Seizures associated with fluoroquinolones

Fluoroquinolones and the risk for incidental seizures: a comparative retrospective study

BACKGROUND

Over the years, reports have associated fluoroquinolones (FQ) with seizures. The incidence and whether FQ compared to non-epileptogenic antibiotic are associated with increased risk of seizures has yet to be examined.

METHODS

A retrospective observational study of hospitalized patients treated with FQ (ofloxacin, ciprofloxacin, levofloxacin, moxifloxacin) or macrolides (MA: azithromycin or roxithromycin) between January 2009 and January 2021 in a large tertiary academic medical centre. The outcome was the occurrence of a seizure during treatment. The Naranjo scale was used to assess causality between FQ treatment and seizures. Comparative analysis was conducted using propensity score matching to correct for possible bias due to non-random selection, followed by inverse probability weighting (IPW) to estimate the difference in seizure risk between FQ and MA.

RESULTS

Overall, 52 722 patients were treated with FQ during a total of 178 982 days. Mean age was 65 (±19) years and 47% were females. Thirty-three patients (0.06%) experienced a seizure, yielding an incidence of 1:5422 treatment days. Causality was deemed probable and possible among 9/33 and 24/33, respectively. The MA group composed of 8522 patients treated during 17 954 treatment days. Mean age was 65 (±21) years, 49% were females. Six (0.07%) patients experienced each a single seizure. IPW estimated OR for seizures among the FQ versus MA group was 1.44 (95%CI 0.59-3.5, P = 0.42).

DISCUSSION

The incidence of FQ associated seizures among hospitalized patients is low and the risk did not significantly exceed that under macrolides. Our results provide evidence for clinicians and decision-makers when balancing fluoroquinolones risks and benefits.

Antibiotic persistence and its impact on the environment

From boon molecules to molecules contributing to rising concern has been the sojourn of antibiotics. The problem of antibiotic contamination has gotten worse due to antibiotics' pervasive use in every aspect of the environment. One such consequence of pollution is the increase in infections with antibiotic resistance. All known antimicrobials being used for human benefit lead to their repetitive and routine release into the environment. The misuse of antibiotics has aggravated the situation to a level that we are short of antibiotics to treat infections as organisms have developed resistance against them. Overconsumption is not just limited to human health care, but also occurs in other areas such as aquaculture, livestock, and veterinary applications for the purpose of improving feed and meat products. Due to their harmful effects on non-target species, the trace level of antibiotics in the aquatic ecosystem presents a significant problem. Since the introduction of antibiotics into the environment is more than their removal, they have been given the status of persistent pollutants. The buildup of antibiotics in the environment threatens aquatic life and may lead to bacterial strains developing resistance. As newer organisms are becoming resistant, there exists a shortage of antibiotics to treat infections. This has presented a very critical problem for the health-care community. Another rising concern is that the development of newer drug molecules as antibiotics is minimal. This review article critically explains the cause and nature of the pollution and the effects of this emerging trend. Also, in the latter sections, why we need newer antibiotics is questioned and discussed.

The tale of antibiotics beyond antimicrobials: Expanding horizons

Antibiotics had proved to be a godsend for mankind since their discovery. They were once the magical solution to the vexing problem of infection-related deaths. German scientist Paul Ehrlich had termed salvarsan as the silver bullet to treatsyphilis.As time passed, the magic of newly discovered silver bullets got tarnished with raging antibiotic resistance among bacteria and associated side-effects. Still, antibiotics remain the primary line of treatment for bacterial infections. Our understanding of their chemical and biological activities has increased immensely with advancement in the research field. Non-antibacterial effects of antibiotics are studied extensively to optimise their safer, broad-range use. These non-antibacterial effects could be both useful and harmful to us. Various researchers across the globe including our lab are studying the direct/indirect effects and molecular mechanisms behind these non-antibacterial effects of antibiotics. So, it is interesting for us to sum up the available literature. In this review, we have briefed the possible reason behind the non-antibacterial effects of antibiotics, owing to the endosymbiotic origin of host mitochondria. We further discuss the physiological and immunomodulatory effects of antibiotics. We then extend the review to discuss molecular mechanisms behind the plausible use of antibiotics as anticancer agents.

Seizures associated with antibiotics: a real-world disproportionality analysis of FAERS database

BACKGROUND

Drug-induced seizures are a common occurrence in clinical practice, with research indicating that around 6% of initial seizures are due to drug toxicity. The use of antibiotics is one such cause of drug-related seizures. Previous systematic review has identified specific antibiotics that pose a risk of seizures, but a comprehensive analysis of a large patient sample is needed to determine the risk associated with various drugs.

OBJECTIVE

This study aimed to evaluate the association between seizures and various antibiotics that are presently accessible.

METHODS

To identify potential risk signals from the US Food and Drug Administration adverse event reporting system (FAERS) database, a disproportionality analysis was conducted. The reporting odds ratio (ROR) using the frequency approach and the information component (IC) using the Bayesian approach were used to detect signals. The median time-to-onset of seizure, as well as the Weibull distribution parameters were calculated to analyze the onset time.

RESULTS

A total of 14,407,157 FAERS reports were analyzed.10 antibiotics were associated with seizures that were defined by 41 preferred terms. Onset time were aligned with the wear out failure type profile.

CONCLUSION

This study identified 10 antibiotics that showed significant associations with seizures. Imipenem-cilastatin had the highest seizure ROR.

Head rebound test in the clinical neurological examination of veterinary patients: a case example and discussion of Stewart and Holmes' rebound phenomenon

In human medical neurology, the clinical neurological examination is variably augmented by specific tests that may be either unsuitable for veterinary patients or not included in the clinical evaluation of veterinary neurological patients due to clinicians presumably being unfamiliar with these tests. An example of the latter can be found in testing for the Stewart and Holmes' rebound phenomenon ("rebound test"). In this article, a veterinary case example is presented in which a modified version of this test was performed ("head rebound test"). The interpretation of the results of this test is discussed, and the literature on the Stewart and Holmes' rebound phenomenon and testing thereof is reviewed.

