Anthony J. Garcia-Prats

Compassionate use of new drugs in children and adolescents with multidrug-resistant and extensively drug-resistant tuberculosis: early experiences and challenges

The World Health Organization (WHO) estimated that 480 000 new multidrug-resistant (MDR) tuberculosis (TB) cases occurred globally in 2014, with 190 000 deaths. Limited data are available on the burden of MDR-TB in children. A recent systematic review estimated that 32 000 children acquire MDR-TB annually; of these, very few are correctly diagnosed and provided with appropriate treatment [1]. First experience and challenges of compassionate use of new anti-TB drugs to treat MDR- and XDR-TB in children http://ow.ly/SWXF300a0UX

Pharmacokinetics of Ofloxacin and Levofloxacin for Prevention and Treatment of Multidrug-Resistant Tuberculosis in Children

ABSTRACT Limited data on fluoroquinolone pharmacokinetics and cardiac effects in children exist. Among 22 children receiving drug-resistant tuberculosis prophylaxis or treatment, serum concentrations following oral doses of levofloxacin (15 mg/kg of body weight) and ofloxacin (20 mg/kg) were lower than those expected from existing pediatric data, possibly due to differences in the formulations (crushed tablets). Drug exposures were lower than those in adults following standard doses and below the proposed pharmacodynamic targets, likely due to more rapid elimination in children. No QT prolongation was observed.

Linezolid for the treatment of drug-resistant tuberculosis in children: A review and recommendations

Options for the treatment of children with drug-resistant tuberculosis (DR-TB) are limited. Emerging evidence in adults from systematic reviews and a randomized trial has shown good efficacy of linezolid in difficult cases of DR-TB but with frequent serious adverse effects. Published data in children are limited and we are unaware of formal guidelines for linezolid in treatment of paediatric DR-TB, though it will likely be an important component of DR-TB treatment for a growing number of children. We performed a structured review of existing literature on the efficacy, adverse effects, pharmacokinetics and pharmacodynamics of linezolid in DR-TB, highlighting the key evidence from the adult literature and systematically evaluating published paediatric data. Our search identified 8 reports of 18 children receiving linezolid for difficult to treat DR-TB. All 18 had culture conversion and 15 of 18 had successful long-term treatment outcomes. Adverse events were reported in 9 of 18; a linezolid dose reduction was required in 5 of 18, and 2 of 18 permanently discontinued linezolid because of adverse events. We make specific recommendations for the use of linezolid in children with DR-TB, and identify priority questions for future research. For children with multidrug-resistant (MDR)-TB with additional resistance or with extensively drug-resistant (XDR)-TB, linezolid may make the difference between a successful or poor outcome, and until newer antituberculosis agents with better efficacy and safety become available in children, linezolid will be an important component of treatment for children with the worst forms of DR-TB.

Fluoroquinolones for the treatment of tuberculosis in children

The fluoroquinolones are key components of current multidrug-resistant tuberculosis (MDR-TB) treatment regimens and are being evaluated in shortened treatment regimens as well as in the prevention of drug-resistant TB. The objective of this review was to identify existing evidence for the use of the fluoroquinolones ofloxacin, levofloxacin and moxifloxacin in the treatment of TB in children. Existing data from in vitro, animal and human studies consistently demonstrate the efficacy of the fluoroquinolones against Mycobacterium tuberculosis, with superiority of levofloxacin and moxifloxacin compared to ofloxacin. In vitro and murine studies demonstrated the potential of moxifloxacin to shorten drug-susceptible TB treatment, but in multiple randomized controlled trials shortened fluoroquinolone-containing regimens have not been non-inferior compared to standard therapy. Resistance occurs frequently via mutations in the gyrA gene, and emerges rapidly depending on the fluoroquinolone concentration, with newer more potent fluoroquinolones less likely to develop resistance. Emerging data from paediatric studies underlines the importance of fluoroquinolones in the treatment of MDR-TB in children. There is a paucity of pharmacokinetic data especially in children <5 years of age and HIV-infected children; existing studies show substantially lower serum concentrations in children compared to adults at currently recommended doses, probably due to faster elimination. This has implications for optimizing paediatric treatment and for the development of resistance. Fluoroquinolone use has been restricted in children due to concerns about drug-induced arthropathy. The available data does not demonstrate any serious arthropathy or other severe toxicity in children. Although there is limited paediatric safety data for the prolonged treatment of MDR-TB, extended administration of fluoroquinolones in adults with MDR-TB does not show serious adverse effects and there is no evidence suggesting less tolerability of fluoroquinolones in children. Additional study of moxifloxacin and levofloxacin for TB treatment and prevention in children is an urgent priority.

