Concentrations of gatifloxacin in plasma and pulmonary compartments following a single 400 mg oral dose in patients undergoing fibre-optic bronchoscopy

Population Pharmacokinetics and Pharmacodynamics of Isoniazid and its Metabolite Acetylisoniazid in Chinese Population

Objective: We aimed to establish a population pharmacokinetic (PPK) model for isoniazid (INH) and its major metabolite Acetylisoniazid (AcINH) in healthy Chinese participants and tuberculosis patients and assess the role of the NAT2 genotype on the transformation of INH to AcINH. We also sought to estimate the INH exposure that would achieve a 90% effective concentration (EC₉₀) efficiency for patients with various NAT2 genotypes.

Method: A total of 45 healthy participants and 157 tuberculosis patients were recruited. For healthy subjects, blood samples were collected 0–14 h after administration of 300 mg or 320 mg of the oral dose of INH; for tuberculosis patients who received at least seven days therapy with INH, blood samples were collected two and/or six hours after administration. The plasma concentration of INH and AcINH was determined by the reverse-phase HPLC method. NAT2 genotypes were determined by allele-specific amplification. The integrated PPK model of INH and AcINH was established through nonlinear mixed-effect modeling (NONMEM). The effect of NAT2 genotype and other covariates on INH and AcINH disposition was evaluated. Monte Carlo simulation was performed for estimating EC90 of INH in patients with various NAT2 genotypes.

Results: The estimated absorption rate constant (K_a), oral clearance (CL/F), and apparent volume of distribution (V₂/F) for INH were 3.94 ± 0.44 h⁻¹, 18.2 ± 2.45 L⋅h⁻¹, and 56.8 ± 5.53 L, respectively. The constant of clearance (K₃₀) and the volume of distribution (V₃/F) of AcINH were 0.33 ± 0.11 h⁻¹ and 25.7 ± 1.30 L, respectively. The fraction of AcINH formation (F_M) was 0.81 ± 0.076. NAT2 genotypes had different effects on the CL/F and F_M. In subjects with only one copy of NAT2 *5, *6, and *7 alleles, the CL/F values were approximately 46.3%, 54.9%, and 74.8% of *4/*4 subjects, respectively. The F_M values were approximately 48.7%, 63.8%, and 86.9% of *4/*4 subjects, respectively. The probability of target attainment of INH EC₉₀ in patients with various NAT2 genotypes was different.

Conclusion: The integrated parent-metabolite PPK model accurately characterized the disposition of INH and AcINH in the Chinese population sampled, which may be useful in the individualized therapy of INH.

Gatifloxacin Pharmacokinetics/Pharmacodynamics-based Optimal Dosing for Pulmonary and Meningeal Multidrug-resistant Tuberculosis

Background

Gatifloxacin is used for the treatment of multidrug-resistant tuberculosis (MDR-TB). The optimal dose is unknown.

Methods

We performed a 28-day gatifloxacin hollow-fiber system model of tuberculosis (HFS-TB) study in order to identify the target exposures associated with optimal kill rates and resistance suppression. Monte Carlo experiments (MCE) were used to identify the dose that would achieve the target exposure in 10000 adult patients with meningeal or pulmonary MDR-TB. The optimal doses identified were validated using probit analyses of clinical data from 2 prospective clinical trials of patients with pulmonary and meningeal tuberculosis. Classification and regression-tree (CART) analyses were used to identify the gatifloxacin minimum inhibitory concentration (MIC) below which patients failed or relapsed on combination therapy.

Results

The target exposure associated with optimal microbial kill rates and resistance suppression in the HFS-TB was a 0-24 hour area under the concentration-time curve-to-MIC of 184. MCE identified an optimal gatifloxacin dose of 800 mg/day for pulmonary and 1200 mg/day for meningeal MDR-TB, and a clinical susceptibility breakpoint of MIC ≤ 0.5 mg/L. In clinical trials, CART identified that 79% patients failed therapy if MIC was >2 mg/L, but 98% were cured if MIC was ≤0.5 mg/L. Probit analysis of clinical data demonstrated a >90% probability of a cure in patients if treated with 800 mg/day for pulmonary tuberculosis and 1200 mg/day for meningeal tuberculosis. Doses ≤400 mg/day were suboptimal.

