Torsades de pointes and QT prolongation Associations with Antibiotics: A Pharmacovigilance Study of the FDA Adverse Event Reporting System

The role of antibacterial prophylaxis in high-risk neutropenia: benefits, risks, and current perspectives

PURPOSE OF REVIEW

To review the benefits, risks and specific considerations surrounding antibacterial prophylaxis (ABP) in adults with neutropenia, focusing primarily on high-risk patients with hematologic malignancies (HM) and/or hematopoietic cell transplantation (HCT).

RECENT FINDINGS

There has been an overall reduction in benefit of fluoroquinolone prophylaxis (FQP) observed in recent studies, with a lack of overall mortality benefit and less efficacy in reducing Gram-negative bloodstream infections (BSI) rates, which may be explained by increasing rates of fluoroquinolone resistance (both on center-level and patient-level) and improved early sepsis management. In the context of FQP, epidemiology of BSIs has changed with greater Gram-positive BSIs and resistant Gram-negative BSIs.

SUMMARY

ABP, most frequently FQP, has been introduced since the 1980s with the aim of reducing rates of infection and mortality. While older meta-analyses support its efficacy in reducing episodes of febrile neutropenia (FN), BSI and most importantly mortality, more recent data report lack of benefit on mortality, and negative impacts such as rising antimicrobial resistance, and in the broader literature, safety concerns for FQP. The role of ABP in neutropenia has been increasingly questioned and should be considered at a center-by-center and an individual-patient level.

Pharmacokinetics, tolerability, and safety of TBI-223, a novel oxazolidinone, in healthy participants

TBI-223 is an oxazolidinone antibiotic under clinical development for the treatment of tuberculosis. Preclinical data indicate potent antituberculosis activity and a potentially improved safety profile over linezolid. In a single-ascending dose study and a multiple-ascending dose study in 114 healthy adults, TBI-223 was generally safe and well tolerated at single doses up to 2,600 mg and multiple doses up to 2,400 mg daily over 14 days. No deaths, serious or severe adverse events, or discontinuations resulting from adverse effects (other than COVID-19) occurred. Except for two instances of orthostatic tachycardia in the single-ascending dose (SAD) study that resolved, no clinically significant electrocardiogram changes were noted. Concentration-QTc modeling found significant relationships of QTc with concentrations of TBI-223 and its main metabolite. However, groups receiving TBI-223 experienced QTc > 450 ms at a similar rate to those receiving placebo. TBI-223 exposures were nearly dose proportional. In the SAD study, TBI-223 exhibited a terminal half-life of 1.9-3.8 hours. Sustained-release tablets achieved a mean AUC0-inf of 70%-80% relative to immediate-release tablets, with more than 50% lower mean Cmax. These results support further investigation of TBI-223 for the treatment of tuberculosis.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT03758612 and NCT04865536.

Data mining in FAERS: association of newer-generation H1-antihistamines with nervous system disorders

BACKGROUND

H1-antihistamines are widely used to treat symptoms depending on histamine release in a variety of conditions. However, neurological adverse events have been reported in post-marketing surveillance studies and there are limited literatures comparing the neurological disorders associated with newer-generation H1-antihistamines from real-world datasets.

AIMS

We performed a comparative analysis of nervous system disorders and several newer-generation H1-antihistamines including: cetirizine, loratadine, levocetirizine, desloratadine and fexofenadine.

METHODS

Disproportionality analysis was used to identify the suspected drug neurological adverse events associated with H1-antihistamines of interest via the Food and Drug Administration Adverse Event Reporting System. The proportional reporting ratio (PRR), χ2 (chi-square) and the reporting odds ratio (ROR) with 95% confidence interval (CI) were used to estimate the association.

RESULTS

AE reports of 43,815 cases from 2017 to 2021 were extracted from FAERS. The H1-antihistamines included in our study were associated with various neurological adverse events that could be classified into 12 aspects, containing 42 preferred terms. The majority of adverse event reports were concentrated at somnolence: cetirizine [N = 1342, ROR (95%CI) = 11.8 (11.2-12.5), PRR = 10.8, χ2 = 11755.4], levocetirizine [N = 1276, ROR(95%CI) = 28.5 (26.7-30.3), PRR = 22.7, χ2 = 26218.4], loratadine[N = 516, ROR(95%CI) = 4.6 (4.2-5.0), PRR = 4.4, χ2 = 1378.1], desloratadine [N = 33, ROR(95%CI) = 6.1 (4.3-8.6), PRR = 5.8, χ2 = 131.9], fexofenadine [N = 498, ROR(95%CI) = 5.0 (4.6-5.5), PRR = 4.8, χ2 = 1519.0].

CONCLUSION

Neurological AEs associated with individual newer generation H1-antihistamines of interest varies a lot, whereas somnolence was the most common AE reports. Fexofenadine was highly associated with headaches. Sedative effects associated with levocetirizine and cetirizine should arouse more concern. Seizures significantly associated with levocetirizine and desloratadine were infrequently reported, further research is needed to avoid possible serious outcomes. Patients taking cetirizine probably have higher risk of dystonia and anticholinergic syndrome.

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.

Safety analysis of fluoroquinolone drugs in elderly patients over 65 based on FAERS

OBJECTIVE

This study investigates adverse drug event (ADE) reports from the FAERS related to FQs drugs in patients aged 65 and older. The findings aim to guide the rational clinical use of these drugs in elderly patients.

METHODS

We employed Reporting Odds Ratio (ROR) and Proportional Reporting Ratio (PRR) methods to analyze ADE reports for the representative FQ drugs from Q1 2015 to Q4 2023, covering 36 quarters.

RESULTS

The analysis identified 6883 ADE cases for ciprofloxacin, 5866 for levofloxacin, 1498 for moxifloxacin, and 317 for ofloxacin. Moxifloxacin showed higher incidences of Cardiac disorders and Psychiatric disorders ADEs (4.01%, 23.11%). Ciprofloxacin and levofloxacin showed higher ADE rates in musculoskeletal and connective tissue diseases (20.18% and 26.97%) compared to moxifloxacin (3.62%) and ofloxacin (9.25%). Additionally, moxifloxacin and ofloxacin showed higher ADE rates for eye disorders (10.61% and 15.03%).

