Ethambutol-related impaired visual function in childrens less than 5 years of age treated for a mycobacterial infection: diagnosis and evolution

Ethambutol and visual assessment in England: current practice and recommendations

BACKGROUND

Standard treatment for tuberculosis (TB) in children and adults includes an initial two-month course of ethambutol, a drug that in rare cases can cause optic neuropathy and irreversible vision loss. There is a lack of clear guidance on what vision assessments are needed before and during treatment with ethambutol, with the Royal College of Ophthalmologists, National Institute for Health and Care Excellence, British National Formulary and British Thoracic Society offering different guidance. We aimed to assess how vision is routinely tested in patients treated with ethambutol in TB services across England.

METHODS

An online survey developed by Public Health England was sent to all TB services in England in 2018 to assess current practice and inform the development of best practice recommendations for visual assessment of patients treated with ethambutol for TB.

RESULTS

Sixty-six TB professionals from across England responded, a response rate of 54%. The results showed variations in practice, including when to omit ethambutol from treatment, the timing and frequency of visual assessment, the type of visual assessment, referral processes and management of visual changes.

CONCLUSION

This national survey highlights the need for clear guidelines on the testing of vision for patients taking ethambutol at recommended doses, before and during treatment. We suggest a pragmatic approach to visual assessment to reduce variation in practice, proposing a stepwise pathway for patients on standard TB treatment for local adaptation.

Pediatric Tuberculosis Management: A Global Challenge or Breakthrough?

Managing pediatric tuberculosis (TB) remains a public health problem requiring urgent and long-lasting solutions as TB is one of the top ten causes of ill health and death in children as well as adolescents universally. Minors are particularly susceptible to this severe illness that can be fatal post-infection or even serve as reservoirs for future disease outbreaks. However, pediatric TB is the least prioritized in most health programs and optimal infection/disease control has been quite neglected for this specialized patient category, as most scientific and clinical research efforts focus on developing novel management strategies for adults. Moreover, the ongoing coronavirus pandemic has meaningfully hindered the gains and progress achieved with TB prophylaxis, therapy, diagnosis, and global eradication goals for all affected persons of varying age bands. Thus, the opening of novel research activities and opportunities that can provide more insight and create new knowledge specifically geared towards managing TB disease in this specialized group will significantly improve their well-being and longevity.

New Perspectives in Drug Delivery Systems for the Treatment of Tuberculosis

BACKGROUND

Tuberculosis is a chronic respiratory disease caused by Mycobacterium tuberculosis. The common treatment regimens of tuberculosis are lengthy with adverse side effects, low patient compliance, and antimicrobial resistance. Drug delivery systems (DDSs) can overcome these limitations.

OBJECTIVE

This review aims to summarize the latest DDSs for the treatment of tuberculosis. In the first section, the main pharmacokinetic and pharmacodynamic challenges, due to the innate properties of the drugs, are put forth. The second section elaborates on the use of DDS to overcome the disadvantages of the current treatment of tuberculosis.

CONCLUSION

We reviewed research articles published in the last 10 years. DDSs can improve the physicochemical properties of anti-tuberculosis drugs, improving solubility, stability, and bioavailability, with better control of drug release and can target alveolar macrophages. However, more preclinical studies and robust bio-relevant analyses are needed for DDSs to become a feasible option to treat patients and attract investors.

Managing latent tuberculosis infection and tuberculosis in children

Tuberculosis (TB) is a major cause of childhood morbidity and mortality worldwide. The aim of this review is to describe the management of the child with TB and latent tuberculosis infection (LTBI). To develop this article, a working group reviewed relevant epidemiological and other scientific studies and established practices in conducting LBTI and TB in children. The article describes how to manage the child with LTBI, considering transmission and infectiousness of tuberculosis, contact screening and prioritization of contacts and recommendations on treatment of children with LTBI and how to manage the child with TB considering the susceptibility of children to developing tuberculosis, epidemiology and classification of tuberculosis in children, diagnosis and treatment.

