Long-term toxicity of fluoroquinolones: a comprehensive review

Fluoroquinolones (FQs) are highly potent bactericidal antibiotics with broad-spectrum activity against Gram-negative/positive bacteria. The Food and Drug Administration (FDA) anticipated the presence of a long-lasting incapacity of Fluoroquinolone Associated Toxicity (FQAT), which is not officially documented yet. This review aimed to précis the existing information on FQA long-term toxicity, such as cardiotoxicity, aortic aneurysm, tendon rupture, nephrotoxicity, hepatotoxicity, peripheral neuropathy, vagus nervous dysfunction, reactive oxygen species (ROS), phototoxicity, glucose hemostasis, and central nervous system (CNS) toxicity. We are focused on the CNS toxicity of FQs, either due to the direct action of the FQs on CNS receptors or by other drug co-administration, including nonsteroidal anti-inflammatory disease (NSAIDs) and theophylline. Due to the nature of the R7 side chain, FQs containing unsubstituted 7-piperazine and 7-pyrrolidine have the most significant effect. The gamma-aminobutyric acid-A (GABAA) receptor and CNS effects are inhibited through at least three possible mechanisms. Firstly, by the pharmacological action of the quinolone directly. Secondly, FQ-NSAIDs interact pharmacodynamically in which the interaction between the FQ and a receptor is significantly altered by the presence of another drug that interacts with the same receptor. An example may be the interaction between NSAIDs and some FQs. Thirdly, a pharmacokinetic drug-drug interaction leads to a higher concentration of quinolone or the other drug. An example may be the interaction between theophylline and benzodiazepines with some FQs.

Fluoroquinolones and the risk of severe hypoglycaemia among sulphonylurea users: Population-based cohort study

AIM

Fluoroquinolone-related hypoglycaemia is rare but may become clinically relevant in individuals at high baseline hypoglycaemic risk, such as patients with diabetes using sulphonylureas. Our population-based cohort study assessed whether fluoroquinolones are associated with an increased risk of severe hypoglycaemia compared with amoxicillin among patients treated with sulphonylureas.

MATERIALS AND METHODS

Using the UK's Clinical Practice Research Datalink Aurum linked to hospitalization and vital statistics data, we assembled a base cohort of patients who initiated second-generation sulphonylureas (1998-2020). The study cohort included patients initiating either fluoroquinolones or amoxicillin while on sulphonylureas. Using an intent-to-treat exposure definition, we assessed the 30-day risk of severe hypoglycaemia (hospitalization with or death because of hypoglycaemia) associated with fluoroquinolones compared with amoxicillin. Cox models estimated hazard ratios (HRs) with 95% confidence intervals (CIs) of severe hypoglycaemia after 1:5 matching on previous sulphonylurea use and propensity scores. Secondary analyses were stratified by demographics and glycated haemoglobin.

RESULTS

Overall, 143 417 patients initiated fluoroquinolones (n = 13 123) or amoxicillin (n = 130 294) while on sulphonylureas. Compared with amoxicillin, fluoroquinolones were not associated with the risk of severe hypoglycaemia (HR, 1.17; 95% CI, 0.91-1.50). Fluoroquinolones were associated with an increased risk in patients <65 years (HR, 2.90; 95% CI, 1.41-5.97) but not in those ≥65 years (HR, 1.03; 95% CI, 0.79-1.35) in stratified analyses. There was no evidence of effect modification by sex or glycated haemoglobin.

CONCLUSIONS

In patients using second-generation sulphonylureas, fluoroquinolones were not associated with an increased risk of severe hypoglycaemia compared with amoxicillin. An increased risk among younger adults is possible.

Tigecycline and Hypoglycemia, When and How?

