Thorough QT/QTc study to evaluate the effect of a single supratherapeutic dose of islatravir on QTc interval prolongation in healthy adults.

Islatravir is a deoxynucleoside analog being developed for the treatment of HIV-1 infection. Clinical studies are being conducted to evaluate islatravir, administered in combination with other antiretroviral therapies, at doses of 0.25 mg once daily and 2 mg once weekly. In multiple previous clinical studies, islatravir was generally well tolerated, with no clear trend in cardiac adverse events. A trial was conducted to evaluate the effect of islatravir on cardiac repolarization. A randomized, double-blind, active- and placebo-controlled phase 1 trial was conducted, in which a single dose of islatravir 0.75 mg, islatravir 240 mg (supratherapeutic dose), moxifloxacin 400 mg (active control), or placebo was administered. Continuous 12-lead electrocardiogram monitoring was performed before dosing through 24 hours after dosing. QT interval measurements were collected, and safety and pharmacokinetics were evaluated. Sixty-three participants were enrolled, and 59 completed the study. Fridericia's QT correction for heart rate was inadequate; therefore, a population-specific correction was applied (QTcP). The placebo-corrected change from baseline in QTcP (ΔΔQTcP) interval at the observed geometric mean maximum plasma concentration associated with islatravir 0.75 mg and islatravir 240 mg was <10 ms at all time points. Assay sensitivity was confirmed because the use of moxifloxacin 400 mg led to a ΔΔQTcP >10 ms. The pharmacokinetic profile of islatravir was consistent with that of previous studies, and islatravir was generally well tolerated. Results from the current trial suggest that single doses of islatravir as high as 240 mg do not lead to QTc interval prolongation.

Effects of buprenorphine on QT intervals in healthy subjects: results of 2 randomized positive- and placebo-controlled trials.

OBJECTIVES: To study the effect of transdermal buprenorphine on QTc prolongation at dose levels of 10, 40, and 80 mcg/h, (BTDS 10, BTDS 40, BTDS 80). METHODS: Two randomized, placebo- and positive-controlled, parallel-group, dose-escalating clinical studies evaluated healthy adult subjects randomized to BTDS, placebo, or moxifloxacin in the first study; and to BTDS only, BTDS plus naltrexone, naltrexone alone at the same dose, placebo, or moxifloxacin in the second study. QT intervals were corrected for heart rate using data from each individual subject (QTcI). RESULTS: In the first study (n = 44), the maximum upper bounds of the 90% confidence interval (CI) for mean placebo-corrected change from baseline in QTcI across 13 time points over 24 h were: 10.0 msec for BTDS 10 (Day 6) and 13.3 msec for BTDS 40 (Day 13); and 17.0 msec (Day 6) and 15.5 msec (Day 13) for moxifloxacin, respectively. Similarly, in the second study (n = 66), the upper bound of the 90% CI for mean placebo-corrected change from baseline for QTcI was under 10 msec at all time points for BTDS 10 (maximum upper bound, 5.63 msec), over 10 msec at 5 time points for BTDS 40 (maximum 11.81 msec) and over 10 msec at all 13 time points for BTDS 80 (maximum, 14.14 msec). Naltrexone administered with BTDS eliminated the QTcI prolongation seen with supratherapeutic BTDS doses (BTDS 40, BTDS 80) administered without naltrexone. CONCLUSIONS: At the therapeutic dose of 10 mcg/h, BTDS has no clinically significant effect on QTc. At supratherapeutic doses of 40 and 80 mcg/h, BTDS treatment produces prolongation of QTcI similar in magnitude to that produced by a 400 mg dose of moxifloxacin. Despite the modest, dose-dependent increase in QTcI noted in these studies, transdermal buprenorphine has not been associated with proarrhythmic effects.

Botanicals, selective insecticides, and predators to control Diaphorina citri (Hemiptera: Liviidae) in citrus orchards.

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically important disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecticides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad-spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, average 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Aneglei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.

Risk of hepatotoxicity associated with fluoroquinolones: a national case-control safety study.

