Tolerability of Isoniazid Preventive Therapy in an HIV-Infected Cohort of Paediatric and Adolescent Patients on Antiretroviral Therapy from a Resource-Limited Setting: A Retrospective Cohort Study

A validated liquid chromatography-tandem mass spectrometry assay for the analysis of isoniazid and its metabolite acetyl-isoniazid in urine

Introduction

Isoniazid (INH) is one of the most effective and potent first-line anti-tubercular drug. INH is also effectively administered as a preventative monotherapy and has been shown to significantly reduce TB incidence. INH is primarily metabolised to acetyl-isoniazid (AcINH) in the liver. AcINH is mainly excreted in urine presenting as a target for monitoring adherence to INH therapy.

Objective

The study aimed to develop and fully validate a bioanalytical method using liquid chromatography-tandem mass spectrometry for the quantification of INH and AcINH in human urine.

Methods

The samples were prepared using solid phase extraction, with the internal standards isoniazid-d4 and acetyl-isoniazid-d4 being used. The extracts were chromatographed on an Atlantis T3 analytical column with an isocratic mobile phase. For detection, a AB Sciex™ API 5500 triple quadrupole mass spectrometer was used at unit resolution in the multiple reaction monitoring mode, following positive electrospray ionization.

Results

The analytical method demonstrated sufficient sensitivity, as indicated by average signal-to-noise ratios of 7.07 and 6.23 at the lower limit of quantification for INH and AcINH, respectively. Validation was performed over three consecutive batches, demonstrating accuracy, precision, and overall robustness based on peak area ratios within the analytical range of 0.234-30.0 µg/mL for both INH and AcINH. All required validation experiments were assessed and met the acceptance criteria guidelines of the US Food and Drug Administration and European Medicines Agency. The validated method was utilized to measure concentrations of AcINH in urine as a means of assessing adherence to the intake of isoniazid in order to prevent TB infection during a phase III open-label multicenter trial.

Conclusion

A bioanalytical method was developed and fully validated for quantifying isoniazid (INH) and acetyl-isoniazid (AcINH) in 100 µL of human urine.

Liver Injury Following Isoniazid Preventive Therapy in HIV Patients Attending Halibet National Referral Hospital, Eritrea: A Prospective Cohort Study

INTRODUCTION

A 6-month course of isoniazid, 300 mg daily, was programmatically introduced in Eritrea in 2014 as tuberculosis preventive therapy in people living with human immunodeficiency virus (PLHIV). The rollout of isoniazid preventive therapy (IPT) in PLHIV was successful in the first 2-3 years. After 2016, rumours based on rare but real incidents of liver injuries following use of IPT spread widely across the country and created concerns amongst healthcare professionals and consumers, that ultimately caused dramatic decline in the rollout of the intervention. Decision makers have been demanding better evidence as previously conducted local studies had inherent methodological limitations. This real-world observational study was conducted to evaluate the risk of liver injury associated with IPT among PLHIV attending Halibet national referral hospital, Asmara, Eritrea.

METHODS

A prospective cohort study, that consecutively enrolled PLHIV attending Halibet hospital, was conducted between 1 March and 30 October 2021. Those exposed to anti-retroviral therapy (ART) plus IPT were considered as exposed and those taking only ART were considered as unexposed. Both groups were prospectively followed up for 4-5 months with monthly liver function tests (LFTs). A Cox proportional hazard model was used to explore whether there was increased risk of drug-induced liver injury (DILI) associated with IPT. Probability of survival without DILI was also estimated using Kaplan-Meier curves.

RESULTS

A total of 552 patients, 284 exposed and 268 unexposed, completed the study, with a mean follow-up time of 3.97 (SD 0.675) months for the exposed and 4.06 (SD 0.675) months for the unexposed. Twelve patients developed drug-induced liver injury (DILI), with a median time-to-onset of 35 days (interquartile range: 26.8, 60 days). All cases were from the exposed group and all except two cases were asymptomatic. The incidence rate of DILI in the exposed group was 10.6 cases per 1000 person-months and zero for the unexposed group (p = 0.002).

CONCLUSION

DILI in PLHIV taking IPT was common; therefore, liver function should be closely monitored to safely administer the product. Despite high levels of deranged liver enzymes, the majority had no symptoms of DILI, emphasising the importance of close laboratory monitoring, especially during the first 3 months of treatment.

Hepatotoxicity induced by isoniazid in patients with latent tuberculosis infection: a meta-analysis

Aim

The aim of the present study was to conduct a meta-analysis of the frequency of isoniazid-induced liver injury (INH-ILI) in patients receiving isoniazid (INH) preventative therapy (IPT).

Background

The frequency of hepatotoxicity (drug-induced liver injury: DILI) of antituberculosis drugs has been studied, especially when INH, rifampin, and pyrazinamide are co-administered. However, little is known about the frequency of DILI in patients with latent tuberculosis infection (LTBI), where IPT is indicated.

Methods

We searched PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews for studies reporting the frequency of INH-ILI in patients with IPT using one or more diagnostic indicators included in the criteria of the DILI Expert Working Group.

Results

Thirty-five studies comprising a total of 22,193 participants were included. The overall average frequency of INH-ILI was 2.6% (95% CI, 1.7-3.7%). The mortality associated with INH-DILI was 0.02% (4/22193). Subgroup analysis revealed no significant differences in the frequency of INH-ILI in patients older or younger than 50 years, children, patients with HIV, candidates for liver, kidney, or lung transplant, or according to the type of study design.

Conclusion

The frequency of INH-ILI in patients receiving IPT is low. Studies on INH-ILI are needed where the current DILI criteria are used.

Tuberculosis in Adolescents and Young Adults: Emerging Data on TB Transmission and Prevention among Vulnerable Young People

Adolescents and young adults (AYA, ages 10-24 years) comprise a uniquely important but understudied population in global efforts to end tuberculosis (TB), the leading infectious cause of death by a single agent worldwide prior to the COVID-19 pandemic. While TB prevention and care strategies often overlook AYA by grouping them with either children or adults, AYA have particular physiologic, developmental, and social characteristics that require dedicated approaches. This review describes current evidence on the prevention and control of TB among AYA, including approaches to TB screening, dynamics of TB transmission among AYA, and management challenges within the context of unique developmental needs. Challenges are considered for vulnerable groups of AYA such as migrants and refugees; AYA experiencing homelessness, incarceration, or substance use; and AYA living with HIV. We outline areas for needed research and implementation strategies to address TB among AYA globally.

Adolescent tuberculosis

Adolescence is characterised by a substantial increase in the incidence of tuberculosis, a known fact since the early 20th century. Most of the world's adolescents live in low-income and middle-income countries where tuberculosis remains common, and where they comprise a quarter of the population. Despite this, adolescents have not yet been addressed as a distinct population in tuberculosis policy or within tuberculosis treatment services, and emerging evidence suggests that current models of care do not meet their needs. This Review discusses up-to-date information about tuberculosis in adolescence, with a focus on the management of infection and disease, including HIV co-infection and rifampicin-resistant tuberculosis. We outline the progress in vaccine development and highlight important directions for future research.