Conclusions

Gatifloxacin doses of 800 mg/day and 1200 mg/day are recommended for pulmonary and meningeal MDR-TB treatment, respectively. Gatifloxacin has a susceptible dose-dependent zone at MICs 0.5-2 mg/L.

Evaluation of initial and steady-state gatifloxacin pharmacokinetics and dose in pulmonary tuberculosis patients by using monte carlo simulations

A 4-month regimen of gatifloxacin with rifampin, isoniazid, and pyrazinamide is being evaluated for the treatment of tuberculosis in a phase 3 randomized controlled trial (OFLOTUB). A prior single-dose study found that gatifloxacin exposure increased by 14% in the combination. The aims of the study are to evaluate the initial and steady-state pharmacokinetics of gatifloxacin when daily doses are given to patients with newly diagnosed drug-sensitive pulmonary tuberculosis as part of a combination regimen and to evaluate the gatifloxacin dose with respect to the probability of attaining a pharmacokinetic/pharmacodynamic target. We describe the population pharmacokinetics of gatifloxacin from the first dose to a median of 28 days in 169 adults enrolled in the OFLOTUB trial in Benin, Guinea, Senegal, and South Africa. The probability of achieving a ratio of ≥125 for the area under the concentration time curve to infinity (AUC0-∞) for the free fraction of gatifloxacin over the MIC (fAUC/MIC) was investigated using Monte Carlo simulations. The median AUC0-∞ of 41.2 μg · h/ml decreased on average by 14.3% (90% confidence interval [CI], -90.5% to +61.5%) following multiple 400-mg daily doses. At steady state, 90% of patients achieved an fAUC/MIC of ≥125 only when the MIC was <0.125 μg/ml. We conclude that systemic exposure to gatifloxacin declines with repeated daily 400-mg doses when used together with rifampin, isoniazid, and pyrazinamide, thus compensating for any initial increase in gatifloxacin levels due to a drug interaction. (The OFLOTUB study has been registered at ClinicalTrials.gov under registration no. NCT00216385.).

Delivering Antibacterials to the Lungs

An important determinant of clinical outcome of a lower respiratory tract infection may be sterilization of the infected lung, which is also dependent on sustained antibacterial concentrations achieved in the lung. For this reason, recently there has been increased interest in measuring the concentration of antimicrobial agents at different potential sites of infection in the lung. Levels of antibacterials are now measured in bronchial mucosa, epithelial lining fluid (ELF) and alveolar macrophages, as well as in sputum. Penicillins and cephalosporins reach only marginal concentrations in bronchial secretions, whereas fluoroquinolones and macrolides have been shown to achieve high concentrations. The extent of penetration of different antibacterials into the bronchial mucosa is relatively high. This is also true for beta-lactams, although their tissue concentrations never reach blood concentrations. Antibacterials penetrate less into the ELF than into the bronchial mucosa, but fluoroquinolones appear to concentrate more into alveolar lavage than into bronchial mucosa. Pulmonary pharmacokinetics is a very useful tool for describing how drugs behave in the human lung, but it does not promote an understanding of the pharmacological effects of a drug. More important, instead, is the correlation between pulmonary disposition of the drug and its minimum inhibitory concentration (MIC) values for the infectious agent. The addition of bacteriological characteristics to in vivo pharmacokinetic studies has triggered a 'pharmacodynamic approach'. Pharmacodynamic parameters integrate the microbiological activity and pharmacokinetics of an anti-infective drug by focusing on its biological effects, particularly growth inhibition and killing of pathogens. Drugs that penetrate well and remain for long periods at the pulmonary site of infection often induce therapeutic responses greater than expected on the basis of in vitro data. However, although the determination of antibacterial concentrations at the site of infection in the lung has been suggested to be important in predicting the therapeutic efficacy of antimicrobial treatment during bacterial infections of the lower respiratory tract, some studies have demonstrated that pulmonary bacterial clearance is correlated more closely to concentrations in the serum than to those in the lung homogenates, probably because they better reflect antibacterial concentration in the interstitial fluid.

