Moxifloxacin-induced QT interval prolongation and torsades de pointes: a narrative review

The safety profile of fluoroquinolones

While they are very useful agents, fluoroquinolones (FQs) are associated with a number of serious adverse effects (AEs). The objective of this paper is to describe the characteristics of frequent serious AEs related to FQs along with their risk factors, their safety in specific populations, and the main drug-drug interactions that may occur. Serious AEs commonly associated with FQs include tendon disorders (particularly tendinopathy and tendon rupture), CNS toxicity (seizure and encephalopathy), peripheral neuropathy (including small fiber neuropathy), cardiovascular toxicity (QT interval prolongation, dissection, and aneurysm rupture), disrupted glucose metabolism, phototoxicity, C. difficile infections, acute renal failure, and hepatic toxicity. Most of these AEs are common to all FQs, but some, such as acute kidney failure on crystallization with ciprofloxacin or norfloxacin, are more specific. Unlike the AEs associated with most other antibiotics, some of these AEs (e.g. tendinopathy or neuropathy) may occur after FQ discontinuation, and others may subsequently progress (e.g. FQ-associated disability). The risk of serious AE is heightened by factors having to do with patient age and comorbidities, the characteristics of the FQ treatment (dose and/or duration) and associated drug intake. To conclude, FQs appear to be associated with a higher risk of serious AEs than most of the other antibiotics available for the same indications, however some AEs can be avoided by bearing in mind the predisposing risk factors.

Which fluoroquinolone is safer when combined with bedaquiline for tuberculosis treatment: evidence from FDA Adverse Event Reporting System database from 2013 to 2024

OBJECTIVE

To investigate which fluoroquinolone is safer when combined with bedaquiline for tuberculosis treatment by using the FDA Adverse Event Reporting System (FAERS) database.

METHODS

We selected data from the first quarter (Q1) of 2013 to the second quarter (Q4) of 2024 from the FDA FAERS database for disproportionality analysis. Signal detection was conducted using the Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Empirical Bayesian Geometric Mean (EBGM).

RESULTS

This study analyzed 12, 303, 879 reports from the FAERS database, including 722 reports related to the combination of bedaquiline and levofloxacin (with 2,723 adverse events) and 573 reports related to the combination of bedaquiline and moxifloxacin (with 2,233 adverse events). For the bedaquiline-levofloxacin regimen, these reports were categorized into 100 preferred terms (PTs) and 24 System Organ Classification (SOCs). The three most common SOCs were hepatobiliary disorders (n = 128, ROR 5.79, PRR 5.56, IC 2.48, EBGM 5.56), blood and lymphatic system disorders (n = 217, ROR 5.04, PRR 4.72, IC 2.24, EBGM 4.71), and metabolism and nutrition disorders (n = 185, ROR 3.44, PRR 3.27, IC 1.71, EBGM 3.27). In terms of PTs, the three strongest signals were portal fibrosis (ROR 330.64), hepatitis C RNA increased (ROR 301.24), and toxic optic neuropathy (ROR 238.11). Reports of prolonged QT interval on ECG (125 cases) and anemia (130 cases) were significantly more frequent than other PTs. For the bedaquiline-moxifloxacin regimen, these reports were categorized into 85 preferred terms (PTs) and 24 System Organ Classification (SOCs). The three most common SOCs were hepatobiliary disorders (n = 141, ROR 7.9, PRR 7.47, IC 2.9, EBGM 7.46), ear and labyrinth disorders (n = 40, ROR 4.03, PRR 3.97, IC 1.99, EBGM 3.97), and cardiac disorders (n = 141, ROR 3.08, PRR 2.95, IC 1.56, EBGM 2.95). The three strongest PT signals were chronic pyelonephritis (ROR 563.29), bronchopleural fistula (ROR 314.86), and toxic neuropathy (ROR 187.11). Prolonged QT interval on ECG (152 cases) remained the most frequently reported PT. In both treatment regimens, individuals under 45 years of age experienced a higher frequency and variety of AEs, indicating the need for enhanced monitoring. For those over 45, particular attention should be given to ECG changes, especially in men. Finally, some PTs with extremely high signal strength, such as chronic pyelonephritis (ROR 563.29), hepatitis C RNA increased (ROR 301.24), and bronchopleural fistula (ROR 301.24), may represent rare adverse events associated with the combination of bedaquiline-fluoroquinolone.