CONCLUSION

Different FQs exhibit varying ADE profiles across cardiovascular, vascular and lymphatic, renal and urinary, psychiatric, musculoskeletal and connective tissue, and ocular systems. Patients with underlying systemic diseases should avoid FQs with higher ADE risks for their conditions. Personalized medication plans for elderly patients should also be strengthened.

Clinical drug interactions between linezolid and other antibiotics: For adverse drug event monitoring

Detailed data on safety associated with drug-drug interactions (DDIs) between Linezolid (LZD) and other antibiotics are limited. The aim of this study was to investigate the safety signals related to these DDIs and to provide a reference for clinically related adverse drug event monitoring. Adverse event (AE) information from 1 January 2004 to 16 June 2022 of the target antibiotics including LZD using alone or in combination with LZD was extracted from the OpenVigil FDA data platform for safety signal analysis. The combined risk ratio model, reporting ratio method, Ω shrinkage measure model, and chi-square statistics model were used to analyze the safety signals related to DDIs. Meanwhile, we evaluated the correlation and the influence of sex and age between the drug(s) and the target AE detected. There were 18991 AEs related to LZD. There were 2293, 1726, 4449, 821, 2431, 1053, and 463 AE reports when LZD was combined with amikacin, voriconazole, meropenem, clarithromycin, levofloxacin, piperacillin-tazobactam, and azithromycin, respectively. Except for azithromycin, there were positive safety signals related to DDIs between LZD and these antibiotics. These DDIs might influence the incidence of 13, 16, 7, 7, 6, and 15 types of AEs, respectively, and is associated with higher reporting rates of AEs compared with use alone. Moreover, sex and age might influence the occurrence of AEs. We found that the combinations of LZD and other antibiotics are related to multiple AEs, such as hepatotoxicity, drug resistance and electrocardiogram QT prolonged, but further research is still required to investigate their underlying mechanisms. This study can provide a new reference for the safety monitoring of LZD combined with other antibiotics in clinical practice.

Antiapoptotic Effects of Hydroxychloroquine on Hypoxic-Ischemic Injury in Neonatal Rat Brain: May Hydroxychloroquine Be an Adjuvant Theraphy?

OBJECTIVE

Hydroxychloroquine (HCQ) has immunomodulatory, antithrombotic, cardiovascular, antimicrobial, and antineoplastic effects. In this study, we aimed to investigate the antiapoptotic and immunomodulator effects of intraperitoneal HCQ on hypoxic-ischemic (HI) injury in newborn rats.

STUDY DESIGN

Wistar albino rats, 7 to 10 days old, were randomly divided into three groups: hypoxic-ischemic encephalopathy (HIE) group, HIE treated with HCQ group, and Sham group. Left common carotid artery ligation and hypoxia model were performed in HIE and HCQ groups. The HCQ group was treated with 80 mg/kg intraperitoneal HCQ every 24 hours for 3 days, while Sham and HIE groups were given physiological saline. After 72 hours, rats were decapitated and brain tissues were stained with hematoxylin and eosin, TUNEL, and IL-1β for histopathological grading and neuronal cell injury.

RESULTS

Neuronal apoptosis was statistically lower in all neuroanatomical areas in the HCQ group compared with the HIE group. IL-1β-stained areas were similar in both HCQ and HIE groups but significantly higher compared with the Sham group. Histopathological grading scores were found to be lower in the HCQ group on the left parietal cortex and hippocampus region.

CONCLUSION

In this study, we have shown for the first time that HCQ treatment decreased apoptosis in HI newborn rat model in both hemispheres. HCQ may be a promising adjuvant therapy in neonatal HIE.

KEY POINTS

· HCQ decreased neuronal apoptosis in the ischemic penumbra of the rat brain.. · HCQ attenuates hypoxia-ischemia-induced brain injury in neonatal rats.. · HCQ has no anti-inflammatory effect on HI injury..

Pharmacovigilance Strategies to Address Resistance to Antibiotics and Inappropriate Use-A Narrative Review

The spread of antimicrobial resistance (AMR) is a global challenge. Close and continuous surveillance for quick detection of AMR can be difficult, especially in remote places. This narrative review focuses on the contributions of pharmacovigilance (PV) as an auxiliary tool for identifying and monitoring the ineffectiveness, resistance, and inappropriate use of antibiotics (ABs). The terms "drug ineffective", "therapeutic failure", "drug resistance", "pathogen resistance", and "multidrug resistance" were found in PV databases and dictionaries, denoting ineffectiveness. These terms cover a range of problems that should be better investigated because they are useful in warning about possible causes of AMR. "Medication errors", especially those related to dose and indication, and "Off-label use" are highlighted in the literature, suggesting inappropriate use of ABs. Hence, the included studies show that the terms of interest related to AMR and use are not only present but frequent in PV surveillance programs. This review illustrates the feasibility of using PV as a complementary tool for antimicrobial stewardship activities, especially in scenarios where other resources are scarce.

Comparison of Empiric Antibiotic Treatment Regimens for Hospitalized, Non-severe Community-acquired Pneumonia: A Retrospective, Multicenter Cohort Study

PURPOSE

Consensus guidelines for hospitalized, non-severe community-acquired pneumonia (CAP) recommend empiric macrolide + β-lactam or respiratory fluoroquinolone monotherapy in patients with no risk factors for resistant organisms. In patients with allergies or contraindications, doxycycline + β-lactam is a recommended alternative. The purpose of this study was to compare differences in outcomes among guideline-recommended regimens in this population.

METHODS

This retrospective, multicenter cohort study included patients ≥18 years of age with CAP who received respiratory fluoroquinolone monotherapy, empiric macrolide + β-lactam, or doxycycline + β-lactam. Major exclusion criteria included patients with immunocompromising conditions, requiring vasopressors or invasive mechanical ventilation within 48 hours of admission, and receiving less than 2 days of total antibiotic therapy. The primary outcome was in-hospital mortality. Secondary outcomes included clinical failure, 14- and 30-day hospital readmission, and hospital length of stay. Safety outcomes included incidence of new Clostridioides difficile infection and aortic aneurysm ruptures.

