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Sunday, July 27, 2025

Ciprofloxacin


Ciprofloxacin is a broad-spectrum synthetic antibiotic belonging to the fluoroquinolone class. It is used to treat a wide range of infections caused by susceptible gram-negative and gram-positive bacteria. It is available in multiple formulations, including oral tablets, oral suspension, and intravenous injection, making it versatile for both outpatient and inpatient care. Ciprofloxacin has excellent tissue penetration and bioavailability, which contribute to its clinical efficacy.

This detailed profile provides a comprehensive professional overview of ciprofloxacin, including its classification, mechanism of action, clinical indications, dosage, contraindications, side effects, precautions, and significant drug interactions.

Pharmacological Classification

  • Therapeutic class: Antibiotic

  • Pharmacologic class: Fluoroquinolone

  • ATC code: J01MA02

Brand Names

  • Cipro® (U.S., Canada)

  • Ciloxan® (ophthalmic)

  • Ciproxin® (UK, Europe)

  • Baycip®, Ciprobay®, Ciprenex®, and generics (worldwide)

Mechanism of Action

Ciprofloxacin inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, essential enzymes in bacterial DNA replication, transcription, repair, and recombination.

  • DNA gyrase inhibition (predominant in gram-negative bacteria): prevents supercoiling of DNA

  • Topoisomerase IV inhibition (more relevant in gram-positive bacteria): interferes with chromosomal separation during cell division

  • Result: Bacterial cell death (bactericidal)

Spectrum of Activity

Effective Against:

Gram-negative bacteria

  • Escherichia coli

  • Klebsiella pneumoniae

  • Proteus spp.

  • Pseudomonas aeruginosa (moderate activity)

  • Neisseria gonorrhoeae

  • Haemophilus influenzae

  • Moraxella catarrhalis

  • Salmonella spp., Shigella spp.

  • Campylobacter jejuni

Gram-positive bacteria

  • Staphylococcus aureus (MSSA)

  • Streptococcus pneumoniae (variable; not first-line)

  • Bacillus anthracis (anthrax)

Other organisms

  • Chlamydia trachomatis

  • Mycoplasma pneumoniae

  • Legionella pneumophila

  • Mycobacterium fortuitum (and some atypical mycobacteria)

Not Active Against:

  • MRSA

  • Anaerobes (e.g., Bacteroides fragilis)

  • Enterococcus faecium (poor susceptibility)

Indications and Clinical Uses

FDA / EMA Approved Indications

  • Urinary tract infections (UTIs), including:

    • Uncomplicated and complicated UTIs

    • Pyelonephritis

  • Prostatitis (acute and chronic bacterial)

  • Lower respiratory tract infections (chronic bronchitis exacerbation, pneumonia)

  • Skin and soft tissue infections

  • Bone and joint infections

  • Gastrointestinal infections:

    • Traveler’s diarrhea

    • Infectious diarrhea (e.g., Shigella, Salmonella, E. coli)

    • Typhoid fever

  • Intra-abdominal infections (in combination with metronidazole)

  • Anthrax (inhalational exposure or post-exposure prophylaxis)

  • Febrile neutropenia (in combination therapy)

  • Otitis externa (topical formulation)

  • Ophthalmic infections (as eye drops/ointment)

  • Gonorrhea (limited by resistance)

Dosage and Administration

Adults (Oral)

  • Uncomplicated UTI: 250 mg twice daily for 3 days

  • Complicated UTI / Pyelonephritis: 500 mg twice daily for 7–14 days

  • Prostatitis: 500–750 mg twice daily for 4–6 weeks

  • Respiratory infections: 500–750 mg twice daily

  • Gastroenteritis: 500 mg twice daily for 3–5 days

  • Anthrax prophylaxis: 500 mg twice daily for 60 days

Intravenous (IV)

  • 200–400 mg every 12 hours, depending on infection site and severity

  • Equivalent oral dose can usually replace IV when the patient is stable

Renal Impairment

  • Dose adjustment required if creatinine clearance <30 mL/min

  • Example: 250–500 mg once daily

Pediatrics

  • Use limited to specific serious infections (e.g., anthrax, complicated UTI, Pseudomonas infection in cystic fibrosis)

  • 10–20 mg/kg every 12 hours (max: 750 mg per dose)