CONCLUSION

Our study suggests that the safety profile of bedaquiline combined with moxifloxacin does not appear superior to that of bedaquiline combined with levofloxacin in terms of cardiac, hepatic, and neurological effects. Therefore, in the BPaLM regimen, considering the substitution of moxifloxacin with levofloxacin may be worthwhile if their efficacy is proven to be similar. Increased monitoring may be required for individuals under 45 years of age and male MDR-TB patients.

Clinical Characteristics of Moxifloxacin-Related Arrhythmias and Development of a Predictive Nomogram: A Case Control Study

This study aimed to analyze the incidence, clinical characteristics, and risk factors of moxifloxacin-related arrhythmias and electrocardiographic alterations in hospitalized patients using real-world data. Concurrently, a nomogram was established and validated to provide a practical tool for prediction. Retrospective automatic monitoring of inpatients using moxifloxacin was performed in a Chinese hospital from January 1, 2017, to December 31, 2021, to obtain the incidence of drug-induced arrhythmias and electrocardiographic alterations. Propensity score matching was conducted to balance confounders and analyze clinical characteristics. Based on the risk and protective factors identified through logistic regression analysis, a prediction nomogram was developed and internally validated using the Bootstrap method. Arrhythmias and electrocardiographic alterations occurred in 265 of 21,711 cases taking moxifloxacin, with an incidence of 1.2%. Independent risk factors included medication duration (odds ratio [OR] 1.211, 95% confidence interval [CI] 1.156-1.270), concomitant use of meropenem (OR 4.977, 95% CI 2.568-9.644), aspartate aminotransferase >40 U/L (OR 3.728, 95% CI 1.800-7.721), glucose >6.1 mmol/L (OR 2.377, 95% CI 1.531-3.690), and abnormally elevated level of amino-terminal brain natriuretic peptide precursor (OR 2.908, 95% CI 1.640-5.156). Concomitant use of cardioprotective drugs (OR 0.430, 95% CI 0.220-0.841) was a protective factor. The nomogram showed good differentiation and calibration, with enhanced clinical benefit. The incidence of moxifloxacin-related arrhythmias and electrocardiographic alterations is in the range of common. The nomogram proves valuable in predicting the risk in the moxifloxacin-administered population, offering significant clinical applications.

Clofazimine and QT prolongation in the treatment of rifampicin-resistant tuberculosis: Findings of aDSM in Taiwan

BACKGROUND

Bedaquiline, delamanid and fluoroquinolones are associated with increased QTcF. Whether clofazimine is associated with QTcF prolongation is less clear.

METHODS

All patients with rifampicin-resistant TB enrolled between May 2017 and Dec 2019 were included. ECGs were performed at baseline, month 1, month 3 and month 6 for patients treated with conventional regimens, and at additional timepoint for patients treated with bedaquiline, delamanid and short regimen. We estimated the maximum increase of QTcF and constructed cox proportional hazards models to assess factors associated with QTcF≥501ms.

RESULTS

Among 321 patients, 59 (18.4%) patients had QTcF≥501ms during a mean follow-up of 242 days (median 189, range 4-1091). The median maximum increase of QTcF was 43.4 ms (IQR 31.3-65.9) in patients treated with clofazimine. Treatment with clofazimine was significantly associated with QTcF≥501ms as compared to without clofazimine (adjusted hazards ratio (adjHR) 4.35, 95% confidence interval (CI) 2.01-9.44). Among patients not treated with bedaquiline and delamanid, those treated with clofazimine and a fluoroquinolone (adjHR 3.43, 95% CI 1.61-7.34) and those treated with clofazimine and high dose moxifloxacin (adjHR 6.54, 95% CI 2.43-17.60) had a significantly higher risk of QTcF≥501ms as compared to those treated with a fluoroquinolone without other QTcF prolonging agents. Four (1.6%) patients had documented ventricular tachycardia, in which one was Torsade de pointes. One patient was found to have sudden death during hospitalization.

CONCLUSIONS

Clofazimine was significantly associated with an increased risk of QTcF prolongation. QTcF≥501ms was potentially associated with fatal event and needed to be managed cautiously.

Validation of a Handheld 6-Lead Device for QT Interval Monitoring in Resource-Limited Settings

Importance

Rifampin-resistant tuberculosis treatment regimens require electrocardiographic (ECG) monitoring due to the use of multiple QTc-prolonging agents. Formal 12-lead ECG devices represent a significant burden in resource-constrained clinics worldwide and a potential barrier to treatment scale-up in some settings.

