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Drug Reference

ciprofloxacin

fluoroquinolone antibiotic· Brands: Cipro, Ciproxin, Cifran, CiprofarIVPOTOP

Mechanism of action
Ciprofloxacin is a fluoroquinolone antibiotic that inhibits bacterial topoisomerase II (DNA gyrase) and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination. By binding to these enzymes and stabilizing DNA-enzyme complexes, it prevents supercoiling and subsequent DNA synthesis, leading to bacterial cell death. It is bactericidal and exhibits concentration-dependent killing.
Pharmacokinetics
It is metabolized in the liver to four metabolites with little antimicrobial activity, primarily via CYP1A2.
Indications & dosing

Complicated urinary tract infection

Typically 7-14 days. Adjust dose in renal impairment.

  • adult · PO: 500 mg twice daily · Typically 7-14 days. Adjust dose in renal impairment.

Acute pyelonephritis

Duration 7-14 days. For severe infection, consider initial IV therapy.

  • adult · PO: 500–750 mg twice daily · Duration 7-14 days. For severe infection, consider initial IV therapy.

Chronic bacterial prostatitis

Duration 28 days. Consider culture and susceptibility.

  • adult · PO: 500 mg twice daily · Duration 28 days. Consider culture and susceptibility.

Inhalational anthrax (post-exposure)

Give soon after suspected exposure. Duration 60 days for post-exposure prophylaxis.

  • adult · PO: 500 mg twice daily · Give soon after suspected exposure. Duration 60 days for post-exposure prophylaxis.

Skin and soft tissue infections

Duration depends on severity; generally 7-14 days.

  • adult · PO: 500–750 mg twice daily · Duration depends on severity; generally 7-14 days.

Severe systemic infections when oral therapy inappropriate

For severe or complicated infections. Switch to oral therapy as soon as clinically appropriate.

  • adult · IV: 200–400 mg every 12 hours · For severe or complicated infections. Switch to oral therapy as soon as clinically appropriate.
Contraindications & precautions
  • Hypersensitivity to ciprofloxacin or other fluoroquinolones · Includes rash, angio-oedema, anaphylaxis.
  • Concomitant use with tizanidine · Risk of severe hypotension and sedation due to CYP1A2 inhibition.
  • History of tendon disorders with fluoroquinolones · Risk of recurrent tendinopathy or rupture.
  • Pregnancy and breastfeeding · Only use if potential benefit outweighs risk; consider alternatives.
  • Children under 18 years · Risk of arthropathy; use only for specific infections with no alternative.
  • Use with caution in epilepsy or history of seizures.
  • Use with caution in QT prolongation, electrolyte disturbances, or with other QT-prolonging drugs.
  • Discontinue treatment if tendon pain or signs of peripheral neuropathy occur.
  • Avoid exposure to sunlight and UV lamps; use sun protection.
  • Separate administration of antacids, iron, zinc, or calcium supplements by at least 2 hours.
  • Adjust dose in renal impairment.
Adverse effects
  • Nausea
  • Diarrhoea
  • Headache
  • Tendonitis or tendon ruptureserious
  • QT interval prolongationserious
  • Peripheral neuropathyserious
  • Seizuresserious
  • Photosensitivity
Interactions
  • warfarinmajorPrescribers should avoid concurrent use if possible, especially in patients with other bleeding risk factors. If co-prescription is necessary, closely monitor the INR at baseline, after 2 to 3 days, and then regularly throughout treatment. Adjust the warfarin dose as needed and warn the patient to seek medical attention if signs of bleeding occur.
  • theophyllinemajorAvoid concurrent use if possible, as alternative antibiotics with minimal CYP1A2 inhibition (e.g., levofloxacin) may be considered. If co-prescription is necessary, reduce the theophylline dose by up to 50% and closely monitor serum theophylline concentrations and clinical signs of toxicity. Repeat theophylline levels should be measured after initiating or adjusting ciprofloxacin therapy, and further dose adjustments made as required.
  • amiodaronemajorConsider alternative antibiotics with less QT prolonging activity, such as doxycycline, if clinically appropriate.
Renal & hepatic adjustment
  • eGFR 0–29: Reduce dose by 50% or extend dosing interval to 24 hours (e.g., 250-500 mg PO once daily; IV: 200-400 mg once daily).
Monitoring, pregnancy & toxicity
  • Renal function (serum creatinine, BUN) · Baseline and at least twice weekly during treatment in elderly or dehydrated patients
  • Liver function tests (ALT, AST) · Baseline and if symptoms of hepatotoxicity occur
  • Tendon pain or inflammation · Assess at each visit; discontinue if tendonitis or tendon rupture is suspected
  • Blood glucose · Monitor in diabetic patients, as fluoroquinolones can cause dysglycaemia
  • ECG (QT interval) · In patients with risk factors for QT prolongation (e.g., electrolyte disturbances, concurrent QT-prolonging drugs)
  • Pregnancy: Ciprofloxacin is not recommended during pregnancy, especially in the first trimester, due to a potential risk of fetal cartilage damage. Use only if the potential benefit outweighs the risk and no alternative is suitable.
  • Toxicity: Tendonitis or tendon rupture · Discontinue at first sign of tendon pain or inflammation; rest the affected limb and avoid exercise.
  • Toxicity: QT interval prolongation and ventricular arrhythmias · Discontinue if QTc prolongation occurs; correct any electrolyte disturbances and monitor ECG.
  • Toxicity: CNS effects including seizures and confusion · Discontinue; manage seizures if they occur; consider anticonvulsant therapy for severe cases.
  • Toxicity: Crystalluria and renal dysfunction · Maintain adequate hydration (especially in elderly or those with reduced fluid intake); monitor renal function.
Clinical notes
Ciprofloxacin is used for a wide range of infections, including complicated urinary tract infections, pyelonephritis, prostatitis, respiratory tract infections (e.g., sinusitis, exacerbations of chronic bronchitis), intra-abdominal infections, and certain skin, bone, and joint infections. It is also a first-line agent for anthrax and plague. Adverse effects include tendinitis and tendon rupture, particularly in older adults or those with corticosteroid use; QT prolongation; central nervous system effects such as dizziness, confusion, and seizures; gastrointestinal upset; photosensitivity; and dysglycemia. It is contraindicated in pregnancy, breastfeeding, and children due to cartilage damage. Ciprofloxacin interacts with antacids, iron, and zinc, so it should be taken 2 hours apart. Antimicrobial stewardship is important; reserve for infections where other options are unsuitable.

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BNF; local formulary