FINDINGS

Of 4685 included patients, 1722 patients received empiric respiratory fluoroquinolone monotherapy, 159 received empiric doxycycline + β-lactam, and 2804 received empiric macrolide + β-lactam. Incidence of in-hospital mortality was not observed to be significantly different among empiric regimens (doxycycline + β-lactam group: 1.9% vs macrolide + β-lactam: 1.9% vs respiratory fluoroquinolone monotherapy: 1.5%, P = 0.588). No secondary outcomes were observed to differ significantly among groups.

IMPLICATIONS

We observed no differences in clinical or safety outcomes among three guideline-recommended empiric CAP regimens. Empiric doxycycline + β-lactam may be a safe empiric regimen for hospitalized CAP patients with non-severe CAP, although additional research is needed to corroborate these observations with larger samples.

Drug-induced QT prolongation and torsade de pointes: a real-world pharmacovigilance study using the FDA Adverse Event Reporting System database

Introduction: Drug-induced QT prolongation and (or) Torsade de Pointes (TdP) is a well-known serious adverse reaction (ADR) for some drugs, but the widely recognized comprehensive landscape of culprit-drug of QT prolongation and TdP is currently lacking. Aim: To identify the top drugs reported in association with QT prolongation and TdP and provide information for clinical practice. Method: We reviewed the reports related to QT prolongation and TdP in the FDA Adverse Event Reporting System (FAERS) database from January 1, 2004 to December 31, 2022, and summarized a potential causative drug list accordingly. Based on this drug list, the most frequently reported causative drugs and drug classes of QT prolongation and TdP were counted, and the disproportionality analysis for all the drugs was conducted to in detect ADR signal. Furthermore, according to the positive-negative distribution of ADR signal, we integrated the risk characteristic of QT prolongation and TdP in different drugs and drug class. Results: A total of 42,713 reports in FAERS database were considered to be associated with QT prolongation and TdP from 2004 to 2022, in which 1,088 drugs were reported as potential culprit-drugs, and the largest number of drugs belonged to antineoplastics. On the whole, furosemide was the most frequently reported drugs followed by acetylsalicylic acid, quetiapine, citalopram, metoprolol. In terms of drug classes, psycholeptics was the most frequently reported drug classes followed by psychoanaleptics, analgesics, beta blocking agents, drugs for acid related disorders. In disproportionality analysis, 612 drugs showed at least one positive ADR signals, while citalopram, ondansetron, escitalopram, loperamide, and promethazine were the drug with the maximum number of positive ADR signals. However, the positive-negative distribution of ADR signals between different drug classes showed great differences, representing the overall risk difference of different drug classes. Conclusion: Our study provided a real-world overview of QT prolongation and TdP to drugs, and the presentation of the potential culprit-drug list, the proportion of reports, the detection results of ADR signals, and the distribution characteristics of ADR signals may help understand the safety profile of drugs and optimize clinical practice.

The Impact of Long-Term Macrolide Exposure on the Gut Microbiome and Its Implications for Metabolic Control

Long-term low-dose macrolide therapy is now widely used in the treatment of chronic respiratory diseases for its immune-modulating effects, although the antimicrobial properties of macrolides can also have collateral impacts on the gut microbiome. We investigated whether such treatment altered intestinal commensal microbiology and whether any such changes affected systemic immune and metabolic regulation. In healthy adults exposed to 4 weeks of low-dose erythromycin or azithromycin, as used clinically, we observed consistent shifts in gut microbiome composition, with a reduction in microbial capacity related to carbohydrate metabolism and short-chain fatty acid biosynthesis. These changes were accompanied by alterations in systemic biomarkers relating to immune (interleukin 5 [IL-5], IL-10, monocyte chemoattractant protein 1 [MCP-1]) and metabolic (serotonin [5-HT], C-peptide) homeostasis. Transplantation of erythromycin-exposed murine microbiota into germ-free mice demonstrated that changes in metabolic homeostasis and gastrointestinal motility, but not systemic immune regulation, resulted from changes in intestinal microbiology caused by macrolide treatment. Our findings highlight the potential for long-term low-dose macrolide therapy to influence host physiology via alteration of the gut microbiome. IMPORTANCE Long-term macrolide therapy is widely used in chronic respiratory diseases although its antibacterial activity can also affect the gut microbiota, a key regulator of host physiology. Macrolide-associated studies on the gut microbiota have been limited to short antibiotic courses and have not examined its consequences for host immune and metabolic regulation. This study revealed that long-term macrolides depleted keystone bacteria and impacted host regulation, mediated directly by macrolide activity or indirectly by alterations to the gut microbiota. Understanding these macrolide-associated mechanisms will contribute to identifying the risk of long-term exposure and highlights the importance of targeted therapy for maintenance of the gut microbiota.

Linezolid and the risk of QT interval prolongation: A pharmacovigilance study of the Food and Drug Administration Adverse Event Reporting System

AIMS

Few studies have investigated linezolid (LZD)-associated cardiotoxicity. This study explored the potential association between LZD and QT interval prolongation.

METHODS

Adverse event reports of QT interval prolongation associated with LZD from the Food and Drug Administration Adverse Event Reporting System from January 2013 to December 2021 were analysed and the reporting odds ratio (ROR) with 95% confidence intervals were calculated.

RESULTS

A total of 6738 adverse event reports of LZD as the primary and secondary suspected drug were obtained from the database, including 192 reports with electrocardiogram QT prolonged (QTp), and the ROR value was 26.1 (95% CI = 22.6-30.2). There were 8 reports of long QT syndrome, ROR 14.2 (95% CI = 7.1-28.5); 5 reports of torsade de pointes, ROR 3.2 (95% CI = 1.3-7.6); and 5 reports of ventricular tachycardia, ROR 1.9 (95% CI = 0.8-4.5). Subgroup analysis revealed that patients with tuberculosis treated with LZD had a higher reporting rate among all QTp reports, exhibiting an odds ratio of 330.0 (95% CI = 223.1-488.1). The odds ratios of QTp associated with LZD treatments in patients with and without tuberculosis were 4.2 (95% CI = 3.4-5.3) and 1.2 (95% CI = 0.8-1.6), respectively.