Objective: To describe the clinical characteristics of hypoglycemia that develop with tigecycline therapy and to review and summarize the current evidence of this uncommonly occurring metabolic adverse effect of tigecycline therapy. Underlying risk factors and potential mechanisms are also discussed. Data source: A 3-phase literature search was performed. In phase 1, the Cochrane Central Register of Controlled Trials (CENTRAL) Library, MEDLINE, and Embase electronic databases were searched for hypoglycemia and tigecycline, published from inception until August 2023. In phase 2, MEDLINE was searched for tigecycline randomized controlled trials and results were manually screened for hypoglycemia. In phase 3, the US Food and Drug Administration Adverse Event Reporting System public dashboard was searched for reports on tigecycline and hypoglycemia from June 2005 until July 2023. Study selection and data extraction: Relevant English-language citations and those conducted in humans were considered. Relevance to patient care and clinical practice: Hypoglycemia of various causes is an independent mortality risk. This review raises awareness among clinicians about the possibility of hypoglycemia with tigecycline therapy. Conclusion: Data on tigecycline-related hypoglycemia are scarce. Hypoglycemia may occur at any time during tigecycline therapy and can be severe and persist for days after tigecycline cessation. Renal dysfunction or renal replacement therapy may predispose to severe hypoglycemia during tigecycline therapy. Tigecycline-related hypoglycemia may develop in patients with or without diabetes mellitus and appears independent of insulin or antidiabetic agents. Intravenous dextrose showed efficacy in the restoration of euglycemia. Studies are needed to determine whether tigecycline-related hypoglycemia is iatrogenic or spontaneous.

Transplant endocrinology

Solid organ transplants and stem cell transplants are becoming more common but a significant proportion of patients are still on waiting lists, awaiting transplants. When endocrinologists treat transplant recipients who have underlying endocrine problems, which might include endocrine emergencies, there are special clinical care considerations to be aware of. The stage of the transplant (pre-transplant, early post-transplant, and chronic post-transplant) must be taken into account. Additionally, it's crucial to be knowledgeable about immunosuppressive medications, their typical adverse effects and drug interactions. The review article addresses a number of endocrine and metabolic abnormalities that are reported after transplantation.

Fluoroquinolone-induced Glycaemic Aberrations: Could Quinolones be Repurposed to Serve as New Antidiabetic Agents?

Nalidixic acid is a synthetic antibiotic discovered in the 1960s during the synthesis of chloroquine, an effective drug for treating malaria. Nalidixic acid became the backbone for developing quinolones that are now widely used clinically for the treatment of various bacterial infections. The mechanism of action of quinolone involves the inhibition of topoisomerase II and topoisomerase IV. In attempts to improve the potency of fluoroquinolones, modifications were made; these modifications resulted in the emergence of newer generations of fluoroquinolones. Also, due to these modifications, several side effects were noted, including blood glucose control aberrations. Among fluoroquinolones that disrupt glucose homeostasis is gatifloxacin, which is in the third-generation category. Fluoroquinolones have been demonstrated to induce glycaemic aberrations by enhancing pancreatic cells' insulin secretion and interaction with antidiabetic agents via inhibition of cytochrome P450 enzymes. Considering their ability to induce hypoglycaemia, few studies have reported repurposing of quinolones as antidiabetic agents. Hyperglycaemia has also been reported to often precede hypoglycaemia. Due to the ability to decrease blood glucose, it is not surprising that some authors have reported novel quinolone derivates with antidiabetic properties in experimental studies. However, there is still a paucity of data regarding the effect of quinolones derivatives on glycaemic control. Understanding how fluoroquinolones lower blood glucose concentration could serve as the basis for developing novel quinolone derivatives with the sole purpose of lowering blood glucose concentrations. Although there are various conventional anti-hyperglycaemic agents, due to their associated shortfalls as well as an increase in the prevalence of diabetes, the discovery and development of new antidiabetics are warranted.

Effect of ciprofloxacin vs levofloxacin on QTc-interval and dysglycemia in diabetic and non-diabetic patients

BACKGROUND

Levofloxacin and ciprofloxacin are more commonly used amongst fluoroquinolone class and the question of cardiac safety and glucose hemostasis of this class has been raised.

OBJECTIVE

To compare intravenous levofloxacin and ciprofloxacin regarding their risk on QTc prolongation and dysglycemia in diabetic and non-diabetic patients.

METHODS

A randomised prospective study at Beni-Suef university hospital was conducted on 200 adult patients over 6 months. The patients received intravenous levofloxacin 750mg once daily or ciprofloxacin 400mg twice daily. Electrocardiogram and fasting blood glucose were obtained from each patient before starting the antibiotic, 24 hours, 72 hours after the first dose, and 72 hours after antibiotics cessation.

RESULTS

The results of the current study showed the relative risk for QTc prolongation with levofloxacin was more than ciprofloxacin by about 4 and 1.5 times in diabetic and non-diabetic patients, respectively. The relative risk for dysglycemia with levofloxacin was 2.28 and 1.39 times more than ciprofloxacin in diabetic and non-diabetic patients, respectively.