Objective

To evaluate the diagnostic accuracy of a handheld 6-lead ECG device within resource-constrained clinics.

Design, Setting, and Participants

This diagnostic study was performed within a multicenter, pragmatic (broad eligibility criteria with no exclusions for randomized participants), phase 3 rifampin-resistant tuberculosis treatment trial (BEAT Tuberculosis [Building Evidence for Advancing New Treatment for Tuberculosis]) in South Africa. A total of 192 consecutive trial participants were assessed, and 191 were recruited for this substudy between January 21, 2021, and March 27, 2023. A low proportion (3 of 432 [0.7%]) of all screened trial participants were excluded due to a QTc interval greater than 450 milliseconds. Triplicate reference standard 12-lead ECG results were human calibrated with readers blinded to 6-lead ECG results.

Main Outcomes and Measures

Diagnostic accuracy, repeatability, and feasibility of a 6-lead ECG device.

Results

A total of 191 participants (median age, 36 years [IQR, 28-45 years]; 81 female participants [42.4%]; 91 participants [47.6%] living with HIV) with a median of 4 clinic visits (IQR, 3-4 visits) contributed 2070 and 2015 12-lead and 6-lead ECG assessments, respectively. Across 170 participants attending 489 total clinic visits where valid triplicate QTc measurements were available for both devices, the mean 12-lead QTc measurement was 418 milliseconds (range, 321-519 milliseconds), and the mean 6-lead QTc measurement was 422 milliseconds (range, 288-574 milliseconds; proportion of variation explained, R2 = 0.4; P < .001). At a QTc interval threshold of 500 milliseconds, the 6-lead ECG device had a negative predictive value of 99.8% (95% CI, 98.8%-99.9%) and a positive predictive value of 16.7% (95% CI, 0.4%-64.1%). The normal expected range of within-individual variability of the 6-lead ECG device was high (±50.2 milliseconds [coefficient of variation, 6.0%]) relative to the 12-lead ECG device (±22.0 milliseconds [coefficient of variation, 2.7%]). The mean (SD) increase in the 12-lead QTc measurement during treatment was 10.1 (25.8) milliseconds, with 0.8% of clinic visits (4 of 489) having a QTc interval of 500 milliseconds or more.

Conclusions and Relevance

This study suggests that simplified, handheld 6-lead ECG devices are effective triage tests that could reduce the need to perform 12-lead ECG monitoring in resource-constrained settings.

A real-world pharmacovigilance study of drug-induced QT interval prolongation: analysis of spontaneous reports submitted to FAERS

Purpose

To identify the most commonly reported drugs associated with QT interval prolongation in the FDA Adverse Event Reporting System (FAERS) and evaluate their risk for QT interval prolongation.

Methods

We employed the preferred term (PT) "electrocardiogram QT prolonged" from the Medical Dictionary for Regulatory Activities (MedDRA) 26.0 to identify adverse drug events (ADEs) of QT interval prolongation in the FAERS database from the period 2004-2022. Reporting odds ratio (ROR) was performed to quantify the signals of ADEs.

Results

We listed the top 40 drugs that caused QT interval prolongation. Among them, the 3 drugs with the highest number of cases were quetiapine (1,151 cases, ROR = 7.62), olanzapine (754 cases, ROR = 7.92), and citalopram (720 cases, ROR = 13.63). The two most frequently reported first-level Anatomical Therapeutic Chemical (ATC) groups were the drugs for the nervous system (n = 19, 47.50%) and antiinfectives for systemic use (n = 7, 17.50%). Patients with missing gender (n = 3,482, 23.68%) aside, there were more females (7,536, 51.24%) than males (5,158, 35.07%) were involved. 3,720 patients (25.29%) suffered serious clinical outcomes resulting in deaths or life-threatening conditions. Overall, most drugs that caused QT interval prolongation had early failure types according to the assessment of the Weibull's shape parameter (WSP) analysis.

Conclusions

Our study offered a list of drugs that frequently caused QT interval prolongation based on the FAERS system, along with a description of some risk profiles for QT interval prolongation brought on by these drugs. When prescribing these drugs in clinical practice, we should closely monitor the occurrence of ADE for QT interval prolongation.

