Safety and Adherence for 12 Weekly Doses of Isoniazid and Rifapentine for Pediatric Tuberculosis Infection

Review of Pediatric Tuberculosis in the Aftermath of COVID-19

In 2014, the World Health Organization developed the End Tuberculosis Strategy with the goal of a 95% reduction in deaths from tuberculosis (TB) by 2035. The start of the COVID-19 pandemic and global lockdown has had a major impact on TB awareness, screening, diagnosis, and prompt initiation of treatment, inevitably leading to a significant setback. We explore pediatric tuberculosis through the lens of the COVID-19 era, investigating how COVID-19 has impacted pediatric TB cases in different regions of the world and what the implications are for management moving forward to mitigate these effects. Furthermore, in light of recent findings showing how exposed infants and children are at higher risk than we thought of contracting the disease, greater attention and resources are needed to prevent further downward trends.

Pharmacokinetics of isoniazid and rifapentine in young paediatric patients with latent tuberculosis infection

OBJECTIVES

This study investigated the steady-state pharmacokinetic profiles of 3-month weekly rifapentine plus isoniazid (3HP) in children with latent tuberculosis infection (LTBI). Factors including tablet integrity, food, and pharmacogenetics were also assessed.

METHODS

During the 3HP treatment, blood and urine samples were collected on week 4. Isoniazid and rifapentine levels were measured using a high-performance liquid chromatography technique. Genetic variation of arylamine N-acetyltransferase 2 (NAT2) and arylacetamide deacetylase (AADAC) were assessed by the MassARRAY®. Safety and clinical outcomes at week 48 were monitored.

RESULTS

Twelve LTBI children [age 3.8 (range 2.1-4.9 years old)] completed the treatment [isoniazid and rifapentine dose 25.0 (range 21.7-26.8) and 25.7 (range 20.7-32.1) mg/kg, respectively]. No serious adverse events or active tuberculosis occurred. Tablet integrity was associated with decreased area under the concentration-time curve (91 vs 73 mg.hr/L, p = 0.026) and increased apparent oral clearance of isoniazid (0.27 vs 0.32 L/hr/kg, p = 0.019) and decreased rifapentine's renal clearance (CL_R, 0.005 vs 0.003 L/hr, p = 0.014). Food was associated with increased CL_R of isoniazid (3.45 vs 8.95 L/hr, p = 0.006) but not rifapentine. Variability in NAT2 and AADAC did not affect the pharmacokinetics of both drugs.

CONCLUSIONS

There is high variability in the pharmacokinetic profiles of isoniazid and rifapentine in young LTBI children. The variability was partly influenced by tablet integrity and food, but not pharmacogenetics. Further study in a larger cohort is warranted to display the relationship of these factors to treatment outcomes.

Adverse events associated with weekly short course isoniazid and rifapentine therapy in pediatric patients with latent tuberculosis: A chart and literature review

BACKGROUND

Effective yet safe treatment of latent tuberculosis is important for preventing the spread of tuberculosis and the progression to active disease in pediatric patients. As of 2017, the short course combination regimen of weekly isoniazid and rifapentine (3HP) administered by directly observed therapy (DOT) has replaced 9 months of isoniazid as the standard of treatment for latent tuberculosis in pediatric patients. The literature, limited in size, has established the 3HP regimen's superior safety and adherence.

METHODS

We completed a retrospective chart review (n = 22) of pediatric patients at our institution receiving the 3HP regimen via DOT between 2017 and 2019. Frequencies of selected outcomes were compared to previously published data collected in a literature review.

RESULTS

In this retrospective chart review, pediatric patients ages 2-20 years receiving 3HP with DOT for latent tuberculosis experienced frequent adverse events, more severe adverse events such as anaphylaxis, and higher treatment discontinuation than that which has been previously reported in the literature. Of note, our cohort's race/ethnicity differed from the cohorts described in the literature.