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.

Cerebrospinal fluid concentrations of fluoroquinolones and carbapenems in tuberculosis meningitis

Background: Tuberculosis meningitis (TBM) is the most lethal form of TB. It is difficult to treat in part due to poor or uncertain drug penetration into the central nervous system (CNS). To help fill this knowledge gap, we evaluated the cerebrospinal fluid (CSF) concentrations of fluoroquinolones and carbapenems in patients being treated for TBM. Methods: Serial serum and CSF samples were collected from hospitalized patients being treated for TBM. CSF was collected from routine lumbar punctures between alternating timepoints of 2 and 6 h after drug administration to capture early and late CSF penetration. Rich serum sampling was collected after drug administration on day 28 for non-compartmental analysis. Results: Among 22 patients treated for TBM (8 with confirmed disease), there was high use of fluoroquinolones (levofloxacin, 21; moxifloxacin, 10; ofloxacin, 6) and carbapenems (imipenem, 11; meropenem, 6). Median CSF total concentrations of levofloxacin at 2 and 6 h were 1.34 mg/L and 3.36 mg/L with adjusted CSF/serum ratios of 0.41 and 0.63, respectively. For moxifloxacin, the median CSF total concentrations at 2 and 6 h were 0.78 mg/L and 1.02 mg/L with adjusted CSF/serum ratios of 0.44 and 0.62. Serum and CSF concentrations of moxifloxacin were not affected by rifampin use. Among the 76 CSF samples measured for carbapenem concentrations, 79% were undetectable or below the limit of detection. Conclusion: Fluoroquinolones demonstrated high CSF penetration indicating their potential usefulness for the treatment of TBM. Carbapenems had lower than expected CSF concentrations.

Responses to antibiotics in human iPSC-derived neurons based on the clinical antibiotic-associated encephalopathy classification

Antibiotic-associated encephalopathy (AAE) is a central nervous system disorder caused by antibiotics administration and classified into three types based on clinical symptoms. Type 1 AAE causes seizures and myoclonus, type 2 causes psychiatric symptoms, and type 3 is characterized by cerebellar ataxia. In this study, we investigated whether the electrical activity of in vitro human iPSC-derived neurons to antibiotics could be classified based on the 3 types of AAEs classified by clinical symptoms. Glutamatergic, GABAergic neurons and astrocytes differentiated from human iPS cells were seeded on micro-electrode array (MEA). The cumulative administration of 13 different antimicrobials detected changes in neural activity that differed according to AAE type. Next, we classified the antimicrobials by principal component analysis (PCA) and confirmed the AAE type of each agent. We found that Types 1-3 AAE agents were distributed separately. The classification of antibiotics depending on electrophysiological response characteristics was consistent with the clinical practice classification of AAEs. In conclusion, the combination of electrophysiological responses of human iPS cell-derived neural networks measured by MEA plus multivariate analysis methods will effectively detect and classify antibiotics developmental risks.

Host bioenergetic parameters reveal cytotoxicity of anti-tuberculosis drugs undetected using conventional viability assays

High attrition rates in tuberculosis (TB) drug development have been largely attributed to safety, which is likely due to the use of endpoint assays measuring cell viability to detect drug cytotoxicity. In drug development for cancer, metabolic, and neurological disorders and for antibiotics, cytotoxicity is increasingly being assessed using extracellular flux (XF) analysis, which measures cellular bioenergetic metabolism in real time. Here, we adopt the XF platform to investigate the cytotoxicity of drugs currently used in TB treatment on the bioenergetic metabolism of HepG2 cells, THP-1 macrophages, and human monocyte-derived macrophages (hMDMs). We found that the XF analysis reveals earlier drug-induced effects on the cells’ bioenergetic metabolism prior to cell death, measured by conventional viability assays. Furthermore, each cell type has a distinct response to drug treatment, suggesting that more than one cell type should be considered to examine cytotoxicity in TB drug development. Interestingly, chemically unrelated drugs with different modes of action on Mycobacterium tuberculosis have similar effects on the bioenergetic parameters of the cells, thus discouraging the prediction of potential cytotoxicity based on chemical structure and mode of action of new chemical entities. The clustering of the drug-induced effects on the hMDM bioenergetic parameters are reflected in the clustering of the effects of the drugs on cytokine production in hMDMs, demonstrating concurrence between the effects of the drugs on the metabolism and functioning of the macrophages. These findings can be used as a benchmark to establish XF analysis as a new tool to assay cytotoxicity in TB drug development.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

Antibiotic-induced epileptic seizures: mechanisms of action and clinical considerations

In recent years, there has been growing interest in the development of epileptic seizures as an adverse effect of antibiotic therapy. The most commonly accepted mechanisms underlying the development of antibiotic-induced seizures include direct- and indirect gamma-aminobutyric acid (GABA) antagonism, inhibition of GABA synthesis, and glutaminergic N-methyl-D-Aspartate (NMDA) receptor agonistic activity. Inhibitory pathway inhibition leads to increased neuronal excitability and lowered seizure threshold. Blockage of myoneural presynaptic acetylcholine release, mitochondrial dysfunction, interference of neural protein synthesis, and oxidative stress caused by the generation of neurotoxic radicals also contributes to the development of neurotoxicity. Patients with pre-existing risk factors such as renal or hepatic insufficiency, central nervous system pathology, neurological diseases, history of epilepsy or seizures, critical illness, and increased age are more susceptible to seizure development as a consequence of antibiotic therapy. Administration of antibiotics, together with antiseizure drugs, may also lead to enhanced seizure risk due to drug interactions, which predisposes to alterations in drug metabolism and therapeutic efficacy.

Quinolones-Induced Musculoskeletal, Neurological, and Psychiatric ADRs: A Pharmacovigilance Study Based on Data From the Italian Spontaneous Reporting System

Background

The use of quinolones has been associated with the development of serious and persistent adverse drug reaction (ADR) mainly affecting muscles, joints and the nervous system. This risk has led the European Medicines Agency (EMA) to endorse some restrictions on the use of this class of antibiotic. Therefore, we performed a study to primary estimate the reporting probability of musculoskeletal, neurological, and psychiatric ADRs among quinolone generations using national data.

