The insulinotropic effect of fluoroquinolones

Synthesis,Antidiabetic and Antitubercular Evaluation of Quinoline-pyrazolopyrimidine hybrids and Quinoline-4-Arylamines

Two libraries of quinoline-based hybrids 1-(7-chloroquinolin-4-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine and 7-chloro-N-phenylquinolin-4-amine were synthesized and evaluated for their α-glucosidase inhibitory and antioxidant properties. Compounds with 4-methylpiperidine and para-trifluoromethoxy groups, respectively, showed the most promising α-glucosidase inhibition activity with IC50 =46.70 and 40.84 μM, compared to the reference inhibitor, acarbose (IC50 =51.73 μM). Structure-activity relationship analysis suggested that the cyclic secondary amine pendants and para-phenyl substituents account for the variable enzyme inhibition. Antioxidant profiling further revealed that compounds with an N-methylpiperazine and N-ethylpiperazine ring, respectively, have good DPPH scavenging abilities with IC50 =0.18, 0.58 and 0.93 mM, as compared to ascorbic acid (IC50 =0.05 mM), while the best DPPH scavenger is NO2 -substituted compound (IC50 =0.08 mM). Also, compound with N-(2-hydroxyethyl)piperazine moiety emerged as the best NO radical scavenger with IC50 =0.28 mM. Molecular docking studies showed that the present compounds are orthosteric inhibitors with their quinoline, pyrimidine, and 4-amino units as crucial pharmacophores furnishing α-glucosidase binding at the catalytic site. Taken together, these compounds exhibit dual potentials; i. e., potent α-glucosidase inhibitors and excellent free radical scavengers. Hence, they may serve as structural templates in the search for agents to manage Type 2 diabetes mellitus. Finally, in preliminary assays investigating the anti-tubercular potential of these compounds, two pyrazolopyrimidine series compounds and a 7-chloro-N-phenylquinolin-4-amine hybrid showed sub-10 μM whole-cell activities against Mycobacterium tuberculosis.

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.

A randomized, double-blind, crossover study of the effect of the fluoroquinolone moxifloxacin on glucose levels and insulin sensitivity in young men and women

AIM

The voltage-gated potassium channel K_v 11.1 is important for repolarizing the membrane potential in excitable cells such as myocytes, pancreatic α- and β-cells. Moxifloxacin blocks the K_v 11.1 channel and increases the risk of hypoglycaemia in patients with diabetes. We investigated glucose regulation and secretion of glucoregulatory hormones in young people with and without moxifloxacin, a drug known to block the K_v 11.1 channel.

MATERIALS AND METHODS

The effect of moxifloxacin (800 mg/day for 4 days) or placebo on glucose regulation was assessed in a randomized, double-blind, crossover study of young men and women (age 20-40 years and body mass index 18.5-27.5 kg/m² ) without chronic disease, using 6-h oral glucose tolerance tests and continuous glucose monitoring.

RESULTS

Thirty-eight participants completed the study. Moxifloxacin prolonged the QTcF interval and increased heart rate. Hypoglycaemia was more frequently observed with moxifloxacin, both during the 8 days of continuous glucose monitoring and during the oral glucose tolerance tests. Hypoglycaemia questionnaire scores were higher after intake of moxifloxacin. Moxifloxacin reduced the early plasma-glucose response (AUC_0-30 min ) by 7% (95% CI: -9% to -4%, p < .01), and overall insulin response (AUC_0-360 min ) decreased by 18% (95% CI: -24% to -11%, p < .01) and plasma glucagon increased by 17% (95% CI: 4%-33%, p = .03). Insulin sensitivity calculated as the Matsuda index increased by 11%, and MISI, an index of muscle insulin sensitivity, increased by 34%.

CONCLUSIONS

In young men and women, moxifloxacin, a drug known to block the K_v 11.1 channel, increased QT interval, decreased glucose levels and was associated with increased muscle insulin sensitivity and more frequent episodes of hypoglycaemia.