Whole-Cell Configuration of the Patch-Clamp Technique in the hERG Channel Assay

In vitro electrophysiological safety studies have become an integral part of the drug development process because, in many instances, compound-induced QT prolongation has been associated with a direct block of human ether-a-go-go-related gene (hERG) potassium channels or their native current, the rapidly activating delayed rectifier potassium current (IKr ). Therefore, according to the ICH S7B guideline, the in vitro hERG channel patch-clamp assay is commonly used as an early screen to predict the ability of a compound to prolong the QT interval prior to first-in-human testing. The protocols described in this article are designed to assess the effects of acute or long-term exposure to new chemical entities on the amplitude of IKr in HEK293 cells stably transfected with the hERG channel (whole-cell configuration of the patch-clamp technique). Examples of results obtained with moxifloxacin, terfenadine, arsenic, pentamidine, erythromycin, and sotalol are provided for illustrative purposes. © 2024 Wiley Periodicals LLC. Basic Protocol: Measurement of the acute effects of test items in the hERG channel test Alternate Protocol: Measurement of the long-term effects of test items in the hERG channel test.

Update on drug-resistant pulmonary tuberculosis treatment in hemodialysis patients

World Health Organization (WHO) issued the latest recommendations regarding the management of drug-resistant Tuberculosis (TB) in 2022, allowing the replacement of ethambutol (6 months) with linezolid (2 months). This recommendation also introduced a new regimen, namely bedaquiline, pretomanide, linezolid, moxifloxacin (BPaLM) for fluoroquinolone-sensitive patients and bedaquiline, pretomanide, linezolid, (BPaL) for patients insensitive to fluoroquinolone (6-9 months). The latest TB regimen introduced by WHO provides a shorter-course treatment, however not much has been discussed about the impact of this new regimen on chronic kidney disease (CKD) patients, particularly on hemodialysis (HD). The condition of CKD can interfere with the pharmacokinetics of TB medication, thus could reduce effectiveness and increase toxicity. The drugs used on this new regimen are mostly safe for renal impairment patients due to the dominant metabolism in the liver. Particular precaution is given to the administration of linezolid due to increased hematology side effects and bedaquiline with the side effect of QTC interval lengthening and increased risk of arrhythmias. Although this regimen research has not been in many studies in renal failure patients, no significant side effects nor kidney damage evidence was found. This remains to be proven by more research on the patient population with renal failure.

The Effects of Moxifloxacin and Gemifloxacin on the ECG Morphology in Healthy Volunteers: A Phase 1 Randomized Clinical Trial

Moxifloxacin and gemifloxacin are the two newer broad-spectrum 8-methoxy-quinolone derivatives that are used to treat various bacterial infections in cardiac patients. In this research study, we assessed the impact of moxifloxacin and gemifloxacin on the QT intervals of electrocardiograms in normal adult doses and draw a comparison, in a controlled environment, on healthy volunteers. Additionally, the effect of both test drugs on the QRS complex was checked. Sixty healthy volunteers were randomly assigned to two groups via R-software, and each respectively received moxifloxacin and gemifloxacin for five days. The research ethics committee approved the research, and it was registered for clinical trial under NCT04692623. The participants' electrocardiograms were obtained before the start of the dose (baseline) and on the fifth day. Significant prolongation of QT interval was noted in moxifloxacin (p < 0.0001) as compared to gemifloxacin treated groups. There were no cases of QTc prolongation over the usual limits (450-470 ms) in the gemifloxacin-treated group, however, QTc prolongations at the rate of 30 and 60 ms from the baseline were noted, interpreted as per the EMEA guidelines. These findings indicate that moxifloxacin caused significant (p < 0.0001) QT interval prolongation (QTIP) as compared to gemifloxacin. In contrast to the previously reported literature, the prominent effect of moxifloxacin on the widening of the QRS-complex was noted with no such effect on QRS-widening in the gemifloxacin-treated group. It is concluded that both drugs have the potential for considerable QT interval prolongation (QTIP) effects, which is one of the risk factors for developing torsade de pointes (TdPs) in cardiac patients. Thus, clinicians should exercise caution when prescribing moxifloxacin and gemifloxacin to cardiac patients and should consider alternate treatment options.

Overview of Side-Effects of Antibacterial Fluoroquinolones: New Drugs versus Old Drugs, a Step Forward in the Safety Profile?

