Fluoroquinolone toxicities. An update

Fluoroquinolone antibiotics show genotoxic effect through DNA-binding and oxidative damage

The fluoroquinolones (FQs) are one the most successful class of synthetic antibiotics that primarily target the type II topoisomerases. With a pursuit to evaluate their genotoxicity, the present work established moderate to good DNA-damaging properties of some of the well-known and clinically prescribed fluoroquinolone antibiotics (2^nd and 3^rd generation). Hypochromic shift in UV-Vis absorption titration, fluorescence quenching in competitive ethidium bromide displacement assay (with calf-thymus DNA) and in-silico studies established DNA-intercalation with binding constants of the order 10⁴. A basic Structure Activity Relationship (SAR) has been derived from the docking results. MTT assay has been also done to evaluate the effect of these antibiotics on cell viability. The expression level of specific DNA-glycosylase enzymes responsible for repairing the oxidized DNA bases are quantified through western blot analysis. The studies revealed that fluoroquinolone antibiotics initiate the genotoxic effect at a concentration of above 50 μg/mL. Recruitment of APE1 and NEIL1 was found to be significantly increased to remove the oxidized nucleobases.

Construction of Bi2O3/CuNiFe LDHs composite and its enhanced photocatalytic degradation of lomefloxacin with persulfate under simulated sunlight

Advanced oxidation methods based on photocatalysis and sulfate radicals have attached most interest towards contaminant degradation. However, there are a lack of coupling two methods in the field of pollutant degradation. In the present study, a new Bi₂O₃/CuNiFe LDHs composite was fabricated and it could efficiently activate persulfate (PS) for lomefloxacin (LOM) decomposition under simulated sunlight, in which 84.6% of LOM (10 mg·L^-1) was degraded over 40 min with 0.4 g·L^-1 of Bi₂O₃/CuNiFe LDHs composite and 0.74 mM of PS at natural pH. In addition, the Bi₂O₃/CuNiFe LDHs composite possessed good reusability and stability at least four runs. Moreover, active radical scavenging experiments indicated that hydroxyl radicals (HO·), sulfate radicals (SO₄·^-), superoxide radicals (O₂·^-) and hole (h⁺) were the main radicals under LOM degradation process. Subsequently, the possible degradation intermediates were determined and the decomposition pathways were put forward. At the same time, activated sludge inhibition experiments were performed to assess the variation of toxicity of LOM and its degradation intermediates during oxidation. Finally, possible reaction mechanism of Bi₂O₃/CuNiFe LDHs composite for PS activation under simulated sunlight was proposed.

A nanocomposite fluorescent probe of polyaniline, graphene oxide and quantum dots incorporated into highly selective polymer for lomefloxacin detection

A nanocomposite fluorescent probe based on fluorescence quenching was fabricated and utilized for the detection of lomefloxacin. The fabricated probe integrated the high sensitivity of quantum dots, the excellent selectivity of molecularly imprinted polymer and the high adsorption affinity of graphene oxide and polyaniline. The probe exhibited good sensitivity, high specificity, and rapidity for lomefloxacin monitoring. Fluorescence emission was reduced linearly by lomefloxacin from 0.10 to 50.0 μg L^-1 and the probe exhibited a low limit of detection of 0.07 μg L^-1. The nanooptosensor successfully detected lomefloxacin in milk, chicken meat and egg samples. Recoveries were obtained in the range of 81.5-99.6% and the RSDs were below 7%. The results of this method agreed well with results of HPLC but provided higher sensitivity. This easily fabricated nanocomposite probe could be developed into a highly sensitive and selective optosensor to detect other organic compounds in various complex samples.

Silver nanoparticles for the visual detection of lomefloxacin in the presence of cystine

A novel optical sensors for lomefloxacin based on the plasma resonance properties of silver nanoparticles (AgNPs) for the first time. The hydrogen bonds and electrostatic force between the lomefloxacin and AgNPs could induce the change in color and absorption spectra of AgNPs suspension, which provided a theoretical basis for the optical detection of lomefloxacin. In addition, we made the AgNPs-lomefloxacin detection system reach the critical point of discoloration by adding cystine to improve the sensitivity. Furthermore, the influence of some factors such as temperature, reaction time and pH on the AgNPs-lomefloxacin detection system was investigated. The results of UV-vis spectra showed that the absorption ratio (A₅₂₀/A₃₉₅) was linear with the concentration of lomefloxacin in the range from 0.2 to 5 μmol/L with linear coefficients of 0.991. The proposed method can be applied to detecting lomefloxacin with an ultralow detection limit of 0.6 μmol/L without any complicated instruments and complex pretreatment. The selectivity of AgNPs-lomefloxacin detection system is proved excellent by comparing with other ions and analytes in urine. The method in our study is appropriate to be used to monitor quantitatively entecavir in human urine owing to its rapid response rate, visible color changes, wide linear range and excellent selectivity.

Severe Acute Axonal Neuropathy Induced by Ciprofloxacin: A Case Report

Fluoroquinolones increase the risk of peripheral neuropathy. The present work aims to report a case of fluoroquinolone-related severe axonal neuropathy. The subject of this study was a 62-year-old man who exhibited generalized sensory disturbances 4 days after treatment by ciprofloxacin prescribed for urinary infection. Electrodiagnostic studies revealed severe motor-sensory axonal neuropathy with widespread fibrillation potentials in support of generalized motor polyradiculopathy. There was no evidence of conduction blocks or albuminocytologic dissociation in favor of an autoimmune inflammatory reaction. The only pathological biomarker was the reduction of serum folate. According to this case, we suggest that folate level could be routinely measured and supplementation should be performed in patients with fluoroquinolone-induced neuropathy.

Early postoperative fluoroquinolone use is associated with an increased revision rate after arthroscopic rotator cuff repair

PURPOSE

To evaluate the association of postoperative fluoroquinolone use following arthroscopic primary rotator cuff repair with failure requiring revision rotator cuff repair.

METHODS

An insurance database was queried for patients undergoing rotator cuff repair from 2007 to 2015. These patients were divided into three groups: (1) patients prescribed fluoroquinolones within 6 months postoperatively (divided into 0-2, 2-4, and 4-6 months), (2) a matched negative control cohort of patients not prescribed fluoroquinolones, and (3) a matched positive control cohort of patients prescribed fluoroquinolones between 6 and 18 months following rotator cuff repair. Rates of failure requiring revision rotator cuff repair were compared within 2 years.

