Global estimates and determinants of antituberculosis drug pharmacokinetics in children and adolescents: a systematic review and individual patient data meta-analysis.

BACKGROUND: Suboptimal exposure to antituberculosis (anti-TB) drugs has been associated with unfavourable treatment outcomes. We aimed to investigate estimates and determinants of first-line anti-TB drug pharmacokinetics in children and adolescents at a global level. METHODS: We systematically searched MEDLINE, Embase and Web of Science (1990-2021) for pharmacokinetic studies of first-line anti-TB drugs in children and adolescents. Individual patient data were obtained from authors of eligible studies. Summary estimates of total/extrapolated area under the plasma concentration-time curve from 0 to 24 h post-dose (AUC0-24) and peak plasma concentration (C max) were assessed with random-effects models, normalised with current World Health Organization-recommended paediatric doses. Determinants of AUC0-24 and C max were assessed with linear mixed-effects models. RESULTS: Of 55 eligible studies, individual patient data were available for 39 (71%), including 1628 participants from 12 countries. Geometric means of steady-state AUC0-24 were summarised for isoniazid (18.7 (95% CI 15.5-22.6) h·mg·L-1), rifampicin (34.4 (95% CI 29.4-40.3) h·mg·L-1), pyrazinamide (375.0 (95% CI 339.9-413.7) h·mg·L-1) and ethambutol (8.0 (95% CI 6.4-10.0) h·mg·L-1). Our multivariate models indicated that younger age (especially <2 years) and HIV-positive status were associated with lower AUC0-24 for all first-line anti-TB drugs, while severe malnutrition was associated with lower AUC0-24 for isoniazid and pyrazinamide. N-acetyltransferase 2 rapid acetylators had lower isoniazid AUC0-24 and slow acetylators had higher isoniazid AUC0-24 than intermediate acetylators. Determinants of C max were generally similar to those for AUC0-24. CONCLUSIONS: This study provides the most comprehensive estimates of plasma exposures to first-line anti-TB drugs in children and adolescents. Key determinants of drug exposures were identified. These may be relevant for population-specific dose adjustment or individualised therapeutic drug monitoring.

New and Repurposed Drugs for the Treatment of Active Tuberculosis: An Update for Clinicians.

Although tuberculosis (TB) is preventable and curable, the lengthy treatment (generally 6 months), poor patient adherence, high inter-individual variability in pharmacokinetics (PK), emergence of drug resistance, presence of comorbidities, and adverse drug reactions complicate TB therapy and drive the need for new drugs and/or regimens. Hence, new compounds are being developed, available drugs are repurposed, and the dosing of existing drugs is optimized, resulting in the largest drug development portfolio in TB history. This review highlights a selection of clinically available drug candidates that could be part of future TB regimens, including bedaquiline, delamanid, pretomanid, linezolid, clofazimine, optimized (high dose) rifampicin, rifapentine, and para-aminosalicylic acid. The review covers drug development history, preclinical data, PK, and current clinical development.

Surveillance of adverse events in the treatment of drug-resistant tuberculosis: first global report.

The World Health Organization (WHO) recommends that countries implement pharmacovigilance and collect information on active drug safety monitoring (aDSM) and management of adverse events.The aim of this prospective study was to evaluate the frequency and severity of adverse events to anti-tuberculosis (TB) drugs in a cohort of consecutive TB patients treated with new (i.e. bedaquiline, delamanid) and repurposed (i.e. clofazimine, linezolid) drugs, based on the WHO aDSM project. Adverse events were collected prospectively after attribution to a specific drug together with demographic, bacteriological, radiological and clinical information at diagnosis and during therapy. This interim analysis included patients who completed or were still on treatment at time of data collection.Globally, 45 centres from 26 countries/regions reported 658 patients (68.7% male, 4.4% HIV co-infected) treated as follows: 87.7% with bedaquiline, 18.4% with delamanid (6.1% with both), 81.5% with linezolid and 32.4% with clofazimine. Overall, 504 adverse event episodes were reported: 447 (88.7%) were classified as minor (grade 1-2) and 57 (11.3%) as serious (grade 3-5). The majority of the 57 serious adverse events reported by 55 patients (51 out of 57, 89.5%) ultimately resolved. Among patients reporting serious adverse events, some drugs held responsible were discontinued: bedaquiline in 0.35% (two out of 577), delamanid in 0.8% (one out of 121), linezolid in 1.9% (10 out of 536) and clofazimine in 1.4% (three out of 213) of patients. Serious adverse events were reported in 6.9% (nine out of 131) of patients treated with amikacin, 0.4% (one out of 221) with ethionamide/prothionamide, 2.8% (15 out of 536) with linezolid and 1.8% (eight out of 498) with cycloserine/terizidone.The aDSM study provided valuable information, but implementation needs scaling-up to support patient-centred care.