Penetration of anti-infective agents into pulmonary epithelial lining fluid: focus on antibacterial agents

The exposure-response relationship of anti-infective agents at the site of infection is currently being re-examined. Epithelial lining fluid (ELF) has been suggested as the site (compartment) of antimicrobial activity against lung infections caused by extracellular pathogens. There have been an extensive number of studies conducted during the past 20 years to determine drug penetration into ELF and to compare plasma and ELF concentrations of anti-infective agents. The majority of these studies estimated ELF drug concentrations by the method of urea dilution and involved either healthy adult subjects or patients undergoing diagnostic bronchoscopy. Antibacterial agents such as macrolides, ketolides, newer fluoroquinolones and oxazolidinones have ELF to plasma concentration ratios of >1. In comparison, β-lactams, aminoglycosides and glycopeptides have ELF to plasma concentration ratios of ≤1. Potential explanations (e.g. drug transporters, overestimation of the ELF volume, lysis of cells) for why these differences in ELF penetration occur among antibacterial classes need further investigation. The relationship between ELF concentrations and clinical outcomes has been under-studied. In vitro pharmacodynamic models, using simulated ELF and plasma concentrations, have been used to examine the eradication rates of resistant and susceptible pathogens and to explain why selected anti-infective agents (e.g. those with ELF to plasma concentration ratios of >1) are less likely to be associated with clinical treatment failures. Population pharmacokinetic modelling and Monte Carlo simulations have recently been used and permit ELF and plasma concentrations to be evaluated with regard to achievement of target attainment rates. These mathematical modelling techniques have also allowed further examination of drug doses and differences in the time courses of ELF and plasma concentrations as potential explanations for clinical and microbiological effects seen in clinical trials. Further studies are warranted in patients with lower respiratory tract infections to confirm and explore the relationships between ELF concentrations, clinical and microbiological outcomes, and pharmacodynamic parameters.

Pharmacokinetics of gatifloxacin after a single oral dose in healthy young adult subjects and adult patients with chronic bronchitis, with a comparison of drug concentrations obtained by bronchoscopic microsampling and bronchoalveolar lavage

BACKGROUND

Bronchoalveolar lavage (BAL) is an established technique for measuring antibiotic concentrations in the epithelial lining fluid (ELF) of the bronchiolar and alveolar regions; however, the results may not reflect concentrations in bronchial regions. Bronchoscopic microsampling (BMS) is a technique that makes it possible to obtain multiple samples from bronchial ELF.

OBJECTIVE

BMS and BAL were used to analyze the pharmacokinetics of gatifloxacin in bronchial ELF from healthy young adult subjects and adult patients with chronic bronchitis.

METHODS

Bronchial ELF samples were obtained by BMS at 1, 2, 3, 4, 6, 10, and 24 hours after administration of a single oral dose of gatifloxacin 200 mg in healthy young adult (aged 20-25 years) subjects, and at 1, 2, 4, and 10 hours after a single dose in patients with chronic bronchitis (aged > or =20 years). At least 1 month after the initial BMS, alveolar (BAL) and bronchial (BMS) ELF samples were obtained from another group of healthy subjects 2 hours after administration of a single oral dose of gatifloxacin 200 mg for comparison of gatifloxacin concentrations in samples obtained by the 2 techniques.

