API Norfloxacin

Norfloxacin More Info

Norfloxacin is a synthetic broad-spectrum fluoroquinolone antibiotic, widely used in clinical practice for the treatment of bacterial infections caused by susceptible pathogens.

Mechanism of Action

Norfloxacin exerts its antibacterial effect by inhibiting the bacterial enzymes DNA gyrase and topoisomerase IV, which are essential for bacterial DNA replication, transcription, repair and recombination. By targeting these enzymes, the drug disrupts bacterial DNA synthesis, leading to bacterial cell death. It is primarily bactericidal against susceptible strains.

Antibacterial Spectrum

Norfloxacin shows strong activity against most gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella and Shigella species. It also has moderate efficacy against some gram-positive bacteria such as Staphylococcus aureus (methicillin-susceptible strains), but is generally less effective against streptococci.

Indications

Clinically, norfloxacin is mainly prescribed for the treatment of the following infections caused by susceptible bacteria:

Urinary tract infections (UTIs) such as cystitis, pyelonephritis and urethritis, which are its primary indications.

Gastrointestinal infections including bacterial dysentery caused by Shigella and traveler’s diarrhea induced by enterotoxigenic E. coli.

Other infections such as prostatitis, cervicitis and gonorrhea (uncomplicated cases) in some cases.

Dosage and Administration

Norfloxacin is usually administered orally in the form of tablets or capsules. The dosage varies depending on the type and severity of the infection, as well as the patient’s age and renal function. For uncomplicated UTIs, the typical adult dose is 400 mg twice daily, with a treatment course of 3–7 days. For more severe infections like pyelonephritis, the course may be extended to 10–21 days. It is recommended to take the drug on an empty stomach (1 hour before or 2 hours after meals) with a full glass of water to enhance absorption.

Contraindications and Precautions

Contraindications: It is strictly contraindicated in patients with a history of hypersensitivity to norfloxacin, other fluoroquinolones or any component of the formulation. It is also contraindicated in pregnant women, breastfeeding women and children under 18 years old, as it may cause cartilage damage in developing bones.

Precautions:

Patients with renal impairment need dosage adjustment to avoid drug accumulation.

It may cause central nervous system (CNS) side effects such as headache, dizziness and insomnia, so caution is advised in patients with epilepsy or a history of CNS disorders.

Prolonged use may lead to the emergence of drug-resistant bacteria, so the drug should be used only for confirmed bacterial infections and not for viral infections like the common cold.

Avoid excessive exposure to sunlight during treatment, as norfloxacin may increase photosensitivity, resulting in skin rashes or burns.

Adverse Reactions

The most common adverse reactions of norfloxacin are mild and involve the gastrointestinal tract, such as nausea, vomiting, abdominal pain and diarrhea. Less common adverse effects include CNS symptoms (headache, dizziness), skin reactions (rash, pruritus) and transient elevation of liver enzymes. Rare but serious adverse reactions include tendon rupture (especially in elderly patients or those taking corticosteroids concurrently), peripheral neuropathy and cardiac QT interval prolongation.

Drug Interactions

Concurrent use with antacids containing aluminum, magnesium or calcium, as well as iron supplements, can reduce the absorption of norfloxacin, so the interval between administration should be at least 2 hours.

Co-administration with theophylline may increase the serum concentration of theophylline, leading to theophylline toxicity (e.g., nausea, tremors, arrhythmias), so monitoring of theophylline levels is recommended.

Use with non-steroidal anti-inflammatory drugs (NSAIDs) may increase the risk of CNS stimulation and seizures.