CONCLUSION

The study showed an association between LZD and QT interval prolongation. In the report on patients with tuberculosis, the incidence of QTp was higher when treated with LZD.

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.

Drug-induced torsades de pointes: Disproportionality analysis of the United States Food and Drug Administration adverse event reporting system

Objective

This study aimed to identify the most common and top drugs associated with the risk of torsades de pointes (TdP) based on the United States Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database.

Materials and methods

We used OpenVigil 2.1 to query FAERS database and data from the first quarter of 2004 to the third quarter of 2021 were retrieved. The Medical Dictionary for Regulatory Activities (MedDRA) was used to identify TdP cases. We listed the most common drugs associated with the reported TdP cases. Then, the reporting odds ratio (ROR) and the proportional reporting ratio (PRR) for the reporting association between different drugs and TdP risk were calculated. Meanwhile, comparisons were conducted with the QT drug lists of CredibleMeds^® in an attempt to identify drugs with a potential risk of TdP that were not on the list.

Results

A total of 9,217,181 adverse event reports were identified, of which 3,807 (0.04%) were related to TdP. TdP was more likely to occur in the elderly and females. Amiodarone (464 cases) was associated with most cases of TdP. According to the disproportionality analysis, the top five drugs with the highest ROR and PRR were tolazoline (ROR 1615.11, 95% confidence interval [CI] 455.59–5725.75, PRR 969.46, χ² 2960.10), levomethadyl (ROR 1211.01, 95% CI 302.75–4844.04, PRR 807.67, χ² 1677.03), ibutilide (ROR 1118.74, 95% CI 425.00–2944.91, PRR 765.77, χ² 3845.27), halofantrine (ROR 660.55, 95% CI 184.21–2368.69, PRR 519.22, χ² 1076.31), and isoproterenol (ROR 352.20, 95% CI 227.19–546.00, PRR 307.82, χ² 6692.53). Approximately half of the top 50 drugs (22 for ROR, 30 for PRR) were not outlined on the QT drug lists of CredibleMeds^®.

Conclusion

Approximately half of the top risk drugs (22 for ROR, 30 for PRR) were not outlined in the QT drug lists of CredibleMeds^®. Notably, potential risks are of great importance and should be closely monitored in clinical practice. Also, further research is needed to investigate the association between these drugs and TdP.

Pharmacologic management of Mycobacterium chimaera Infections: A Primer for Clinicians

Mycobacterium chimaera, a member of the Mycobacterium avium complex, can cause infections in individuals after open heart surgery due to contaminated heater-cooler units. The diagnosis can be challenging, as the incubation period can be quite variable, and symptoms are nonspecific. In addition to aggressive surgical management, combination pharmacologic therapy is the cornerstone of therapy, which should consist of a macrolide, a rifamycin, ethambutol, and amikacin. Multiple second-line agents may be utilized in the setting of intolerances or toxicities. In vitro susceptibility of these agents is similar to activity against other species in the Mycobacterium avium complex. Drug–drug interactions are frequently encountered, as many individuals have chronic medical comorbidities and are prescribed medications that interact with the first-line agents used to treat M. chimaera. Recognition of these drug–drug interactions and appropriate management are essential for optimizing treatment outcomes.

A Rare Case of Metronidazole Overdose Causing Ventricular Fibrillation

Ventricular fibrillation is not known as a complication of metronidazole poisoning. Although some arrhythmias have been reported as a complication of metronidazole intake while taking antiarrhythmic medications, most such arrhythmias are possibly related to co-ingestion of drugs with metronidazole as it affects the metabolism of these drugs. In this case, ventricular fibrillation occurred in a young patient without preexisting medical conditions or any other known drug ingestion, which was never been reported before.

We present a case of an 18-year-old male brought in by the ambulance service after attempting to end his life by overdosing on metronidazole. While being transported he developed ventricular fibrillation and received an electric shock, which reverted the episode. Laboratory investigations did not show any clear cause that might have precipitated his arrhythmia.

Arrhythmogenic mechanisms of interleukin-6 combination with hydroxychloroquine and azithromycin in inflammatory diseases

Inflammatory diseases including COVID-19 are associated with a cytokine storm characterized by high interleukin-6 (IL-6) titers. In particular, while recent studies examined COVID-19 associated arrhythmic risks from cardiac injury and/or from pharmacotherapy such as the combination of azithromycin (AZM) and hydroxychloroquine (HCQ), the role of IL-6 per se in increasing the arrhythmic risk remains poorly understood. The objective is to elucidate the electrophysiological basis of inflammation-associated arrhythmic risk in the presence of AZM and HCQ. IL-6, AZM and HCQ were concomitantly administered to guinea pigs in-vivo and in-vitro. Electrocardiograms, action potentials and ion-currents were analyzed. IL-6 alone or the combination AZM + HCQ induced mild to moderate reduction in heart rate, PR-interval and corrected QT (QTc) in-vivo and in-vitro. Notably, IL-6 alone was more potent than the combination of the two drugs in reducing heart rate, increasing PR-interval and QTc. In addition, the in-vivo or in-vitro combination of IL-6 + AZM + HCQ caused severe bradycardia, conduction abnormalities, QTc prolongation and asystole. These electrocardiographic abnormalities were attenuated in-vivo by tocilizumab (TCZ), a monoclonal antibody against IL-6 receptor, and are due in part to the prolongation of action potential duration and selective inhibition of Na⁺, Ca²⁺ and K⁺ currents. Inflammation confers greater risk for arrhythmia than the drug combination therapy. As such, in the setting of elevated IL-6 during inflammation caution must be taken when co-administering drugs known to predispose to fatal arrhythmias and TCZ could be an important player as a novel anti-arrhythmic agent. Thus, identifying inflammation as a critical culprit is essential for proper management.