RESULTS

A total of 1292 patients were prescribed fluoroquinolones within 6 months after rotator cuff repair, including 442 within 2 months, 433 within 2 to 4 months, and 417 within 4 to 6 months, and were compared to 5225 matched negative controls and 1597 matched positive controls. The rate of revision rotator cuff repair was significantly higher in patients prescribed fluoroquinolones within 2 months (6.1 %) compared to matched negative (2.2 %, P = 0.0009) and positive controls (2.4 %, P = 0.0026). There were no significant differences in the rate of revision rotator cuff repair when fluoroquinolones were prescribed >2 months after rotator cuff repair.

CONCLUSIONS

Early use of fluoroquinolones following rotator cuff repair was independently associated with significantly increased rates of failure requiring revision rotator cuff repair. This is the first clinical study examining the association of postoperative fluoroquinolone use with failure following arthroscopic rotator cuff repair.

LEVEL OF EVIDENCE

III.

Antibiotic Prescriptions and Prophylaxis in Italian Children. Is It Time to Change? Data from the ARPEC Project

BACKGROUND

Antimicrobials are the most commonly prescribed drugs. Many studies have evaluated antibiotic prescriptions in the paediatric outpatient but few studies describing the real antibiotic consumption in Italian children's hospitals have been published. Point-prevalence survey (PPS) has been shown to be a simple, feasible and reliable standardized method for antimicrobials surveillance in children and neonates admitted to the hospital. In this paper, we presented data from a PPS on antimicrobial prescriptions carried out in 7 large Italian paediatric institutions.

METHODS

A 1-day PPS on antibiotic use in hospitalized neonates and children was performed in Italy between October and December 2012 as part of the Antibiotic Resistance and Prescribing in European Children project (ARPEC). Seven institutions in seven Italian cities were involved. The survey included all admitted patients less than 18 years of age present in the ward at 8:00 am on the day of the survey, who had at least one on-going antibiotic prescription. For all patients data about age, weight, underlying disease, antimicrobial agent, dose and indication for treatment were collected.

RESULTS

The PPS was performed in 61 wards within 7 Italian institutions. A total of 899 patients were eligible and 349 (38.9%) had an on-going prescription for one or more antibiotics, with variable rates among the hospitals (25.7% - 53.8%). We describe antibiotic prescriptions separately in neonates (<30 days old) and children (> = 30 days to <18 years old). In the neonatal cohort, 62.8% received antibiotics for prophylaxis and only 37.2% on those on antibiotics were treated for infection. Penicillins and aminoglycosides were the most prescribed antibiotic classes. In the paediatric cohort, 64.4% of patients were receiving antibiotics for treatment of infections and 35.5% for prophylaxis. Third generation cephalosporins and penicillin plus inhibitors were the top two antibiotic classes. The main reason for prescribing antibiotic therapy in children was lower respiratory tract infections (LRTI), followed by febrile neutropenia/fever in oncologic patients, while, in neonates, sepsis was the most common indication for treatment. Focusing on prescriptions for LRTI, 43.3% of patients were treated with 3rd generation cephalosporins, followed by macrolides (26.9%), quinolones (16.4%) and carbapenems (14.9%) and 50.1% of LRTI cases were receiving more than one antibiotic. For neutropenic fever/fever in oncologic patients, the preferred antibiotics were penicillins with inhibitors (47.8%), followed by carbapenems (34.8%), aminoglycosides (26.1%) and glycopeptides (26.1%). Overall, the 60.9% of patients were treated with a combination therapy.

CONCLUSIONS

Our study provides insight on the Italian situation in terms of antibiotic prescriptions in hospitalized neonates and children. An over-use of third generation cephalosporins both for prophylaxis and treatment was the most worrisome finding. A misuse and abuse of carbapenems and quinolones was also noted. Antibiotic stewardship programs should immediately identify feasible targets to monitor and modify the prescription patterns in children's hospital, also considering the continuous and alarming emergence of MDR bacteria.

Fluoroquinolones impair tendon healing in a rat rotator cuff repair model: a preliminary study

BACKGROUND

Recent studies suggest that fluoroquinolone antibiotics predispose tendons to tendinopathy and/or rupture. However, no investigations on the reparative capacity of tendons exposed to fluoroquinolones have been conducted.

HYPOTHESIS

Fluoroquinolone-treated animals will have inferior biochemical, histological, and biomechanical properties at the healing tendon-bone enthesis compared with controls.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ninety-two rats underwent rotator cuff repair and were randomly assigned to 1 of 4 groups: (1) preoperative (Preop), whereby animals received fleroxacin for 1 week preoperatively; (2) pre- and postoperative (Pre/Postop), whereby animals received fleroxacin for 1 week preoperatively and for 2 weeks postoperatively; (3) postoperative (Postop), whereby animals received fleroxacin for 2 weeks postoperatively; and (4) control, whereby animals received vehicle for 1 week preoperatively and for 2 weeks postoperatively. Rats were euthanized at 2 weeks postoperatively for biochemical, histological, and biomechanical analysis. All data were expressed as mean ± standard error of the mean (SEM). Statistical comparisons were performed using either 1-way or 2-way ANOVA, with P < .05 considered significant.

RESULTS

Reverse transcriptase quantitative polymerase chain reaction (RTqPCR) analysis revealed a 30-fold increase in expression of matrix metalloproteinase (MMP)-3, a 7-fold increase in MMP-13, and a 4-fold increase in tissue inhibitor of metalloproteinases (TIMP)-1 in the Pre/Postop group compared with the other groups. The appearance of the healing enthesis in all treated animals was qualitatively different than that in controls. The tendons were friable and atrophic. All 3 treated groups showed significantly less fibrocartilage and poorly organized collagen at the healing enthesis compared with control animals. There was a significant difference in the mode of failure, with treated animals demonstrating an intrasubstance failure of the supraspinatus tendon during testing. In contrast, only 1 of 10 control samples failed within the tendon substance. The healing enthesis of the Pre/Postop group displayed significantly reduced ultimate load to failure compared with the Preop, Postop, and control groups. There was no significant difference in load to failure in the Preop group compared with the Postop group. Pre/Postop animals demonstrated significantly reduced cross-sectional area compared with the Postop and control groups. There was also a significant reduction in area between the Preop and control groups.

CONCLUSION

In this preliminary study, fluoroquinolone treatment negatively influenced tendon healing.

CLINICAL RELEVANCE

These findings indicate that there was an active but inadequate repair response that has potential clinical implications for patients who are exposed to fluoroquinolones before tendon repair surgery.