A review of the use of ethionamide and prothionamide in childhood tuberculosis

Ethionamide (ETH) and prothionamide (PTH), both thioamides, have proven efficacy in clinical studies and form important components for multidrug-resistant tuberculosis treatment regimens and for treatment of tuberculous meningitis in adults and children. ETH and PTH are pro-drugs that, following enzymatic activation by mycobacterial EthA inhibit InhA, a target shared with isoniazid (INH), and subsequently inhibit mycolic acid synthesis of Mycobacterium tuberculosis. Co-resistance to INH and ETH is conferred by mutations in the mycobacterial inhA promoter region; mutations in the ethA gene often underlie ETH and PTH monoresistance. An oral daily dose of ETH or PTH of 15-20 mg/kg with a maximum daily dose of 1000 mg is recommended in children to achieve adult-equivalent serum concentrations shown to be efficacious in adults, although information on optimal pharmacodynamic targets is still lacking. Gastrointestinal disturbances, and hypothyroidism during long-term therapy, are frequent adverse effects observed in adults and children, but are rarely life-threatening and seldom necessitate cessation of ETH therapy. More thorough investigation of the therapeutic effects and toxicity of ETH and PTH is needed in childhood TB while child-friendly formulations are needed to appropriately dose children.

New and Repurposed Drugs for Pediatric Multidrug-Resistant Tuberculosis. Practice-based Recommendations

&NA; It is estimated that 33,000 children develop multidrug‐resistant tuberculosis (MDR‐TB) each year. In spite of these numbers, children and adolescents have limited access to the new and repurposed MDR‐TB drugs. There is also little clinical guidance for the use of these drugs and for the shorter MDR‐TB regimen in the pediatric population. This is despite the fact that these drugs and regimens are associated with improved interim outcomes and acceptable safety profiles in adults. This review fills a gap in the pediatric MDR‐TB literature by providing practice‐based recommendations for the use of the new (delamanid and bedaquiline) and repurposed (linezolid and clofazimine) MDR‐TB drugs and the new shorter MDR‐TB regimen in children and adolescents.

False-negative post-18-month confirmatory HIV tests in HIV DNA PCR-positive children: a retrospective analysis.

Objective:The WHO guidelines for children less than 18 months old diagnosed with HIV based on presumptive clinical diagnosis or one virologic test recommend confirmatory HIV antibody testing after 18 months of age. This study describes post-18-month HIV test results following this WHO-recommended confirmatory testing strategy. Design:Case series and retrospective review of routine program data. Methods:Children enrolled at the Baylor Childrens Clinical Center of Excellence, a pediatric and family HIV clinic in Maseru, Lesotho from December 2005 through January 2009 with a positive HIV DNA PCR at less than 18 months of age and HIV rapid test results after 18 months of age were included. Post-18-month confirmatory HIV test results are described. Factors associated with non-positive confirmatory rapid tests were determined using binary logistic regression. Results:Of the 109 children meeting inclusion criteria, 22 (20.2%) had negative and 27 (24.8%) discordant confirmatory rapid tests. Forty-six of these 49 were on antiretroviral therapy (ART). Among these 49, 11 of 24 post-18-month HIV DNA PCRs were negative, whereas nine of 10 post-18-month HIV ELISAs were positive; 29 were definitively and 17 probably HIV-infected, two were uninfected, and one had undetermined status. Only age less than 9 months at ART initiation (odds ratio 4.25, P = 0.002) was associated with non-positive rapid tests. Conclusion:False-negative post-18-month confirmatory rapid tests and HIV DNA PCRs in children on ART are common, associated with early ART initiation, and may lead to inappropriate ART discontinuation and discharge from care of truly HIV-infected children.