Preclinical safety evaluation of levonadifloxacin, a novel anti-methicillin-resistant Staphyloccocus aureus benzoquinolizine fluoroquinolone by intravenous and oral administration

Fluoroquinolone (FQ) antibacterials have drawn heightened attention from various international regulatory agencies due to their class-specific side effects. Levonadifloxacin is a novel broad spectrum benzoquinolizine FQ active against methicillin-resistant Staphyloccocus aureus (MRSA). Owing to FQ-associated safety concerns, extensive preclinical safety pharmacology (central nervous system and cardiac safety) and toxicology studies (subacute repeat-dose toxicity, genotoxicity, phototoxicity and chondrotoxicity) of levonadifloxacin were performed at relatively high doses. Intravenous (IV) and oral studies were conducted using WCK 771 (l-arginine salt of levonadifloxacin) and WCK 2349 (l-alanine ester prodrug of levonadifloxacin), respectively. Safety pharmacology studies following single dose revealed no adverse effects on central nervous system (including seizure) in mice and cardiovascular system (hERG and monkey telemetry). In repeat-dose toxicity studies, except for IV bolus dosing related effects in rat (hyperactivity, mild convulsion, polypnoea and injection site irritation) and dog (emesis and salivation), no other adverse findings limiting the dosing duration were observed. No major biochemical, haematological, gross or histopathological changes suggestive of damage to vital organs were observed in either WCK 771- or WCK 2349-treated groups. WCK 771 and WCK 2349 were found to be nongenotoxic; however, they showed weak phototoxicity that was comparable with levofloxacin. WCK 771 showed chondrotoxicity in the Beagle dog pups on repeat-dose administration; however, the severity level was lower than ofloxacin. Overall, preclinical safety studies helped establish wider safety margin for WCK 771 and WCK 2349 that supports administration of higher therapeutic doses in humans by both IV and oral routes, thereby enabling safe anti-MRSA treatment.

Risk for hypoglycemic emergency with levofloxacin use, a population-based propensity score matched nested case-control study

Potential association between oral levofloxacin use and hypoglycemic emergency (HE) have been established. However, a large epidemiological study is required to verify this observation. This study aimed to determine if use of oral levofloxacin increased the risk of HE. The nationwide database between 1999 and 2013, including 1.6 million patients with type 2 diabetes (T2D), was used to conduct a nested case-control study. Cases and controls comprised of patients with and without HE, respectively. To avoid indication bias the control subjects were chosen through propensity score matching with cases in a 10-fold ratio. T2D severity was classified based on the adjusted diabetic complication severity index score. 26,695 and 266,950 matched patients with T2D, were finally used as cases and controls, respectively, for the analysis. Multivariate logistic regression analysis showed that antibiotic use was associated with an increased risk for HE (adjusted odds ratio (aOR) = 6.08, 95% confidence interval (95% CI): 5.79–6.38). When compared with antibiotic non-users, those who used fluoroquinolones and sulfonamides displayed the highest (aOR = 12.05, 95% CI: 10.66–13.61) and second highest (aOR = 7.20, 95% CI: 6.29–8.24) risks of HE, respectively. The associated risk for HE was significantly higher with levofloxacin than that with cephalosporins (aOR = 5.13, 95% CI: 2.28–11.52) and penicillin (aOR = 9.40, 95% CI: 2.25–39.24). In the joint effect analyses, the risk for HE increased with the combination of levofloxacin with insulin (aOR = 8.42, 95% CI: 1.91–37.00) or sulfonylurea (aOR = 3.56, 95% CI: 1.12–11.33). Use of oral levofloxacin, compared to that of other antibiotics, was found to be significantly associated with HE in T2D patients. Clinicians should exercise caution while prescribing levofloxacin, especially when combined with insulin or sulfonylurea.

High Concurrent Use of Sulfonylureas and Antimicrobials With Drug Interactions Causing Hypoglycemia

OBJECTIVES

Sulfonylureas, the second most common oral diabetes treatment, have interactions with antimicrobials that substantially increase the risk of hypoglycemia. The objectives of this study are to quantify the concurrent use of sulfonylureas and interacting antimicrobial in U.S. ambulatory care and to examine whether interacting antimicrobials are used for an appropriate indication.