Epileptogenic drugs: a systematic review

A wide range of substances, including drugs and illicit compounds, increase the risk of epileptic seizures. In this systematic review, the authors address the issue of the epileptogenic potential of marketed drugs, with the aims of providing criteria for the assessment of the cause-effect relationship between drug exposure and the risk of seizures; and to identify the compounds better fulfilling the requirements of an epileptogenic drug. Finding a correlation between drug exposure and occurrence of seizures does not necessarily establish a causal association. In light of the available evidence, even with these limitations, some conclusive remarks can be made on the epileptogenic potential of some active principles. Drugs with high epileptogenic potential include meperidine, sevoflurane, clozapine, phenothiazines and cyclosporine. Drugs with intermediate epileptogenic potential include propofol, maprotiline, tricyclic antidepressants and chlorambucil. Drugs with low epileptogenic potential include fluorquinolones, carbapenems, bupropion and iodinated contrast media. Drugs with minimal or inconclusive epileptogenic potential include interferon alpha.

Systemic use of fluoroquinolone in children

Fluoroquinolones are an important class of antibiotics that are widely used in adult patients because of their broad spectrum of activity, good tissue penetration, and oral bioavailability. However, fluoroquinolone use in children is limited because juvenile animals developed arthropathy in previous experiments on fluoroquinolone use. Indications for fluoroquinolone use in patients younger than 18 years, as stated by the U.S. Food and Drug Administration, include treatment of complicated urinary tract infections and postexposure treatment for inhalation anthrax. In Korea, the systemic use of fluoroquinolones has not been approved in children younger than 18 years. Although concerns remain regarding the adverse musculoskeletal effects of fluoroquinolones in children, their use in the pediatric population has increased in many circumstances. While pediatricians should be aware of the indications and adverse effects of fluoroquinolones, recent studies have shown that the risk for musculoskeletal complications in children did not significantly increase following fluoroquinolone treatment. In addition, fluoroquinolones may be particularly helpful in treating multidrug-resistant infections that have not responded to standard antibiotic therapy in immunocompromised patients. In the present article, we provide an updated review on the safety and current recommendations for using fluoroquinolones in children.

Medicinal potential of ciprofloxacin and its derivatives

Ciprofloxacin (CP) is a fluoroquinolone that is highly active against diverse microorganisms. At concentrations less than 1 µg/ml it is active against a diverse types of bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Bacillius subtilius, Escherichia coli and Mycobacterium tuberculosis. In addition, it has shown to be effective against other diseases such as malaria, cancer and AIDS. The extended antimicrobial activity, lack of plasmid-mediated resistance, large volume of distribution and minimal adverse effects of CP are therapeutically advantageous. In the pursuit of increasing their effectiveness against these diseases and prevent unwanted resistance, researchers have begun to synthesize a class of organic, inorganic and organometallic derivatives, which have displayed interesting activities. This review describes the development and recent advances on the evaluation of CP and its derivatives as a new class of drugs with potential for clinical development.

Oxidative stress induced by fluoroquinolones on treatment for complicated urinary tract infections in Indian patients

The aim of the study is to examine the oxidative stress in patients on fluoroquinolones (ciprofloxacin, levofloxacin, gatifloxacin) therapy for complicated urinary tract infections and to correlate with plasma concentrations at different time intervals. Superoxide dismutase (SOD), glutathione, plasma antioxidant status and lipid peroxides were evaluated in 52 patients on different dosage regimens up to 5 days. There is significant and gradual elevation of lipid peroxide levels in patients on ciprofloxacin (3.6 ± 0.34 nmol/ml to 6.2 ± 0.94 nmol/ml) and levofloxacin (3.5 ± 0.84 nmol/ml to 5.1 ± 0.28 nmol/ml) dosage regimen but not with gatifloxacin (3.5 ± 0.84 nmol/ml to 3.74 ± 0.17 nmol.ml). There was substantial depletion in both SOD and glutathione levels particularly with ciprofloxacin. On the 5(th) day of treatment, plasma antioxidant status decreased by 77.6% %, 50.5%, 7.56% for ciprofloxacin, levofloxacin and gatifloxacin respectively. In conclusion ciprofloxacin and levofloxacin induce more reactive oxygen species that lead to cell damage than gatifloxacin irrespective of their concentrations in patient population.

Modification of innervation pattern by fluoroquinolone treatment in the rat salivary glands

Fluoroquinolone antibiotics (FQAs) are widely used in dental and medical therapy. Despite their known severe adverse actions on the central and peripheral nervous system, little attention has been directed toward the potential toxic side effects of these compounds on the oral tissues. As the saliva secretion is controlled by the nervous system and neuropeptides, the neurotoxic effect of pefloxacin (PEF), a representative member of FQAs, was studied in rats in the present work. Previously, we demonstrated a significant weight loss of parotid gland tissue, a marked decrease in 3H-thymidine incorporation, a decreased volume of saliva and amylase activity of the glandular tissue in response to PEF. Animals received intraperitoneal injection of PEF (20 mg/100 g body weight daily) for 3 and 7 days. Normal histology, and neurofilament 200, substance P (SP) and calcitonin gene-related polypeptide (CGRP) containing nerve fibers were detected with immunohistochemical methods. A marked decrease of the weights in salivary glands and the acinar diameters were measured. Similarly, a strong and significant decrease of the number of SP and CGRP containing nerve fibers were detected. These findings suggest that the impaired morphology and innervation pattern of salivary glands is related to the neurotoxic adverse effect of FQA treatment.

Radiation-Inducedin VitroPhototoxic Potential of Some Fluoroquinolones

Photosensitizing drugs that can damage cellular biomolecules is a matter of concern. Lomefloxacin, norfloxacin, ofloxacin, and enoxacin (broad-spectrum antibiotics of fluoroquinolone group) are used for the treatment of Gram-positive and Gram-negative bacterial infections. Phototoxicity and possible mechanism of their action was assessed under the exposure of ambient levels of UV-A, UV-B, and sunlight at a concentration generally used in the treatment of various diseases. Singlet oxygen (1O2), superoxide anion radical (O2.-) generation, DNA damage, and lipid peroxidation in human blood were studied. All the fluoroquinolones tested in this study produced 1O2 and O2.- under exposure to UV-A, UV-B, and sunlight depending on the concentrations (0 to 60 microg/mL) of the drugs. Enoxacin showed a higher yield of 1O2 and O2.- than other drugs. These materials also degraded deoxyguanosine and induced lipid peroxidation in vitro under exposure to UV-A, UV-B, and sunlight (depending on the dose of radiation). The formation of the reactive oxygen species (ROS) by the photoexcited drugs may be considered as a possible mechanism of their action.

Fluoroquinolones-Induced Tendinitis and Tendon Rupture in Kidney Transplant Recipients: 2 Cases and a Review of the Literature

Fluoroquinolones are an important class of synthetic antibiotics and their use recently expanded with a new activity against Gram positive and anaerobics. In the literature many side effects were documented and, among them, tendinitis and subsequent tendon rupture are important causes of morbidity. The incidence is 0.14% to 0.4% but, in the kidney recipient population, the phenomenon is even more common (incidence, 12.2%-15.6%). Advanced age seems to be the most significant risk factor. Long period of hemodialysis, diabetes mellitus, hyperparathyroidism, rheumatic diseases, gout, and corticosteroids are the other predisposing factors in kidney recipients, even if they are still under discussion. All of these risk factors can create a synergistic toxicity or at least an additive effect. A case of tendinitis and a case of bilateral Achilles tendon ruptures in 2 kidney recipients are described and a brief discussion of the literature is presented.