Antibacterial fluoroquinolones (FQs) are frequently used in treating infections. However, the value of FQs is debatable due to their association with severe adverse effects (AEs). The Food and Drug Administration (FDA) issued safety warnings concerning their side-effects in 2008, followed by the European Medicine Agency (EMA) and regulatory authorities from other countries. Severe AEs associated with some FQs have been reported, leading to their withdrawal from the market. New systemic FQs have been recently approved. The FDA and EMA approved delafloxacin. Additionally, lascufloxacin, levonadifloxacin, nemonoxacin, sitafloxacin, and zabofloxacin were approved in their origin countries. The relevant AEs of FQs and their mechanisms of occurrence have been approached. New systemic FQs present potent antibacterial activity against many resistant bacteria (including resistance to FQs). Generally, in clinical studies, the new FQs were well-tolerated with mild or moderate AEs. All the new FQs approved in the origin countries require more clinical studies to meet FDA or EMA requirements. Post-marketing surveillance will confirm or infirm the known safety profile of these new antibacterial drugs. The main AEs of the FQs class were addressed, highlighting the existing data for the recently approved ones. In addition, the general management of AEs when they occur and the rational use and caution of modern FQs were outlined.

Outcomes of Beta-Lactam Allergic and Non-Beta-Lactam Allergic Patients with Intra-Abdominal Infection: A Case-Control Study

Background: In the case of intra-abdominal infections (IAI) in beta-lactam (BL) allergic patients, empiric antimicrobial therapy without BL is recommended; however, data regarding the outcome with alternative regimens are scarce. This study aimed to compare the outcomes of BL allergic (BLA) patients with IAI to those who were non-BLA (NBLA). Method: We conducted a case−control study in a French teaching hospital, between 1 January 2016 and 31 August 2021. BLA patients with IAI treated with fluoroquinolone or aztreonam and metronidazole were matched with controls treated with BL, on age, sex, disease severity, IAI localization, and healthcare-associated infection (HAI) status. We compared rates of therapeutic failures, adverse events, and HAI, and then assessed factors associated with therapeutic failure using a logistic regression model. Results: The therapeutic failure rate was 14% (p > 0.99) in both groups of 43 patients, and there was no significant difference in the adverse events rate (p > 0.99) and HAI rate (p = 0.154). Factors independently associated with therapeutic failure were higher BMI (OR 1.16; 95%CI [1.00−1.36]; p = 0.041), longer hospital length of stay (OR 1,20; 95%CI [1.08−1.41]; p = 0.006), and inadequate empiric antimicrobial therapy (OR 11.71; 95%CI [1.43−132.46]; p = 0.025). Conclusion: The outcomes of BLA patients with IAI treated without BL were the same as those for NBLA patients treated with BL.

Establishment and validation of a torsade de pointes prediction model based on human iPSC‑derived cardiomyocytes

Drug-induced cardiotoxicity is one of the main causes of drug failure, which leads to subsequent withdrawal from pharmaceutical development. Therefore, identifying the potential toxic candidate in the early stages of drug development is important. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a useful tool for assessing candidate compounds for arrhythmias. However, a suitable model using hiPSC-CMs to predict the risk of torsade de pointes (TdP) has not been fully established. The present study aimed to establish a predictive TdP model based on hiPSC-CMs. In the current study, 28 compounds recommended by the Comprehensive in vitro Proarrhythmia Assay (CiPA) were used as training set and models were established in different risk groups, high- and intermediate-risk versus low-risk groups. Subsequently, six endpoints of electrophysiological responses were used as potential model predictors. Accuracy, sensitivity and area under the curve (AUC) were used as evaluation indices of the models and seven compounds with known TdP risk were used to verify model differentiation and calibration. The results showed that among the seven models, the AUC of logistic regression and AdaBoost model was higher and had little difference in both training and test sets, which indicated that the discriminative ability and model stability was good and excellent, respectively. Therefore, these two models were taken as submodels, similar weight was configured and a new TdP risk prediction model was constructed using a soft voting strategy. The classification accuracy, sensitivity and AUC of the new model were 0.93, 0.95 and 0.92 on the training set, respectively and all 1.00 on the test set, which indicated good discrimination ability on both training and test sets. The risk threshold was defined as 0.50 and the consistency between the predicted and observed results were 92.8 and 100% on the training and test sets, respectively. Overall, the present study established a risk prediction model for TdP based on hiPSC-CMs which could be an effective predictive tool for compound-induced arrhythmias.

Model-based efficacy and toxicity comparisons of moxifloxacin for multi-drug-resistant tuberculosis

Background

Moxifloxacin (MOX) is used as a first-choice drug to treat multi-drug-resistant tuberculosis (MDR-TB), however, evidence-based dosing optimization should be strengthened by integrative analysis. The primary goal of this study was to evaluate MOX efficacy and toxicity using integratvie model-based approaches in MDR-TB patients.