A bedaquiline/clofazimine combination regimen might add activity to the treatment of clinically relevant non-tuberculous mycobacteria.

BACKGROUND: Non-tuberculous mycobacteria (NTM) infections are hard to treat. New antimicrobial drugs and smarter combination regimens are needed. OBJECTIVES: Our aim was to determine the in vitro activity of bedaquiline against NTM and assess its synergy with established antimycobacterials. METHODS: We determined MICs of bedaquiline for clinically relevant NTM species and Mycobacterium tuberculosis by broth microdilution for 30 isolates. Synergy testing was performed using the chequerboard method for 22 reference strains and clinical isolates of Mycobacterium abscessus (MAB) and Mycobacterium avium complex (MAC). Time-kill kinetics (TK) assays with resistance monitoring of bedaquiline alone and combined with clofazimine were performed for MAB CIP 104536 and M. avium ATCC 700898; bedaquiline/clarithromycin combinations were evaluated against M. avium ATCC 700898. Interactions were assessed for TK experiments based on Bliss independence. RESULTS: Bedaquiline had modest activity against tested NTM, with MICs between <0.007 and 1 mg/L. Bedaquiline showed no interaction with tested drugs against MAB or MAC. Lowest mean fractional inhibitory concentration index (FICI) values were 0.79 with clofazimine for MAB and 0.97 with clofazimine and 0.82 with clarithromycin for MAC. In TK assays, bedaquiline showed a bacteriostatic effect. Clofazimine extended the bacteriostatic activity of bedaquiline against MAB and yielded a slight bactericidal effect against M. avium. The bedaquiline/clofazimine combination slowed emergence of bedaquiline resistance for M. avium but promoted it for MAB. Relative to Bliss independence, bedaquiline/clofazimine showed synergistic interaction over time for MAB and no interaction for M. avium and bedaquiline/clarithromycin showed antagonistic interaction for M. avium. CONCLUSIONS: Following these in vitro data, a bedaquiline/clofazimine combination might add activity to MAB and MAC treatment. The bedaquiline/clarithromycin combination might have lower activity compared with bedaquiline alone for MAC treatment.

Quality Assessment of Dried Blood Spots from Patients With Tuberculosis from 4 Countries.

BACKGROUND: Dried blood spot (DBS) sampling is a blood collection tool that uses a finger prick to obtain a blood drop on a DBS card. It can be used for therapeutic drug monitoring, a method that uses blood drug concentrations to optimize individual treatment. DBS sampling is believed to be a simpler way of blood collection compared with venous sampling. The aim of this study was to evaluate the quality of DBSs from patients with tuberculosis all around the world based on quality indicators in a structured assessment procedure. METHODS: Total 464 DBS cards were obtained from 4 countries: Bangladesh, Belarus, Indonesia, and Paraguay. The quality of the DBS cards was assessed using a checklist consisting of 19 questions divided into 4 categories: the integrity of the DBS materials, appropriate drying time, blood volume, and blood spot collection. RESULTS: After examination, 859 of 1856 (46%) blood spots did not comply with present quality criteria. In 625 cases (34%), this was due to incorrect blood spot collection. The DBS cards from Bangladesh, Indonesia, and Paraguay seemed to be affected by air humidity, causing the blood spots not to dry appropriately. CONCLUSIONS: New tools to help obtain blood spots of sufficient quality are necessary and environmental specific recommendations to determine plasma concentration correctly. In addition, 3% of the DBS cards were rejected because the integrity of the materials suggesting that the quality of plastic ziplock bags currently used to protect the DBS cards against contamination and humidity may not be sufficient.