Evidence of tendinitis provoked by fluoroquinolone treatment: a case-control study

OBJECTIVE

To investigate the association between the use of fluoroquinolone agents and the risk of tendinitis in a large population-based case-control study.

METHODS

The study was performed by linking automated health databases from the Region of Lombardia, Italy. Cases were patients aged > or =18 years who had a hospital discharge diagnosis of non-traumatic tendinitis in 2002-3. For each case, up to five controls were randomly selected among those eligible for inclusion in the study. A conditional logistic regression model was used to estimate the odds ratio of tendinitis associated with the current, recent and past use of fluoroquinolones. Odds ratios were adjusted for exposure to other antibacterials and other drugs.

RESULTS

22,194 cases and 104,906 controls met the inclusion criteria. Current use of fluoroquinolones significantly increased the risk of tendon disorders as a whole (odds ratio [OR] = 1.7; 95% CI 1.4, 2.0), tendon rupture (OR = 1.3; 95% CI 1.0, 1.8) and rupture of the Achilles' tendon (OR = 4.1; 95% CI 1.8, 9.6). Concomitant use of corticosteroids and fluoroquinolones increased the risk of both tendon rupture (OR = 3.1; 95% CI 1.5, 6.3) and rupture of the Achilles' tendon (OR = 43.2; 95% CI 5.5, 341.1).

DISCUSSION

Evidence that exposure to fluoroquinolones is associated with the sudden occurrence of tendinitis is supported by this large population-based study. We can estimate that a single case of rupture of the Achilles' tendon would occur for every 5958 persons treated with fluoroquinolones (95% CI 2148, 23,085). The corresponding number needed to harm is 979 (95% CI 122, 9172) for patients who concomitantly use corticosteroids and 1638 (95% CI 351, 8843) for those aged >60 years.

CONCLUSION

Clinicians should be aware of this adverse effect, and the increased risk for fluoroquinolone-associated tendinitis in elderly patients with corticosteroid use must be considered when these agents are prescribed.

Synthesis and antibacterial activity of N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] and N-[2-[5-(methylthio)thiophen-2-yl]-2-(oxyimino)ethyl]piperazinylquinolone derivatives

A number of N-substituted piperazinylquinolone derivatives were synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative bacteria. Preliminary results indicated that most compounds tested in this study demonstrated comparable or better activity against Staphylococcus aureus and Staphylococcus epidermidis than their parent piperazinylquinolones as reference drugs. Among these derivatives, ciprofloxacin derivative 5a, containing N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] residue, showed significant improvement of potency against staphylococci, maintaining Gram-negative coverage.

Les insuffisances rénales aiguës aux quinolones. Revue générale à propos d'une observation avec cristallisation liée à la ciprofloxacine

A 58 year-old woman developed an acute renal failure very quickly after ingestion of two 500 mg tablets of ciprofloxacin, without any other identifiable risk factor. Renal biopsy was performed. No sign of acute interstitial nephritis was observed but tubular lesions were found, accompanied by deposits of a brown-yellowish substance identified by infrared microscopy as a ciprofloxacin salt. The outcome was favourable. This observation gives the opportunity to remind the different forms of quinolone-induced renal injury and to discuss the possible ways for preventing renal side-effects related to the quinolone use.

Once-daily oral gatifloxacin vs three-times-daily co-amoxiclav in the treatment of patients with community-acquired pneumonia

A double-blind, double-dummy, multicentre, multinational, parallel-group study was designed to establish proof of equivalence between oral gatifloxacin and oral co-amoxiclav in the treatment of 462 patients with mild-to-moderate community-acquired pneumonia. Eligible patients were randomised equally to either gatifloxacin 400 mg once-daily plus matching placebo for 5-10 days, or amoxycillin 500 mg + clavulanic acid 125 mg three-times-daily for 5-10 days. The primary efficacy endpoint was clinical response (clinical cure plus improvement) at the end of treatment. Overall, a successful clinical response was achieved in 86.8% of gatifloxacin-treated patients, compared with 81.6% of those receiving co-amoxiclav, while corresponding rates of bacteriological efficacy (eradication plus presumed eradication) were 83.1% and 78.7%, respectively. The safety and tolerability profile of gatifloxacin was comparable to that of co-amoxiclav, with adverse gastrointestinal events, e.g., diarrhoea and nausea, being the most common treatment-related adverse events in both groups. The study showed no evidence of gatifloxacin-induced phototoxicity, musculoskeletal disorders, or hepatic and renal problems. Overall, this study showed that gatifloxacin was equivalent clinically to a standard course of co-amoxiclav in patients with community-acquired pneumonia, and that gatifloxacin was safe and well-tolerated.

Chemometric Studies on the Bactericidal Activity of Quinolones via an Extended VolSurf Approach

An extended VolSurf approach, that additionally includes SHAPE descriptors, was applied to a dataset of 55 quinolones. Bactericidal activity was measured at Bayer AG, Germany, for Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis). Chemometric analysis was first approached via a classical VolSurf approach. The following descriptors were found most important: bactericidal activity particularly increases with high values of the best volume (BV11(OH2)) and the minimum energy (Emin1(OH2)) of the water probe, high values of the integy moment (ID(DRY)) of the lipophilic probe, and high values of the hydrophilic region (W(O)) of the hydrogen bond acceptor probe. Best volume (BV31(OH2)) of the water probe and best volume (BV12(DRY)) and lipophilic regions (D(DRY)) of the lipophilic probe as well as H-bonding capacity derived with the CO probe (HB(O)) are inversely related to activity. PLS analysis yields a five-component model with an r(2) of 0.83 and a q(2) of 0.43 after variable selection via fractional factorial design (FFD). Chemometric modeling could be improved by including newly derived SHAPE descriptors, which were merged with the VolSurf descriptors and subjected to PLS analysis. The global model of this extended VolSurf approach is optimal with two components and exhibits a significantly improved statistical quality; a marginally reduced r(2) (0.75 versus 0.83) is more than compensated by a highly improved predictivity with a q(2) of 0.63 versus 0.43. To prove model quality, external prediction of seven test set quinolones was performed. The precise prediction of all test set molecules nicely demonstrates the robustness and statistical significance of the obtained chemometric model using the extended VolSurf approach.

