Clinical use of Fluoroquinolones - The quinolones have undergone a "structural evolution" since the inadvertent discovery of nalidixic acid in 1962. A better understanding of structure-activity and structure-toxicity relationships has allowed chemists to modify the adaptable quinolone structure to enhance or limit the extent of antimicrobial activity and to improve various other product attributes such as the pharmacokinetic profile, tolerability, drug interaction potential, and toxicity of each new agent. Ciprofloxacin and levofloxin/oflofloxin have demonstrated relatively clean safety profiles over several years of clinical use. Newer fluorquinolones should be fully evaluated by clinicians prior to their use so as to avoid potentially life-threatening adverse events. Several newer quinolones are available or are being investigated for clinical use, including gatifloxacin, moxifloxican, clinafloxacin, and gemifloxacin. Rare but life-threatening toxicities (e.g., cardiotoxicity, hepato