Thorough QT Study To Evaluate the Effect of Zoliflodacin, a Novel Therapeutic for Gonorrhea, on Cardiac Repolarization in Healthy Adults

Zoliflodacin is a novel spiropyrimidinetrione antibiotic being developed as single oral dose treatment to address the growing global threat of Neisseria gonorrhoeae. To evaluate the cardiac safety of zoliflodacin, a thorough QT/QTc (TQT) study was performed in healthy subjects. In this randomized, double-blind, placebo-controlled, 4-period crossover study, 72 subjects in a fasted state received a single dose of zoliflodacin at 2 g (therapeutic), zoliflodacin at 4 g (supratherapeutic), placebo, and moxifloxacin at 400 mg as a positive comparator. Cardiac repolarization was measured by duration of the corrected QT interval by Fridericia's formula (QTcF). At each time point up to 24 h after zoliflodacin administration, the upper limit of the one-sided 95% confidence interval (CI) for the placebo-corrected change from the predose baseline in QTcF (ΔΔQTcF) was less than 10 ms, indicating an absence of a clinically meaningful increase in QT prolongation. The lower limit of the one-sided multiplicity-adjusted 95% CI of ΔΔQTcF for moxifloxacin was longer than 5 ms at four time points from 1 to 4 h after dosing, demonstrating adequate sensitivity of the QTc measurement. There were no clinically significant effects on heart rate, PR and QRS intervals, electrocardiogram (ECG) morphology, or laboratory values. Treatment-emergent adverse events (AEs) were mild or moderate in severity and transient. This was a negative TQT study according to regulatory guidelines (E14) and confirms that a single oral dose of zoliflodacin is safe and well tolerated. These findings suggest that zoliflodacin is not proarrhythmic and contribute to the favorable assessment of cardiac safety for a single oral dose of zoliflodacin. (This study has been registered at ClinicalTrials.gov under registration no. NCT03613649.).

Effectiveness of Beta-Lactam plus Doxycycline for Patients Hospitalized with Community-Acquired Pneumonia

BACKGROUND

Despite clinical practice guideline recommendations to use doxycycline as part of combination therapy for some patients hospitalized with pneumonia, there is minimal evidence supporting this recommendation. Our aim was to examine the association between beta-lactam plus doxycycline and mortality for patients hospitalized with community-acquired pneumonia.

METHODS

We identified patients > 65 years of age admitted to any United States Department of Veterans Affairs hospital in fiscal years 2002-2012 with a discharge diagnosis of pneumonia. We excluded those patients who did not receive antibiotic therapy concordant with the 2019 ATS/IDSA clinical practice guidelines. Using propensity score matching, we examined the association of doxycycline with 30- and 90-day mortality.

RESULTS

Our overall cohort was comprised of 70,533 patients and 5,282 (7.49%) received doxycycline. Unadjusted 30-day mortality was 6.4% for those who received a beta-lactam plus doxycycline vs. 9.1% in those who did not (p<0.0001), and 90-day mortality was 13.8% for those who received a beta-lactam + doxycycline vs. 16.8% for those who did not (p<0.0001). In the propensity score matched models, both 30- (odds ratio 0.72, 95% confidence interval, 0.63-0.84) and 90-day (0.83, 0.74-0.92) mortality were significantly lower for those who received doxycycline.

CONCLUSIONS

In this retrospective observational cohort study, we found that doxycycline use, as part of guideline-concordant antibiotic therapy, was associated with lower 30- and 90-day mortality than regimens without doxycycline. While this supports the safety and effectiveness of antibiotic regimes that include doxycycline, additional studies, especially randomized clinical trials, are needed to confirm this.

Descriptive analysis of reported adverse events associated with anti-obesity medications using FDA Adverse Event Reporting System (FAERS) databases 2013-2020

Background Obesity is a globally growing health problem, and its treatment has been challenging. The use of anti-obesity medications (AOMs) has been associated with severe adverse events (AEs). Several AOMs have been withdrawn from the market owing to documented AEs. Aim To describe, estimate and characterize the frequency of AEs attributable to the use of the AOMs, and investigate previously unreported potential AEs associated with AOMs. Method Using the US FDA Adverse Event Reporting System (FAERS) between January 2013 and June 2020, a retrospective, descriptive analysis was conducted to analyze all major reported AEs and outcomes including death, life-threatening, hospitalization, disability, and required intervention or congenital anomaly. The total numbers of AEs reports, cases, adverse reactions and outcomes were calculated for each medication. Results A total of 18,675 unique AEs reports associated with AOMs used for 15,143 patients. The mean age was 49.8 years [SD 1.83], while most patients were female adults (73.4%). The most frequently reported AEs were nausea and vomiting, followed by dizziness and headache, drug ineffectiveness, cardiovascular diseases, and kidney complications. There were 21,229 unique outcomes, including 1039 deaths (fatality ratio of 4.9% of all analyzed reports), 1613 (7.6%) life-threatening events, 7426 (35%) hospitalizations, and 1249 (5.9%) disability cases. Phentermine/topiramate fatal cases represent 6% of the overall medication's reported AEs. Cardiovascular AEs represented 31%, 23%, and 22% of phentermine, liraglutide, and phentermine/topiramate total AEs, respectively. Conclusion The analysis of FAERS database revealed numerous serious AEs associated with AOMs. These AEs can lead to serious cardiovascular and kidney complications. It is necessary to continue and systematically monitor safety of AOMs' to optimize patient anti-obesity therapy.