Ocular tuberculosis: Position paper on diagnosis and treatment management

Delay in diagnosis or treatment of ocular tuberculosis can result in loss of vision. However, due to the fact that early diagnosis is rarely achieved, there are still a broad variety of diagnostic and treatment approaches. Our aim was to reach a consensus on the management of diagnosis and treatment of ocular tuberculosis.

METHODS

Critical appraisal of the literature and expert opinion on diagnosis and treatment of ocular tuberculosis.

RESULTS AND CONCLUSION

The currently recommended method for ocular TB diagnosis is screening for tuberculosis in any uveitis of unknown etiology, recurrent or not responding to conventional therapy; in ocular findings highly suggestive of ocular TB and before immunosuppression (particularly biologic agents). TB screening in these cases includes tuberculosis skin testing and interferon gamma testing, along with complete medical history, ophthalmologic evaluation and chest imaging. Positively screened patients should be treated for active tuberculosis with 4 drugs (isoniazid, rifampicin, pyrazinamide and ethambutol) for 6-9 months. Patients should be reviewed at the end of the initiation phase (two months) and at the end of the overall treatment (6-9 months).

Pharmacokinetics of Rifampin, Isoniazid, Pyrazinamide, and Ethambutol in Infants Dosed According to Revised WHO-Recommended Treatment Guidelines

There are limited pharmacokinetic data for use of the first-line antituberculosis drugs during infancy (<12 months of age), when drug disposition may differ. Intensive pharmacokinetic sampling was performed in infants routinely receiving antituberculosis treatment, including rifampin, isoniazid, pyrazinamide, and ethambutol, using World Health Organization-recommended doses. Regulatory-approved single-drug formulations, including two rifampin suspensions, were used on the sampling day. Assays were conducted using liquid chromatography-mass spectrometry; pharmacokinetic parameters were generated using noncompartmental analysis. Thirty-nine infants were studied; 14 (36%) had culture-confirmed tuberculosis. Fifteen (38%) were premature (<37 weeks gestation); 5 (13%) were HIV infected. The mean corrected age and weight were 6.6 months and 6.45 kg, respectively. The mean maximum plasma concentrations (Cmax) for rifampin, isoniazid, pyrazinamide, and ethambutol were 2.9, 7.9, 41.9, and 1.3 μg/ml, respectively (current recommended adult target concentrations: 8 to 24, 3 to 6, 20 to 50, and 2 to 6 μg/ml, respectively), and the mean areas under the concentration-time curves from 0 to 8 h (AUC0-8) were 12.1, 24.7, 239.4, and 5.1 μg · h/ml, respectively. After adjusting for age and weight, rifampin exposures for the two formulations used differed inCmax(geometric mean ratio [GMR],2.55; 95% confidence interval [CI], 1.47 to 4.41;P= 0.001) and AUC0-8(GMR, 2.52; 95% CI, 1.34 to 4.73;P= 0.005). HIV status was associated with lower pyrazinamideCmax(GMR, 0.85; 95% CI, 0.75 to 0.96;P= 0.013) and AUC0-8(GMR, 0.79; 95% CI, 0.69 to 0.90;P< 0.001) values. No other important differences were observed due to age, weight, prematurity, ethnicity, or gender. In summary, isoniazid and pyrazinamide concentrations in infants compared well with proposed adult target concentrations; ethambutol concentrations were lower but similar to previously reported pediatric studies. The low rifampin exposures require further investigation. (This study has been registered at ClinicalTrials.gov under registration no. NCT01637558.).

Recommendations Concerning the First-Line Treatment of Children with Tuberculosis

This document describes the recommendations of a group of scientific societies concerning the first-line therapeutic approach to paediatric tuberculosis (TB). The treatment of pulmonary TB should be based on the existence of parenchymal involvement and the risk of antibiotic resistance. The treatment of extra-pulmonary TB is based on the regimens used for severe pulmonary TB. The administration of corticosteroids is recommended only in cases of miliary TB, tuberculous meningitis and tuberculous pericarditis. Vitamin B6 may be indicated in the case of isoniazid-treated TB in breastfeeding infants, severely malnourished subjects, or patients with other diseases at high risk of vitamin deficiency. Once having started treatment, children with TB should be carefully followed up in order to evaluate compliance, the response to treatment, the need for treatment changes, and the presence of drug-related adverse events. Primary care paediatricians can support reference centres in providing family healthcare education and encouraging treatment compliance.