PURPOSE: Results of a pharmacoepidemiologic evaluation of fluoroquinolone-associated hepatotoxicity using national hospital admissions data on Veterans Affairs (VA) patients are reported. METHODS: In a retrospective case-control study, all adults with a primary diagnosis of hepatotoxicity on admission to a VA facility during a 6.5-year period (January 2002-June 2008) were identified. After the exclusion of patients whose records indicated known causes of hepatotoxicity or a history of liver disease, a subgroup of 7,862 patients with exposure to fluoroquinolone antibiotics in the six months prior to hospital admission were matched with nonexposed controls (n = 45,512). Conditional logistic regression was used to assess the overall and drug-specific risks of hepatotoxicity in the case group, controlling for comorbidities, concomitant use of known hepatotoxic medications, and other variables. RESULTS: After adjusting for confounders, logistic regression analysis indicated a significantly higher overall risk of hepatotoxicity development among fluoroquinolone users relative to controls (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.04-1.38). Drug-specific risk analyses focused on three fluoroquinolone agents (ciprofloxacin, levofloxacin, and moxifloxacin) indicated a significant association between ciprofloxacin use and an increased risk of hepatotoxicity (OR, 1.29; 95% CI, 1.05-1.58); when considered as independent variables, levofloxacin use and moxifloxacin use were not significantly associated with hepatotoxicity risk. CONCLUSION: The findings of a national VA safety study suggested an increased hepatotoxicity risk asssociated with fluoroquinolone exposure in the study population.

Sexual side effects of serotonergic antidepressants: mediated by inhibition of serotonin on central dopamine release?

Antidepressant-induced sexual dysfunction adversely affects the quality of life of antidepressant users and reduces compliance with treatment. Animal models provide an instructive approach for examining potential sexual side effects of novel drugs. This review discusses the stability and reproducibility of our standardized test procedure that assesses the acute, subchronic and chronic effects of psychoactive compounds in a 30 minute mating test. In addition, we present an overview of the effects of several different (putative) antidepressants on male rat sexual behavior, as tested in our standardized test procedure. By comparing the effects of these mechanistically distinct antidepressants (paroxetine, venlafaxine, bupropion, buspirone, DOV 216,303 and S32006), this review discusses the putative mechanism underlying sexual side effects of antidepressants and their normalization. This review shows that sexual behavior is mainly inhibited by antidepressants that increase serotonin neurotransmission via blockade of serotonin transporters, while those that mainly increase the levels of dopamine and noradrenaline are devoid of sexual side effects. Those sexual disturbances cannot be normalized by simultaneously increasing noradrenaline neurotransmission, but are normalized by increasing both noradrenaline and dopamine neurotransmission. Therefore, it is hypothesized that the sexual side effects of selective serotonin reuptake inhibitors may be mediated by their inhibitory effects on dopamine signaling in sex brain circuits. Clinical development of novel antidepressants should therefore focus on compounds that simultaneously increase both serotonin and dopamine signaling.

A diagnostic dilemma: drug-induced aseptic meningitis in a 45-year-old HIV-positive man.

We describe a case of aseptic meningitis following the administration of moxifloxacin in a 45-year-old man with human immunodeficiency virus (HIV). At presentation he was receiving tuberculosis treatment on a modified regimen following severe hepatotoxicity; this included moxifloxacin, started 8 days previously. Initial cerebrospinal fluid (CSF) analysis was grossly abnormal. Anti-viral and -bacterial treatments were started. All microbiological tests proved negative and his moxifloxacin was withheld resulting in a complete normalisation of CSF. Drug-induced aseptic meningitis is a diagnosis of exclusion and presents a serious diagnostic dilemma. The decision to withhold medication cannot be taken lightly.

Gender analysis of moxifloxacin clinical trials.