CONCLUSIONS

Our data suggests that the short course combination regimen for pediatric latent tuberculosis patients may have a higher adverse event rate than previously established. Although this sample size is small, this study urges further investigation of more diverse cohorts to better establish the 3HP regimen's safety and tolerability.

Tuberculosis and TNF-α inhibitors in children: how to manage a fine balance

Since the introduction of biologic response modifiers (BRMs) in the management of children affected by the immune-mediated inflammatory disease, these patients substantially improved their quality of life. BRMs are generally well tolerated and effective in most children and adolescents refractory to conventional immunosuppressive therapy. On the other hand, patients receiving BRMs, especially TNF-α inhibitors, display an increased risk of primary infections or reactivations, i.e. due to Mycobacterium tuberculosis. M. tuberculosis can cause severe disease with consequent short- and long-term morbidity in children on anti-TNF-α treatment. The present paper analyses the increased risk of reactivation of latent tuberculosis infection (LTBI) or de novo TB infection in children treated with TNF-α inhibitors, with the purpose to provide recommendations for screening strategies and safety monitoring of paediatric patients. Special attention is also given to the currently available TB screening tools (IGRAs and TST) and their utility in the diagnosis of LTBI before starting the biologic therapy and during the treatment. Finally, the paper analyses the suggested TB-preventing therapies to adopt in these children and the correct timing to overlap anti-TB and anti-TNF-a treatment.

Isoniazid-Rifapentine for Latent Tuberculosis Infection: A Systematic Review and Meta-analysis

CONTEXT

Latent tuberculosis infection diagnosis and treatment is a strategic priority for eliminating tuberculosis in the U.S. The Centers for Disease Control and Prevention has recommended the short-course regimen of 3-month isoniazid-rifapentine administered by directly observed therapy. However, longer-duration regimens remain the most widely prescribed latent tuberculosis infection treatments. Limitation on adoption of 3-month isoniazid-rifapentine in the U.S. might be because of patients' preference for self-administered therapy, providers' lack of familiarity with 3-month isoniazid-rifapentine, or lack of resources to support directly observed therapy. This review examines the most recent evidence regarding 3-month isoniazid-rifapentine's effectiveness, safety, and treatment completion when directly compared with other latent tuberculosis infection regimens primarily comprising 9-month isoniazid treatment.

EVIDENCE ACQUISITION

Using Community Guide methodology, reviewers identified, evaluated, and summarized available evidence published during January 2006-June 2017. Analysis of the data was completed in 2017.

EVIDENCE SYNTHESIS

The analysis included 15 unique studies. Three-month isoniazid-rifapentine was determined to be equal to other latent tuberculosis infection regimens in effectiveness (OR=0.89, 95% CI=0.46, 1.70), and has higher treatment completion (87.5%, 95% CI=83.2%, 91.3%) compared with other latent tuberculosis infection regimens (65.9%, 95% CI=53.5%, 77.3%). Three-month isoniazid-rifapentine was associated with similar risk to other latent tuberculosis infection regimens for adverse events (relative risk=0.59, 95% CI=0.23, 1.52); discontinuing treatment because of adverse events (relative risk=0.48, 95% CI=0.17, 1.34); and death (relative risk=0.79, 95% CI=0.56, 1.11).

CONCLUSIONS

The 3-month isoniazid-rifapentine regimen is as safe and effective as other recommended latent tuberculosis infection regimens and achieves significantly higher treatment completion rates.

Completion Rate and Safety of Tuberculosis Infection Treatment With Shorter Regimens

BACKGROUND

The traditional treatment of tuberculosis (TB) infection (9 months of daily isoniazid [9H]) is safe but completion rates of <50% are reported. Shorter regimens (3 months of once-weekly isoniazid and rifapentine [3HP] or 4 months of daily rifampin [4R]) are associated with improved adherence in adults.