METHODS

We analyzed the 2006-2016 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey, annual probability samples of visits to U.S. office-based physicians. We determined nationally representative estimates of visits for adults with concurrent use of sulfonylureas and 7 antimicrobials with established interactions. We examined whether visit diagnoses included appropriate indications for antibiotics according to national guidelines.

RESULTS

There were 2.5 million visits per year (95% confidence interval [CI] 2.2-2.9) in which sulfonylureas were used with systemic antimicrobials, of which 1 million (95% CI, 0.8-1.2) or 38.0% (95% CI, 32.3%-44.0%) were interacting antimicrobials. Sulfonylurea users had similar odds of interacting antimicrobial use as patients using diabetes medications without antimicrobial interactions (adjusted odds ratio, 1.07; 95% CI, 0.82-1.40). The most common interacting antimicrobials used with sulfonylureas were fluoroquinolones, accounting for 59.9% (95% CI, 50.7%-68.2%) of antimicrobials, and sulfamethoxazole-trimethoprim, accounting for 21.1% (95% CI, 14.8%-29.2%). There was no appropriate antibiotic indication in 69.7% (95% CI, 55.2%-81.1) of visits with interacting antibiotic use.

CONCLUSIONS

Sulfonylureas and antimicrobials with potentially hazardous interactions are frequently used together. To reduce resultant hypoglycemic events, there is a need for interventions to increase physician awareness and promote antibiotic stewardship.

How Safe are Fluoroquinolones for Diabetic Patients? A Systematic Review of Dysglycemic and Neuropathic Effects of Fluoroquinolones

Introduction

The US Food and Drug Administration issued safety warnings about neuropathy in 2013 and dysglycemia in 2018 caused by fluoroquinolone use, mainly based on case reports and case series. We conducted this systematic review to evaluate the safety of fluoroquinolones in diabetic patients by investigating their dysglycemic and neuropathic effects.

Methods

PubMed, Scopus, and Google Scholar were searched for randomized controlled trials and observational studies published from inception till September 2019 evaluating the safety of fluoroquinolones. Efficacy studies of fluoroquinolones reporting these adverse effects were also included. Primary outcomes were hypoglycemia, hyperglycemia, and neuropathy among patients with or without diabetes and treated with fluoroquinolones compared with placebo or other antibiotics. The Cochrane Collaboration tool for randomized controlled trials and modified Newcastle-Ottawa quality-assessment scale were used for assessment of the included studies.

Results and Discussion

A total of 725 studies were identified in the initial search. After screening of titles and abstracts and full-text review, 16 articles fulfilled the inclusion criteria. The sampled patients were aged 30-78 years. Hyperglycemia was reported in 1,588 patients that received fluoroquinolone among eight studies with 4,663 patients, and hypoglycemia was reported in 2,179 patients that received fluoroquinolones among eleven studies with 6,208 patients. Dysglycemia was not generally associated with diabetes mellitus per se. Nevertheless, patients with more comorbidities, especially those with chronic kidney disease, receiving antidiabetics and/or steroids had more glycemic events when treated with fluoroquinolones.

Conclusion

Moxifloxacin was found to be associated the most and ciprofloxacin the least with dysglycemia. fluoroquinolones must be used with great caution among diabetic patients who have comorbidities and are receiving antidiabetics and/or steroids. Further evidence is required from studies on neuropathy caused by fluoroquinolones.

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.

Ciprofloxacin and risk of hypolycemia in non-diabetic patients

Background

Fluoroquinolones have been associated with hypoglycemia in patients taking diabetic medications, most commonly due to drug-drug interactions and other associated risk factors. Except for four published case reports, there are no studies that have found positive associations between ciprofloxacin and hypoglycemia. In all but one of the cases, ciprofloxacin was taken with other hypoglycemic drugs. Recently, the Eritrean National Pharmacovigilance Centre received a serious case of hypoglycemia with recurrent episodes in a young and healthy patient without diabetes following use of oral ciprofloxacin. The aim of the present study is therefore to assess the causal relationship between ciprofloxacin and hypoglycemia in patients without diabetes using the World Health Organization-Uppsala Monitoring Centre global adverse drug reaction database (VigiBase®).