Randomised double-blind comparison of oral gatifloxacin and co-amoxiclav for acute exacerbation of chronic Bronchitis

Antimicrobial therapy can have a significant impact in the treatment of acute infectious exacerbations in patients with chronic bronchitis, in whom repeated episodes are common. The aim of this randomised, double-blind, double-dummy, parallel group study was to compare the efficacy and safety of oral gatifloxacin (200 and 400 mg once daily) administered for 5 days with co-amoxiclav (500 mg amoxicillin/125 mg clavulanic acid t.i.d.) administered for 10 days in 414 adult patients with acute exacerbation of chronic bronchitis. Overall clinical response rates (cure plus improvement) were 86.2%, 79.4% and 81.7% in the gatifloxacin 200 mg, gatifloxacin 400 mg and co-amoxiclav groups, respectively, and the equivalence hypothesis used for statistical analysis showed equivalent efficacy for both gatifloxacin 200 and 400 mg compared to co-amoxiclav. The same was true for rates of bacterial response, with eradication or presumed eradication of causative pathogens achieved in 87.5%, 87.3% and 79.1% of cases in the gatifloxacin 200 mg, gatifloxacin 400 mg and co-amoxiclav groups, respectively. All treatments were well tolerated, with the nature and frequency of treatment-related adverse events similar in all groups. The results of the study show that gatifloxacin is a safe and effective agent for the treatment of patients with chronic bronchitis experiencing an acute infectious exacerbation.

Safety of fluoroquinolones: An update

The fluoroquinolone class of antimicrobials has been in clinical use for over 13 years. During that period, some representatives of the class have been extensively prescribed, such as ciprofloxacin and levofloxacin, while others have seen minimal use and have been restricted or withdrawn, namely, trovafloxacin and grepafloxacin. Manipulation of the fluoroquinolone structure by substituting a range of moieties around the core has yielded enhanced antibacterial activity, but in some cases this has come at a price. Specific substitutions are discussed in relation to particular recognized adverse events. In the present paper, newly introduced fluoroquinolones, such as moxifloxacin and gatifloxacin, are examined in terms of anticipated class effects and recent clinical experience. These antimicrobials are associated with reactions such as diarrhea, nausea, headache and other typical antimicrobial phenomena at rates less than 5%. New fluoroquinolone agents should be examined carefully in light of structural findings until adequate clinical data are amassed.

In vitro method for prediction of the phototoxic potentials of fluoroquinolones

The phototoxic potential of eight fluoroquinolones (norfloxacin, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, tosufloxacin, sparfloxacin and gatifloxacin) was evaluated by using three in vitro methods of cytotoxicity against mammalian cells, erythrocyte lysis and DNA strand breakage. All fluoroquinolones tested with the exception of gatifloxacin, an 8-methoxy quinolone, showed DNA strand breaking activities under UV-A irradiation. Their cytotoxicity against HeLa cells was also enhanced by UV-A irradiation. In particular, the phototoxic potential of sparfloxacin, enoxacin and lomefloxacin was high in both methods. Ofloxacin is very photocytotoxic against HeLa cells, while it has low potential to cause DNA strand breakage. Norfloxacin, ciprofloxacin and enoxacin were very photohemolytic, but sparfloxacin was not, indicating that the in vivo phototoxic potencies of fluoroquinolones might not be predictable by the photohemolysis study. Gatifloxacin, a non-phototoxic quinolone, showed no phototoxic potential in any of these three in vitro tests. These results suggest that determination of DNA strand breaking activity, combined with cytotoxicity against mammalian cells, is available to predict the phototoxic potential of fluoroquinolones without laboratory animals.

Peripheral neuropathy associated with fluoroquinolones

OBJECTIVE

To survey cases of fluoroquinolone-associated adverse events that included peripheral nervous system (PNS) symptoms posted on Internet Web sites.

METHODS

Cases were obtained with the assistance of members of Web sites formed by people sustaining fluoroquinolone-related events. Information obtained met the standards of MedWatch, and each reported case was assessed using the Naranjo probability scale.

RESULTS

In contrast to previous reports suggesting that fluoroquinolone-associated PNS events are mild and short-term, 36 of the 45 cases reported severe events that typically involved multiple organ systems. Although many newer cases are still evolving, symptoms had lasted more than three months in 71% of cases and more than one year in 58%. Onset of adverse events was usually rapid, with 15 (33%) events beginning within 24 hours of initiating treatment, 26 (58%) within 72 hours, and 38 (84%) within one week. Sixty courses of fluoroquinolones were prescribed: levofloxacin (n = 33 cases), ciprofloxacin (n = 11), ofloxacin (n = 6), lomefloxacin (n = 1), trovafloxacin (n = 1); in eight cases the same antibiotic was prescribed twice.

CONCLUSIONS

These cases suggest a possible association between fluoroquinolone antibiotics and severe, long-term adverse effects involving the PNS as well as other organ systems. The severity of these cases may reflect a different population than typically reported to drug companies or MedWatch, which often originate from healthcare providers. In contrast, Internet Web sites may provide a forum for patients experiencing adverse effects that have not resolved promptly. Further study is warranted. Meanwhile the occurrence of PNS symptoms during fluoroquinolone therapy should prompt immediate discontinuation of the agent used.

Fluoroquinolone adverse effects and drug interactions

Extensive pharmacologic and clinical development of quinolone antimicrobial agents has resulted in improved antimicrobial activity, pharmacokinetic features, toxicity, and drug-drug interaction profiles. Nalidixic acid and other early quinolones had limited use due to poor pharmacokinetics, relatively narrow antimicrobial spectrum of activity, and frequent adverse effects. Beginning with the development of fluoroquinolones, such as norfloxacin and ciprofloxacin, in the 1980s, the agents assumed a greatly expanded clinical role because of their broad antimicrobial spectrum of action, improved pharmacokinetic properties, and more acceptable safety profile. Although the pharmacokinetics and efficacy of the drugs have improved significantly, a major area of continued emphasis is to further reduce the frequency and severity of adverse events and drug-drug interactions. Older agents such as ciprofloxacin and ofloxacin are still extensively prescribed, but the focus of this article is on the newer fluoroquinolones (levofloxacin and other drugs that have been approved or have been under investigation since approximately 1997).