Methods

In total, 113 MDR-TB patients from five different clinical trials were analyzed for the development of a population pharmacokinetics (PK) model. A final population PK model was merged with a previously developed lung-lesion distribution and QT prolongation model. Monte Carlo simulation was used to calculate the probability target attainment (PTA) value based on concentration. An area under the concentration-time curve (AUC)-based target was identified as the minimum inhibitory concentration (MIC) of MOX isolated from MDR-TB patients.

Results

The presence of human immunodeficiency virus (HIV) increased clearance by 32.7% and decreased the AUC by 27.4%, compared with HIV-negative MDR-TB patients. A daily dose of 800 mg or a 400 mg twice daily dose of MOX is expected to be effective in MDR-TB patients with an MIC of ≤ 0.25 µg/mL, regardless of PK differences resulting from the presence of HIV. The effect of MOX in HIV-positive MDR-TB patients tended to be decreased dramatically from 0.5 µg/mL, in contrast to the findings in HIV-negative patients. A regimen of twice-daily doses of 400 mg should be considered safer than an 800 mg once-daily dosing regimen, because of the narrow fluctuation of concentrations.

Conclusions

Our results suggest that a 400 mg twice-daily dose of MOX is an optimal dosing regimen for MDR-TB patients because it provides superior efficacy and safety.

Evaluation of moxifloxacin in canine and non-human primate telemetry assays: Comparison of QTc interval prolongation by timepoint and concentration-QTc analysis

The in vivo correct QT (QTc) assay is used by the pharmaceutical industry to characterize the potential for delayed ventricular repolarization and is a core safety assay mentioned in International Conference on Harmonization (ICH) S7B guideline. The typical telemetry study involves a dose‐response analysis of QTc intervals over time using a crossover (CO) design. This method has proven utility but does not include direct integration of pharmacokinetic (PK) data. An alternative approach has been validated and is used routinely in the clinical setting that pairs pharmacodynamic (PD) responses with PK exposure (e.g., concentration‐QTc (C‐QTc) analysis. The goal of our paper was to compare the QTc sensitivity of two experimental approaches in the conscious dog and non‐human primate (NHP) QTc assays. For timepoint analysis, a conventional design using eight animals (8 × 4 CO) to detect moxifloxacin‐induced QTc prolongation was compared to a PK/PD design in a subset (N = 4) of the same animals. The findings demonstrate that both approaches are equally sensitive in detecting threshold QTc prolongation on the order of 10 ms. Both QTc models demonstrated linearity in the QTc prolongation response to moxifloxacin dose escalation (6 to 46 ms). Further, comparison with human QTc findings with moxifloxacin showed agreement and consistent translation across the three species: C‐QTc slope values were 0.7‐ (dog) and 1.2‐ (NHP) fold of the composite human value. In conclusion, our data show that dog and NHP QTc telemetry with an integrated PK arm (C‐QTc) has the potential to supplement clinical evaluation and improve integrated QTc risk assessment.

Association of H1-antihistamines with torsade de pointes: a pharmacovigilance study of the food and drug administration adverse event reporting system

Background: This study aimed to measure the association of various H1-antihistamines (H1A) with Torsade de Pointes (TdP), and present a comprehensive overview of H1A-induced TdP cases reported to the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: All H1A-induced TdP cases (n = 406) were retrieved from the FAERS database using the preferred term 'Torsade de Pointes' of MedDRA version-22 from 1990 to 2019. Four data-mining algorithms were used for disproportionality analysis: Reporting Odds Ratio (ROR); Proportional Reporting Ratio (PRR), Empirical Bayes Geometric Mean (EBGM), and Information Content (IC). H1A with >3 TdP cases were included. Results: A total of 12 signals (Astemizole, cetirizine, chlorpheniramine, clemastine, desloratadine, diphenhydramine, hydroxyzine, loratadine, meclizine, promethazine, terfenadine, and trimeprazine) were identified including six new signals (cetirizine, chlorpheniramine, clemastine, desloratadine, loratadine, and meclizine). The number of risk factors (p = 0.031) and concomitant QT-prolonging drugs (p = <0.001) were significantly lower among new signals vs old signals. Moreover, new signals were strongly associated with QT-prolongation, cardiac reactions, and electrolyte abnormalities as compared with old signals. Conclusions: Our study found the increased torsadogenic potential of new signals compared with previously known old signals, hence necessitating clinical studies to determine the actual torsadogenic potential of newly identified signals.