METHODS

This was a retrospective cohort study (2014-2017) of children (0-18 years old) seen at a children's TB clinic in a low-incidence nation. We compared the frequency of completion and adverse events (AEs) in children receiving 3HP, 4R, and 9H; the latter 2 regimens could be administered by families (termed self-administered therapy [SAT]) or as directly observed preventive therapy (DOPT); 3HP was always administered under DOPT.

RESULTS

TB infection treatment was started in 667 children: 283 (42.4%) 3HP, 252 (37.8%) 9H, and 132 (19.8%) 4R. Only 52% of children receiving 9H via SAT completed therapy. Children receiving 3HP were more likely to complete therapy than the 9H (SAT) group (odds ratio [OR] 27.4, 95% confidence interval [CI]: 11.8-63.7). Multivariate analyses found receipt of medication under DOPT (OR: 5.72, 95% CI: 3.47-9.43), increasing age (OR: 1.09, 95% CI: 1.02-1.17), and the absence of any AE (OR: 1.70, 95% CI: 0.26-0.60) to be associated with completing therapy. AEs were more common in the 9H group (OR: 2.51, 95% CI: 1.48-4.32). Two (0.9%) children receiving 9H developed hepatotoxicity; no child receiving 3HP or 4R developed hepatotoxicity.

CONCLUSIONS

Shorter regimens are associated with increased completion rates and fewer AEs than 9H.

Tuberculosis in Infants and Children

One million children develop tuberculosis disease each year, and 210,000 die from complications of tuberculosis. Childhood tuberculosis is very different from adult tuberculosis in epidemiology, clinical and radiographic presentation, and treatment. This review highlights the many unique features of childhood tuberculosis, with special emphasis on very young children and adolescents, who are most likely to develop disease after infection has occurred.

Treatment of Latent Tuberculosis Infection

There are approximately 56 million people who harbor Mycobacterium tuberculosis that may progress to active tuberculosis (TB) at some point in their lives. Modeling studies suggest that if only 8% of these individuals with latent TB infection (LTBI) were treated annually, overall global incidence would be 14-fold lower by 2050 compared to incidence in 2013, even in the absence of additional TB control measures. This highlights the importance of identifying and treating latently infected individuals, and that this intervention must be scaled up to achieve the goals of the Global End TB Strategy. The efficacy of LTBI treatment is well established, and the most commonly used regimen is 9 months of daily self-administered isoniazid. However, its use has been hindered by limited provider awareness of the benefits, concern about potential side effects such as hepatotoxicity, and low rates of treatment completion. There is increasing evidence that shorter rifamycin-based regimens are as effective, better tolerated, and more likely to be completed compared to isoniazid. Such regimens include four months of daily self-administered rifampin monotherapy, three months of once weekly directly observed isoniazid-rifapentine, and three months of daily self-administered isoniazid-rifampin. The success of LTBI treatment to prevent additional TB disease relies upon choosing an appropriate regimen individualized to the patient, monitoring for potential adverse clinical events, and utilizing strategies to promote adherence. Safer, more cost-effective, and more easily completed regimens are needed and should be combined with interventions to better identify, engage, and retain high-risk individuals across the cascade from diagnosis through treatment completion of LTBI.

Rifapentine for the treatment of latent tuberculosis

INTRODUCTION

The goal of this article is to review the use of rifapentine in the treatment of latent tuberculosis infection (LTBI). Controlling LTBI is an important part of the global strategy to end the spread of tuberculosis. Rifapentine's potent sterilizing effect against Mycobacterium tuberculosis combined with its long half-life make it an attractive LTBI treatment option. Areas covered: A systematic literature search of Pubmed using the terms 'rifapentine' and 'tuberculosis' was performed. Articles identified were cross-referenced for other relevant publications. The mechanisms of action and resistance, pharmacokinetic and pharmacodynamics, potential drug interactions and side effects are discussed. Expert commentary: Rifapentine in combination with isoniazid for twelve weeks is the best available option for treating latent TB in the majority of patients in the United States due to its favorable safety profile and the increased likelihood of completing therapy. Currently, rifapentine is not registered or available in other countries.