Methods

A search was made on the World Health Organization global adverse drug reaction database (August 15, 2018) using “ciprofloxacin” as the drug substance and “hypoglycemia” as the reaction term. Cases that used hypoglycemic drugs (patients with diabetes) concurrently with ciprofloxacin and those with a completeness score below 50% were excluded to control for confounders and to improve the strength of the data. Hill criteria were used to assess causation.

Results

A total of 35 cases of hypoglycemia reported since 1989 from 17 countries in patients without diabetes associated with ciprofloxacin use with a median time to onset of 4 days were retrieved. The cases have a median age of 64 years (interquartile range, 50–85) with a similar male–to-female ratio. Ciprofloxacin was the only suspect and the sole drug administered in 48.5% of the cases. In ten cases, hypoglycemia abated following withdrawal of ciprofloxacin, and reaction recurred in one case on the subsequent rechallenge. Hypoglycemia was marked as “serious” in 20 cases, and the outcome was fatal in two cases.

Conclusions

This assessment found a suggestive causal link between use of ciprofloxacin and hypoglycemia in patients without diabetes.

Successful Use of Octreotide Therapy for Refractory Levofloxacin-Induced Hypoglycemia: A Case Report and Literature Review

Fluoroquinolones are commonly prescribed antimicrobials that have been implicated in alterations of glucose metabolism. We report a case of refractory fluoroquinolone-induced hypoglycemia in a patient with type-2 diabetes mellitus on glipizide that was successfully treated with octreotide. A patient was admitted with hypoglycemia after having been initiated on levofloxacin therapy. Despite treating the hypoglycemia supportively with multiple boluses of 25 g of dextrose, a continuous dextrose infusion, and glucagon, the patient experienced repeated episodes of rebound hypoglycemia. The persistent hypoglycemia was eventually reversed with the administration of subcutaneous octreotide. Clinicians should be cognizant of this adverse effect of fluoroquinolones, as well as predisposing risk factors, and consider octreotide as an adjunctive therapy for refractory hypoglycemia cases.

HERG Protein Plays a Role in Moxifloxacin-Induced Hypoglycemia

The purpose of this study was to investigate the effect of moxifloxacin on HERG channel protein and glucose metabolism. HERG expression was investigated using immunohistochemistry. The whole-cell patch clamp method was used to examine the effect of moxifloxacin on HERG channel currents. A glucose tolerance test was used to analyze the effects of moxifloxacin on blood glucose and insulin concentrations in mice. Results show that HERG protein was expressed in human pancreatic β-cells. Moxifloxacin inhibited HERG time-dependent and tail currents in HEK293 cells in a concentration-dependent manner. The IC50 of moxifloxacin inhibition was 36.65 μmol/L. Moxifloxacin (200 mg/kg) reduced blood glucose levels and increased insulin secretion in wild-type mice at 60 min after the start of the glucose tolerance test. In contrast, moxifloxacin did not significantly alter blood glucose and insulin levels in HERG knockout mice. Serum glucose levels increased and insulin concentrations decreased in HERG knockout mice when compared to wild-type mice. The moxifloxacin-induced decrease in blood glucose and increase in insulin secretion occurred via the HERG protein; thus, HERG protein plays a role in insulin secretion.

Evaluation of the appropriate use of commonly prescribed fluoroquinolones and the risk of dysglycemia

Background

Fluoroquinolones are among the most widely prescribed antibiotics. However, concerns about increasing resistant microorganisms and the risk of dysglycemia associated with the use of these agents have emerged.

Objective

The primary objective of the study was to evaluate the appropriate use of commonly prescribed fluoroquinolones, including appropriate indication, dose, dose adjustment in renal impairment, and duration of treatment. The secondary objective was to investigate the dysglycemic effect of fluoroquinolone use (hypoglycemia and/or hyperglycemia) in diabetic and nondiabetic patients.