CONCLUSION

The present study showed that the risk for QTc prolongation and hyperglycemia was greater with levofloxacin than ciprofloxacin in diabetic and non-diabetic patients. In addition, the risk for hypoglycemia was greater with levofloxacin than ciprofloxacin in non-diabetic patients.

Etiological Agents of Urinary Tract Infection and 7 Years Trend of Antibiotic Resistance of Bacterial Uropathogens in Sudan

Introduction:

Bacterial infections of the urinary tract represent a major cause of outpatient visits as well as hospital-acquired infections. As the prevalence of multidrug-resistant uropathogens is increasing, updated knowledge of the commonest bacterial causes and their susceptibility patterns is crucial for the proper selection and use of antimicrobial drugs and the development of effective local prescribing guidelines.

Methods:

Handling of urine samples, identification of organisms and antimicrobial susceptibility testing were made according to guidelines in Monica Cheesbrough 2000, 2006. The prevalence of resistance of the pathogens against each antibiotic was calculated as the proportion of resistant isolates over the entire tested isolates. Data were analyzed using Epi info; the chi-square test and Fisher exact test were used to assess the statistical significance of results.

Results:

In this study, 774 samples were cultured from patients with suspected urinary tract infection (UTI), 705 (91%) urinary isolates showed significant growth (>105 CFU /L) while the other 69 samples showed no significant growth. 431 (61%) of the patients were female, while the other 274 (39%) were males. 13 types of pathogens were identified in 705 urinary isolates. E.Coli was the main bacterial uropathogen identified. Microbiological susceptibility of a total of 28 antibiotics was tested; for each urinary isolate, different sets of these antibiotics were used. 601(96%) of the bacteria were resistant to at least one antibiotic. 17 antibiotics were found to have a bacterial resistance rate of more than 50%, including all B lactams (except cefuroxime), Nalidixic acid, Ciprofloxacin, Norfloxacin, Clindamycin, Co-Trimoxazole and Tetracyclines(Tetracycline and Doxycycline). Other antibiotics were found to have resistance rates of less than 50%. Amikacin & Imipenem had the highest susceptibility rates. Throughout the 7 years, resistance to most of the antibiotics showed an incremental pattern.

Conclusion:

Current empirical antibiotic therapy for UTI should be modified, and new guidelines should be established based on local resistance rates. This study comes up with precious regional data for evidence-based empirical antibiotic treatment, but a national sentinel surveillance system and regional antibiograms should be established to track the bacterial susceptibility profiles in Sudan.

Fluoroquinolones suppress gluconeogenesis by inhibiting fructose 1,6-bisphosphatase in primary monkey hepatocytes

Dysglycemia is one of the most serious adverse events associated with the clinical use of certain fluoroquinolones. The purpose of this study was to investigate the effects of the representative fluoroquinolones moxifloxacin and gatifloxacin on hepatic gluconeogenesis using primary monkey hepatocytes. Glucose production was induced after the cells were incubated for 4 h with 10 mM sodium lactate and 1 mM sodium pyruvate as gluconeogenic substrates. Under these conditions, moxifloxacin and gatifloxacin dose-dependently suppressed gluconeogenesis at concentrations of 100 μM or higher. Transcriptome analysis of rate-limiting enzymes involved in hepatic gluconeogenesis revealed that moxifloxacin and gatifloxacin at a concentration of 1000 μM did not affect the expression of key gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase, glucose 6-phosphatase, and fructose 1,6-bisphosphatase. Furthermore, metabolome analysis, in vitro glucose production assay using additional gluconeogenic substrates, and fructose 1,6-bisphosphatase assay using the cell extracts showed that fluoroquinolones enzymatically suppressed hepatic gluconeogenesis by inhibiting fructose 1,6-bisphosphatase. These inhibitory effects may involve in the clinically relevant dysglycemia associated with fluoroquinolones in human.

