Norfloxacin is a second-generation synthetic fluoroquinolone antibacterial agent. It is a broad-spectrum antibiotic effective against a wide range of Gram-negative and some Gram-positive bacteria. It works by inhibiting bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination. In the Indian context, it is widely used for uncomplicated urinary tract infections (UTIs), bacterial gastroenteritis, and certain sexually transmitted infections, though its use has been tempered by growing antimicrobial resistance and safety concerns associated with fluoroquinolones.
Adult: For Uncomplicated UTI: 400 mg orally twice daily for 3-7 days. For Gastroenteritis: 400 mg twice daily for 5 days. For Prostatitis: 400 mg twice daily for 28 days.
Note: Take on an empty stomach, at least 1 hour before or 2 hours after meals. Can be taken with a full glass of water. Do NOT take with dairy products (milk, yogurt), calcium-fortified juices, or antacids containing magnesium, aluminum, calcium, iron, or zinc supplements. Maintain a minimum 2-hour gap. Complete the full prescribed course even if symptoms improve.
Norfloxacin is a bactericidal agent. Its primary target in Gram-negative bacteria is DNA gyrase (topoisomerase II), an enzyme responsible for introducing negative supercoils into DNA, essential for DNA replication and transcription. In Gram-positive bacteria, its primary target is topoisomerase IV, an enzyme crucial for separating daughter DNA strands during cell division. By binding to the enzyme-DNA complex, it stabilizes it and prevents the resealing of DNA breaks, leading to rapid bacterial cell death.
Pregnancy: Category C (US FDA). Animal studies show fetal arthropathy. Avoid in pregnancy unless the potential benefit justifies the potential risk to the fetus. Not recommended.
Driving: May cause dizziness, lightheadedness, or visual disturbances. Patients should be cautioned about operating machinery or driving until they are sure they are not affected.
| Antacids (Al, Mg, Ca), Sucralfate, Iron, Zinc Salts | Markedly reduced absorption of Norfloxacin due to chelation | Major |
| Theophylline | Increased theophylline plasma levels; risk of toxicity (nausea, seizures) | Major |
| Warfarin | Potentiation of anticoagulant effect; increased INR and bleeding risk | Major |
| NSAIDs (e.g., Ibuprofen) | Increased risk of CNS stimulation and seizures | Moderate |
| Cyclosporine | Increased risk of nephrotoxicity | Moderate |
| Probenecid | Decreased renal clearance of norfloxacin, increasing its blood levels | Moderate |
| Oral Hypoglycemics (Sulfonylureas) / Insulin | May potentiate hypoglycemic effect; monitor blood glucose | Moderate |
| Other QT-prolonging drugs (e.g., Amiodarone, Sotalol, Macrolides) | Additive effect on QT prolongation; increased arrhythmia risk | Major |