Methods

A prospective observational study at a teaching hospital in Lebanon was conducted over a 6-month period. A total of 118 patients receiving broad-spectrum fluoroquinolones (levofloxacin, ciprofloxacin, and moxifloxacin) were identified. Patients were mainly recruited from internal medicine floors and intensive care units.

Results

The final percentage for the appropriate indication, dose, and duration of fluoroquinolone therapy was 93.2%, 74.6%, and 57.6%, respectively. A total of 57.1% of the patients did not receive the appropriate dose adjustment according to their level of renal impairment. In addition, dysglycemia occurred in both diabetic and nondiabetic patients. Dysglycemia was more frequently encountered with ciprofloxacin (50.0%), followed by levofloxacin (42.4%) and moxifloxacin (7.6%). Hyperglycemia was more common than hypoglycemia in all groups. The highest incidence of hyperglycemia occurred with levofloxacin (70.0%), followed by ciprofloxacin (39.0%) and moxifloxacin (33.3%). In contrast, hypoglycemia did not occur in the ciprofloxacin group, but it was more common with moxifloxacin (11.1%) and levofloxacin (6.0%).

Conclusion

The major clinical interventions for the future will adjust the dose and duration of therapy with commonly prescribed fluoroquinolones. The incidence of hypoglycemia was less common than hyperglycemia.

Hypoglycemia after antimicrobial drug prescription for older patients using sulfonylureas

IMPORTANCE

Certain antimicrobial drugs interact with sulfonylureas to increase the risk of hypoglycemia.

OBJECTIVE

To determine the risk of hypoglycemia and associated costs in older patients prescribed glipizide or glyburide who fill a prescription for an antimicrobial drug.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective cohort study of Texas Medicare claims from 2006 to 2009 for patients 66 years or older who were prescribed glipizide or glyburide and who also filled a prescription for 1 of the 16 antimicrobials most commonly prescribed for this population.

METHODS

We assessed hypoglycemia events and associated Medicare costs in patients prescribed 1 of 7 antimicrobial agents thought to interact with sulfonylureas, using noninteracting antimicrobials as a comparison. We used a repeated measure logistic regression, controlling for age, sex, ethnicity, Medicaid eligibility, comorbidity, prior emergency department visits for hypoglycemia, prior hospitalizations for any cause, nursing home residence, and indication for the antimicrobial. We estimated odds of hypoglycemia, number needed to harm, deaths during hospitalization for hypoglycemia, and Medicare costs for hypoglycemia treatment.

MAIN OUTCOMES AND MEASURES

Any hospitalization or emergency department visit owing to hypoglycemia within 14 days of antimicrobial exposure.

RESULTS

In multivariable analyses controlling for patient characteristics and indication for antimicrobial drug use, clarithromycin (odds ratio [OR], 3.96 [95% CI, 2.42-6.49]), levofloxacin (OR, 2.60 [95% CI, 2.18-3.10]), sulfamethoxazole-trimethoprim (OR, 2.56 [95% CI, 2.12-3.10]), metronidazole (OR, 2.11 [95% CI, 1.28-3.47]), and ciprofloxacin (OR, 1.62 [95% CI, 1.33-1.97]) were associated with higher rates of hypoglycemia compared with a panel of noninteracting antimicrobials. The number needed to harm ranged from 71 for clarithromycin to 334 for ciprofloxacin. Patient factors associated with hypoglycemia included older age, female sex, black or Hispanic race/ethnicity, higher comorbidity, and prior hypoglycemic episode. In 2009, 28.3% of patients prescribed a sulfonylurea filled a prescription for 1 of these 5 antimicrobials, which were associated with 13.2% of all hypoglycemia events in patients taking sulfonylureas. The treatment of subsequent hypoglycemia adds $30.54 in additional Medicare costs to each prescription of 1 of those 5 antimicrobials given to patients taking sulfonylureas.

CONCLUSIONS AND RELEVANCE

Prescription of interacting antimicrobial drugs to patients on sulfonylureas is very common, and is associated with substantial morbidity and increased costs.