Pharmacokinetics

  • Bioavailability: ~70% (oral)

  • Peak serum concentration: 1–2 hours

  • Half-life: 3.5–5 hours (may be prolonged in renal dysfunction)

  • Protein binding: ~20–40%

  • Elimination: Primarily renal (~50% unchanged); also fecal and biliary

Contraindications

  • Hypersensitivity to ciprofloxacin or other fluoroquinolones

  • Concomitant use of tizanidine (risk of hypotension and CNS depression)

  • History of tendon rupture associated with fluoroquinolones

  • Children and adolescents (except when clearly indicated)

  • Pregnancy and lactation (generally avoided unless benefits outweigh risks)

Warnings and Precautions

  • Tendinitis and tendon rupture (especially in elderly or corticosteroid users)

  • QT prolongation: Avoid in patients with QT prolongation, on antiarrhythmics

  • Peripheral neuropathy: May be irreversible

  • CNS effects: Including confusion, hallucinations, seizures (risk increased in epilepsy or renal failure)

  • Hypoglycemia or hyperglycemia: Especially in diabetics

  • Photosensitivity: Avoid excessive sun exposure

  • Aortic aneurysm/dissection risk: Use with caution in patients with vascular disorders

  • Superinfection: Prolonged use may lead to overgrowth of non-susceptible organisms

  • Clostridioides difficile–associated diarrhea (CDAD): Risk with broad-spectrum coverage

Adverse Effects

Common (>1%)

  • Nausea, vomiting, diarrhea

  • Abdominal pain

  • Headache, dizziness

  • Rash

  • Abnormal liver function tests

  • Taste disturbances

Less Common

  • Insomnia or anxiety

  • Confusion, agitation, tremors

  • Photosensitivity

  • Tendonitis, tendon rupture (Achilles tendon most common)

  • Seizures (rare)

  • Peripheral neuropathy

  • Hypoglycemia/hyperglycemia

Rare but Serious

  • QT prolongation and torsades de pointes

  • Stevens-Johnson syndrome

  • Agranulocytosis

  • Hepatotoxicity

  • Pseudomembranous colitis

  • Aortic aneurysm/dissection

  • Anaphylaxis

Drug Interactions

Agents that Decrease Ciprofloxacin Absorption

  • Antacids (aluminum, magnesium)

  • Calcium, iron, zinc supplements

  • Sucralfate

  • Multivitamins (containing divalent/trivalent cations)

  • Take ciprofloxacin 2 hours before or 6 hours after these agents

Increased QT Prolongation Risk

  • Amiodarone, sotalol, quinidine, macrolides, TCAs, antipsychotics

CYP1A2 Inhibition

  • Theophylline: Increased toxicity — monitor levels

  • Caffeine: May increase CNS stimulation

  • Tizanidine: Severe hypotension, sedation — contraindicated

  • Warfarin: Potentiation of anticoagulant effect — monitor INR

Others

  • NSAIDs: May increase risk of seizures when combined

  • Ciclosporin: Risk of nephrotoxicity

  • Metformin: Monitor for hypoglycemia

Pregnancy and Lactation

Pregnancy

  • Generally not recommended

  • Animal studies suggest risk of cartilage damage

  • May be used if benefits outweigh risks, especially for serious infections (e.g., anthrax exposure)

Lactation

  • Excreted in breast milk

  • Avoid if possible; use alternative agents (e.g., penicillins, cephalosporins)

  • Monitor infant for GI disturbances or allergic reactions if used

Patient Counseling

  • Take with water, with or without food

  • Do not take with dairy products or calcium-fortified juices alone

  • Separate dosing from antacids, iron, calcium, magnesium by several hours

  • Avoid excessive sun exposure; use sunscreen

  • Report joint pain, tendon swelling, or neuropathic symptoms

  • Do not drive or operate machinery if experiencing dizziness or confusion

  • Complete the full course, even if symptoms improve early

  • Stay well hydrated during treatment

Monitoring Parameters

  • Renal function in elderly or renally impaired patients

  • Signs of tendon injury (pain, swelling)

  • CNS side effects in patients with seizure history

  • Blood glucose in diabetic patients

  • INR if on warfarin

  • ECG in high-risk cardiac patients (QT prolongation)

  • Superinfections or signs of C. difficile colitis




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