A case of torsades de pointes induced by the third-generation EGFR-TKI, osimertinib combined with moxifloxacin

Background

Torsade de pointes (TdP) is a malignant arrhythmia that can be induced by QT internal prolongation due to a variety of factors. Here we report an elderly patient with advanced non-small cell lung cancer (NSCLC) had sudden TdP during hospitalization, which was caused by multiple factors such as osimertinib, moxifloxacin and patient self-factors.

Case presentation

An 85-year-old man with advanced NSCLC with brain andbone metastasis was initially treated with gefitinib targeted therapy. After 4 months treatment, the patient developed drug resistance and a second genetic testing revealed that the T790M mutation was positive. And the patient was then changed to targeted therapy with osimertinib, followed by adverse reactions of varying severity such as diarrhea, electrolyte imbalance, decreased cardiac function, leukopenia, and prolonged QTc interval. Six months after the administration of osimertinib, the patient was admitted to the hospital, chest CT showed the lesion progressed again, and during which hospital-acquired infection occurred. After concomitant use of moxifloxacin, the patient had sudden TdP, and finally died of this cardiac event.

Conclusions

It is suggested that clinicians need to identify patients with high risk factors of TdP, and consider comprehensively in concomitant medication to avoid such events to the greatest extent.

V. Kumar A, Ramaswamy G, Htun T, Thanh Hoang Thi T, Hoai Nguyen G, Quelapio M, Gebhard A, Nguyen HB, Nguyen NV. High Levels of Treatment Success and Zero Relapse in Multidrug-Resistant Tuberculosis Patients Receiving a Levofloxacin-Based Shorter Treatment Regimen in Vietnam

Vietnam has been using a levofloxacin-based shorter treatment regimen (STR) for rifampicin resistant/multidrug-resistant tuberculosis (RR/MDR-TB) patients since 2016 on a pilot basis. This regimen lasts for 9–11 months and is provided to RR/MDR-TB patients without second-line drug resistance. We report the treatment outcomes and factors associated with unsuccessful outcomes. We conducted a cohort study involving secondary analysis of data extracted from electronic patient records maintained by the national TB program (NTP). Of the 302 patients enrolled from April 2016 to June 2018, 259 (85.8%) patients were successfully treated (246 cured and 13 ‘treatment completed’). Unsuccessful outcomes included: treatment failure (16, 5.3%), loss to follow-up (14, 4.6%) and death (13, 4.3%). HIV-positive TB patients, those aged ≥65 years and patients culture-positive at baseline had a higher risk of unsuccessful outcomes. In a sub-group of patients enrolled in 2016 (n = 99) and assessed at 12 months after treatment completion, no cases of relapse were identified. These findings vindicate the decision of the Vietnam NTP to use a levofloxacin-based STR in RR/MDR-TB patients without second-line drug resistance. This regimen may be considered for nationwide scale-up after a detailed assessment of adverse drug events.

Measurement and Management of QT Interval Prolongation for General Physicians

One of the more challenging aspects of ECG interpretation is measurement and interpretation of the QT interval. This interval represents the time taken for the ventricles to completely repolarise after activation. Abnormal prolongation of the QT interval can lead to torsades de pointes, a form of potentially life-threatening polymorphic ventricular tachycardia (VT). Detection of a prolonged QT interval is essential as this can be a reversible problem, particularly in the context of the use of a variety of commonly prescribed medications in the hospital setting. Automated ECG printouts cannot be relied upon to diagnose QT interval prolongation; thus, the onus is on the clinician to identify it. This is a difficult task, as the normal QT interval is typically measured relative to the heart rate. Therefore, the QT interval often requires "correction" for the current heart rate, in order to correctly stratify the risk of torsades de pointes. A wealth of correctional formulae have been derived, but none has proven superior. We present an approach to the ECG in this context, and a step-by-step guide to manually measuring and correcting the QT interval, and an approach to management in common hospital-based clinical scenarios.

A Computational Pipeline to Predict Cardiotoxicity: From the Atom to the Rhythm

RATIONALE

Drug-induced proarrhythmia is so tightly associated with prolongation of the QT interval that QT prolongation is an accepted surrogate marker for arrhythmia. But QT interval is too sensitive a marker and not selective, resulting in many useful drugs eliminated in drug discovery.