Advances in Drug Discovery and Development for Pediatric Tuberculosis

Pediatric tuberculosis is an underappreciated global epidemic estimated to afflict around half a million children worldwide. This problem has historically been overlooked, due in part to their low social status and the difficulty in diagnosis of tuberculosis in children. Children are more susceptible to tuberculosis infection and disease progression, including rapid dissemination into extrapulmonary infection sites. Treatment of pediatric tuberculosis infections has been traditionally built around agents used to treat the adult disease, but the disease pathology, drug pharmacokinetics and the safety window in children differs from the adult disease. This produces additional concerns for drug discovery and development of new agents. This review examines: (i) the safety concerns for current front and second line agents used to treat complex drug resistant infections and how this knowledge can be used to identify, prioritize and dose agents that may be better tolerated in pediatric populations; and (ii) the chemistry and suitability of new drugs in the clinical development pipeline for tuberculosis for the treatment of pediatric infections indicating several new agents may offer significant improvements for the treatment of multi-drug resistant tuberculosis in children.

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

INTRODUCTION

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.

DISCUSSION

The majority of HIV-infected children live in countries with a high burden of TB. In settings with a high burden of both diseases such as in sub-Saharan Africa, up to 57% of children diagnosed with and treated for TB are HIV-infected. TB results in substantial morbidity and mortality in HIV-infected children, so preventing TB and optimizing its treatment in HIV-infected children will be important to ensuring good long-term outcomes. Prevention of TB can be achieved by increasing access to ART to both children and adults, and appropriate provision of isoniazid preventative therapy. Co-treatment of HIV and TB is complicated by drug-drug interactions particularly due to the use of rifampicin; these may compromise virologic outcomes if appropriate corrective actions are not taken. There remain substantial operational challenges, and improved integration of paediatric TB and HIV services, including with antenatal and routine under-five care, is an important priority.

CONCLUSIONS

TB may be an important barrier to achievement of the 90-90-90 targets, but specific attention to TB care in HIV-infected children may provide important opportunities to enhance the care of both TB and HIV in children.

[The challenge of administering anti-tuberculosis treatment in infants and pre-school children. pTBred Magistral Project]

INTRODUCTION

There are no paediatric formulations of anti-tuberculous drugs in Spain, with the only exception being rifampicin. Some paediatricians often prescribe composite formulations (CF), while others prefer to give crushed tablets. Nevertheless, there is no consensus in this regard, or any pharmacokinetic studies validating these procedures. In this situation, the Spanish Network for the Study of Paediatric Tuberculosis (pTBred) has launched the Magistral Project, which has as its first phase aims to analyse the desirability of developing child-friendly pharmaceutical formulations and other aspects regarding the anti-tuberculous drug prescription in children.

MATERIAL AND METHODS

A cross-sectional, multicentre, nationwide study was conducted, based on an online questionnaire sent to members of pTBred between February and March 2015.

RESULTS

Fifty-four responses from 67 consulted institutions were received. Most of the respondents reported prescribing crushed tablets. A significant number of those surveyed, although being fewer, prescribe CF, for which availability varies widely among institutions. Eighty-three percent replied that it would be essential to have fixed dose combinations of anti-tuberculous drugs, specifically adapted to paediatric doses and administered by CF or tablets. Among the surveyed institutions, differences were found in the management of latent tuberculosis infection, in the use of directly observed therapy, and in the monitoring of adverse events.

CONCLUSIONS

Our survey reveals great diversity in anti-tuberculous drug prescription in children, due to the lack of suitable infant formulations, which could have an impact on treatment adherence and outcomes. pTBred intends to develop a pioneering and useful consensus document on the management of anti-tuberculous medication in children.