Clinical Management of Multidrug-Resistant Tuberculosis in 16 European Countries.

RATIONALE: Multidrug-resistant tuberculosis (MDR-TB) is a major burden to public health in Europe. Reported treatment success rates are around 50% or less, and cure rates are even lower. OBJECTIVES: To document the management and treatment outcome in patients with MDR-TB in Europe. METHODS: We performed a prospective cohort study, analyzing management and treatment outcomes stratified by incidence of patients with MDR-TB in Europe. Treatment outcomes were compared by World Health Organization and alternative simplified definitions by the Tuberculosis Network European Trialsgroup (TBNET). MEASUREMENTS AND MAIN RESULTS: A total of 380 patients with MDR-TB were recruited and followed up between 2010 and 2014 in 16 European countries. Patients in high-incidence countries compared with low-incidence countries were treated more frequently with standardized regimen (83.2% vs. 9.9%), had delayed treatment initiation (median, 111 vs. 28 d), developed more additional drug resistance (23% vs. 5.8%), and had increased mortality (9.4% vs. 1.9%). Only 20.1% of patients using pyrazinamide had proven susceptibility to the drug. Applying World Health Organization outcome definitions, frequency of cure (38.7% vs. 9.7%) was higher in high-incidence countries. Simplified outcome definitions that include 1 year of follow-up after the end of treatment showed similar frequency of relapse-free cure in low- (58.3%), intermediate- (55.8%), and high-incidence (57.1%) countries, but highest frequency of failure in high-incidence countries (24.1% vs. 14.6%). CONCLUSIONS: Conventional standard MDR-TB treatment regimens resulted in a higher frequency of failure compared with individualized treatments. Overall, cure from MDR-TB is substantially more frequent than previously anticipated, and poorly reflected by World Health Organization outcome definitions.

Minocycline Has No Clear Role in the Treatment of Mycobacterium abscessus Disease.

Mycobacterium abscessus causes a difficult-to-treat pulmonary disease (MAb-PD). After initial intravenous treatment, minocycline is recommended in the oral continuation phase of treatment. We determined the MICs, synergy, and time-kill kinetics of minocycline against M. abscessus With MICs of 8 to 512 mg/liter, rapid emergence of tolerance in time-kill assays, and no synergy with other drugs used to treat MAb-PD, minocycline appears ineffective against M. abscessus These in vitro data question its role as a MAb-PD treatment modality.

A dose-ranging trial to optimize the dose of rifampin in the treatment of tuberculosis.

RATIONALE: Rifampin at a dose of 10 mg/kg was introduced in 1971 based on pharmacokinetic, toxicity, and cost considerations. Available data in mice and humans showed that an increase in dose may shorten the duration of tuberculosis treatment. OBJECTIVES: To evaluate the safety and tolerability, the pharmacokinetics, and the extended early bactericidal activity of increasing doses of rifampin. METHODS: Patients with drug-susceptible tuberculosis were enrolled into a control group of eight patients receiving the standard dose of 10 mg/kg rifampin, followed by consecutive experimental groups with 15 patients each receiving rifampin 20, 25, 30, and 35 mg/kg, respectively, for 14 days. In all patients isoniazid, pyrazinamide, and ethambutol were added in standard doses for the second 7 days of treatment. Safety, pharmacokinetics of rifampin, and fall in bacterial load were assessed. MEASUREMENTS AND MAIN RESULTS: Grade 1 and 2 adverse events were equally distributed between the five dose groups; there were five grade 3 events of which one was a possibly related hepatotoxicity. Areas under the time-concentration curves and peak serum concentrations of rifampin showed a more than proportional increase with dose. The daily fall in bacterial load over 14 days was 0.176, 0.168, 0.167, 0.265, and 0.261 log10 colony-forming units/ml sputum in the 10, 20, 25, 30, and 35 mg/kg groups, respectively. CONCLUSIONS: Two weeks of rifampin up to 35 mg/kg was safe and well tolerated. There was a nonlinear increase in exposure to rifampin without an apparent ceiling effect and a greater estimated fall in bacterial load in the higher dosing groups. Clinical trial registered with www.clinicaltrials.gov (NCT 01392911).