Effect of fluoroquinolones on mitochondrial function in pancreatic beta cells

Hyper- and hypoglycaemias are known side effects of fluoroquinolone antibiotics, resulting in a number of fatalities. Fluoroquinolone-induced hypoglycaemias are due to stimulated insulin release by the inhibition of the KATP channel activity of the beta cell. Recently, it was found that fluoroquinolones were much less effective on metabolically intact beta cells than on open cell preparations. Thus the intracellular effects of gatifloxacin, moxifloxacin and ciprofloxacin were investigated by measuring NAD(P)H- and FAD-autofluorescence, the mitochondrial membrane potential, and the adenine nucleotide content of isolated pancreatic islets and beta cells. 100 μM of moxifloxacin abolished the NAD(P)H increase elicited by 20mM glucose, while gatifloxacin diminished it and ciprofloxacin had no significant effect. This pattern was also seen with islets from SUR1 Ko mice, which have no functional KATP channels. Moxifloxacin also diminished the glucose-induced decrease of FAD-fluorescence, which reflects the intramitochondrial production of reducing equivalents. Moxifloxacin, but not ciprofloxacin or gatifloxacin significantly reduced the effect of 20mM glucose on the ATP/ADP ratio. The mitochondrial hyperpolarization caused by 20mM glucose was partially antagonized by moxifloxacin, but not by ciprofloxacin or gatifloxacin. Ultrastructural analyses after 20 h tissue culture showed that all three compounds (at 10 and 100 μM) diminished the number of insulin secretory granules and that gatifloxacin and ciprofloxacin, but not moxifloxacin induced fission/fusion configurations of the beta cell mitochondria. In conclusion, fluoroquinolones affect the function of the mitochondria in pancreatic beta cells which may diminish the insulinotropic effect of KATP channel closure and contribute to the hyperglycaemic episodes.

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.

The mechanisms of insulin secretion and calcium signaling in pancreatic β-cells exposed to fluoroquinolones

Fluoroquinolones reportedly induce hypoglycemia through stimulation of insulin secretion from pancreatic β-cells via inhibition of K(ATP) channels and activation of L-type voltage-dependent Ca(2+) channels. In physiological condition, the cytosolic Ca(2+) concentration ([Ca(2+)](c)) is also regulated by release of Ca(2+) from intracellular Ca(2+) stores. In this study, we investigated the mechanism of insulin secretion induced by fluoroquinolones, with respect to intracellular Ca(2+) stores. Even where the absence of supplemental extracellular Ca(2+), insulin secretion and [Ca(2+)](c) were increased by gatifloxacin, levofloxacin or tolbutamide. Insulin secretion and the rise of [Ca(2+)](c) induced by fluoroquinolones were reduced by depleting of Ca(2+) in endoplasmic reticumum (ER) by thapsigargin, and inhibiting ryanodine receptor of ER by dantrolene. Inhibition of inositol 1,4,5-triphosphate receptor of ER by xestospongin C suppressed insulin secretion induced by fluoroquinolones, whereas it did not affect [Ca(2+)](c). Destruction of acidic Ca(2+) stores such as lysosome and lysosome-related organelles by glycyl-L-phenylalanine-2-nephthylamide (GPN) did not affect insulin secretion and the rise of [Ca(2+)](c) induced by fluoroquinolones. The increase in insulin and [Ca(2+)](c) induced by tolbutamide were reduced by thapsigargin, dantrolene, and GPN but not by xestospongin C. In conclusion, fluoroquinolones induces Ca(2+) release from ER mediated by the ryanodine receptor, and the reaction might involve in insulin secretion. Sulfonylureas induce Ca(2+) release from GPN-sensitive acidic Ca(2+) stores, but fluoroquinolones did not.