OBJECTIVE

To predict the impact of a drug from the drug chemistry on the cardiac rhythm.

METHODS AND RESULTS

In a new linkage, we connected atomistic scale information to protein, cell, and tissue scales by predicting drug-binding affinities and rates from simulation of ion channel and drug structure interactions and then used these values to model drug effects on the hERG channel. Model components were integrated into predictive models at the cell and tissue scales to expose fundamental arrhythmia vulnerability mechanisms and complex interactions underlying emergent behaviors. Human clinical data were used for model framework validation and showed excellent agreement, demonstrating feasibility of a new approach for cardiotoxicity prediction.

CONCLUSIONS

We present a multiscale model framework to predict electrotoxicity in the heart from the atom to the rhythm. Novel mechanistic insights emerged at all scales of the system, from the specific nature of proarrhythmic drug interaction with the hERG channel, to the fundamental cellular and tissue-level arrhythmia mechanisms. Applications of machine learning indicate necessary and sufficient parameters that predict arrhythmia vulnerability. We expect that the model framework may be expanded to make an impact in drug discovery, drug safety screening for a variety of compounds and targets, and in a variety of regulatory processes.

Fluoroquinolones for the treatment of latent Mycobacterium tuberculosis infection in liver transplantation

Solid organ transplantation (SOT) is the best treatment option for end-stage organ disease. Newer immunosuppressive agents have reduced the incidence of graft rejection but have increased the risk of infection, particularly due to the reactivation of latent infections due to opportunistic agents such as Mycobacterium tuberculosis. Active tuberculosis (TB) after SOT is a significant cause of morbidity and mortality. Most cases of posttransplant TB are secondary to reactivation of latent tuberculosis infection (LTBI) due to the effects of long-term immunosuppressive therapy. Risk minimization strategies have been developed to diagnose LTBI and initiate treatment prior to transplantation. Isoniazid with vitamin B6 supplementation is the treatment of choice. However, liver transplantation (LT) candidates and recipients have an increased risk of isoniazid-induced liver toxicity, leading to lower treatment completion rates than in other SOT populations. Fluoroquinolones (FQs) exhibit good in vitro antimycobacterial activity and a lower risk of drug-induced liver injury than isoniazid. In the present review, we highlight the disease burden posed by posttransplant TB and summarize the emerging clinical evidence supporting the use of FQs for the treatment of LTBI in LT recipients and candidates.

A Phase 1 Study of Intravenous Plazomicin in Healthy Adults to Assess Potential Effects on the QT/QTc Interval, Safety, and Pharmacokinetics

Plazomicin is an aminoglycoside with in vitro activity against multidrug-resistant Enterobacteriaceae. A phase 1, randomized, double-blind, crossover study assessed the potential effects of plazomicin on cardiac repolarization (NCT01514929). Fifty-six healthy adults (24 men, 32 women) received a single therapeutic dose of plazomicin (15 mg/kg administered by 30-minute intravenous infusion), a single supratherapeutic dose of plazomicin (20 mg/kg administered by 30-minute intravenous infusion), placebo, or oral moxifloxacin (400 mg). The primary end point was the baseline-adjusted, placebo-corrected QTc interval using the Fridericia formula (ΔΔQTcF). Assay sensitivity was concluded if the lower limit of a 1-sided 95%CI (adjusted for multiplicity using the Hochberg procedure) for moxifloxacin ΔΔQTcF was >5 milliseconds at ≥1 prespecified time points. No QT prolongation effect for plazomicin was concluded if the largest mean effect was <5 milliseconds, and the upper limit of a 2-sided 90%CI for plazomicin ΔΔQTcF was <10 milliseconds at all time points. Assay sensitivity was demonstrated based on moxifloxacin ΔΔQTcF. No QT prolongation effect for plazomicin was concluded because the largest mean ΔΔQTcF for plazomicin was 3.5 milliseconds, and the highest upper limit was 5.6 milliseconds. No clinically relevant changes were observed in electrocardiograms. For the 15- and 20-mg/kg dose levels of plazomicin, mean peak plasma concentration values were 76.0 and 96.6 mg/L, and mean values of the area under the concentration-time curve over 24 hours were 263 and 327 mg·h/L, respectively. Model-derived pharmacokinetic parameters and safety findings were generally consistent with previously reported plazomicin studies. In conclusion, therapeutic and supratherapeutic doses of plazomicin had no clinically significant effect on cardiac repolarization and were generally well tolerated.