Methods

We retrieved Individual Case Safety Reports (ICSRs) with a quinolone as suspected drug among those reported through the Campania spontaneous reporting system from January 1^st, 2001 to April 30^th 2019. Moreover, we retrieved national aggregated safety data from the online public report system (RAM system) for the period from January 1^st, 2002 to March 31^st, 2019. Risk factors were classified as “age greater than 60 years,” “therapeutic indication,” “renal failure,” “organ transplantation,” “use of corticosteroid,” and “history of side effects”. Reporting odds ratio (ROR) was computed to evaluate the reporting probability of musculoskeletal, neurological, or psychiatric events among quinolones generations.

Results

A total of 87 ICSRs with a quinolone as suspected drug that reported at least one musculoskeletal, neurological, and psychiatric adverse event were identified in the Campania spontaneous reporting system. Forty-nine (56.3%) ICSRs reported risk factors (total risk factors 59). The most reported risk factor was “age greater than 60 years” (69.5%), followed by “therapeutic indication” (16.9%), “renal failure” (5.1%), “organ transplantation” (3.4%), “use of corticosteroid” (3.4%), and “history of side effects” (1.7%). Second-generation quinolones were associated with a lower reporting probability of musculoskeletal (ROR 0.70; 95% CI 0.63–0.79), neurological (ROR 0.81; 95% CI 0.73–0.90), and psychiatric (ROR 0.55; 95% CI 0.44–0.63) ADRs compared to the third generation of quinolones.

Conclusions

Our findings showed that third-generation quinolones were always associated with a higher reporting probability of musculoskeletal, neurological, and psychiatric ADRs compared to the second generation ones. Moreover, we described risk factors in more than half of our cases suggesting that the inappropriate use of quinolones is a phenomenon that may frequently predispose patients to the occurrence of these ADRs.

Delafloxacin: an improved fluoroquinolone developed through advanced molecular engineering

The emergence of antimicrobial resistance threatens current clinical practice across a range of infection types. Delafloxacin, a non-zwitterionic fluoroquinolone recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections, has been developed to address some of these challenges. Uniquely delafloxacin has increased intracellular penetration and enhanced antibacterial activity under acidic conditions, an environment seen in many infection sites including abscesses. Delafloxacin is active against a wide range of Gram-positive and -negative species including methicillin-resistant Staphylococcus aureus and many fluoroquinolone-resistant strains. Additionally, according to preclinical and clinical trial data, well-known adverse events related to fluoroquinolone class do not appear to occur with this new molecule. Delafloxacin has been studied in acute bacterial skin and skin structure infections with >1400 patients exposed to both intravenous and oral formulation for up to 14 days and has shown noninteriority to vancomycin with or without aztreonam. For its interesting microbiological and pharmacokinetic/pharmacodynamics characteristics and for its safety profile, delafloxacin represents a very promising option for the treatment of infections caused by multidrug-resistant pathogens.

Moxifloxacin-Induced Seizures in an Epileptic Patient

Objective:

To report a patient with seizures probably related to the use of moxifloxacin, a fourth-generation quinolone.

Case Summary:

A 79-year-old white man developed status epilepticus after a 4-day course of moxifloxacin for respiratory infection. He had experienced seizures 2 years before presentation. The patient was currently receiving warfarin, theophylline 400 mg/d, albuterol; furosemide, potassium, and digoxin; and omeprazole for chronic obstructive pulmonary disease, atrial fibrillation with mild heart failure, and heartburn, respectively. He also had moderate renal failure. Despite aggressive therapy, the patient developed progressive respiratory insufficiency and died.

Discussion:

Quinolone use is associated with a variety of central nervous system (CNS) adverse effects in approximately 1–2% of patients. In fact, CNS adverse effects represent the second most frequently encountered form of quinolone toxicity after gastrointestinal involvement. Occasionally, quinolones induce seizures, but, as of October 17, 2003, none have been reported in the literature. Use of the Naranjo probability scale indicated a probable relationship between seizures and moxifloxacin administration in this patient. Seizures may be mediated by CNS stimulation secondary to quinolone binding to γ-aminobutyric acid receptors. Coexisting medical conditions and concurrent medications also facilitate seizure appearance. Risk factors include seizure history, hypokalemia, alkalosis, renal failure, and concomitant treatment with agents that lower the seizure threshold. These factors were not present in this patient except for a prior history of seizures and mild renal failure.

Conclusions:

Seizures with quinolones, albeit rare, need to be considered in certain populations, particularly patients who have had prior seizures, the elderly, patients with renal dysfunction, and patients on multiple medications.

Pharmacokinetic Alterations of Antimicrobials in the Critically Ill

Critical illness is accompanied by multiple physiologic alterations that affect the pharmacokinetics of antimicrobials. Although the pharmacokinetics of a number of antimicrobials have been studied in critically ill individuals, an understanding of the physiological alterations in critical illness and general pharmacokinetic principles of antimicrobials is imperative for appropriate selection, dosing, and prediction of toxicity.

Kynurenine Aminotransferase Isozyme Inhibitors: A Review

Kynurenine aminotransferase isozymes (KATs 1–4) are members of the pyridoxal-5’-phosphate (PLP)-dependent enzyme family, which catalyse the permanent conversion of l-kynurenine (l-KYN) to kynurenic acid (KYNA), a known neuroactive agent. As KATs are found in the mammalian brain and have key roles in the kynurenine pathway, involved in different categories of central nervous system (CNS) diseases, the KATs are prominent targets in the quest to treat neurodegenerative and cognitive impairment disorders. Recent studies suggest that inhibiting these enzymes would produce effects beneficial to patients with these conditions, as abnormally high levels of KYNA are observed. KAT-1 and KAT-3 share the highest sequence similarity of the isozymes in this family, and their active site pockets are also similar. Importantly, KAT-2 has the major role of kynurenic acid production (70%) in the human brain, and it is considered therefore that suitable inhibition of this isozyme would be most effective in managing major aspects of CNS diseases. Human KAT-2 inhibitors have been developed, but the most potent of them, chosen for further investigations, did not proceed in clinical studies due to the cross toxicity caused by their irreversible interaction with PLP, the required cofactor of the KAT isozymes, and any other PLP-dependent enzymes. As a consequence of the possibility of extensive undesirable adverse effects, it is also important to pursue KAT inhibitors that reversibly inhibit KATs and to include a strategy that seeks compounds likely to achieve substantial interaction with regions of the active site other than the PLP. The main purpose of this treatise is to review the recent developments with the inhibitors of KAT isozymes. This treatise also includes analyses of their crystallographic structures in complex with this enzyme family, which provides further insight for researchers in this and related studies.