Functional and Morphological Characteristics of Pancreatic Islet Lesions Induced by Quinolone Antimicrobial Agent Gatifloxacin in Rats

We characterized pancreatic islet lesions induced by several quinolones using functional and morphological examinations of the pancreatic islets in male rats orally administered gatifloxacin, lomefloxacin, or levofloxacin at 300 mg/kg for 14 consecutive days. Consequently, in contrast to lomefloxacin or levofloxacin, gatifloxacin increased serum glucose and glycosylated albumin on day 14 and elevated serum glucose tended to decrease insulin in the intravenous glucose tolerance test. Microscopically, only gatifloxacin induced cytoplasmic vacuoles containing eosinophilic homogenous contents in islet cells. Immunohistochemical examination revealed that vacuolated islet cells were positively stained for insulin, demonstrating they were pancreatic β cells. Electron microscopy showed that the cytoplasmic vacuoles represented dilated cisterna of the rough endoplasmic reticulum filled with electron-lucent materials in pancreatic β cells. Moreover, insulin secretory granules were drastically decreased in vacuolated islet cells, suggesting impaired insulin synthesis and/or transport. This gatifloxacin-induced pancreatic toxicity in rats was considered to be associated with high pancreatic drug distribution. These results demonstrated that gatifloxacin provoked functional and morphological pancreatic β cell alteration associated with impaired insulin synthesis and/or transport, leading to hyperglycemia.

Quinolone antibiotics and suicidal behavior: analysis of the World Health Organization's adverse drug reactions database and discussion of potential mechanisms

RATIONALE

Several case-reports suggest that the use of quinolones may increase the risk of psychiatric adverse reactions such as suicidal behaviors.

OBJECTIVES

The aim of this study is to investigate whether there is a safety signal for quinolone-related suicidal behaviors in a global adverse drug reactions database.

METHODS

All antibiotic-related adverse reactions were extracted from VigiBase, the World Health Organization (WHO) global Individual Case Safety Report (ICSR) database. Disproportionality analyses were performed to investigate the association between reports of suicidal behavior and exposure to quinolones, in comparison with other antibiotics.

RESULTS

From December 1970 through January 2015, we identified 992,097 antibiotic-related adverse reactions. Among them, 608 were quinolone-related suicidal behaviors including 97 cases of completed suicides. There was increased reporting of suicidal behavior (adjusted reporting odds ratios [ROR] 2.78, 95 % CI 2.51-3.08) with quinolones as compared to other antibiotics. Candidate mechanisms for quinolone-induced suicidal behaviors include GABAA antagonism, activation of NMDA receptors, decreased serotonin levels, oxidative stress, and altered microRNA expressions.

CONCLUSIONS

We found a strong safety signal suggesting an increased risk of suicidal behaviors associated with quinolone use. Plausible psychopharmacological mechanisms could underlie this association. Further investigations are urgent to confirm and better understand these findings.

Dysglycemia associated with quinolones

Antimicrobial therapy is well known to be associated with fluctuations of blood glucose levels. This review aims at exploring the association between glycemic fluctuations and antibiotics mainly focusing on quinolones. Quinolones are associated with hypoglycemia and hyperglycemia. Several mechanism are proposed to explain this causality.

Susceptibility of bacterial isolates to vancomycin and ceftazidime from patients with endophthalmitis: Is there a need to change the empirical therapy in suspected bacterial endophthalmitis?

To review the susceptibility of bacterial isolates to ceftazidime and vancomycin isolated from patients with endophthalmitis. Microbiology records of patients with endophthalmitis between June 2010 and May 2013 were reviewed. Vitreous and AC fluids obtained from patients with endophthalmitis were subjected to direct microscopy examination and culture. Antibiotic susceptibility of the isolates was performed by Kirby Bauer disk diffusion method. Resistant to ceftazidime in Gram negative bacteria (GNB) by disk diffusion method is confirmed by minimum inhibitory concentration using E test. Culture was positive for bacteria/Fungi in 224/356 patients (62.9 %). Out of 224 patients, 191 (85.2 %) patients showed bacterial growth and 33 (14.0 %) showed fungal growth. Mixed bacterial infection was seen in five patients. Among the GNB, 23/123 (18 %) of the isolates were resistant to ceftazidime, and all the Gram positive bacteria 73/73 (100 %) were susceptible to vancomycin. Sixteen of 123 (13 %) GNB were resistant to amikacin. Although there is an increase in resistance to ceftazidime compared to amikacin in GNB, amikacin intravitreal injection is associated with macular toxicity and no single antibiotic has full coverage for all GNB. Combination of vancomycin and ceftazidime empiric therapy can be continued in patients with suspected endophthalmitis and treatment is modified based on clinical response and susceptibility results.

Risk of severe dysglycemia among diabetic patients receiving levofloxacin, ciprofloxacin, or moxifloxacin in Taiwan

BACKGROUND

Observational studies and fatal case reports raise concern about the safety of severe dysglycemia associated with fluoroquinolone use. The objective of this study was to assess the risk of severe dysglycemia among diabetic patients who received different fluoroquinolones.

