Treatment Outcomes and Adverse Drug Effects of Ethambutol, Cycloserine, and Terizidone for the Treatment of Multidrug-Resistant Tuberculosis in South Africa

Second-line antituberculosis drug exposure thresholds predictive of adverse events in multidrug-resistant tuberculosis treatment

OBJECTIVES

This study aimed to investigate the association between drug exposure and adverse events (AEs) during the standardized multidrug-resistant tuberculosis (MDR-TB) treatment, as well as to identify predictive drug exposure thresholds.

METHODS

We conducted a prospective, observational multicenter study among participants receiving standardized MDR-TB treatment between 2016 and 2019 in China. AEs were monitored throughout the treatment and their relationships to drug exposure (e.g., the area under the drug concentration-time curve from 0 to 24 h, AUC0-24 h) were analyzed. The thresholds of pharmacokinetic predictors of observed AEs were identified by boosted classification and regression tree (CART) and further evaluated by external validation.

RESULTS

Of 197 study participants, 124 (62.9%) had at least one AE, and 15 (7.6%) experienced serious AEs. The association between drug exposure and AEs was observed including bedaquiline, its metabolite M2, moxifloxacin and QTcF prolongation (QTcF >450 ms), linezolid and mitochondrial toxicity, cycloserine and psychiatric AEs. The CART-derived thresholds of AUC0-24 h predictive of the respective AEs were 3.2 mg·h/l (bedaquiline M2); 49.3 mg·h/l (moxifloxacin); 119.3 mg·h/l (linezolid); 718.7 mg·h/l (cycloserine).

CONCLUSIONS

This study demonstrated the drug exposure thresholds predictive of AEs for key drugs against MDR-TB treatment. Using the derived thresholds will provide the knowledge base for further randomized clinical trials of dose adjustment to minimize the risk of AEs.

High Incidence of Psychiatric Disorders Associated with Cycloserine Treatment of Multidrug-Resistant Tuberculosis Patients: A Cohort Study in Beijing, China

Objective

Cycloserine (CS) is a group B anti-tuberculosis (TB) drug endorsed by the World Health Organization (WHO) for the treatment of drug-resistant (DR)-TB. Despite CS widespread acceptance and known efficacy, the high potential of drug-associated psychiatric disorders is a major concern to multidrug-resistant (MDR)-TB patients. In this study, we investigated CS-associated psychiatric disorders in a cohort of MDR-TB patients in Beijing, China. Our aim was to determine psychiatric disorder prevalence rates and associated risk factors in this population.

Methods

This MDR-TB cohort study was conducted at Beijing Chest Hospital between February 2018 and February 2021. All patients received individualized treatment regimens that included CS at some point during the full treatment course. Patient psychological status was assessed using the Symptom Checklist (SCL-90) questionnaire during the post-treatment follow-up period.

Results

Two hundred and thirty-seven MDR-TB patients were included in the final analysis. Overall, psychiatric disorders were recorded in 22 (9.28%) of the 237 patients in our cohort, with severity grades of 1 or 2 observed for the majority (8.44%) of psychiatric adverse events. As compared to results obtained for control group patients who were ≥40 years of age, patients who were <40 years of age (77.3%, 17/22) were more likely to experience psychiatric disorders [adjusted odds ratio (aOR) = 3.060; 95% CI (1.060–8.828)]. Additionally, patients with body mass index (BMI)s of <18.5 kg/m² [aOR = 3.824; 95% CI (1.502–9.739)] had significantly higher odds of being afflicted with psychiatric disorders as compared with patients with BMIs that were ≥18.5 kg/m².

Conclusion

Our results demonstrated that approximately one-tenth of Chinese MDR-TB patients experienced psychiatric disorders during CS treatment, with the majority of adverse events of moderate severity. In addition, low BMI and age <40 years were identified as independent risk factors for psychiatric disorders in MDR-TB patients receiving CS therapy.