Multidrug-resistant tuberculosis in Europe, 2010-2011.

Drug-resistant Mycobacterium tuberculosis is challenging elimination of tuberculosis (TB). We evaluated risk factors for TB and levels of second-line drug resistance in M. tuberculosis in patients in Europe with multidrug-resistant (MDR) TB. A total of 380 patients with MDR TB and 376 patients with non-MDR TB were enrolled at 23 centers in 16 countries in Europe during 2010-2011. A total of 52.4% of MDR TB patients had never been treated for TB, which suggests primary transmission of MDR M. tuberculosis. At initiation of treatment for MDR TB, 59.7% of M. tuberculosis strains tested were resistant to pyrazinamide, 51.1% were resistant to ≥1 second-line drug, 26.6% were resistant to second-line injectable drugs, 17.6% were resistant to fluoroquinolones, and 6.8% were extensively drug resistant. Previous treatment for TB was the strongest risk factor for MDR TB. High levels of primary transmission and advanced resistance to second-line drugs characterize MDR TB cases in Europe.

Elderly patients with tuberculosis in a low-incidence country - Clinical characteristics, inflammation and outcome.

BACKGROUND: Susceptibility to respiratory infections increases with age. Diagnosing and treating tuberculosis in the elderly comes with the challenges of fewer specific symptoms and possibly more side effects of treatment. Much is unknown when it comes to tuberculosis in the elderly, especially in relation to inflammation, which may impact mortality. We, therefore, investigated a clinical cohort of elderly tuberculosis patients. METHODS: Patients aged ≥65 years, admitted to our tuberculosis reference center between 2005 and 2021, were retrospectively included in our cohort. Sociodemographic data, clinical characteristics, laboratory results, including inflammatory markers at baseline (monocyte, neutrophil, lymphocyte count, and CRP levels), and treatment outcomes were collected. They were compared to the National Dutch TB Registry and analyzed using descriptive statistics. Survival analysis was performed using univariate Cox regression analysis and a log-rank test. Results were visualized in Kaplan-Meier curves. RESULTS: 104 elderly tuberculosis patients, mostly European, with a mean age of 75 years, were included. None were HIV-infected. Miliary tuberculosis cases were overrepresented (14 %) compared to the National Dutch TB Registry (5 % in elderly, 2 % adults). Fever occurred in 77 % (57/74), and the duration of fever decreased with age. Innate immune markers, including monocyte/lymphocyte-ratio, moderately correlated with CRP. Overall mortality was 15 %, and highest (33 %) in patients with CRP levels >100 mg/mL. CONCLUSION: In elderly tuberculosis patients in a low-incidence setting, mortality rates are higher in comparison to younger patients. The overrepresentation of miliary tuberculosis may suggest waning immunity, with a subset of patients exhibiting strong inflammation associated with increased mortality.

The accuracy of an electronic nose to diagnose tuberculosis in patients referred to an expert centre.

INTRODUCTION: An electronic nose (eNose) device has shown a high specificity and sensitivity to diagnose or rule out tuberculosis (TB) in the past. The aim of this study was to evaluate its performance in patients referred to INERAM. METHODS: Patients aged ≥15 years were included. A history, physical examination, chest radiography (CRX) and microbiological evaluation of a sputum sample were performed in all participants, as well as a 5-minute breath test with the eNose. TB diagnosis was preferably established by the gold standard and compared to the eNose predictions. Univariate and multivariate logistic regression analyses were performed to assess potential risk factors for erroneous classification results by the eNose. RESULTS: 107 participants with signs and symptoms of TB were enrolled of which 91 (85.0%) were diagnosed with TB. The blind eNose predictions resulted in an accuracy of 50%; a sensitivity of 52.3% (CI 95%: 39.6-64.7%) and a specificity of 36.4% (CI 95%: 12.4-68.4%). Risk factors for erroneous classifications by the eNose were older age (multivariate analysis: OR 1.55, 95% CI 1.10-2.18, p = 0.012) and antibiotic use (multivariate analysis: OR 3.19, 95% CI 1.06-9.66, p = 0.040). CONCLUSION: In this study, the accuracy of the eNose to diagnose TB in a tertiary referral hospital was only 50%. The use of antibiotics and older age represent important factors negatively influencing the diagnostic accuracy of the eNose. Therefore, its use should probably be restricted to screening in high-risk communities in less complex healthcare settings.

