Ciprofloxacin Dosing Frequency
Ciprofloxacin is typically administered every 12 hours (twice daily) for most infections in adults, with the standard oral dose being 500 mg every 12 hours. 1
Standard Adult Dosing
- Oral ciprofloxacin is given every 12 hours, with doses ranging from 250 mg to 750 mg depending on infection severity 2, 3
- The most common oral dosing regimen is 500 mg every 12 hours, which produces steady-state serum concentrations equivalent to 400 mg IV every 12 hours 1
- For severe infections, 750 mg orally every 12 hours produces an AUC equivalent to 400 mg IV every 8 hours 1
Intravenous Dosing Frequency
- IV ciprofloxacin is typically administered every 12 hours at doses of 200-400 mg 4, 5
- For serious Pseudomonas or staphylococcal infections, every 8 hours dosing or higher doses every 12 hours should be considered 6
- Higher-dose regimens (400-600 mg IV every 12 hours) have been used successfully for life-threatening nosocomial infections 7
Pediatric Dosing Frequency
- Children receive ciprofloxacin every 12 hours at weight-based doses of 10-15 mg/kg orally (maximum 1 g/day) 3, 8
- IV dosing in children is every 8-12 hours at 10 mg/kg (maximum 400 mg/dose) 3
- Neonates receive 15 mg/kg twice daily (every 12 hours) 3, 8
Renal Dose Adjustments
Dosing frequency must be extended in renal impairment:
The serum elimination half-life is approximately 4 hours in patients with normal renal function, supporting the every 12-hour dosing interval 1
Important Clinical Considerations
- Maximum serum concentrations are attained 1-2 hours after oral dosing, with mean concentrations at 12 hours of 0.1-0.4 μg/mL depending on dose 1
- Ciprofloxacin must be administered at least 2 hours before or 6 hours after products containing divalent cations (antacids, iron, calcium) to avoid chelation and reduced absorption 2, 3
- The bioavailability of oral ciprofloxacin is approximately 70%, allowing for effective sequential IV-to-oral therapy without changing the every 12-hour frequency 1, 5
Special Situations
- Single-dose ciprofloxacin (500 mg) for meningococcal carriage eradication is the only exception to the every 12-hour rule, used specifically to eliminate throat carriage 2
- For uncomplicated UTIs in women, 100 mg every 12 hours for 3 days represents the minimum effective dose, though this is less effective than conventional 7-day therapy 9