A randomized, double-blind, placebo- and positive-controlled crossover study of the effects of durlobactam on cardiac repolarization in healthy subjects

Durlobactam (formerly ETX2514) is a diazabicyclooctane β-lactamase inhibitor that inhibits class A, C, and D β-lactamases. Sulbactam combined with durlobactam has in vitro and in vivo activity against Acinetobacter baumannii including carbapenem- and colistin-resistant isolates and is being developed for treating serious infections due to A. baumannii. The effect of a single supratherapeutic dose of durlobactam on the heart rate corrected QT interval (QTc) was evaluated in healthy subjects in a placebo- and active-controlled, single-infusion, three-way crossover study. Subjects were randomized to 1 of 6 sequences that included a single 3-h i.v. infusion of durlobactam 4 g (supratherapeutic dose), a single 3-h i.v. infusion of placebo, and a single 3-h i.v. infusion of placebo plus a single oral dose of moxifloxacin 400 mg given open-label at the end of the i.v. infusion. In each treatment period, Holter electrocardiogram (ECG) measurements were obtained from predose through 24 h post-start of infusion. For the primary ECG end point, placebo-corrected change-from-baseline corrected QT Fridericia's formula (ΔΔQTcF), no significant change was observed with durlobactam. A concentration-QT analysis demonstrated no significant effect of durlobactam on ECG parameters, including QT interval prolongation. Thus, durlobactam has a low risk for prolonging the QT interval and is unlikely to produce any proarrhythmic effects.

Empirical Antimicrobial Therapy and QTc Interval Prolongation in Emergency Medicine

BACKGROUND

QTc prolongation is common though dangerous clinical condition associated with increased risk of life-threatening arrhythmia torsades de pointes. The goal of this short communication is to evaluate the principal causes of risk of QTc prolongation that are observed in an emergency department and discuss the differences between drug- and non-drug-associated factors.

METHODS

The retrospective analysis is carried out on 130 patients that presented a QTc prolongation (>480 ms for males and >470 for female, respectively) admitted to the emergency department of a single Italian hospital. Patients with pacemaker (22) were excluded from this study. For each patient a minimum of 3 ECGs (12 leads) was recorded. Attention is paid to electrolytes disturbances and pharmacotherapy, with a particular emphasis on the use of antibiotics.

RESULTS

Mean age of the patients was 79.6 years (SD=11.3), and females and males were almost equally present (46.6 % F, 53.7 % M). The average QTc value is 492.2 ms (493.3 ms F, 492.8 M). The patients were divided into those with electrolytes disturbances (24.0 %), antimicrobial therapy (35.2%), both antimicrobial therapy and electrolytes disturbances (24.1 %), and other causes of QTc prolongation (16.7 %).

CONCLUSION

This analysis shows the relevance of the empirical therapy established at the admission, in particular for infective diseases, as an important risk factor for the prolongation of QTc. Other factors that can increase the risk are electrolytes alterations, advanced age, cardiovascular diseases, and drug-drug interaction.

Randomized, Double-Blind, Placebo- and Positive-Controlled Crossover Study of the Effects of Tebipenem Pivoxil Hydrobromide on QT/QTc Intervals in Healthy Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an orally available prodrug of tebipenem (TBP), a carbapenem with in vitro activity against multidrug-resistant Gram-negative pathogens. This study evaluated the effects of single therapeutic and supratherapeutic doses of TBP-PI-HBr on the heart rate-corrected QT interval (QTc) by assessing the concentration-QT interval relationship using exposure-response modeling. This was a randomized, double-blind, placebo- and active-controlled, single-dose, four-way crossover study. Subjects received single oral doses of TBP-PI-HBr at 600 and 1,200 mg, placebo, and positive control (moxifloxacin at 400 mg). Cardiodynamic electrocardiograms (ECGs) and blood samples were collected in each period. Twenty-four subjects were enrolled. TBP-PI-HBr had no clinically significant adverse effects on heart rate or ECG parameters. The model-predicted slope suggests that the baseline-corrected difference in heart rate from placebo was not importantly affected by plasma TBP concentrations, supporting the use of the QT interval corrected by Fridericia's method as an appropriate correction. The model-predicted difference in QTc at the mean maximum concentration (Cmax) for TBP had negative predicted values for each dose, and no QTc prolongation was detected following TBP-PI-HBr at 600 mg or 1,200 mg. Assay sensitivity was established with moxifloxacin at 400 mg. Exposure to TBP increased in a dose-dependent manner with 600- and 1,200-mg doses. The TBP area under the concentration-time curve from time zero to infinity and Cmax with the 1,200-mg dose were 1.8- and 1.3-fold greater, respectively, than those with the 600-mg dose. TBP-PI-HBr was generally safe and well tolerated, with no effect in QT interval prolongation.

Torsades de pointes episode in a woman with high-grade fever and inflammatory activation: A case report

BACKGROUND

QT interval prolongation can induce torsades de pointes (TdP), a potentially fatal ventricular arrhythmia. Recently, an increasing number of non-cardiac drugs have been found to cause QT prolongation and/or TdP onset. Moreover, recent findings have demonstrated the key roles of systemic inflammatory activation and fever in promoting long-QT syndrome (LQTS) and TdP development.

CASE SUMMARY

A 30-year-old woman was admitted with a moderate to high-grade episodic fever for two weeks. The patient was administered with multiple antibiotics after hospitalization but still had repeating fever and markedly elevated C-reactive protein. Once after a high fever, the patient suddenly lost consciousness, and electrocardiogram (ECG) showed transient TdP onset after frequent premature ventricular contraction. The patient recovered sinus rhythm and consciousness spontaneously, and post-TdP ECG revealed a prolonged QTc interval of 560 ms. The patient’s clinical manifestations and unresponsiveness to the antibiotics led to the final diagnosis of adult-onset Still’s disease (AOSD). There was no evidence of cardiac involvement. After the AOSD diagnosis, discontinuation of antibiotics and immediate initiation of intravenous dexamethasone administration resulted in the normal temperature and QTc interval. The genetic analysis identified that the patient and her father had heterozygous mutations in KCNH2 (c.1370C>T) and AKAP9 (c.7725A>C). During the 2-year follow-up period, the patient had no recurrence of any arrhythmia and maintained normal QTc interval.

CONCLUSION

This case study highlights the risk of systemic inflammatory activation and antibiotic-induced TdP/LQTS onset. Genetic analysis should be considered to identify individuals at high risk of developing TdP.

