title: Gemifloxacin for the treatment of respiratory tract infections: in vitro susceptibility, pharmacokinetics and pharmacodynamics, clinical efficacy, and safety.
abstract: Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent exhibiting potent activity against most gram-negative and gram-positive organisms, such as the important community-acquired respiratory pathogens Streptococcus pneumoniae (including multidrug-resistant S. pneumoniae), Haemophilus influenzae , and Moraxella catarrhalis . The agent's mechanism of action involves dual targeting of two essential bacterial enzymes: DNA gyrase and topoisomerase IV. Gemifloxacin was approved by the Food and Drug Administration in April 2003 for treatment of community-acquired pneumonia and acute bacterial exacerbation of chronic bronchitis. The drug has an oral bioavailability of approximately 71%. Approximately 20-35% of gemifloxacin is excreted unchanged in the urine after 24 hours. The elimination half-life of gemifloxacin is 6-8 hours in patients with normal renal function, supporting once-daily dosing. The 24-hour free-drug area under the plasma concentration-time curve:minimum inhibitory concentration ratio (fAUC(0-24):MIC) associated with efficacy, based on results from in vitro and animal models of infection, is approximately 30. With a mean fAUC(0-24) of approximately 3 microg*hour/ml (35% of total AUC(0-24) of 8.4) and a median S. pneumoniae MIC for 90% of tested strains of 0.03, a fAUC(0-24):MIC ratio of 100 would be expected after standard dosing (320 mg once/day). In clinical studies involving both hospitalized and outpatient populations, gemifloxacin has been highly effective in the treatment of community-acquired pneumonia and acute exacerbation of chronic bronchitis. Clinical success rates ranged from 93.9-95.9% in patients with community-acquired pneumonia and 96.1-97.5% in those with acute exacerbation of chronic bronchitis. Gemifloxacin is well tolerated; the frequency of adverse events with this agent is low. Most adverse events are mild-to-moderate in severity, with diarrhea (< 4%), nausea and rash (< 3%), and headache (< 2%) most commonly reported. Drug interactions with gemifloxacin are not common, although absorption is greatly reduced when given with divalent and trivalent cation-containing compounds, such as antacids. Due to its potent activity against many common gram-positive and gram-negative respiratory pathogens, its proven clinical efficacy, and its favorable safety profile, gemifloxacin is a highly effective empiric treatment for community-acquired lower respiratory tract infections.
authors.affiliation: Institute for Clinical Pharmacodynamics, Ordway Research Institute, Albany, NY 12208, USA. SBhavnani-ICPD@ordway.research.org
authors.forename: Sujata M
authors.initials: SM
authors.lastname: Bhavnani
authors.forename: David R
authors.initials: DR
authors.lastname: Andes
mesh_terms: D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use*; D017714:Community-Acquired Infections / Q000188:drug therapy; D004347:Drug Interactions; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use*; D000077735:Gemifloxacin; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006801:Humans; D009287:Naphthyridines / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use*; D018410:Pneumonia, Bacterial / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic; D012141:Respiratory Tract Infections / Q000188:drug therapy*
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D009287:Naphthyridines; D000077735:Gemifloxacin