PURPOSE: To determine the inclusion of women and the sex-stratification of results in moxifloxacin Clinical Trials (CTs), and to establish whether these CTs considered issues that specifically affect women, such as pregnancy and use of hormonal therapies. Previous publications about women's inclusion in CTs have not specifically studied therapeutic drugs. Although this type of drug is taken by men and women at a similar rate, adverse effects occur more frequently in the latter. METHODS: We reviewed 158 published moxifloxacin trials on humans, retrieved from MedLine and the Cochrane Library (1998-2010), to determine whether they complied with the gender recommendations published by U.S. Food and Drug Administration Guideline. RESULTS: Of a total of 80,417 subjects included in the moxifloxacin CTs, only 33.7% were women in phase I, in contrast to phase II, where women accounted for 45%, phase III, where they represented 38.3% and phase IV, where 51.3% were women. About 40.9% (n=52) of trials were stratified by sex and 15.3% (n=13) and 9% (n=7) provided data by sex on efficacy and adverse effects, respectively. We found little information about the influence of issues that specifically affect women. Only 3 of the 59 journals that published the moxifloxacin CTs stated that authors should stratify their results by sex. CONCLUSIONS: Women are under-represented in the published moxifloxacin trials, and this trend is more marked in phase I, as they comprise a higher proportion in the other phases. Data by sex on efficacy and adverse effects are scarce in moxifloxacin trials. These facts, together with the lack of data on women-specific issues, suggest that the therapeutic drug moxifloxacin is only a partially evidence-based medicine.

Cardiac repolarization with Gabapentin enacarbil in a randomized, double-blind, placebo- and active-controlled, crossover thorough QT/QTc study in healthy adults.

BACKGROUND: Gabapentin enacarbil (GEn) is a prodrug of gabapentin and is approved in the United States in adults for the management of postherpetic neuralgia and in the United States and Japan for the treatment of moderate-to-severe primary restless legs syndrome. OBJECTIVE: This study examined the lack of effect of GEn on cardiac repolarization in accordance with International Conference on Harmonisation E14 guidance. METHODS: This was a randomized, double-blind, double-dummy, placebo- and active- controlled, crossover study in healthy adults (age range, 18-50 years). Study participants received the following in randomized order with a minimum 7-day washout period between treatments: placebo at 0 hours and GEn 1200 mg at 2 hours (GEn 1200 mg group), placebo at 0 hours and GEn 6000 mg at 2 hours (GEn 6000 mg group), placebo at 0 and 2 hours (placebo group), moxifloxacin 400 mg (active control group) at 0 hours, and placebo at 2 hours (moxifloxacin group). Dose offsetting permitted moxifloxacin to be administered in the fasted state and GEn to be administered in the fed state. Assessments included continuous ECG monitoring, pharmacokinetic parameters, and safety and tolerability profiles. The primary end point was the change from baseline in the Fridericia corrected QT interval, at each time point, for the GEn 6000 mg and placebo groups. RESULTS: Of 52 adults enrolled (mean [SD] age, 30.8 [8.55] years; 50% women), 44 adults (85%) completed the study. Forty-nine adults received GEn 1200 mg, 47 received GEn 6000 mg, 48 received placebo, and 47 received moxifloxacin. The highest estimated (upper limit of the 95% CI) model-adjusted difference in mean change from baseline in the Fridericia corrected QT interval between GEn and placebo was 3.55 (5.66) msec for 1200 mg and 1.20 (3.32) msec for 6000 mg. Assay sensitivity was confirmed with moxifloxacin 400 mg. The geometric mean (%CV) Cmax (between-subject coefficient of variation) was 7.49 (21.2) µg/mL for GEn 1200 mg, 32.46 (23.9) µg/mL for GEn 6000 mg, and 2.08 (24.5) µg/mL for moxifloxacin 400 mg. The most frequently reported adverse events with GEn 6000 mg were dizziness (30%), feeling drunk (26%), nausea (15%), headache (13%), and vomiting (13%). CONCLUSION: Single doses of GEn, up to 6000 mg, had no effect on cardiac repolarization in this thorough-QT study and are unlikely to cause clinically relevant QT prolongation in clinical use. Assay sensitivity was confirmed with moxifloxacin as an active control. ClinicalTrials.gov identifier: NCT01516372.

Effects of probucol, a typical hERG expression inhibitor, on in vivo QT interval prolongation in conscious dogs.