RESULTS

Bronchial ELF samples were obtained from 8 healthy subjects and 5 patients with chronic bronchitis; alveolar ELF samples were obtained from a separate group of 5 healthy subjects. For the healthy subjects, the mean (SD) AUC(0-24) in serum and bronchial ELF, corrected for mg/kg doses, was 4.6 (1.1) and 7.6 (3.5) mg x h/L, respectively. In the patients with chronic bronchitis, the AUC(0-10) in serum and bronchial ELF, corrected for mg/kg doses, was 3.9 (0.8) and 4.1 (1.5) mg x h/L. The C(max) in serum and bronchial ELF, corrected for mg/kg doses, was 0.6 (0.2) and 1.4 (0.8) mg/L in healthy subjects and 0.7 (0.2) and 0.7 (0.2) mg/L in patients with chronic bronchitis. In healthy subjects, the C(max) and AUC(0-24) were significantly higher in bronchial ELF than in serum (both, P < 0.05). Gatifloxacin concentrations were significantly lower in bronchial ELF obtained by BMS than in alveolar ELF obtained by BAL (P < 0.05).

CONCLUSIONS

Based on the findings of this study in small numbers of healthy young adult volunteers and patients with chronic bronchitis, BMS appears to be a promising method for measuring drug concentrations and determining the pharmacokinetic profile of gatifloxacin in bronchial ELF. Additional studies are needed to correlate measured concentrations obtained by BMS with clinical and/or microbiologic outcomes in larger populations.

Penetration of garenoxacin into lung tissues and bone in subjects undergoing lung biopsy or resection

OBJECTIVE

Concentrations of garenoxacin in plasma and samples of lung parenchyma, bronchial mucosa, and bone were determined following single-dose administration.

RESEARCH DESIGN AND METHODS

Open-label, non-randomized study in which subjects undergoing invasive lung biopsy or resection were given a single 600-mg oral dose of garenoxacin. Lung parenchyma, and, if possible, bronchial mucosa and bone (i.e., flat bone with sinus mucosa or long bone from the lower legs) samples and corresponding plasma samples were obtained 2-4, 4-6, 10-12, or 20-24 h post-dose. Garenoxacin concentrations were measured using validated liquid chromatography with dual mass spectrometry. Safety was also assessed.

RESULTS

Twenty-seven subjects enrolled and completed the study. Garenoxacin plasma concentrations (mean +/- standard deviation) during the 24-h period ranged from 1.9 +/- 1 to 7.4 +/- 3 mug/mL. Garenoxacin concentrations in lung tissue (15.2 +/- 9 mug/g) peaked at 4-6 h and decreased to 3.7 +/- 3 mug/g at 20-24 h. Mean ratios between bronchial mucosa and plasma ranged from 0.82 to 0.99 over a 24-h period. At 12 h, the mean ratio between bone and plasma was 0.56. Garenoxacin concentrations in lung tissue exceeded the MIC(90) for common respiratory pathogens by at least 61-fold. Garenoxacin was safe and well tolerated. Forty-five adverse events were reported by 26 subjects; none were determined to be attributable to garenoxacin by the investigators. Most of the adverse events were mild to moderate in severity.

CONCLUSIONS

Garenoxacin achieved 24-h concentrations in pulmonary tissues that exceeded the MIC(90) for common respiratory pathogens. A controlled study involving a larger number of lung and bone tissue samples is needed to further confirm these findings.

Estudio de la actividad comparada de varias fluoroquinolonas frente a Pseudomonas aeruginosa mediante la determinación de la concentración preventiva de mutantes

INTRODUCTION

The objective of this study was to compare the activity of ciprofloxacin, levofloxacin, moxifloxacin, gatifloxacin and ofloxacin against Pseudomonas aeruginosa by determining the mutant prevention concentration (MPC).

METHODS

Thirty-four clinical isolates of Pseudomonas aeruginosa causing nosocomial infection were studied. MPC values were determined using an inoculum of 10(10) cfu/mL on Mueller-Hinton plates with serial dilutions of the antibiotics. The microorganisms were classified according to whether the patients had been previously treated with fluoroquinolones or not.

RESULTS

The fluoroquinolone with the lowest MPC values was ciprofloxacin, followed by levofloxacin. Analysis of strains from patients previously treated with fluoroquinolones showed persistent susceptibility according to the CLSI criteria, but with lower activity of all the drugs.

CONCLUSIONS

Although the microorganism remained susceptible to fluoroquinolones according to classical methods, the suitability of using these drugs in patients with severe infection and a history of fluoroquinolone use should be evaluated.

