Ciprofloxacin
Ciprofloxacin is a fluoroquinolone antibiotic used in adults for selected urinary, gastrointestinal, respiratory and skin infections. It carries boxed warnings for tendon, nerve and central nervous system effects and should be used only when alternatives are not appropriate.
- Chemical formula
- C17H18FN3O3
- CAS number
- 85721-33-1
- ATC code
- J01MA02
- Molecular weight
- 331.34 g/mol
- Drug class
- Fluoroquinolone antibiotic
- Also known as
- Bay o 9867, Ciprofloxacino
What is it?
Ciprofloxacin is a second-generation fluoroquinolone approved in the late 1980s. It is supplied as oral tablets, oral suspension, intravenous solution and topical formulations for the eye and ear. Ciprofloxacin is dispensed only on prescription. Several regulatory agencies have introduced boxed warnings or restrictions for fluoroquinolones because of disabling and potentially permanent adverse events involving tendons, nerves, joints and the central nervous system.
Mechanism of action
Ciprofloxacin inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription and repair. The result is rapid bactericidal activity against many Gram-negative bacteria, including Pseudomonas aeruginosa, and selected Gram-positive organisms. Resistance through gyrase mutations and efflux pumps has increased significantly in many regions, particularly for Escherichia coli and Salmonella spp.
Pharmacokinetics
Ciprofloxacin is well absorbed orally, with bioavailability of approximately 70%. Plasma protein binding is low (20% to 40%). Metabolism is partial, with most of the drug excreted unchanged in urine; renal impairment requires dose adjustment. The terminal half-life is approximately four hours, supporting twice-daily oral dosing. Co-administration with antacids, calcium, iron and zinc-containing products substantially reduces absorption due to chelation of the molecule.
Indications
Ciprofloxacin is approved in adults for the treatment of complicated urinary tract infections, acute pyelonephritis, prostatitis, gastrointestinal infections including travellers' diarrhoea, selected respiratory and skin infections, anthrax exposure and certain bone and joint infections. According to clinical guidelines and regulatory communications, ciprofloxacin should not be used as first-line therapy for uncomplicated infections when other antibiotics are appropriate, because of the risk of disabling adverse events.
Safety profile
Common adverse effects include gastrointestinal symptoms, headache, dizziness and rash. Serious adverse events include tendinopathy and tendon rupture (especially the Achilles tendon and in older adults or those on corticosteroids), peripheral neuropathy, central nervous system effects and aortic dissection or aneurysm in susceptible patients. According to the prescribing information and boxed warnings, ciprofloxacin should be discontinued at the first sign of these adverse events, and the medical history must be reviewed by a clinician before any prescription.
Products containing this ingredient
Frequently asked questions
Why are fluoroquinolones restricted in many countries? ▾
Several regulatory agencies, including the FDA and the European Medicines Agency, have introduced restrictions or boxed warnings for fluoroquinolones such as ciprofloxacin because of reports of disabling and potentially permanent adverse events involving tendons, nerves, muscles, joints and the central nervous system. According to these communications, fluoroquinolones should not be used as first-line therapy in uncomplicated infections when alternatives are available.
Can ciprofloxacin be taken with milk or yogurt? ▾
No. Calcium in dairy products, as well as iron, zinc, magnesium and aluminium-containing antacids and supplements, can chelate ciprofloxacin in the gastrointestinal tract and substantially reduce its absorption. According to the prescribing information, ciprofloxacin should be taken at least two hours before or six hours after these products. Adequate hydration is also important to reduce the risk of crystalluria.
Why is ciprofloxacin associated with tendon problems? ▾
Fluoroquinolones, including ciprofloxacin, can cause tendinopathy and tendon rupture, most often involving the Achilles tendon. Risk factors include age over 60, concurrent corticosteroid therapy, transplant recipients and pre-existing tendon disorders. According to the prescribing information, treatment should be discontinued at the first sign of tendon pain, swelling or inflammation, and the affected tendon should be rested under medical supervision.
Can ciprofloxacin be used in children? ▾
Use of ciprofloxacin in children is restricted because of the theoretical risk of cartilage damage observed in juvenile animals. According to the prescribing information, ciprofloxacin is reserved for selected paediatric indications such as complicated urinary tract infection, anthrax exposure and pulmonary exacerbations of cystic fibrosis, after specialist evaluation. Routine paediatric use is not recommended.
What are the main contraindications for ciprofloxacin? ▾
Ciprofloxacin is contraindicated in known hypersensitivity to fluoroquinolones, in concomitant use with tizanidine, and in a history of fluoroquinolone-associated tendon disorders. Caution is required in QT-prolonging conditions, myasthenia gravis (which can be exacerbated), aortic aneurysm risk, severe renal impairment and pregnancy. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.