Association between oral fluoroquinolones and seizures: A self-controlled case series study

OBJECTIVES

The aim of this study was to investigate the association and to estimate the crude absolute risk of seizure among patients exposed to fluoroquinolones (FQs) in Hong Kong and the United Kingdom.

METHODS

A self-controlled case series study was conducted. Data were collected from the Hong Kong Clinical Data Analysis and Reporting System database and the Clinical Practice Research Datalink. Patients who were prescribed any oral FQ and had an incident seizure diagnosis from 2001 to 2013 were included. The risk windows were defined as pre-FQ start, FQ-exposed, and post-FQ completion. Incidence rate ratios were estimated in all risk windows and compared with baseline periods. A post hoc subgroup analysis was conducted to examine the effect of patients with a history of seizure.

RESULTS

An increased incidence rate ratio was found in the pre-FQ start periods and no association was found in the post-FQ completion periods in both databases. The crude absolute risk of an incident seizure in 10,000 oral FQ prescriptions was 0.72 (95% confidence interval 0.47-1.10) in the Clinical Data Analysis and Reporting System and 0.40 (95% confidence interval 0.30-0.54) in the Clinical Practice Research Datalink. The rate ratio during treatment was not higher than pre-FQ start periods among patients with a history of seizure, therefore the results did not raise serious concerns.

CONCLUSIONS

This study does not support a causal association between the use of oral FQs and the subsequent occurrence of seizure. An increased risk before the FQ exposure period suggests that the clinical indication for which FQ was prescribed may have contributed to the development of seizure rather than the drug itself.

Safety and tolerability profile of second-line anti-tuberculosis medications

Tuberculosis (TB) remains a major public health problem, representing the second leading cause of death from infectious diseases globally, despite being nearly 100 % curable. Multidrug-resistant (MDR)-TB, a form of TB resistant to isoniazid and rifampicin (rifampin), two of the key first-line TB drugs, is becoming increasingly common. MDR-TB is treated with a combination of drugs that are less effective but more toxic than isoniazid and rifampicin. These drugs include fluoroquinolones, aminoglycosides, ethionamide, cycloserine, aminosalicyclic acid, linezolid and clofazimine among others. Minor adverse effects are quite common and they can be easily managed with symptomatic treatment. However, some adverse effects can be life-threatening, e.g. nephrotoxicity due to aminoglycosides, cardiotoxicity due to fluoroquinolones, gastrointestinal toxicity due to ethionamide or para-aminosalicylic acid, central nervous system toxicity due to cycloserine, etc. Baseline evaluation may help to identify patients who are at increased risk for adverse effects. Regular clinical and laboratory evaluation during treatment is very important to prevent adverse effects from becoming serious. Timely and intensive monitoring for, and management of adverse effects caused by, second-line drugs are essential components of drug-resistant TB control programmes; poor management of adverse effects increases the risk of non-adherence or irregular adherence to treatment, and may result in death or permanent morbidity. Treating physicians should have a thorough knowledge of the adverse effects associated with the use of second-line anti-TB drugs, and routinely monitor the occurrence of adverse drug reactions. In this review, we have compiled safety and tolerability information regarding second-line anti-TB drugs in both adults and children.

Fluoroquinolone antibiotics and type 2 diabetes mellitus

Exposure to fluoroquinolone antibiotics is postulated as a risk factor for subsequent development of type 2 diabetes. It is hypothesized that fluoroquinolones induce an intracellular magnesium deficit that can lead to insulin resistance. A temporal correlation is reported between the rate of outpatient prescription of quinolones and the incidence of diabetes during the period 1980-2011 with a lag of approximately two years (R(2)=0.86, P<10(-9)). The increase in incidence of diabetes after 1990 and the recent decrease in the number of new cases are both reflected in the fluoroquinolone prescription rates. A geographical correlation is reported (adj. R(2)=0.7, P<0.0001) between rates of increase in prevalence of diabetes in each U.S. state and a model using only local rates of outpatient fluoroquinolone prescription, local rates of increase in the prevalence of obesity, and local rates of population growth as predictor variables. Prescription rates of non-quinolone antibiotics correlated less well with the local rates of increase in prevalence of diabetes. The data are consistent with fluoroquinolone exposure predisposing an individual to develop diabetes with a probability that strongly depends upon factors that also lead to an increase in obesity. According to the hypothesis, much of the increase in the incidence of type 2 diabetes in the U.S. from 1990 to the present can be attributed to fluoroquinolone exposure.

Compliance with Renal Dosing Guidelines for Outpatient Antiinfective Prescriptions

Background:

More than 80–95% of adverse drug events occurring among renally impaired patients are related to excessive dosing.

Objective:

To assess current prescribing practices with antiinfectives for patients with estimated creatinine clearance (CrCl) less than 51 mL/min who were in a local health care system.

Methods:

Outpatient antiinfective prescriptions written during a 10-day period in July 2012 were reviewed. The following information was collected for each patient: age, sex, serum creatinine, weight, height, drug dose and schedule, and discharge unit/outpatient service. Kidney function was estimated by calculating CrCl using either the Cockcroft-Gault or the Jelliffe equation. Two resources were used to identify appropriate dosing for renal function; if the 2 resources differed, the stricter of the 2 was used for assessment. Institutional review board approval was obtained for this study.