Clinafloxacin pharmacokinetics in subjects with various degrees of renal function

As the primary route for elimination of clinafloxacin is renal clearance (CL(R)) of unchanged drug, studies were conducted to determine the pharmacokinetic profile of clinafloxacin following administration to young and elderly subjects, subjects with various degrees of renal function, and subjects requiring dialysis. These were open-label studies in which subjects received single oral clinafloxacin doses. Sixteen young subjects (18 to 35 years old) and 16 elderly subjects (>65 years old) were enrolled in a study comparing pharmacokinetic profiles of clinafloxacin in young and elderly subjects. Twenty subjects having various degrees of renal function were enrolled into one of three groups based on degree of renal function as measured by creatinine clearance (CL(CR)). Twelve subjects with severe renal impairment requiring dialysis enrolled in a third study. Clinafloxacin was generally well tolerated by all subjects. Clinafloxacin pharmacokinetic profiles in elderly subjects were dependent only on age-related decreases in renal function. Clinafloxacin maximum concentrations in plasma, areas under the concentration-time curves, and terminal elimination half-life values increased with decreasing CL(CR) values. Total apparent body clearance of clinafloxacin from the plasma after oral administration (CL(oral)) and CL(R) were dependent on CL(CR) according to the following relationships: CL(oral) = 2.3. CL(CR) + 77 and CL(R) = 1.74. CL(CR). Hemodialysis had no significant effect on clinafloxacin clearance. Based on the relationship between CL(CR) and clinafloxacin CL(oral) and CL(R) values, the clinafloxacin dose should be halved in patients having a CL(CR) of <40 ml/min. Further dose adjustment is not warranted in patients requiring hemodialysis.

Tendon disorders attributed to fluoroquinolones: a study on 42 spontaneous reports in the period 1988 to 1998

OBJECTIVE

Fluoroquinolone antibiotics have been associated with tendinitis and tendon rupture. In this paper we report on the followup of 42 spontaneous reports of fluoroquinolone-associated tendon disorders.

METHODS

This study is based on cases of fluoroquinolone-associated tendon disorders reported to the Netherlands Pharmacovigilance Foundation Lareb and the Drug Safety Unit of the Inspectorate for Health Care between January 1, 1988, and January 1, 1998. By means of a mailed questionnaire, we collected information on the site of injury, onset of symptoms, treatment, and course of the tendon disorder as well as information on possible risk factors and concomitant medication.

RESULTS

Of 50 mailed questionnaires, 42 (84%) were returned. The data concerned 32 patients (76%) with tendinitis and 10 patients (24%) with a tendon rupture. Sixteen cases (38%) were attributed to ofloxacin, 13 (31%) to ciprofloxacin, 8 (19%) to norfloxacin, and 5 (12%) to pefloxacin. There was a male predominance, and the median age of the patients was 68 years. Most of the reports concerned the Achilles tendon, and 24 patients (57%) had bilateral tendinitis. The latency period between the start of treatment and the appearance of the first symptoms ranged from 1 to 510 days with a median of 6 days. Most patients recovered within 2 months after cessation of therapy, but 26% had not yet recovered at followup.

CONCLUSION

These reports suggest that fluoroquinolone-associated tendon disorders are more common in patients over 60 years of age. Ofloxacin was implicated most frequently relative to the number of filled prescriptions in the Netherlands.

Anaphylactoid reaction to levofloxacin

Anaphylactoid and/or anaphylactic reactions to fluoroquinolones are estimated to occur in 0.46-1.2/100,000 patients. A 49-year-old woman with a history of asthma was admitted for a presumed asthma exacerbation related to an infectious process. She was given levofloxacin and standard management for an acute exacerbation. On two occasions the patient's respiratory distress worsened, requiring intubation. The second reaction occurred immediately after levofloxacin administration and was accompanied by a marked cutaneous reaction. Levofloxacin was discontinued, and supportive care was provided. No further symptoms occurred. The patient later was found to have been started on levofloxacin before admission for a suspected upper respiratory infection.

Photochemical decomposition of lomefloxacin in vitro and in vivo

To obtain an idea of the photostability of Lomefloxacin (Lom) under in vivo conditions the compound was exposed to UV-A (310-360 nm) in PBS buffer pH 7.4. Exposure of 10 microg/ml of Lom in PBS pH 7.4 led to more than 50% decomposition within 10 min. Loss of the fluorine atom at C-8 and partial breakdown of the piperazine ring occurred. The only two photoproducts formed under these conditions were AEA, 1-ethyl-6-fluoro-1,4-dihydro-7-(2-aminoethyl-amino)-4-oxo-3-quinolinecarboxylic acid, and APA, 1-ethyl-6-fluoro-1,4-dihydro-7-(2-aminopropyl-amino)-4-oxo-3-quinolinecarboxylic acid. When Lom was exposed in whole blood in vitro, the same photochemical decomposition was observed in the plasma as in PBS buffer: APA and AEA were the only products. During UV-A exposure, Lom was shown to be taken up by the leukocytes. This process appeared to be less rapid during UV-A exposure than in the dark. As soon as UV-A exposure commenced, AEA and APA were found. As in the plasma, the total amount of Lom and the two photoproducts in the leukocytes was not significantly different from the amount of Lom found in unexposed cells at the same time point. The erythrocytes did not take up Lom, but exposure of whole blood to Lom and UV-A under the above conditions led to more than 7% haemolysis. Treatment of rats with a combination of Lom and UV-A demonstrated photodecomposition of Lom in vivo. In urine produced during exposure and by the irradiated rats during the twilight period after exposure, a considerable amount of AEA and APA was found. The blood plasma from rats exposed simultaneously to UV-A and Lom proved to contain AEA and APA and, in the leukocytes, APA. This was not the case with animals kept in twilight.

Characterization of clinafloxacin photodegradation products by LC-MS/MS and NMR

Exposure of clinafloxacin to light results in photochemical degradation. The polar and nonpolar photodegradation products were profiled by HPLC using two sets of conditions. Clinafloxacin was subjected to severe light exposure conditions to obtain elevated levels of the photodegradation products for characterization. The structures of eight new degradation products were elucidated based on information from LC-MS/MS fragmentation and NMR spectra following isolation by preparative HPLC. Two photodegradation routes were identified: (1) dechlorination, followed by further reactions involving the quinolone ring, to yield polar photodegradation products; and (2) degradation of the pyrrolidine side-chain, yielding the nonpolar photodegradation products.

Sparfloxacin for the treatment of acute bacterial maxillary sinusitis documented by sinus puncture

PURPOSE

To evaluate the efficacy and safety of sparfloxacin in the treatment of patients with acute bacterial maxillary sinusitis, the microbiologic etiology of which was determined by maxillary sinus puncture.

PATIENTS AND METHODS

Two hundred fifty-three patients enrolled in the open, noncomparative trial received sparfloxacin as a 400-mg loading dose followed by 200 mg once daily doses for a total of 10 days. One hundred ninety-eight patients were clinically evaluable and 82 were also bacteriologically evaluable. All treated patients were included in the safety analysis. Overall success was determined based on clinical success (resolution or reduction of signs and symptoms and sinus x-rays) and bacteriologic success (eradication and presumed eradication of baseline pathogens obtained by maxillary sinus puncture and aspiration).

