antibiotic .(quinolone group):-
The newer fluoroquinolones have broad-spectrum bactericidal activity, excellent oral bioavailability, good tissue penetration and favorable safety and tolerability profiles. A new four-generation classification of the quinolone drugs takes into account the expanded antimicrobial spectrum of the more recently introduced fluoroquinolones and their clinical indications. First-generation drugs (e.g., nalidixic acid) achieve minimal serum levels. Second-generation quinolones (e.g., ciprofloxacin) have increased gram-negative and systemic activity. Third-generation drugs (e.g., levofloxacin) have expanded activity against gram-positive bacteria and atypical pathogens. Fourth-generation quinolone drugs (currently only trovafloxacin) add significant activity against anaerobes. The quinolones can be differentiated within classes based on their pharmacokinetic properties.