Results:

A total of 91 prescriptions, written for 87 different patients, met inclusion criteria and were reviewed. Average CrCl and age among the study population was 37.82 mL/min, and 75.7 years, respectively. Doses were excessive in 30% of outpatient prescriptions. The most common medications involved in excessive dosing were trimethoprim/sulfamethoxazole (TMP/SMX), cephalexin, fluconazole, and acyclovir. TMP/SMX was dosed excessively in 80% of prescriptions. Both fluconazole and acyclovir were dosed excessively in 75% of prescriptions, while cephalexin was dosed in excess in 36% of prescriptions. A comparison of discharge units/outpatient services revealed that 56% of prescriptions from urgent care centers were dosed in excess, compared with 30% from hospital discharge, 20% from emergency department discharge, and 25% from outpatient services.

Conclusions:

Our study indicates that there is room for improvement when dosing antiinfective medications for outpatients with renal insufficiency. Appropriate renal dosing can help protect patients from dangerous toxicities and other adverse drug events.

Fluoroquinolone toxicity symptoms in a patient presenting with low back pain

Fluoroquinolone medications have been shown to contribute to tendinopathies, cardiotoxicity, and neurotoxicity. Low back pain is a common musculoskeletal condition for which chiropractic treatment is most often sought. This case report details a patient presenting with low back pain and a history of fluoroquinolone toxicity. The patient was initially treated with chiropractic manipulation, which increased her symptoms. She was then referred to an osteopathic physician who treated the patient with intravenous antioxidants and amino acids, an elimination diet, and probiotic supplementation. Within 4 months of therapy, the patient reported a decrease in pain, a resolution of her dizziness, shortness of breath, panic attacks, tachycardia, and blurred vision. After an additional 8 weeks of antioxidant therapy, she reported further reductions in pain and improved disability. People susceptible to fluoroquinolone toxicity may present with common musculoskeletal symptoms. A past medical history and medication history may help to identify this population of patients. People presenting with fluoroquinolone toxicity may have unidentified contributing factors that predispose them to this anomaly. This patient reported improvements in pain and disability following antioxidant amino acid therapy for a total of 6 months. The natural history of fluoroquinolone toxicity is unknown and may account for the observed improvements.

Sustained ocular delivery of ciprofloxacin using nanospheres and conventional contact lens materials

PURPOSE

To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity.

METHODS

A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL).

RESULTS

Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 10(7) or 10(8) bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 10(7)/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 10(9) total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours.

CONCLUSIONS

Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders.

Levofloxacin-induced delirium: is it a dangerous drug in patients with renal dysfunction?

The central nervous system (CNS) toxicity of fluoroquinolones is well known but usually occurs benign. In the literature, there are a few number of severe CNS toxicity cases related to fluoroquinolones. Levofloxacin is a third-generation fluorinated quinolone antibiotic, is the active levo stereoisomer of ofloxacin, and has one of the most favorable adverse reaction profiles. We describe a case of delirium associated with levofloxacin in a 55-year-old man who was hospitalized in our medical clinic for pneumonia.

Neurotoxic effects associated with antibiotic use: management considerations

The clinical manifestations of antibiotic-induced neurotoxic effects, the underlying mechanisms and management strategies have been reviewed. PubMed and OVID searches (January 1960-June 2010) were conducted using search terms such as antibiotics, side effects, neurotoxicity and encephalopathy which yielded approximately 300 articles. All relevant case reports, case series, letters and retrospective reviews describing neurotoxic effects and those discussing mechanisms of neurotoxicity were included. Antibiotic-induced neurotoxic side effects can have a myriad of neurologic presentations. Patients with prior central nervous system (CNS) disease, renal insufficiency and advanced age may be particularly vulnerable. Treatment consists of discontinuation of the offending agent, use of antiepileptic drugs in the case of seizures or status epilepticus and haemodialysis in certain cases. The risk of CNS toxicity may be reduced via dosage adjustments in high risk populations. Awareness of the potential neurotoxic clinical manifestations of various antibiotics and high degree of vigilance in critically ill patients is essential in identifying a potentially serious, though reversible complications of antibiotic therapy particularly with the advent of newer antimicrobial agents.

Quinolones: review of psychiatric and neurological adverse reactions

Quinolones are a class of antibacterial agents for the treatment of several infectious diseases (e.g. urinary and respiratory tract infections). They are used worldwide due to their broad spectrum of activity, high bioavailability and good safety profile. The safety profile varies from quinolone to quinolone. The aim of this article was to review the neurological and psychiatric adverse drug reaction (ADR) profile of quinolones, using a literature search strategy designed to identify case reports and case series. A literature search using PubMed/MEDLINE (from inception to 31 October 2010) was performed to identify case reports and case series related to quinolone-associated neurological and psychiatric ADRs. The search was conducted in two phases: the first phase was the literature search and in the second phase relevant articles were identified through review of the references of the selected articles. Relevant articles were defined as articles referring to adverse events/reactions associated with the use of any quinolone. Abstracts referring to animal studies, clinical trials and observational studies were excluded. Identified case reports were analysed by age group, sex, active substances, dosage, concomitant medication, ambulatory or hospital-based event and seriousness, after Medical Dictionary for Regulatory Activities (MedDRA®) coding. From a total of 828 articles, 83 were identified as referring to nervous system and/or psychiatric disorders induced by quinolones. 145 individual case reports were extracted from the 83 articles. 40.7% of the individual case reports belonged to psychiatric disorders only, whereas 46.9% related to neurological disorders only. Eight (5.5%) individual case reports presented both neurological and psychiatric ADRs. Ciprofloxacin, ofloxacin and pefloxacin were the quinolones with more neurological and psychiatric ADRs reported in the literature. Ciprofloxacin has been extensively used worldwide, which may explain the higher number of reports, while for ofloxacin and pefloxacin, the number of reports may be over-representative. A total of 232 ADRs were identified from the selected articles, with 206 of these related to psychiatric and/or neurological ADRs. The other 26 were related to other body systems but were reported together with the reactions of interest. Mania, insomnia, acute psychosis and delirium were the most frequently reported psychiatric adverse events; grand mal convulsion, confusional state, convulsions and myoclonus were the most frequently reported neurological adverse events. Several aspects should be taken into account in the development of CNS adverse effects, such as the pharmacokinetics of quinolones, chemical structure and quinolone uptake in the brain. These events may affect not only susceptible patients but also 'healthy' patients.