RESULTS

Overall success in the bacteriologically evaluable population at test-of-cure was 91.5% [75/82; 95% confidence interval (85.4%, 97.5%)]. For all pathogens, the eradication rate was 93.2% (109/117 baseline pathogens); individual pathogen eradication rates were 88.9% (16/18) for S. pneumoniae (including those strains exhibiting decreased susceptibility to penicillin); and 100% for H. influenzae (17/17), S. aureus (14/14), and M. catarrhalis (11/11). The majority of adverse events were of mild or moderate severity; the most frequently related adverse events were photosensitivity reaction, headache, nausea, and diarrhea.

CONCLUSION

Sparfloxacin had an overall success rate of 91.5% for patients in this study and was generally well tolerated in the treatment of acute bacterial maxillary sinusitis.

Quinolones in the aged

Pharmacokinetic studies of fluoroquinolone antibacterials generally demonstrate some quantitative alterations in elderly compared with younger populations. The most common observations are an increased maximal plasma drug concentration and area under the concentration-time curve, which are primarily attributable to the 10 to 15% decrease in lean body mass in the elderly. For quinolones excreted primarily by the renal route, there is a prolongation in elimination half-life correlated with the aging-associated decline in creatinine clearance. Quinolones with major routes of nonrenal clearance will not usually show a prolongation in half-life because of compensatory relative increases in nonrenal mechanisms. Alterations directly attributable to aging alone, however, are minor, and vary between different quinolones. They do not justify a consistent need for dosage alterations on the basis of age alone. Agents with primarily renal excretion, such as ofloxacin or levofloxacin, may require dosage adjustment in the very elderly or the frail elderly, if significant decreases in creatinine clearance are present. No age-related differences in adverse effects of fluoroquinolones have been reported. Studies in both community-dwelling and institutionalised elderly populations have consistently shown quinolones to be as effective as comparative parenteral or oral therapy. While elderly populations may be at greater risk of adverse effects because of comorbidities and concurrent therapies, an increased occurrence of adverse events in elderly populations receiving quinolone antimicrobials relative to younger populations has not been reported.

Cutaneous reactions to drugs. An analysis of spontaneous reports in four Italian regions

AIMS

Cutaneous manifestations are frequently reported in association with drug use. The aim of this study was to analyse the skin reactions reported to the spontaneous surveillance systems of four Italian regions (Friuli Venezia Giulia, Lombardy, Sicily and the Veneto), and correlate the reports with estimated drug consumption during the same period, paying particular attention to the reactions to antimicrobial agents and nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS

All of the adverse drug reactions (ADRs) reported spontaneously between January 1996 and December 1997 to the surveillance systems of four Italian regions (a total population of about 20 million people) were analysed by a panel of experts including dermatologists. On the basis of the Critical Term List of the World Health Organization (WHO), the reactions were classified as either serious or nonserious events. Drug consumption was expressed as a daily defined dose (DDD)/1000 inhabitants/day.

RESULTS

A total of 2224 adverse skin reaction reports (44.7% of all of the reported ADRs) were identified, making a reporting rate of about 5.5 per 100 000 inhabitants/year. The female/male ratio was 1.58, and the reporting rate progressively increased with age. The drug categories with the highest number of cutaneous reactions were antimicrobials, followed by NSAIDs, analgesics and radiology contrast media. There was a total of 372 (16.9%) serious reaction reports, the most frequent being angioedema (171 cases), erythema multiforme (68 cases) and photosensitivity (37 cases). Co-trimoxazole, followed by the cephalosporins and fluoroquinolones, were associated with the highest consumption-related reporting rate among the antimicrobials, and aspirin and dipyrone among the NSAIDs and analgesics.

CONCLUSIONS

Spontaneous reports from four Italian regions revealed that the skin was the organ most frequently affected by ADRs. The paper shows the validity of a regional decentralized system in Italy.

The new fluoroquinolones: A critical review

OBJECTIVE

This paper reviews the literature available on the new fluoroquinolones - clinafloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, sparfloxacin and trovafloxacin - to compare these agents with each other and contrast them with ciprofloxacin, an older fluoroquinolone.

DATA SELECTION

Published papers used were obtained by searching MEDLINE for articles published between 1994 and 1998, inclusive. References of published papers were also obtained and reviewed. Abstracts from scientific proceedings were reviewed.

DATA EXTRACTION

Due to the limited data available on several of the agents, criteria for study inclusion in the in vitro, pharmacokinetics and in vivo sections were not restrictive.

DATA SYNTHESIS

The new fluoroquinolones offer excellent Gram-negative bacillary activity and improved Gram-positive activity (eg, against Streptococcus pneumoniae and Staphylococcus aureus) over ciprofloxacin. Clinafloxacin, gatifloxacin, moxifloxacin, sparfloxacin and trovafloxacin display improved activity against anaerobes (eg, Bacteriodes fragilis). All of the new fluoroquinolones have a longer serum half-life than ciprofloxacin (allowing for once daily dosing), and several are eliminated predominantly by nonrenal means. No clinical trials are available comparing the new fluoroquinolones with each other. Clinical trials comparing the new fluoroquinolones with standard therapy have demonstrated good efficacy in a variety of infections. Their adverse effect profile is similar to that of ciprofloxacin. Clinafloxacin and sparfloxacin cause a high incidence of phototoxicity (1.5% to 14% and 2% to 11.7%, respectively), grepafloxacin causes a high incidence of taste perversion (9% to 17%) and trovafloxacin causes a high incidence of dizziness (11%). They all interact with metal ion-containing drugs (eg, antacids), and clinafloxacin and grepafloxacin interact with theophylline. The new fluoroquinolones are expensive; however, their use may result in savings in situations where, because of their potent and broad spectrum of activity, they can be used orally in place of intravenous antibiotics.

CONCLUSIONS

The new fluoroquinolones offer advantages over ciprofloxacin in terms of improved in vitro activity and pharmacokinetics. Whether these advantages translate into improved clinical outcomes is presently unknown. The new fluoroquinolones have the potential to emerge as important therapeutic agents in the treatment of respiratory tract and genitourinary tract infections.