The cholesterol-lowering drug, probucol, is known to induce QT interval prolongation and torsades de pointes in patients. Recent in vitro studies have indicated that probucol reduces hERG expression in the plasma membrane and does not directly block human ether-a-go-go-related gene (hERG) channels. The present study was performed to investigate the effects of probucol on in vivo QT interval prolongation. Epicardial electrocardiograms were recorded in conscious dogs given oral single or repeated (7 days) doses of probucol (100mg/kg), and in combination with moxifloxacin (20mg/kg). QTc intervals were analyzed by a probabilistic method with individual rate collection formulae. Values of change in QTc (QTc) interval and its integration from 1 to 21 h (AUC1-21h) were calculated to evaluate drug-induced QT prolongation. A single dose of probucol slightly but significantly increased the AUC1-21h QTc interval on days 2 and 3. The QT prolongation was markedly augmented by repeated doses of probucol in a time-dependent manner, despite the lack of increase in plasma concentration. The combination of probucol and moxifloxacin produced additive effects on QT interval prolongation. These results suggest that long-term exposure to the hERG expression inhibitor, probucol, is required to evaluate its maximal effects on in vivo QT interval prolongation. A combination of direct and indirect hERG inhibitors may produce simple additive effects on QT interval prolongation.

Evaluation of the effect of Naloxegol on cardiac repolarization: a randomized, placebo- and positive-controlled crossover thorough QT/QTc study in healthy volunteers.

BACKGROUND: Opioid-induced constipation (OIC) is a common adverse effect associated with opioid use. Naloxegol is a PEGylated derivative of naloxone in clinical development as a once-daily oral treatment of OIC. OBJECTIVES: A thorough QT/QTc study was conducted, according to International Conference on Harmonisation E14 guidelines, to characterize the effect of naloxegol on cardiac repolarization. METHODS: In this randomized, positive- and placebo-controlled crossover study, healthy men received a single dose of naloxegol 25 mg (therapeutic dose), naloxegol 150 mg (supratherapeutic dose), moxifloxacin 400 mg (positive control), or placebo in 1 of 4 sequences (Williams Latin square design). The washout time between treatment periods was at least 5 days. Digital 12-lead ECGs were recorded at baseline and at 10 time points over 24 hours after dosing in each treatment period. QT intervals were corrected for heart rate using the Fridericia formula (QTcF) and the Bazett formula (QTcB). RESULTS: A total of 52 subjects were enrolled (mean age, 28 years), and 45 received all 4 treatments. The placebo-corrected, baseline-adjusted, mean increases in QTcF with naloxegol 25 and 150 mg were both <5 msec at each time point, and all upper limits of the 2-sided 90% CI were <10 msec. Similar findings were observed using QTcB; the upper limits of the 2-sided 90% CI were <10 msec at all time points after dosing with naloxegol 25 or 150 mg. With moxifloxacin 400 mg, mean QTcF was increased by a maximum of 11.1 msec (90% CI, 9.3-12.9 msec), supporting assay sensitivity. CONCLUSION: Naloxegol at 25 and 150 mg was not associated with QT/QTc interval prolongation in these healthy men, and at the proposed therapeutic dose of 25 mg/d, naloxegol is not expected to have a clinically relevant effect on cardiac repolarization in patients with OIC. ClinicalTrials.gov identifier: NCT01325415.

[Fluoroquinolone associated myasthenia gravis exacerbation: clinical analysis of 9 cases].

OBJECTIVE: To explore the characteristics of acute exacerbations of myasthenia gravis after fluoroquinolone exposure. METHODS: Gender, age, prior type, absolute score, concurrent disease, precipitated disease, use of antibiotic, onset/symptom/degree of exacerbation, therapeutic measures and prognosis at Month 1 were retrospectively analyzed for 9 patients after fluoroquinolone systemic exposure. RESULTS: Ciprofloxacin (n = 4), levofloxacin (n = 1) and moxifloxacin (n = 4) exposure resulted in myasthenia gravis exacerbation. Myasthenia gravis exacerbations developed at 15 minutes to 4 days post-exposure. And the clinical scores of quantitative myasthenia gravis (QMG) increased by an average of 10. The main syndromes included dyspnea, diplopia, ptosis and dysphagia. All patients improved upon the withdrawal of fluoroquinolone in conjunctions with other interventions. CONCLUSION: Fluoroquinolone exposure may result in myasthenia gravis exacerbations in patients with underlying diseases. Healthcare professionals should be aware of this serious drug-disease association.

Single daily dose of moxifloxacin versus ofloxacin plus metronidazole as a new treatment approach to uncomplicated pelvic inflammatory disease: a multicentre prospective randomized trial.

