There was no adverse event of QT prolongation or any other grade 3 or 4 adverse events.

CONCLUSION

Levofloxacin at a higher dose of 20-30 mg/kg/day could achieve the fAUC/MIC target in children.

Treatment of Rifampicin-Resistant Tuberculosis Disease and Infection in Children: Key Updates, Challenges and Opportunities

Children affected by rifampicin-resistant tuberculosis (RR-TB; TB resistant to at least rifampicin) are a neglected group. Each year an estimated 25,000–30,000 children develop RR-TB disease globally. Improving case detection and treatment initiation is a priority since RR-TB disease is underdiagnosed and undertreated. Untreated paediatric TB has particularly high morbidity and mortality. However, children receiving TB treatment, including for RR-TB, respond well. RR-TB treatment remains a challenge for children, their caregivers and TB programmes, requiring treatment regimens of up to 18 months in duration, often associated with severe and long-term adverse effects. Shorter, safer, effective child-friendly regimens for RR-TB are needed. Preventing progression to disease following Mycobacterium tuberculosis infection is another key component of TB control. The last few years have seen exciting advances. In this article, we highlight key elements of paediatric RR-TB case detection and recent updates, ongoing challenges and forthcoming advances in the treatment of RR-TB disease and infection in children and adolescents. The global TB community must continue to advocate for more and faster research in children on novel and repurposed TB drugs and regimens and increase investments in scaling-up effective approaches, to ensure an equitable response that prioritises the needs of this vulnerable population.

A Review of Clinical Pharmacokinetic and Pharmacodynamic Relationships and Clinical Implications for Drugs Used to Treat Multi-drug Resistant Tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is becoming a global health crisis. The World Health Organization has released new guidelines for the use of tuberculosis-active drugs for the treatment of patients with MDR-TB. Despite documented activity against tuberculosis isolates, doses and exposure targets are yet to be optimized. Our objective was therefore to review the clinical pharmacokinetic and pharmacodynamic literature pertaining to drugs recommended to treat MDR-TB and to identify target areas for future research. To date, published research is limited but studies were identified that evaluated the pharmacokinetics and pharmacodynamics of these drugs. Exposure targets were assessed and summarized for each drug. Exposure-based targets (e.g., area under the concentration curve/minimum inhibitory concentration) appear to be most commonly associated with predicting drug efficacy. Dose variation studies based on these targets were largely inconclusive. Future research should focus on determining the risks and benefits of dose optimization to meet exposure targets and improve patient outcomes. The role of therapeutic drug monitoring also remains yet to be confirmed, both from a clinical perspective as well as a resource allocation perspective in regions where MDR-TB is active.