Norfloxacin is a synthetic, broad-spectrum fluoroquinolone with antibacterial activity. Norfloxacin inhibits activity of dna gyrase, thereby blocking bacterial dna replication.norfloxacin concentrates in the renal tubules and bladder and is bactericidal against a wide range of aerobic gram-positive and gram-negative organisms.norfloxacin inhibits bacterial dna gyrase. Norfloxacin is a quinolone antimicrobial. The chemical classification of norfloxacin is quinolones.