Quinolonesnorfloxacin

Quinolonesnorfloxacin, commonly referred to as norfloxacin, is a synthetic antibiotic belonging to the fluoroquinolone class. It was first introduced in the 1980s and has been widely used in the treatment of bacterial infections. Norfloxacin functions by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for DNA replication, transcription, and repair. This inhibition results in the accumulation of double‑strand breaks in bacterial DNA, leading to cell death.

The drug is effective primarily against Gram‑negative organisms, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa. It also exhibits activity against a range of Gram‑positive cocci such as Staphylococcus aureus and Enterococcus species. Clinical indications include urinary tract infections, prostatitis, typhoid fever, and gynecological infections. It can be administered orally, often at a dosage of 400 mg twice daily, or intravenously in severe cases.

Pharmacokinetically, norfloxacin exhibits good oral bioavailability, with peak plasma concentrations achieved within 1–2 hours. It is primarily excreted unchanged by the kidneys, which necessitates dose adjustments in renal impairment. The drug’s half‑life ranges from 5 to 6 hours in adults with normal renal function, allowing for twice‑daily dosing. Common adverse effects include gastrointestinal upset, headache, dizziness, and, rarely, phototoxicity. Serious side‑effects, though uncommon, encompass tendonitis, tendon rupture, and peripheral neuropathy, particularly in older patients or those on concurrent corticosteroids.

Resistance to norfloxacin has emerged through mutations in the genes encoding bacterial DNA gyrase and topoisomerase IV, as well as through efflux pump overexpression. Consequently, susceptibility testing is recommended before treatment. Norfloxacin remains a valuable antimicrobial agent in settings where susceptibility patterns support its use, but careful stewardship is essential to preserve its effectiveness.