Effect of enoxacin, felbinac, and sparfloxacin on fatty acid metabolism and glucose concentrations in rat tissues

Multiple changes in metabolic levels could be useful for understanding physiological toxicity. To explore further risk factors for the convulsions induced by the interaction of nonsteroidal anti-inflammatory and new quinolone antimicrobial drugs, the effect of sparfloxacin, enoxacin, and felbinac on fatty acid metabolism and glucose concentrations in the liver, brain, and blood of rats was investigated. The levels of long-chain acyl-CoAs (C(18:1) and C(20:4)) in the liver and brain were decreased at the onset of convulsions induced by the coadministration of enoxacin with felbinac. Then, glucose concentrations in the liver and blood were decreased, whereas they were increased in a dose-dependant manner in the brain. However, the formation of acyl-CoAs and glucose levels in the liver, brain, and blood was not significantly influenced by enoxacin, felbinac, and sparfloxacin alone, respectively. The disturbance of both fatty acid metabolism and glucose levels might be associated with the increased susceptibility to convulsions, which may contribute to further understanding of the toxic effects associated with these drugs.

Seizures after cardiac surgery

INTRODUCTION

Cardiac surgery, mainly in the form of coronary artery bypass graft surgery, is known to be associated with a risk of injury to the central and peripheral nervous systems. The most commonly encountered central nervous system injury associated with cardiac surgery continues to be stroke, with seizures occurring less commonly but with significant consequences. Seizures in the cardiac surgery recovery unit (CSRU) always cause great concern to the attending physicians and families of the patient. Therefore, it is of critical importance that the attending physician has an accurate and efficient approach to the differential diagnosis, investigations, and management of these patients, who represent a unique group requiring specific investigations and management.

METHODS

A review and discussion of experience with seizures in the CSRU.

DISCUSSION

Cardiac surgery poses a significant threat to the nervous system through various mechanisms although newer technologies and surgical techniques have led to improved outcomes in recent years. Although the incidence of seizures remains low, the causes and management are relatively unique in this setting, including a probable "toxic syndrome" related to certain antibiotics or other perioperative drugs such as tranexamic acid. A targeted approach based on recognizing focal versus generalized seizures, a careful review of history and medications, and a focused workup will lead the clinician to choosing the most effective therapy when one is required. Special concerns regarding the side effect profile of phenytoin in this setting have led to valproate and levetiracetam becoming useful alternatives, which are effective and well tolerated. The incidence of nonconvulsive seizures in the CSRU remains to be elucidated with prospective monitoring studies, as does their effect on outcome.

Nervous system effects of antituberculosis therapy

Nervous system toxicity with current antituberculosis pharmacotherapy is relatively uncommon, although the frequency of the usage of antituberculosis therapy requires that physicians be aware of such toxicity. Antituberculosis therapy manifests both central and peripheral nervous system effects, which may compromise patient compliance. Among the traditional forms of first-line antituberculosis therapy, isoniazid is most often associated with nervous system effects, most prominently peripheral neuropathy, psychosis and seizures. Adverse events are reported with other antituberculosis therapies, the most prominent being optic neuropathy with ethambutol and ototoxicity and neuromuscular blockade with aminoglycosides. The second-line agent with the most adverse effects is cycloserine, with psychosis and seizures, the psychosis in particular limiting its usage. Fluoroquinolones are rare causes of seizures and delirium. Newer forms of therapy are under development, but to date no significant neurotoxicity is documented with these agents. Future needs include the development of surveillance mechanisms to increase recognition of nervous system toxicities. It is also hoped that the development of new pharmacogenomic assays will help with the identification of patients at risk for these toxicities.

Safety profile of the fluoroquinolones: focus on levofloxacin

The fluoroquinolone class of antibacterial agents are among the most frequently prescribed drugs, with utility in a broad range of bacterial infections. Although very useful agents, the fluoroquinolones as a class are associated with a number of adverse events, some with considerable clinical significance. In the past 15-20 years, tolerability concerns have led to restrictions on the use of the fluoroquinolones and, in some instances, the withdrawal of agents from the market. This review focuses on the safety and tolerability of levofloxacin, a third-generation fluoroquinolone, relative to other fluoroquinolones. A literature search was performed of the MEDLINE database encompassing the dates 1980-2009, using as keywords the drug names levofloxacin and concurrently marketed fluoroquinolones combined with the words 'safety', 'adverse effect' or 'adverse drug reaction', or the name of the specific adverse effect. Adverse events commonly associated with the fluoroquinolones include gastrointestinal and CNS toxicity (most frequently headache and dizziness), as well as other adverse events including ECG abnormalities (for example QT interval prolongation), disrupted glucose metabolism, phototoxicity, tendon and joint disorders, hypersensitivity and skin disorders, and hepatic toxicity. Package inserts for the fluoroquinolones in Europe and the US contain warnings regarding these risks. US package inserts also carry 'black-box' warnings regarding the risk of tendon rupture and joint disorders with these agents; however, there is a substantial body of evidence to indicate that there are marked differences in the tolerability profiles of the individual agents within the fluoroquinolone class. These differences may be explained, at least in part, by structural differences: all fluoroquinolones share a basic quinolone core, with differences in specific side chains underlying the adverse event relationships. Furthermore, many of the fluoroquinolone-associated adverse effects and toxicities occur more frequently in patients with pre-existing risk factors, or in certain subpopulations. Notably, package inserts for the fluoroquinolones carry warnings regarding use in the elderly, paediatric patients and patients with pre-existing, or factors predisposing to, seizure disorders. Because of this, many adverse reactions with these agents could be prevented by improving patient screening and education. The recent withdrawal of gatifloxacin due to dysglycaemia makes it timely to review the safety and tolerability of the individual agents in this class. Overall, it appears that levofloxacin is relatively well tolerated, with low rates of clinically important adverse events such as CNS toxicity, cardiovascular toxicity and dysglycaemia.