Sparfloxacin versus ciprofloxacin for the treatment of community-acquired, complicated skin and skin-structure infections

Fluoroquinolones have been shown to be effective in the treatment of complicated skin and skin-structure infections, in part because of their broad-spectrum antibacterial activity against causative pathogens that are resistant to older antimicrobial agents. We enrolled 603 adult patients (>58% male, >85% white) in a double-masked, double-dummy, randomized, multicenter trial to compare the efficacy and tolerability of sparfloxacin (400-mg loading dose followed by 200 mg once daily) with those of ciprofloxacin (750 mg twice daily) for 10 days in the treatment of community-acquired, complicated skin and skin-structure infections. The primary efficacy variable was clinical response, based on assessment of signs and symptoms, in the clinically assessable population. Patients in the sparfloxacin and ciprofloxacin groups were comparable with respect to demographic characteristics, underlying diseases, medical history, and laboratory test results. Wound infection was the most common diagnosis, and Staphylococcus aureus was the most frequently isolated pathogen. For the 475 clinically assessable patients, the clinical success rate (percentage of patients cured or improved) was 90.1% (210/233) with sparfloxacin and 87.2% (211/242) with ciprofloxacin. In this analysis (95% confidence interval [CI], -2.8 to 8.6) and the intent-to-treat analyses (95% CI, -4.2 to 6.2), results with sparfloxacin were statistically equivalent to those with ciprofloxacin (95% CI, -1 to 15.3). For bacteriologically assessable patients, eradication rates were 87.0% (141/162) with sparfloxacin and 79.9% (123/154) with ciprofloxacin (95% CI, -1 to 15.3). Eradication rates of S. aureus and coagulase-negative staphylococcal infections were 90.2% (101/112) with sparfloxacin and 77.9% (88/113) with ciprofloxacin. For patients with 2 or more pathogens at baseline (mixed infections), bacteriologic success was 87.6% for sparfloxacin and 77.9% for ciprofloxacin. Pseudomonas aeruginosa infections were eradicated or presumed eradicated in 71.4% (10/14) of sparfloxacin-treated patients and 87.5% (7/8) of ciprofloxacin-treated patients. Overall success rates in the bacteriologically assessable patients for sparfloxacin (84.6% [137/162]) and ciprofloxacin (78.6% [121/154]) were statistically equivalent (95% CI, -2.5 to 14.5). Tolerability was assessed in all patients who received study medication. The overall frequency of treatment-related adverse events was comparable in the 2 treatment groups (26.5% sparfloxacin, 23.3% ciprofloxacin). Drug-related adverse events involving the digestive system occurred in 7.1% of sparfloxacin-treated patients and 19.0% of ciprofloxacin-treated patients; photosensitivity reactions were reported in 11.1% of patients in the sparfloxacin group and 0.7% of patients in the ciprofloxacin group (P < 0.001). The mean change in QTc interval from baseline to the maximum on-treatment value was greater in the sparfloxacin group (9 milliseconds) than in the ciprofloxacin group (3 milliseconds) (P = 0.005; 95% CI, 0.002 to 0.010). The efficacy of sparfloxacin was comparable to that of ciprofloxacin in the treatment of community-acquired, complicated skin and skin-structure infections, including those caused by staphylococci, the most common pathogens. Sparfloxacin's once-daily regimen, high skin-tissue penetration, and improved activity against gram-positive cocci make it a therapeutic alternative to ciprofloxacin for patients who are not at risk for photosensitivity reactions or adverse events associated with prolongation of the QTc interval.

Fluoroquinolone-induced motor changes in the guinea-pig isolated ileum

The effects of norfloxacin and enoxacin were examined on spontaneous motor activity in the guinea-pig isolated ileum. Micromolar concentrations of both compounds caused a biphasic response consisting of relaxation followed by transient contraction. Relaxation to norfloxacin, which was unaffected by phentolamine, propranolol and hyoscine (each at 1 microM), was partially sensitive to tetrodotoxin (1 microM). This indicates that the response is partly mediated by non-adrenergic non-cholinergic (NANC) inhibitory nerves, and partly related to a direct action on the smooth muscle. Apamin (0.1 microM) and suramin (300 microM) inhibited norfloxacin-induced relaxations to an extent similar to that of tetrodotoxin. Conversely, NG-nitro-L-arginine (300 microM) was ineffective. In the presence of theophylline (100 microM) and 3-isobutyl-1-methylxanthine (10 microM), norfloxacin caused relaxation less effective than when added alone. Based on this observation, the NANC component of the relaxation apparently depends on ATP release, whereas the direct component might be due, at least in part, to phosphodiesterase inhibition. Norfloxacin-induced contractions were neurogenic and cholinergic in nature. They were reduced by indomethacin or S-ketoprofen (both at 0.01-1 microM) and suramin (300 microM), suggesting involvement of local prostaglandin production probably induced by ATP release. Previous findings revealed that norfloxacin acted as a non-competitive antagonist at enteric GABAA receptors. In this study the same property was shared by enoxacin against the contractile response to 3-aminopropane sulphonic acid (3-APS), a GABAA receptor agonist. In conclusion, fluoroquinolones exert inhibitory and excitatory effects in the guinea-pig ileum. These are mediated by ATP, prostaglandin and acetylcholine release that might underlie, at least in part, the alterations of gastrointestinal motility observed after fluoroquinolone administration. Furthermore, isolated intestinal preparations might be useful to predict the GABAA-antagonist potential of this class of compounds.

Sparfloxacin vs ofloxacin in the treatment of acute bacterial exacerbations of chronic bronchitis: a multicenter, double-blind, randomized, comparative study. Sparfloxacin Multicenter ABECB Study Group

STUDY OBJECTIVE

Comparison of efficacy and safety of sparfloxacin vs ofloxacin for treatment of acute bacterial exacerbations of chronic bronchitis (ABECB).

DESIGN

Multicenter, double-blind, randomized study.

SETTING

Sixty-eight private offices and outpatient clinics in the United States and Canada.

PATIENTS

Seven hundred ninety-eight adults with ABECB, as confirmed by the acute onset of new (or worsened from the immediate premorbid state) cough and sputum production.

INTERVENTIONS

Randomization 1:1 to sparfloxacin, 400 mg on day 1, then 200 mg once daily, or ofloxacin, 400 mg twice daily, with matching comparator placebos, given concurrently for 10 consecutive days.

RESULTS

The primary efficacy parameter was overall response in the bacteriologically evaluable population. Overall success rates in this population were 85.3% and 89.3% for sparfloxacin and ofloxacin, respectively. The two-sided 95% confidence interval was -9.9, 1.9, indicating that sparfloxacin was statistically equivalent to ofloxacin. The all-treated population analysis was similar to that in the evaluable population. Bacterial eradication rates were similar in both treatment groups for Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Chlamydia pneumoniae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Enterobacter cloacae, and Staphylococcus aureus. The frequency of adverse events overall was comparable in the two treatment groups. The sparfloxacin group had a lower frequency of digestive and nervous system adverse events, but a higher frequency of photosensitivity reactions than the ofloxacin group.

CONCLUSIONS

Once-daily oral treatment with 200 mg sparfloxacin (after initial 400 mg dose) is as effective as twice-daily treatment with 400 mg ofloxacin in patients with ABECB.