[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Fluoroquinolones](https://durgical.com/en/pharmacology/classes/fluoroquinolones/) › Norfloxacin # Norfloxacin ## Fluoroquinolones? Fluoroquinolones Old oral fluoroquinolone, the least potent of the group: blood levels are low, so it is limited to urinary and prostate infections. Updated Nov 1, 2026 ## Quick facts **Group** [Fluoroquinolones](https://durgical.com/en/pharmacology/classes/fluoroquinolones/) **Target** Bacterial DNA gyrase and topoisomerase IV **Used for** Urinary tract infections · Bacterial prostatitis **Key effects** Nausea · Headache and dizziness · Joint pain **Monitor** Tendon pain or swelling · Neuropathy symptoms **ATC** J01MA06 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ✂**Bacterial DNA gyrase and topoisomerase IV**Norfloxacin ⓘ No structure of norfloxacin bound to its target is published; the figure shows ciprofloxacin, its direct derivative (an ethyl swapped for a cyclopropyl), wedged into the DNA cut by Staphylococcus aureus DNA gyrase. **Target in 3D:** Bacterial DNA gyrase and topoisomerase IV. PDB structure 2XCT (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/2XCT) · Drag to rotate · pinch to zoom Norfloxacin traps DNA gyrase and topoisomerase IV after they have cut the DNA, so the break is not resealed and the bacterium dies. Its gram-negative activity resembles ciprofloxacin's, though weaker, and it is also the least active of the group against gram-positives. Because blood levels are low, it is limited to urinary and prostate infections. - Enters the gram-negative bacterium - Wedges between gyrase and the cut DNA - The break is not resealed and the helix breaks - The bacterium dies (bactericidal) ## Indications - Urinary tract infections by susceptible gram-negatives, when other recommended antibiotics cannot be used [Urinary tract infection (acute cystitis) →](https://durgical.com/en/conditions/urinary-tract-infection/) - Bacterial prostatitis [Prostatitis →](https://durgical.com/en/conditions/prostatitis/) - Not used for systemic infections (blood, lung, bone) because of its low blood levels ## Adverse effects ### Common - Nausea, abdominal pain and diarrhoea - Headache and dizziness - Rash and photosensitivity - Joint pain ### Serious (rare, important) - Tendinitis and tendon rupture, above all of the Achilles tendon, even months later - Peripheral neuropathy (pain, burning, tingling, numbness or weakness), sometimes permanent - Seizures, above all with epilepsy or with NSAIDs or theophylline - Clostridioides difficile diarrhoea ## Contraindications - Allergy to any quinolone - History of a serious adverse effect with a quinolone or fluoroquinolone ## Key interactions **Antacids, calcium, iron and multivitamins with minerals** Chelate norfloxacin and reduce absorption; separated by at least 2 hours. **Corticosteroids** Increase the risk of tendon injury. **NSAIDs and theophylline** Raise the risk of seizures with fluoroquinolones. ## What is monitored - Tendon pain or swelling - Neuropathy symptoms (tingling, burning, weakness) - Urine culture and clinical response ## Administration and safety - Oral, separated from antacids, iron and calcium products - Not used for mild or self-limiting infections, nor to prevent travellers' diarrhoea or recurrent urinary infections ## Nursing care - Ask about previous adverse effects with quinolones - Teach to stop and seek advice if tendon pain, tingling or weakness appears - Watch people over 60, transplant recipients and those on corticosteroids more closely - Teach sun protection ## Pharmacokinetics **Absorption** Oral; cations (calcium, iron, aluminium) chelate it and reduce absorption. **Distribution** Low blood levels, not enough for systemic infections. **Metabolism** Partly hepatic. **Elimination** About a quarter leaves unchanged in the urine. **Half-life** 3 to 5 hours. ## Memory aid «NOR = NOt in the blood»: norfloxacin stays in the urine, so it only treats the urinary tract. ## Test yourself Think of the answer, then tap the question to see it. ## Why is norfloxacin not used for pneumonia or bacteraemia? Its blood levels are low, not enough outside the urinary tract. ## Which groups have a higher risk of tendon rupture with fluoroquinolones? People over 60, those on corticosteroids and solid-organ transplant recipients. ## How is norfloxacin related to ciprofloxacin? Ciprofloxacin derives from it (an ethyl swapped for a cyclopropyl) and is more potent, with useful systemic levels. ## Which uses did the European Medicines Agency restrict for fluoroquinolones? They are not used for mild or self-limiting infections, nor to prevent travellers' diarrhoea or recurrent lower urinary infections. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/norfloxacin/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## Connections ## Related drugs 3 - [Ciprofloxacin](https://durgical.com/en/pharmacology/ciprofloxacin/) - [Levofloxacin](https://durgical.com/en/pharmacology/levofloxacin/) - [Nitrofurantoin](https://durgical.com/en/pharmacology/nitrofurantoin/) ## Related conditions 2 - [Urinary tract infection (acute cystitis)](https://durgical.com/en/conditions/urinary-tract-infection/) - [Prostatitis](https://durgical.com/en/conditions/prostatitis/) [← Back to the class: Fluoroquinolones](https://durgical.com/en/pharmacology/classes/fluoroquinolones/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Quinolone- and fluoroquinolone-containing medicinal products - referral](https://www.ema.europa.eu/en/medicines/human/referrals/quinolone-fluoroquinolone-containing-medicinal-products) (European Medicines Agency, 2019); [The twinned 3.35A structure of S. aureus Gyrase complex with Ciprofloxacin and DNA](https://www.rcsb.org/structure/2XCT) (RCSB Protein Data Bank, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/norfloxacin/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/norfloxacin/