METHODS

In a population-based inception cohort study of diabetic patients covering the period from January 2006 to November 2007, outpatient new users of levofloxacin, ciprofloxacin, moxifloxacin, cephalosporins, and macrolides orally were identified. Study events were defined as emergency department visits or hospitalization for dysglycemia within 30 days following the initiation of antibiotic therapy. Results were analyzed with adjusted multinomial propensity score.

RESULTS

A total of 78 433 diabetic patients receiving the antibiotics of interest were included in the study. The absolute risk of hyperglycemia per 1000 persons was 6.9 for moxifloxacin and 1.6 for macrolides. In contrast, the risk of hypoglycemia was 10.0 for moxifloxacin and 3.7 for macrolides. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) of levofloxacin, ciprofloxacin, and moxifloxacin compared with macrolides were 1.75 (1.12-2.73), 1.87 (1.20-2.93), and 2.48 (1.50-4.12), respectively, for hyperglycemia and 1.79 (1.33-2.42), 1.46 (1.07-2.00), and 2.13 (1.44-3.14), respectively, for hypoglycemia. Patients taking moxifloxacin faced a significantly higher risk of hypoglycemia than those receiving ciprofloxacin. A significant increase in the risk of hypoglycemia was also observed among patients receiving moxifloxacin concomitantly with insulin (AOR, 2.28; 95% CI, 1.22-4.24).

CONCLUSIONS

Diabetics using oral fluoroquinolones faced greater risk of severe dysglycemia. The risk of hypoglycemia varied according to the type of fluoroquinolone administered, and was most commonly associated with moxifloxacin.

Pregnane X receptor agonists impair postprandial glucose tolerance

We conducted a randomized, open, placebo-controlled crossover trial to investigate the effects of the pregnane X receptor (PXR) agonist rifampin on an oral glucose tolerance test (OGTT) in 12 healthy volunteers. The subjects were administered 600 mg rifampin or placebo once daily for 7 days, and OGTT was performed on the eighth day. The mean incremental glucose and insulin areas under the plasma concentration-time curves (AUC(incr)) increased by 192% (P = 0.008) and 45% (P = 0.031), respectively. The fasting glucose, insulin, and C-peptide, and the homeostasis model assessment for insulin resistance, were not affected. The glucose AUC(incr) during OGTT was significantly increased in rats after 4-day treatment with pregnenolone 16α-carbonitrile (PCN), an agonist of the rat PXR. The hepatic level of glucose transporter 2 (Glut2) mRNA was downregulated by PCN. In conclusion, both human and rat PXR agonists elicited postprandial hyperglycemia, suggesting a detrimental role of PXR activation on glucose tolerance.

The effect of levofloxacin and moxifloxacin on cardiovascular functions of rats with streptozotocin-induced diabetes

Fluoroquinolone antibiotics cause rare, but clinically important, adverse events including hyperglycaemia and hypoglycaemia. The present study focuses on the possible effect of levofloxacin and moxifloxacin on the cardiovascular functions of rats with type I diabetes. Both antibiotics caused bradycardia. Levofloxacin but not moxifloxacin caused hypoglycaemia in diabetic rats and an increase in amplitude of the ST segment revealed by electrocardiogram (ECG) analysis of isolated hearts. In pressurized mesenteric arteries, levofloxacin did not affect the endothelium-derived hyperpolarising factor (EDHF) pathway or its main components, the small-conductance Ca(2+) activated potassium (SK(Ca)) and intermediate-conductance Ca(2+) activated potassium (IK(Ca)) channels. In moxifloxacin-treated rats, an increase in the EDHF response was observed, which was largely attributed to SK(Ca)-activation. In conclusion, levofloxacin and moxifloxacin use appeared to vary but with no evidence of impairment of the cardiovascular function. However, it is still possible that these antibiotics may produce different effects if there are co-morbidities and therefore their use must be with care.

Potentially harmful drug-drug interactions in the elderly: a review

BACKGROUND

Elderly patients are vulnerable to drug interactions because of age-related physiologic changes, an increased risk for disease associated with aging, and the consequent increase in medication use.

OBJECTIVE

The purpose of this narrative review was to describe findings from rigorously designed observational cohort and case-control studies that have assessed specific drug interactions in elderly patients.