Clofazimine Is a Safe and Effective Alternative for Rifampicin in Mycobacterium avium Complex Pulmonary Disease Treatment: Outcomes of a Randomized Trial.

BACKGROUND: Results of retrospective studies have suggested clofazimine as an alternative for rifampicin in the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD). RESEARCH QUESTION: Is a treatment regimen consisting of clofazimine-ethambutol-macrolide noninferior to the standard treatment regimen (rifampicin-ethambutol-macrolide) in the treatment of MAC-PD? STUDY DESIGN AND METHODS: In this single-center, nonblinded clinical trial, adult patients with MAC-PD were randomly assigned in a 1:1 ratio to receive rifampicin or clofazimine as adjuncts to an ethambutol-macrolide regimen. The primary outcome was sputum culture conversion following 6 months of treatment. RESULTS: Forty patients were assigned to receive either rifampicin (n = 19) or clofazimine (n = 21) in addition to ethambutol and a macrolide. Following 6 months of treatment, both arms showed similar percentages of sputum culture conversion based on an intention-to-treat analysis: 58% (11 of 19) for rifampicin and 62% (13 of 21) for clofazimine. Study discontinuation, mainly due to adverse events, was equal in both arms (26% vs 33%). Based on an on-treatment analysis, sputum culture conversion following 6 months of treatment was 79% in both groups. In the clofazimine arm, diarrhea was more prevalent (76% vs 37%; P = .012), while arthralgia was more frequent in the rifampicin arm (37% vs 5%; P = .011). No difference in the frequency of QTc prolongation was seen between groups. INTERPRETATION: A clofazimine-ethambutol-macrolide regimen showed similar results to the standard rifampicin-ethambutol-macrolide regimen and should be considered in the treatment of MAC-PD. The frequency of adverse events was similar in both arms, but their nature was different. Individual patient characteristics and possible drug-drug interactions should be taken into consideration when choosing an antibiotic regimen for MAC-PD. CLINICAL TRIAL REGISTRATION: EudraCT; No.: 2015-003786-28; URL: https://eudract.ema.europa.eu.

Dried Blood Spot Sampling to Assess Rifampicin Exposure and Treatment Outcomes among Native and Non-Native Tuberculosis Patients in Paraguay: An Exploratory Study.

The aim of this study was to evaluate the difference in drug exposure of rifampicin in native versus non-native Paraguayan populations using dried blood spots (DBS) samples collected utilizing a limited sampling strategy. This was a prospective pharmacokinetic study that enrolled hospitalized tuberculosis (TB) patients from both native and non-native populations receiving oral rifampicin 10 mg/kg once-daily dosing. Steady-state DBS samples were collected at 2, 4, and 6 h after intake of rifampicin. The area under the time concentration curve 0-24 h (AUC0-24) was calculated using a Bayesian population PK model. Rifampicin AUC0-24 < 38.7 mg*h/L was considered as low. The probability of target attainment (PTA) was calculated using AUC0-24/MIC > 271 as a target and estimated MIC values of 0.125 and 0.25 mg/L. In total, 50 patients were included. Native patients (n = 30) showed comparable drug exposure to the non-natives (n = 20), median AUC0-24 24.7 (17.1-29.5 IQR) and 21.6 (15.0-35.4 IQR) mg*h/L (p = 0.66), respectively. Among total patients, only 16% (n = 8) had a rifampicin AUC0-24 > 38.7 mg*h/L. Furthermore, PTA analysis showed that only 12 (24%) of the patients met a target AUC0-24 /MIC ≥ 271, assuming an MIC of 0.125 mg/L, which plummeted to 0% at a wild-type MIC of 0.25 mg/L. We successfully used DBS and limited sampling for the AUC0-24 estimation of rifampicin. Currently, our group, the EUSAT-RCS consortium, is preparing a prospective multinational, multicenter phase IIb clinical trial evaluating the safety and efficacy of high-dose rifampicin (35 mg/kg) in adult subjects using the DBS technique for AUC0-24 estimation.