Combined contributions of over-secreted glucagon-like peptide 1 and suppressed insulin secretion to hyperglycemia induced by gatifloxacin in rats

Accumulating evidences have showed that gatifloxacin causes dysglycemia in both diabetic and non-diabetic patients. Our preliminary study demonstrated that gatifloxacin stimulated glucagon-like peptide 1 (GLP-1) secretion from intestinal cells. The aim of the study was to investigate the association between gatifloxacin-stimulated GLP-1 release and dysglycemia in both normal and streptozotocin-induced diabetic rats and explore the possible mechanisms. Oral administration of gatifloxacin (100 mg/kg/day and 200 mg/kg/day) for 3 and 12 days led to marked elevation of GLP-1 levels, accompanied by significant decrease in insulin levels and increase in plasma glucose. Similar results were found in normal rats treated with 3-day gatifloxacin. Gatifloxacin-stimulated GLP-1 release was further confirmed in NCI-H716 cells, which was abolished by diazoxide, a K(ATP) channel opener. QT-PCR analysis showed that gatifloxacin also upregulated expression of proglucagon and prohormone convertase 3 mRNA. To clarify the contradiction on elevated GLP-1 without insulinotropic effect, effects of GLP-1 and gatifloxacin on insulin release were investigated using INS-1 cells. We found that short exposure (2h) to GLP-1 stimulated insulin secretion and biosynthesis, whereas long exposure (24 h and 48 h) to high level of GLP-1 inhibited insulin secretion and biosynthesis. Moreover, we also confirmed gatifloxacin acutely stimulated insulin secretion while chronically inhibited insulin biosynthesis. All the results gave an inference that gatifloxacin stimulated over-secretion of GLP-1, in turn, high levels of GLP-1 and gatifloxacin synergistically impaired insulin release, worsening hyperglycemia.

Erlotinib and gefitinib, small-molecule EGFR inhibitors. New uses for old drugs?

The process of drug discovery and development takes decades and costs billions, therefore it is pertinent to consider the clinical ‘off-target’ actions of currently approved agents. The safety profile of these agents is already established and there is experience of specific clinical utility. The investigation of recognised ‘off-target’ actions may provide a more rapid avenue to address ‘non-target’ disease states. Herein the potential of the epidermal growth factor receptor inhibitors erlotinib and geritinib are considered within the context of diabetes.

Pharmacological stimulation and inhibition of insulin secretion in mouse islets lacking ATP-sensitive K+ channels

BACKGROUND AND PURPOSE

ATP-sensitive potassium channels (K(ATP) channels) in beta cells are a major target for insulinotropic drugs. Here, we studied the effects of selected stimulatory and inhibitory pharmacological agents in islets lacking K(ATP) channels.

EXPERIMENTAL APPROACH

We compared insulin secretion (IS) and cytosolic calcium ([Ca(2+)](c)) changes in islets isolated from control mice and mice lacking sulphonylurea receptor1 (SUR1), and thus K(ATP) channels in their beta cells (Sur1KO).

KEY RESULTS

While similarly increasing [Ca(2+)](c) and IS in controls, agents binding to site A (tolbutamide) or site B (meglitinide) of SUR1 were ineffective in Sur1KO islets. Of two non-selective blockers of potassium channels, quinine was inactive, whereas tetraethylammonium was more active in Sur1KO compared with control islets. Phentolamine, efaroxan and alinidine, three imidazolines binding to K(IR)6.2 (pore of K(ATP) channels), stimulated control islets, but only phentolamine retained weaker stimulatory effects on [Ca(2+)](c) and IS in Sur1KO islets. Neither K(ATP) channel opener (diazoxide, pinacidil) inhibited Sur1KO islets. Calcium channel blockers (nimodipine, verapamil) or diphenylhydantoin decreased [Ca(2+)](c) and IS in both types of islets, verapamil and diphenylhydantoin being more efficient in Sur1KO islets. Activation of alpha(2)-adrenoceptors or dopamine receptors strongly inhibited IS while partially (clonidine > dopamine) lowering [Ca(2+)](c) (control > Sur1KO islets).

CONCLUSIONS AND IMPLICATIONS

Those drugs retaining effects on IS in islets lacking K(ATP) channels, also affected [Ca(2+)](c), indicating actions on other ionic channels. The greater effects of some inhibitors in Sur1KO than in control islets might be relevant to medical treatment of congenital hyperinsulinism caused by inactivating mutations of K(ATP) channels.