METHODS

The PubMed and International Pharmaceutical Abstracts databases were searched for studies published in English over the past 10 years (December 2000-December 2010) using relevant Medical Subject Headings terms (aged; aged, 80 and over; and drug interactions) and search terms (drug interaction and elderly). Search strategies were saved and repeated through September 2011 to ensure that the most recent relevant published articles were identified. Additional articles were found using a search of review articles and reference lists of the identified studies. Studies were included if they were observational cohort or case-control studies that reported specific adverse drug interactions, included patients aged ≥65 years, and evaluated clinically meaningful end points. Studies were excluded if they used less rigorous observational designs, assessed pharmacokinetic/pharmacodynamic properties, evaluated drug-nutrient or drug-disease interactions or interactions of drug combinations used for therapeutic benefit (eg, dual antiplatelet therapy), or had inconclusive evidence.

RESULTS

Seventeen studies met the inclusion criteria. Sixteen studies reported an elevated risk for hospitalization in older adults associated with adverse drug interactions. The drug interactions included: angiotensin-converting enzyme (ACE) inhibitors and potassium-sparing diuretics, ACE inhibitors or angiotensin receptor blockers and sulfamethoxazole/trimethoprim, benzodiazepines or zolpidem and interacting medications, calcium channel blockers and macrolide antibiotics, digoxin and macrolide antibiotics, lithium and loop diuretics or ACE inhibitors, phenytoin and sulfamethoxazole/trimethoprim, sulfonylureas and antimicrobial agents, theophylline and ciprofloxacin, and warfarin and antimicrobial agents or nonsteroidal anti-inflammatory drugs. One study reported the risk for breast cancer-related death as a function of paroxetine exposure among women treated with tamoxifen.

CONCLUSIONS

Several population-based studies have reported significant harm associated drug interactions in elderly patients. Increased awareness and interventions aimed at reducing exposure and minimizing the risks associated with potentially harmful drug combinations are needed.

Cumulative clinical experience from over a decade of use of levofloxacin in urinary tract infections: critical appraisal and role in therapy

The treatment of urinary tract infections (UTIs) continues to evolve as common uropathogens increasingly become resistant to previously active antimicrobial agents. In addition, bacterial isolates, which were once considered to be either colonizers or contaminants, have emerged as true pathogens, likely related to the more complex array of settings where health care is now delivered. Even though the reliability of many antimicrobial agents has become less predictable, the fluoroquinolone group of agents has remained a frequent, if not the most often prescribed, antimicrobial therapy for almost all types of UTIs. Levofloxacin has taken its position at the top of the list as one of the most regularly administered fluoroquinolone agents given to patients with a suspected or proven UTI. The authors review the clinical experience of the use of levofloxacin over the past decade and suggest that the use of levofloxacin for the treatment of UTIs, although still fairly dependable, is perhaps not the best use of this important antimicrobial agent.

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.

Cardiovascular and metabolic safety profiles of the fluoroquinolones

INTRODUCTION

Certain fluoroquinolones share similar indications of use. A comparison among Cardiovascular and metabolic (i.e., dysglycemia) safety profiles of the fluoroquinolones might be particularly useful for the prescribers' decision-making process as well as to hypothesize future researcher purposes.

AREAS COVERED

A literature search was conducted using keywords apt to identify information on safety profile of the fluoroquinolones. Publications concerned with descriptive and etiological surveys were manually reviewed.

EXPERT OPINION

Cardiac alterations and blood glucose impairments might be associated with any fluoroquinolone. However, the benefit/risk profile of these agents could be stratified for the single compounds. Several predisposing factors, such as diabetes, heart illnesses and their related pharmacotherapies, might exacerbate the risk of potentially serious adverse events. In this context, the opportunity of the more appropriate choice among different fluoroquinolones could be applicable.

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.

Diabetes-Related Medication-Induced Hypoglycemia

Hypoglycemia is a common adverse event in patients with both type 1 and type 2 diabetes and may be a barrier to patients achieving tight glycemic control. It is diagnosed either biochemically, as a blood glucose value, or clinically based on symptoms caused by an autonomic response to changes in blood glucose. Patients that experience repeated episodes of hypoglycemia lose the counterregulatory response that produces symptoms and results in hypoglycemia unawareness. Medications account for the most frequent cause of hypoglycemia in both the inpatient and outpatient setting. Treatment of hypoglycemia may be accomplished via the oral or parenteral route with 15 to 20 g of carbohydrate. Following treatment of the episode, it is important to evaluate for the cause and, if medication related, adjust the patient’s treatment regimen.