OBJECTIVES: To evaluate the efficacy and safety of moxifloxacin versus ofloxacin plus metronidazole in patients with uncomplicated pelvic inflammatory disease (uPID; defined as PID symptoms and signs, but no complications such as septicemia, perihepatitis, and tubo-ovarian abscess) in Turkey. STUDY DESIGN: This was a multicenter, prospective, randomized, parallel-group study conducted between June 2010 and March 2013 in four hospitals in Turkey. Women received a 14-day course of either oral moxifloxacin at 400mg once daily (n = 560) or oral ofloxacin at 400mg twice daily plus oral metronidazole at 500 mg twice daily (n = 543). RESULTS: A total of 1156 women were randomized to the study. Total compliance was achieved in 1103 patients. For the primary measure of efficacy (clinical cure), moxifloxacin showed no difference compared with ofloxacin plus metronidazole (445/560 [79.5%] vs. 449/543 [82.7%]; p = 0.172). Bacteriological cure rates were high and comparable between treatment arms (99/119 [83.2%] vs. 93/110 [84.5%]; p = 0.781). Drug-related adverse events occurred less frequently with moxifloxacin than with ofloxacin plus metronidazole (210/560 [37.5%] vs. 252/543 [46.4%]; p = 0.003). Furthermore, moxifloxacin treatment was lower in cost and achieved higher patient compliance compared with ofloxacin plus metronidazole (31.4 Euros vs. 23.4 Euros and 7/578 (1.2%) vs. 22/578 (3.8%), respectively; p = 0.005). CONCLUSIONS: In patients with uPID, once-daily moxifloxacin monotherapy was clinically and microbiologically as efficacious as twice-daily ofloxacin plus metronidazole therapy and was associated with fewer drug-related adverse events, lower patient non-compliance, and a lower treatment cost.

Efficacy and safety of prophylactic intracameral moxifloxacin injection in Japan.

PURPOSE: To report endophthalmitis rates after cataract surgery and the incidence of complications after intracameral moxifloxacin injection. SETTING: Nineteen clinics in Japanese institutions. DESIGN: Retrospective survey cohort study. METHODS: The number of surgeries and endophthalmitis cases in the past 4 years before and after the introduction of intracameral moxifloxacin was evaluated. The survey was performed by mail or interview in February 2013. RESULTS: All institutions used total-replacement administration rather than small-volume injection. At 3 institutions, 50 to 100 µg/mL moxifloxacin; at 9 institutions, 100 to 300 µg/mL moxifloxacin; and at 7 institutions, 500 µg/mL moxifloxacin was administered. The highest concentration (500 µg/mL) was administered in 14,124 cases. Endophthalmitis cases occurred 1 month or sooner postoperatively in 8 of 15,958 cases (ie, 1 in 1955) without intracameral moxifloxacin administration and in 3 of 18,794 cases (ie, 1 in 6265) with intracameral moxifloxacin administration. CONCLUSIONS: Intracameral moxifloxacin (50 to 500 µg/mL) administration decreased the risk for endophthalmitis by 3-fold. In more than 18,000 cases, moxifloxacin administration of 500 µg/mL or less did not result in severe complications, such as toxic anterior segment syndrome or corneal endothelial cell loss.

Sequential intravenous/oral moxifloxacin monotherapy for complicated skin and skin structure infections: a meta-analysis of randomised controlled trials.

OBJECTIVES: The presumed superiority of moxifloxacin for the treatment of complicated skin and skin structure infections (cSSSIs) is based on laboratory data, but has not yet been established on clinical grounds. The aim of this meta-analysis was to evaluate the efficacy and safety of sequential intravenous (i.v.)/oral (p.o.) moxifloxacin monotherapy for the treatment of cSSSIs. METHODS: Randomised controlled trials (RCTs) published prior to November 2012 were systematically retrieved from PubMed, MEDLINE, EMBASE, ScienceDirect, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials. Finally, a meta-analysis of all RCTs eligible for inclusion criteria was performed. RESULTS: Three studies that enrolled 2255 patients were included in the meta-analysis. There were no statistically significant differences between patients given moxifloxacin and those given other antibiotics with regard to clinical success rate [1667 patients, odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.63 to 1.09, p = 0.18], bacteriological success rate (bacteriological success rates: 1502 patients, OR = 0.90, 95% CI 0.68-1.18, p = 0.45) or mortality (2207 patients, OR = 1.96, 95% CI 0.79-4.88, p = 0.15). Significantly, more overall adverse events (AEs) were associated with the use of moxifloxacin than with other antibiotics (2207 patients, OR = 1.21, 95%CI 1.00-1.45, p = 0.04). However, there was no statistically significant difference in the occurrence of drug-related AEs, serious AEs or serious drug-related AEs between patients given moxifloxacin and those given other antibiotics. CONCLUSION: Sequential i.v./p.o. moxifloxacin monotherapy is an effective and relatively safe option for the treatment of cSSSIs. Other benefits of moxifloxacin may make it a more viable option compared with the currently used regimens.