Safety considerations of fluoroquinolones in the elderly: an update

The fluoroquinolones ciprofloxacin, levofloxacin, moxifloxacin and gemifloxacin are widely used for the treatment of various types of bacterial infections. Overall, these antibacterial agents can be considered safe and well tolerated drugs. Comparative studies have evaluated the use of quinolones in elderly and younger populations. Although age per se does not seem to decrease their tolerability, specific adverse effects of the quinolones must be considered when they are chosen for antibacterial treatment. Renal function declines consistently with age and doses of renally excreted quinolones (e.g. ofloxacin, levofloxacin, gatifloxacin) need to be adjusted if a clinically relevant reduction of creatinine clearance is identified. Reactions of the gastrointestinal tract, such as nausea, dyspepsia, vomiting or diarrhoea, are among the most often registered adverse drug reactions during therapy with fluoroquinolones. Treatment with a quinolone causes diarrhoea less frequently than treatment with other classes of antimicrobials. Conflicting data have been published with respect to the incidence of Clostridium difficile-associated diarrhoea in quinolone-treated patients. Hypersensitivity reactions, often manifested on the skin, occur less commonly during therapy with quinolones than, for example, during therapy with beta-lactam antibacterials. Adverse reactions of the CNS are of particular concern in the elderly population. Given the CNS excitatory effects of quinolones, elderly patients should be monitored carefully for such symptoms. It is likely that many signs of possible adverse reactions, such as confusion, weakness, loss of appetite, tremor or depression, are often mistakenly attributed to old age and remain unreported. Quinolones should be used with caution in patients with known or suspected CNS disorders that predispose to seizures (e.g. severe cerebral arteriosclerosis or epilepsy). Quinolones can cause QT interval prolongation. They should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalaemia or hypomagnesaemia and patients receiving class IA (e.g. quinidine, procainamide) or class III (e.g. amiodarone, sotalol) antiarrhythmic agents. Tendinitis and tendon ruptures are recognized as quinolone-induced adverse effects that can occur during treatment or as late as several months after treatment. Chronic renal diseases, concomitant use of corticosteroids and age >60 years are known risk factors for quinolone-induced tendopathies. Overall, the specific adverse-effect profile of quinolones must be considered when they are chosen for treatment of bacterial infections. Because of physiological changes in renal function and when certain co-morbidities are present, some special considerations are necessary when elderly patients are treated with these drugs.

A seizure attributed to ofloxacine in a woman undergoing detoxification for alcohol dependence

Objective. To report one case of seizure following administration of ofloxacin. Case Summary. A 38-year-old woman with alcohol dependence but no prior history of seizure disorder admitted in our inpatient alcohol detoxification program was prescribed ofloxacin four days after admission for a lower urinary tract infection. She was currently prescribed diazepam 30 mg per day. This treatment was continued without modification following admission. Forty eight hours after starting ofloxacin and after receiving five doses of oral ofloxacin, the patient experienced a seizure. Ofloxacin treatment was stopped and no further seizures occurred. Neurological examination of the patient, laboratory tests, computerized tomography with contrast enhancement and electroencephalography did not detect any abnormalities. Up to the last consultation, six months after admission, the patient has reported no recurrence of the seizure. Discussion. Quinolone antibiotics vary in their ability to induce seizures, with ofloxacin having one of the least potentials. In the present case, the seizure could be attributed in all probability to taking ofloxacin; since she had no previous history of seizures, she did not present an alcohol withdrawal syndrome, benzodiazepine treatment was not modified, the seizure occurred 48 h after taking ofloxacin, but seven days after stopping drinking, no alternative aetiologies for the seizure could be identified and no seizure recurrence was reported over the following seven months. Of reported cases of seizures in patients treated with fluoroquinolones, none concerned patients with alcohol dependence or patients treated with benzodiazepines. Conclusions. The present case alerts us to the possibility that seizures may occur in alcohol dependent patients treated with benzodiazepines who concomitantly prescribed a fluoroquinolone. These widely-used antibiotics should thus be prescribed with caution to patients undergoing detoxification for alcohol dependence, particularly if they are also taking benzodiazepines, irrespective of whether they have a previous history of seizures or not.

Gemifloxacin-associated neurotoxicity presenting as encephalopathy

OBJECTIVE

To report a case of acute encephalopathy associated with ingestion of gemifloxacin, a fluoroquinolone.

CASE SUMMARY

A 67-year-old woman presented to the emergency department with an acute alteration in mental status. Twenty-four hours earlier she had taken one 320-mg tablet of her husband's gemifloxacin prescription to treat symptoms of a mild upper respiratory infection. During her initial evaluation at our institution, the woman was dysphasic, unable to follow commands, and agitated, suggesting encephalopathy. A thorough diagnostic investigation did not reveal any structural, metabolic, or infectious etiology. Her mental status returned to normal within 2 days without any definitive treatment.

DISCUSSION

Fluoroquinolone-associated neurotoxicity may manifest as encephalopathy, seizures, confusion, or toxic psychosis. To date, none of these adverse effects, specifically encephalopathy, has been reported with gemifloxacin. An objective causality assessment revealed that encephalopathy was probably associated with gemifloxacin use. Seizures, either convulsive or nonconvulsive, may have contributed to our patient's presentation, but she denied seizures prior to this event and did not suffer a seizure in the 18 months following her discharge. However, her second electroencephalograph revealed an underlying predisposition to seizures, which gemifloxacin may have unmasked.

CONCLUSIONS

This report illustrates that severe central nervous system adverse effects associated with some fluoroquinolones may also occur with gemifloxacin. Gemifloxacin and other fluoroquinolones should be considered in the etiologic evaluation of patients with acute encephalopathy.

