ciprofloxacin and metronidazole

J01RA10

Forms & Strengths

Combination packs containing Ciprofloxacin (as hydrochloride) and Metronidazole oral tablets
Ciprofloxacin 500 mg / Metronidazole 400 mg oral tablets
Intravenous infusion combination formulations available in clinical practice

Adult Dosing

Typical oral dose: Ciprofloxacin 500 mg combined with Metronidazole 400 mg to 500 mg every 8 to 12 hours
Intravenous dosing varies by infection severity; typically Ciprofloxacin 400 mg IV every 12 hours plus Metronidazole 500 mg IV every 8 hours
Duration of therapy depends on the specific infection, typically 7 to 14 days
Renal dose adjustment required for ciprofloxacin if creatinine clearance is < 30 mL/min

Pediatric Dosing

Generally not recommended for routine pediatric use due to risk of arthropathy and musculoskeletal adverse effects from ciprofloxacin
Use in children restricted to specific indications such as complicated urinary tract infections or anthrax exposure when safer alternatives are unavailable
Dosing must be strictly individualized based on weight and specific infectious disease guidelines

Indications

Mechanism of Action

Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA gyrase and topoisomerase IV, preventing DNA replication and transcription
Metronidazole is a nitroimidazole that is reduced by anaerobic bacterial proteins, forming reactive nitro radicals that damage microbial DNA
Combined action provides broad-spectrum coverage against aerobic Gram-negative bacilli and obligate anaerobic pathogens

Contraindications

Known hypersensitivity to ciprofloxacin, other fluoroquinolones, metronidazole, or nitroimidazole derivatives
Concurrent administration with tizanidine due to potentiation of hypotensive and sedative effects
History of fluoroquinolone-associated tendinopathy or tendon rupture
First trimester of pregnancy for metronidazole (relative contraindication)

Adverse Reactions

Common: Nausea, diarrhea, vomiting, metallic taste, headache, dizziness
Serious: Tendonitis and tendon rupture, peripheral neuropathy, central nervous system toxicity (seizures, psychosis)
QT interval prolongation and severe cardiac arrhythmias
Clostridioides difficile-associated diarrhea
Disulfiram-like reaction with alcohol consumption (due to metronidazole)

Drug Interactions

Coadministration with antacids, sucralfate, or multivalent cations (magnesium, aluminum, calcium, iron) significantly reduces ciprofloxacin absorption
Metronidazole inhibits CYP2C9 and CYP3A4, significantly increasing plasma concentrations and toxicity risk of warfarin and lithium
Ciprofloxacin inhibits CYP1A2, increasing levels of theophylline, tizanidine, and methotrexate
Concurrent use with QT-prolonging drugs (e.g., antiarrhythmics, antipsychotics) increases risk of ventricular arrhythmias

Curated Content: Needs Vetting Before Put to Clinical Use