Electrocardiographic safety of cangrelor, a new intravenous antiplatelet agent: a randomized, double-blind, placebo- and moxifloxacin-controlled thorough QT study.

Cangrelor is an intravenous P2Y12 inhibitor under investigation as an antiplatelet drug in the setting of acute coronary syndromes. To determine the electrophysiologic safety of parenteral cangrelor, cardiac repolarization effects were measured in 67 healthy volunteers (aged 18-45 years) in a randomized crossover design, including 4 treatment sequences of therapeutic cangrelor, supratherapeutic cangrelor, placebo, and moxifloxacin (positive control). Triplicate electrocardiogram measurements and pharmacokinetic samples were collected at baseline and 9 time points postdose on day 1. For both cangrelor and moxifloxacin, time-matched, placebo-adjusted change in QT from baseline was evaluated using an individual (QTcI) heart rate correction. After cangrelor dosing, change in QTcI was <5 ms at all times points and all corresponding upper 2-sided 90% confidence intervals (CIs) were <10 ms. Although moxifloxacin failed to show a lower CI >5 ms, expected time trends and lower CI >4.0 ms demonstrate assay sensitivity. QTcI was not affected by plasma concentrations of cangrelor metabolites, and cangrelor had no other adverse effects on electrocardiographic parameters. Clinically, cangrelor exposure was well tolerated. Thus, this thorough QT study demonstrated that therapeutic and supratherapeutic cangrelor doses do not adversely affect cardiac repolarization in normal volunteers (clinicaltrials.gov; identifier NCT00699504).

US-based emergency department visits for fluoroquinolone-associated hypersensitivity reactions.

PURPOSE: To estimate the rate of hypersensitivity reactions per 100,000 prescription dispensings of fluoroquinolones based on care rendered in a nationally representative sample of US hospital emergency departments (ED). METHODS: We analyzed the frequency of fluoroquinolone-associated hypersensitivity reactions using the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance system (2004-2010) in conjunction with US retail outpatient prescription data from IMS Health (2004-2010). We further categorized reaction severity into three subgroups (mild, moderate, and severe). RESULTS: Based on 1422 cases of fluoroquinolone-associated hypersensitivity reactions and national drug utilization projections, we estimated risk of hypersensitivity reactions for moxifloxacin, ciprofloxacin, and levofloxacin. The absolute risk of a fluoroquinolone-related hypersensitivity reaction of any severity was low (44.0 (95% CI 34.8-53.3) ED visits/100,000 prescriptions); however, we identified a statistically significant difference in the relative risk (rate ratios) of seeking care in an ED attributed to moxifloxacin hypersensitivity compared to either levofloxacin or ciprofloxacin. For all reaction severities, the estimated ED visits/100,000 prescriptions were 141.3 (95% CI 99.9-182.7) for moxifloxacin, 40.8 (95% CI 31.5-50.0) for levofloxacin, and 26.3 (95% CI 20.8-31.9) for ciprofloxacin. When the rates were stratified by reaction severity category (mild or moderate-severe), moxifloxacin continued to be implicated in more ED visits per 100,000 prescriptions dispensed than either levofloxacin or ciprofloxacin. CONCLUSION: Fluoroquinolones may cause hypersensitivity reactions requiring care in an ED, and relative to use, the rate of moxifloxacin-related hypersensitivity reactions is higher compared to levofloxacin or ciprofloxacin.