Seizures and status epilepticus in the critically ill

Seizures represent stereotypic electroencephalographic (EEG) and behavioral paroxysms as a consequence of electrical neurologic derangement. Seizures are usually described as focal or generalized motor convulsions; however, nonconvulsive seizures that occur in the absence of motor activity may escape clinical detection. Because of the admission diagnoses and dramatic physiologic and metabolic derangements common to critically ill patients, the entire spectrum of seizure disorders may be encountered in the ICU. Seizures in the ICU are attributable to primary neurologic pathology or secondary to critical illness and clinical management. For optimal treatment, early diagnosis of the seizure type and its cause is important to ensure appropriate therapy. Convulsive status epilepticus requires emergent treatment before irreversible brain injury and severe metabolic disturbances occur.

Electroconvulsive therapy and antibiotics: a case report

Infections are common comorbid conditions in hospitalized patients, including those receiving electroconvulsive therapy (ECT). In this report, we demonstrate the fluoroquinolone class of antibiotics can be associated with prolonged electroconvulsive seizure duration. We describe an 82-year-old woman treated with the fluoroquinolone, moxifloxacin, during a course of ECT. After previously tolerating ECT well, introduction of moxifloxacin for a respiratory tract infection was associated with prolonged seizure duration despite complete resolution of her respiratory complaint. Taken together with other evidence that fluoroquinolones lower seizure threshold, this report suggests fluoroquinolones should be avoided in patients receiving ECT.

Maximizing Pharmacodynamics with High-Dose Levofloxacin

Objective

To review published literature of levofloxacin 750 mg for the treatment of community-acquired pneumonia (CAP), nosocomial-acquired pneumonia (NAP), and skin and skin-structure infections (SSSI) focusing on microbiology, pharmacokinetic, and pharmacodynamic parameters.

Data Sources

MEDLINE was searched for clinical trials and review articles (1966 to September 2004). Also included were data from the manufacturer. Search terms utilized were levofloxacin, pneumonia, skin infections, adverse effects, pharmacokinetics, pharmacodynamics, and resistance.

Study Selection and Data Extraction

All articles and product labeling regarding levofloxacin for the treatment of CAP, NAP, and SSSI were included for review.

Data Synthesis

Compared with the other currently marketed fluoroquinolones, levofloxacin demonstrates similar in vitro activity to a number of commonly identified microorganisms. Levofloxacin 750 mg has shown equivalency to various non-fluoroquinolone regimens for the treatment of NAP and SSSI. Furthermore, a short, 5-day course of levofloxacin 750 mg was similar in efficacy to a longer, 10-day course of levofloxacin 500 mg for the treatment of CAP. Adverse events associated with levofloxacin therapy are dose independent; therefore, the adverse effects seen with high-dose levofloxacin are comparable to lower doses.

Conclusions

The levofloxacin 750 mg dosage formulation is a logical option when evaluating the antimicrobial armamentarium commonly utilized for the empiric treatment of CAP, NAP, and SSSI. Pharmacodynamic parameters are optimized and resistance is minimized when high-dose, short-course therapy is implemented.

Safety of Newer Parenteral Antibiotics

Several parenteral antimicrobials have been introduced into clinical practice over the course of the last decade. Some of these agents (e.g., linezolid, daptomycin, and tigecycline) are prototypes of new classes of compounds. In comparative clinical trials, these newer anti-infectives have been shown to be safe and to have low rates of discontinuation by patients. However, long-term use has revealed unique toxicities associated with the use of some of these drugs. The adverse events and potential drug interactions associated with the use of these antibiotics are variable and require familiarity with the safety profile of each drug. It is especially important that clinicians be able to recognize serious adverse events associated with the use of specific drugs, because most of the adverse events can be readily reversed by cessation of therapy.

A multicenter, randomized, double-blind, retrospective comparison of 5- and 10-day regimens of levofloxacin in a subgroup of patients aged ≥65 years with community-acquired pneumonia

OBJECTIVE

This subgroup analysis sought to determine the efficacy and tolerability of a 5-day regimen of levofloxacin 750 mg/d compared with a 10-day regimen of levofloxacin 500 mg/d in the treatment of community-acquired pneumonia (CAP) in elderly patients (aged > or =65 years).

METHODS

This subgroup analysis was based on the outcomes in patients aged > or =65 years from a randomized, double-blind, controlled trial conducted at 70 US centers. Patients in Pneumonia Severity Index (PSI) class I/II and III/IV were randomized to receive levofloxacin 750 mg/d for 5 days or levofloxacin 500 mg/d for 10 days. Study investigators assessed clinical and microbiologic outcomes 7 to 14 days after administration of the last dose of medication and collected adverse events for 30 days after the last dose.

RESULTS

This analysis included 177 elderly patients, 80 receiving levofloxacin 750 mg/d for 5 days and 97 receiving levofloxacin 500 mg/d for 10 days. Although most demographic and baseline clinical characteristics were comparable between the 2 groups, the group that received levofloxacin 500 mg/d was older than the group that received levofloxacin 750 mg/d (median age, 76.0 vs 72.5 years, respectively; P = 0.029) and had a higher mean PSI score (90.7 vs 83.1; P = 0.017). Despite the halved duration of therapy, unadjusted clinical success rates were comparable between the 2 groups (89.0% and 91.9% in the 750- and 500-mg arms, respectively; 95% CI, -7.1 to 12.7). Microbiologic eradication rates were 90.3% (28/31) in the 750-mg arm and 87.5% (14/16) in the 500-mg arm (P = NS). Multivariate analysis adjusting for baseline PSI score indicated that treatment assignment was not statistically associated with clinical success (adjusted odds ratio for clinical success with 500-mg dose, 1.92; 95% CI, 0.62 to 5.99). The incidence of treatment-emergent adverse events did not differ between the 2 study treatments. The most common adverse events in both groups were insomnia, constipation, and headache.

CONCLUSIONS

This subgroup analysis found that levofloxacin 750 mg/d for 5 days was well tolerated in the treatment of CAP in elderly patients. Undajusted and adjusted rates of clinical success were statistically similar between levofloxacin 750 mg/d for 5 days and levofloxacin 500 mg/d for 10 days.