Antimicrobial Stewardship: A Review for Internal Medicine Physicians

Antimicrobial stewardship is the need of the hour to prevent the collapse of our health care system at the hands of a pandemic of resistant pathogens. Inappropriate and indiscriminate abuse of antibiotics has left very few options for prescribing physicians as most of the pathogens, particularly gram-negative, are resistant to the major antibiotics. This article reviews the importance of Antimicrobial Stewardship Programs (ASP) for internal medicine physicians and residents. Commonly encountered clinical scenarios are discussed. Appropriate indications of antibiotics, pathogen-guided prescriptions, adverse effects of common antibiotics, and options to use newer antibiotics are reviewed. The role of a health care team is highlighted. The evidence-based steps taken to ensure ASPs implementation are reiterated to serve as an educational guide for medical residents and physicians.

Effect of Hydroxychloroquine and Azithromycin on QT Interval Prolongation and Other Cardiac Arrhythmias in COVID-19 Confirmed Patients

BACKGROUND

Hydroxychloroquine with or without azithromycin was one of the common therapies at the beginning of the COVID-19 pandemic. They can prolong QT interval, cause torsade de pointes, and lead to sudden cardiac death. We aimed to assess QT interval prolongation and its risk factors in patients who received hydroxychloroquine with or without azithromycin.

METHODS

This study was a retrospective cohort study. One hundred seventy-two confirmed COVID-19 patients were included in this study, hospitalized at Babol University of Medical Sciences hospitals between March 5, 2020, and April 3, 2020. Patients were divided into two groups: hydroxychloroquine alone and hydroxychloroquine with azithromycin. Electrocardiograms were used for outcome assessment.

RESULTS

83.1% of patients received hydroxychloroquine plus azithromycin vs. 16.9% of patients who received only hydroxychloroquine. The mean age of patients was 59.2 ± 15.4.The mean of posttreatment QTc interval in the monotherapy group was shorter than the mean of posttreatment QTc interval in the combination therapy group, but it had no significant statistical difference (462.5 ± 43.1 milliseconds vs. 464.3 ± 59.1 milliseconds; p = 0.488). Generally, 22.1% of patients had a prolonged QTc interval after treatment. Male gender, or baseline QTc ≥ 450 milliseconds, or high-risk Tisdale score increased the likelihood of prolonged QTc interval. Due to QTc prolongation, fourteen patients did not continue therapy after four days.

CONCLUSIONS

Hospitalized patients treated by hydroxychloroquine with or without azithromycin had no significant difference in prolongation of QT interval and outcome. The numbers of patients with prolonged QT intervals in this study emphasize careful cardiac monitoring during therapy, especially in high-risk patients.

Optimization of hydroxychloroquine dosing scheme based on COVID-19 patients' characteristics: a review of the literature and simulations

During the recent COVID-19 outbreak hydroxychloroquine (HCQ) has been proposed as a safe and effective therapeutic option. However, a wide variety of dosing schemes has been applied in the clinical practice and tested in clinical studies. An extended literature survey was performed investigating the pharmacokinetics, the efficacy and safety of HCQ in COVID-19 treatment. Population pharmacokinetic models were retrieved from the literature and after evaluation and assessment one was selected in order to perform simulations. The most commonly applied dosing schemes were explored for patients with different weights and different levels of HCQ clearance impairment. Model-based simulations of HCQ concentrations revealed that high initial doses followed by low and sparse doses may offer significant benefits to patients by decreasing the viral load without reaching levels considered to produce adverse effects. For instance, the dosing scheme proposed for a 70 kg adult with moderate COVID-19 symptoms would be 600 mg upon diagnosis, 400 mg after 12 h, 300 mg after 24 h, 200 mg after 36 h, followed by 200 mg BID for 4 d, followed by 200 mg OD for 5 d. Based on the results from simulations performed and the currently published knowledge regarding HCQ in COVID-19 treatment, this study provides evidence that a high loading dose followed by sparse doses could offer significant benefits to the patients.

Assessing the association between fluoroquinolones and emerging adverse drug reactions raised by regulatory agencies: An umbrella review

BACKGROUND

Regulatory agencies warned against fluoroquinolones for the management of minor infections because of the risk of emerging adverse events (collagen-associated adverse events, neuropsychiatric toxicity and long-term disability). We aimed to assess quality and credibility of evidence as well as causality regarding these putative associations.

METHODS

MEDLINE, Scopus, Web of Science and PROSPERO were searched, from inception to August 2019, for systematic reviews with meta-analyses investigating emerging adverse events. Two investigators extracted data to grade quality (through validated AMSTAR-2 tool), rank credibility of the evidence (convincing, highly suggestive, suggestive, weak) through adapted criteria including E-value calculation, and assess causality (Hill's criteria).

RESULTS

Seven systematic reviews of observational studies providing 16 risk estimates [seven, five and four, respectively, for aortic aneurysm/dissection (AAD), retinal detachment (RD) and any tendon disorders (ATD)] met inclusion criteria. No systematic reviews with meta-analysis investigating the risk of neuropsychiatric toxicity or long-term disability were found. The associations between fluoroquinolones and AAD/ATD showed highly suggestive credibility and were supported by strong evidence of causality (double increased risk, especially within first 2 months of treatment). Conflicting data concerning the emergence of RD were retrieved, resulting in weak evidence of causality. Quality of the evidence ranged from high to low for AAD, from moderate to critically low for RD, and it was moderate for ATD.

CONCLUSION

Our analysis supports credible, plausible and highly suggestive associations with AAD (rare occurrence but strong causality) and ATD. Limitations of both umbrella reviews and observational evidence should be considered.

Safety signals for QT prolongation or Torsades de Pointes associated with azithromycin with or without chloroquine or hydroxychloroquine

Background

Combinations of hydroxychloroquine (HCQ) and azithromycin have been promoted as treatments for COVID-19 based on small, uncontrolled clinical trials that have not assessed potential risks. Risks of treatment include QT segment prolongation, Torsades de Pointes (TdP), and death. This comparative pharmacovigilance analysis evaluated the risk of these events.