Should patients with acute exacerbation of chronic bronchitis be treated with antibiotics? Advantages of the use of fluoroquinolones

The pathological changes in chronic bronchitis (CB) produce airflow obstruction, reduce the effectiveness of the mucocilliary drainage system and lead to bacterial colonisation of bronchial secretion. The presence of bacteria induces an inflammatory response mediated by leukocytes. There is a direct relationship between the degree of impairment of the mucocilliary drainage system, the density of bacteria in mucus and the number of leukocytes in the sputum. Purulent sputum is a good marker of a high bacterial load. Eventually, if the number of leukocytes is high, their normal activity could decrease the effectiveness of the drainage system, increase the bronchial obstruction and probably damage the lung parenchyma. Whenever the density of bacteria in the bronchial lumen is >or=10(6) CFU/mL, there is a high probability that the degree of inflammatory response will lead to a vicious cycle which in turn tends to sustain the process. This situation can arise during the clinical course of any acute exacerbation of CB, independently of its aetiology, provided the episode is sufficiently severe and/or prolonged. Fluoroquinolones of the third and fourth generation are bactericidal against most microorganisms usually related to acute exacerbations of CB. Their diffusion to bronchial mucus is adequate. When used in short (5-day) treatment they reduce the bacterial load in a higher proportion than is achieved by beta-lactam or macrolide antibiotics given orally. Although the clinical cure rate is similar to that obtained with other antibiotics, the time between exacerbations could be increased.

Gatifloxacin in community-acquired respiratory tract infection

Gatifloxacin (Tequin, Kyorin Pharmaceutical Co. Ltd) is a new fluoroquinolone with a broad spectrum of activity for pathogens implicated in community-acquired respiratory tract infections, including Gram-positive, -negative and atypical bacteria. Excellent oral bioavailability, a half-life allowing once-daily administration and excellent penetration into respiratory tissues are desirable pharmacokinetic characteristics of gatifloxacin. Monte Carlo simulation of gatifloxacin in Streptococcus pneumoniae infection demonstrates that adequate levels of pharmacokinetic/pharmacodynamic parameters are obtained with gatifloxacin in almost all instances. In randomised, controlled trials and a large open-label, community-based study, gatifloxacin has shown excellent clinical and bacteriological efficacy in acute bacterial sinusitis, acute exacerbations of chronic bronchitis and community-acquired pneumonia. Current guidelines recommend the initial empiric use of gatifloxacin (along with the other new fluoroquinolones) for community-acquired respiratory tract infection in patients who have increased likelihood of infection with resistant pathogens. Another group of patients where this agent is recommended for initial antimicrobial therapy are those who, because of underlying disease and/or comorbid conditions, need an antibiotic with high antimicrobial efficacy to achieve optimal outcomes.

Guide to selection of fluoroquinolones in patients with lower respiratory tract infections