Tuberculosis: opportunities and challenges for the 90-90-90 targets in HIV-infected children

In 2014 the Joint United Nations Programme on HIV/AIDS defined the ambitious 90–90–90 targets for 2020, in which 90% of people living with HIV must be diagnosed, 90% of those diagnosed should be on sustained therapy and 90% of those on therapy should have an undetectable viral load. Children are considered to be a key focus population for these targets. This review will highlight key components of the epidemiology, prevention and treatment of tuberculosis (TB) in HIV‐infected children in the era of increasing access to antiretroviral therapy (ART) and their relation to the 90–90–90 targets.

Paediatric formulations of second-line anti-tuberculosis medications: challenges and considerations

There is a growing number of children worldwide accessing second-line anti-tuberculosis drugs for multidrug-resistant tuberculosis (TB); however, there are very few child-friendly formulations. For paediatric use, dispersible tablets offer distinct advantages over liquid formulations and other approaches. This is particularly relevant for TB, where stability, long shelf-life and reduced manufacturing, transport and storage costs are all critical to ensuring that drugs are accessible and affordable. In addition, fixed-dose combinations that reduce the pill burden and provide adequate taste masking may promote long-term adherence to anti-tuberculosis treatment and prevention regimens likely to last many months in children. Partial adherence may result in treatment failure and the further selection and spread of resistant mycobacteria. Unfortunately, no second-line TB paediatric drugs exist in dispersible formulations. We discuss here the main obstacles to developing such tablets and present strategies for overcoming them. We also advocate for timely anticipation of paediatric use when new TB drugs are being developed, and for the development of child-friendly anti-tuberculosis formulations in general.There is a growing number of children worldwide accessing second-line anti-tuberculosis drugs for multidrug-resistant tuberculosis (TB); however, there are very few child-friendly formulations. For paediatric use, dispersible tablets offer distinct advantages over liquid formulations and other approaches. This is particularly relevant for TB, where stability, long shelf-life and reduced manufacturing, transport and storage costs are all critical to ensuring that drugs are accessible and affordable. In addition, fixed-dose combinations that reduce the pill burden and provide adequate taste masking may promote long-term adherence to anti-tuberculosis treatment and prevention regimens likely to last many months in children. Partial adherence may result in treatment failure and the further selection and spread of resistant mycobacteria. Unfortunately, no second-line TB paediatric drugs exist in dispersible formulations. We discuss here the main obstacles to developing such tablets and present strategies for overcoming them. We also advocate for timely anticipation of paediatric use when new TB drugs are being developed, and for the development of child-friendly anti-tuberculosis formulations in general.

Antituberculosis drugs in children

Tuberculosis (TB) remains a global threat to children, as it often goes undiagnosed and leads to high morbidity and mortality. Active contact tracing leading to initiation of preventive therapy and early diagnosis with immediate effective treatment, whether it is drug‐susceptible or drug‐resistant TB, could reduce mortality and morbidity. In order to achieve this it is necessary to understand the currently available drugs, their role in treatment, their doses, and adverse effects. However, there is still limited pharmacokinetic data on antituberculosis drugs in children, few child‐friendly formulations, and knowledge gaps regarding their pharmacodynamics. A discussion of the available antituberculosis drugs is presented, with a focus on their pharmacokinetics and pharmacodynamics, to provide reasoning for the currently recommended doses for children. More pharmacokinetic and pharmacodynamics studies, for both existing and novel drugs, are urgently needed to optimize dosing of antituberculosis drugs in children and for development of child‐friendly formulations.