Methods

Data from the U.S. Food and Drug Administration's Adverse Event Reporting System (FAERS) (>13 million total reports) were used. Queries extracted reports based on exposures of HCQ/chloroquine (CQ) alone, azithromycin alone, HCQ/CQ + azithromycin, amoxicillin alone, HCQ/CQ + amoxicillin alone. Amoxicillin served as a control. Events of interest included death and TdP/QT prolongation as well as accidents/injuries and depression as control events. Proportional Reporting Ratios (PRR) and 95% confidence intervals (CI) were calculated where a lower limit of the of 95% CI (Lower95CI) value of ≥2.0 is interpreted as a potential safety signal.

Results

Lower95CIs for HCQ/CQ alone showed no potential safety signals for TdP/QT prolongation, death, or any of the control events included. The PRRs and 95% CIs for TdP/QT prolongation was 1.43 (1.29–2.59) with HCQ/CQ use alone and 4.10 (3.80–4.42) for azithromycin alone. For the combined HCQ/CQ + azithromycin group, the PRR and 95% CI was 3.77 (1.80–7.87). For the control of amoxicillin, there were no safety signals when used alone or in combination with HCQ/CQ.

Conclusions

HCQ/CQ use was not associated with a safety signal in this analysis of FAERS data. However, azithromycin used alone was associated with TdP/QT prolongation events and should be used with caution.

Hypoglycemia Associated with Antibiotics Alone and in Combination with Sulfonylureas and Meglitinides: An Epidemiologic Surveillance Study of the FDA Adverse Event Reporting System (FAERS)

INTRODUCTION

Fluoroquinolones, clarithromycin, linezolid, tigecycline, cefditoren, doxycycline, and trimethoprim-sulfamethoxazole are known to be associated with hypoglycemia, but few studies have considered concomitant glucose-lowering medications.

OBJECTIVE

The objective of this study was to evaluate the association between hypoglycemia and antibiotics using the US Food and Drug Administration Adverse Event Reporting System (FAERS), while accounting for concomitant glucose-lowering medications including sulfonylureas and meglitinides.

METHODS

FAERS reports from 1 January 2004 to 31 December 2017 were included in the study. Reporting odds ratios (RORs) and corresponding 95% confidence intervals (CIs) for the association between antibiotics and hypoglycemia were calculated. An association was considered to be statistically significant when the lower limit of the 95% CI was > 1.0.

RESULTS

A total of 2,334,959 reports (including 18,466 hypoglycemia reports) were considered, after inclusion criteria were applied. Statistically significant hypoglycemia RORs (95% CI) for antibiotics were: cefditoren 14.03 (8.93-22.03), tigecycline 3.32 (1.95-5.65), clarithromycin 2.41 (1.89-3.08), ertapenem 2.07 (1.14-3.75), moxifloxacin 2.06 (1.59-2.65), levofloxacin 1.66 (1.37-2.01), and linezolid 1.54 (1.07-2.20). After adjusting for concomitant sulfonylureas and meglitinides, the following antibiotics were still significantly associated with hypoglycemia: cefditoren 14.25 (9.08-22.39), tigecycline 3.34 (1.96-5.68), ertapenem 1.93 (1.03-3.60), and clarithromycin 1.56 (1.15-2.11).

CONCLUSION

In many patients, antibiotics, including fluoroquinolones, are associated with hypoglycemia when they are also taking sulfonylureas or meglitinides. Cefditoren, tigecycline, ertapenem, and clarithromycin are associated with hypoglycemia even if not taken with sulfonylureas or meglitinides. The association between ertapenem and hypoglycemia has not been previously reported.

Rhabdomyolysis Associations with Antibiotics: A Pharmacovigilance Study of the FDA Adverse Event Reporting System (FAERS)

Introduction: Daptomycin, macrolides, trimethoprim-sulfamethoxazole, linezolid, fluoroquinolones, and cefdinir are known to be associated with rhabdomyolysis. Other antibiotics may also lead to rhabdomyolysis, but no study has systemically compared rhabdomyolysis associations for many available antibiotics. Objectives: The objective of this study was to evaluate the association between rhabdomyolysis and many available antibiotics using the FDA Adverse Event Report System (FAERS). Methods: FAERS reports from January 1, 2004 to December 31, 2017 were included in the study. The Medical Dictionary for Regulatory Activities (MedDRA) was used to identify rhabdomyolysis cases. Reporting Odds Ratios (RORs) and corresponding 95% confidence intervals (95%CI) for the association between antibiotics and rhabdomyolysis were calculated. An association was considered statistically significant when the lower limit of the 95%CI was greater than 1.0. Results: A total of 2,334,959 reports (including 7,685 rhabdomyolysis reports) were considered, after inclusion criteria were applied. Daptomycin had the greatest proportion of rhabdomyolysis reports, representing 5.5% of all daptomycin reports. Statistically significant rhabdomyolysis RORs (95% CI) for antibiotics were (in descending order): daptomycin 17.94 (14.08-22.85), cefditoren 8.61 (3.54-20.94), cefaclor 7.16 (2.28-22.49), erythromycin 5.93 (3.17-11.10), norfloxacin 4.50 (1.44-14.07), clarithromycin 3.95 (2.77-5.64), meropenem 3.19 (1.51-6.72), azithromycin 2.94 (1.96-4.39), cefdinir 2.84 (1.06-7.62), piperacillin-tazobactam 2.61 (1.48-4.61), trimethoprim-sulfamethoxazole 2.53 (1.52-4.21), linezolid 2.49 (1.47-4.21), ciprofloxacin 2.10 (1.51-2.92). Conclusions: This study confirms prior evidence for rhabdomyolysis associations with daptomycin, macrolides, trimethoprim-sulfamethoxazole, linezolid, fluoroquinolones, and cefdinir. This study also identifies previously unknown rhabdomyolysis associations with meropenem, cefditoren, cefaclor, and piperacillin-tazobactam.