MDR Tuberculosis Treatment

Multidrug-resistant (MDR) tuberculosis (TB), resistant to isoniazid and rifampicin, continues to be one of the most important threats to controlling the TB epidemic. Over the last few years, there have been promising pharmacological advances in the paradigm of MDR TB treatment: new and repurposed drugs have shown excellent bactericidal and sterilizing activity against Mycobacterium tuberculosis and several all-oral short regimens to treat MDR TB have shown promising results. The purpose of this comprehensive review is to summarize the most important drugs currently used to treat MDR TB, the recommended regimens to treat MDR TB, and we also summarize new insights into the treatment of patients with MDR TB.

Modern approaches to pharmacotherapy of tuberculosis infection in children

Anti-TB drugs for children: Aetiotropic therapy is used for the treatment of tuberculosis (TB) in children, as well as in adult patients. Anti-tuberculosis drugs (anti-TB drugs) are divided into 3 lines, taking into account drug sensitivity in Mycobacterium tuberculosis (MBT). First-line anti-TB drugs (basic) are used to treat TB caused by drug-susceptible MBT. Second- and third-line (reserve) drugs are recommended for the treatment of MBT-induced multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB, respectively.

Stages and regimens to treat tuberculosis: Chemotherapy of tuberculosis in children is carried out in 2 stages (intensive treatment and continuation of treatment) and includes 5 regimens. Each regimen assumes a certain combination of anti-TB drugs, indicating the duration and frequency of their administration. The final chemotherapy regimen is chosen only according to the results of determining the drug sensitivity. To improve the TB epidemic among children, it is important to improve the regimens for the use of anti-TB drugs. The effectiveness of anti-tuberculosis pharmacotherapy is largely determined by the MBT sensitivity and the rational choice of the chemotherapy regimen. The wrong choice of a chemotherapy regimen or its violation threatens to reduce the effectiveness of pharmacotherapy and expand the spectrum of resistance of the pathogen. The development of fixed-dose combination anti-TB drugs and special dosage forms for children will improve the quality of chemotherapy and adherence to treatment. Pharmacoeconomic studies are needed to increase the effectiveness of drug pharmacotherapy for tuberculosis infection in children and to optimize the costs of its implementation.

Influence of anti-tuberculosis drugs plus cycloserine on sputum negative conversion rate, adverse reactions and inflammatory factors in multi-drug resistant tuberculosis

OBJECTIVE

The aim of this investigation was to determine the influence of anti-tuberculosis (anti-TB) drugs plus cycloserine (CS) on the sputum negative conversion rate, adverse reactions and inflammatory factors in the treatment of multidrug-resistant tuberculosis (MDR-TB).

METHODS

Seventy patients with MDR-TB who were referred to Nanjing Hospital Affiliated with Nanjing University of Traditional Chinese Medicine from April 2017 to April 2020 were assigned into the research group (RG; 38 cases) for anti-TB drugs plus CS, and the control group (CG; 32 cases) for conventional anti-TB drugs. The two groups were compared in their sputum negative conversion rate, incidence of adverse reactions, and foci absorption rate after 6, 12 and 24 months of treatment. The levels of inflammatory factors; tumor necrosis factor (TNF-α), interleukin-6 (IL-6) and interferon-γ (IFN-γ), both pre- and post-treatment were detected. Also, pre- and post-treatment, pulmonary function (PF) indexes (forced expiratory volume in 1 s/forced vital capacity, FEV1/FVC; FEV1; peak expiratory flow, PEF), and the scores of anxiety and depression (self-rating anxiety/depression scale, SAS/SDS), as well as Pittsburgh Sleep Quality Index (PSQI) were compared.

RESULTS

After 6, 12 and 24 months of treatment, the sputum negative conversion rate and foci absorption rate were higher in the RG than in the CG (both P<0.05). The RG presented with fewer adverse reactions, lower TNF-α, IL-6 and IFN-γ levels, higher FEV1, FEV1/FVC and PEF, and lower SAS, SDS and PSQI scores than the CG, post treatment (all P<0.05).

CONCLUSIONS

While helping to raise the sputum negative conversion rate, improve prognosis, and reduce adverse reactions, anti-TB drugs plus CS can also inhibit the release of inflammatory factors, improve PF and alleviate negative emotion and sleep disorders.