Newer fluoroquinolones such as levofloxacin, moxifloxacin, gatifloxacin and gemifloxacin have several attributes that make them excellent choices for the therapy of lower respiratory tract infections. In particular, they have excellent intrinsic activity against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and the atypical respiratory pathogens. Fluoroquinolones may be used as monotherapy to treat high-risk patients with acute exacerbation of chronic bronchitis, and for patients with community-acquired pneumonia requiring hospitalisation, but not admission to intensive care. Overall, the newer fluoroquinolones often achieve clinical cure rates in > or =90% of these patients. However, rates may be lower in hospital-acquired pneumonia, and this infection should be treated on the basis of anticipated organisms and evaluation of risk factors for specific pathogens such as Pseudomonas aeruginosa. In this setting, an antipseudomonal fluoroquinolone may be used in combination with an antipseudomonalbeta-lactam. Concerns are now being raised about the widespread use, and possibly misuse, of fluoroquinolones and the emergence of resistance among S. pneumoniae, Enterobacteriaceae and P. aeruginosa. A number of pharmacokinetic parameters such as the peak concentration of the antibacterial after a dose (C(max)), and the 24-hour area under the concentration-time curve (AUC24) and their relationship to pharmacodynamic parameters such as the minimum inhibitory and the mutant prevention concentrations (MIC and MPC, respectively) have been proposed to predict the effect of fluoroquinolones on bacterial killing and the emergence of resistance. Higher C(max)/MIC or AUC24/MIC and C(max)/MPC or AUC24/MPC ratios, either as a result of dose administration or the susceptibility of the organism, may lead to a better clinical outcome and decrease the emergence of resistance, respectively. Pharmacokinetic profiles that are optimised to target low-level resistant minor subpopulations of bacteria that often exist in infections may help preserve fluoroquinolones as a class. To this end, optimising the AUC24/MPC or C(max)/MPC ratios is important, particularly against S. pneumoniae, in the setting of lower respiratory tract infections. Agents such as moxifloxacin and gemifloxacin with high ratios against this organism are preferred, and agents such as ciprofloxacin with low ratios should be avoided. For agents such as levofloxacin and gatifloxacin, with intermediate ratios against S. pneumoniae, it may be worthwhile considering alternative dose administration strategies, such as using higher dosages, to eradicate low-level resistant variants. This must, of course, be balanced against the potential of toxicity. Innovative approaches to the use of fluoroquinolones are worth testing in further in vitro experiments as well as in clinical trials.

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.

Bactericidal activities of methoxyfluoroquinolones gatifloxacin and moxifloxacin against aerobic and anaerobic respiratory pathogens in serum

Gatifloxacin (Bristol-Myers Squibb) and moxifloxacin (Bayer) are new methoxyfluoroquinolones with broad-spectrum activity against aerobic and anaerobic pathogens of the respiratory tract. In this investigation, we analyzed the bactericidal activity in serum over time of these antimicrobials against three aerobic (Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus) and four anaerobic (Peptostreptococcus micros, Peptostreptococcus magnus, Fusobacterium nucleatum, and Prevotella melaninogenica) bacteria associated with respiratory tract infections. Serum samples were obtained from 11 healthy male subjects following a single 400-mg oral dose of gatifloxacin and moxifloxacin. These samples were collected prior to and at 2, 6, 12, and 24 h after the dose of each drug. Gatifloxacin exhibited bactericidal activity for a median of 12 h against Streptococcus pneumoniae (MIC = 0.5 micro g/ml), Peptostreptococcus micros (MIC = 0.25 micro g/ml), and F. nucleatum (MIC = 0.5 micro g/ml) and 24 h against H. influenzae (MIC = 0.03 micro g/ml), Staphylococcus aureus (MIC = 0.125 micro g/ml), Peptostreptococcus magnus (MIC = 0.125 micro g/ml), and Prevotella melaninogenica (MIC = 0.5 micro g/ml). Moxifloxacin exhibited bactericidal activity for a median of 24 h against Streptococcus pneumoniae (MIC = 0.125 micro g/ml), H. influenzae (MIC = 0.015 micro g/ml), Staphylococcus aureus (MIC = 0.06 micro g/ml), F. nucleatum (MIC = 0.5 micro g/ml), Prevotella melaninogenica (MIC =0.5 micro g/ml), Peptostreptococcus magnus (MIC = 0.125 micro g/ml), and Peptostreptococcus micros (MIC = 0.25 micro g/ml). The results from this pharmacodynamic study suggest that these fluoroquinolones would have prolonged killing activity against these organisms in vivo and may have clinical utility in the treatment of mixed aerobic-anaerobic respiratory tract infections.

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.

IV-to-oral switch therapy for community-acquired pneumonia requiring hospitalization: focus on gatifloxacin

The majority of the 1.1 million patients hospitalized for community-acquired pneumonia (CAP) in the United States begin therapy with an intravenous antibiotic. A switch to oral therapy as soon as patients are clinically stable reduces the length of hospitalization and associated costs. Fluoroquinolones are appropriate candidates for switch therapy. Gatifloxacin is an excellent choice when a fluoroquinolone is being considered for sequential switch therapy in the treatment of CAP requiring hospitalization.