Pediatric Dosing for Ofloxacin and Ornidazole
Ofloxacin Dosing
For systemic infections in children, ofloxacin should be dosed at 7.5 mg/kg every 12 hours (maximum 400 mg per dose), which translates to 15 mg/kg/day total, and should be reserved exclusively for multidrug-resistant tuberculosis or when first-line agents have failed due to safety concerns regarding cartilage development. 1
Standard Systemic Dosing (Oral/IV)
- General pediatric dose: 7.5 mg/kg every 12 hours, with a maximum of 400 mg per dose 1
- Alternative dosing for MDR-TB: 15-20 mg/kg/day as a single daily dose or divided into two doses (maximum 1.0 g/day) 1
Weight-Based Dosing Table for MDR-TB
The following weight-based dosing provides practical guidance for children with drug-resistant tuberculosis 1:
| Weight (kg) | Total Daily Dose (mg) | Typical Regimen |
|---|---|---|
| 5-6.9 | 150 | 75 mg twice daily |
| 7-9.9 | 200 | 100 mg twice daily |
| 10-13.9 | 300 | 150 mg twice daily |
| 14-19.9 | 400 | 200 mg twice daily |
| 20-29.9 | 600 | 300 mg twice daily |
| 30-39.9 | 800 | 400 mg twice daily |
| ≥40 | 1,200 | 600 mg twice daily |
Age-Specific Considerations
- Children ≥1 month to <15 years: Use weight-based dosing as outlined above 1
- Adolescents ≥15 years: Adult dosing applies (typically 400 mg twice daily for most indications) 1
Critical Safety Restrictions
- Ofloxacin must be reserved for multidrug-resistant tuberculosis as the primary indication 1
- Use only when organisms are resistant to both isoniazid and rifampin, or when there is documented intolerance to first-line agents 1
- Fluoroquinolones should NOT be used for long-term treatment (>several weeks) in children due to potential effects on bone and cartilage growth 1
- The risk of permanent tooth discoloration and enamel hypoplasia exists, so use only when benefits clearly outweigh risks 1
Formulation Challenges
- Ofloxacin oral suspension is not available in the United States; tablets must be crushed or split for weight-based dosing in smaller children 1
Ornidazole Dosing
Ornidazole should be administered at 20-30 mg/kg as a single daily dose for pediatric patients. 1
Standard Dosing
- Recommended dose: 20-30 mg/kg once daily 1
- This single daily dosing improves adherence and is the standard recommendation from major pediatric guideline societies 1
Clinical Context
- Ornidazole is typically combined with ofloxacin for mixed bacterial and protozoal infections, particularly in diarrheal illnesses 2
- The combination has gained acceptance for treating infections caused by both bacteria and protozoa 2
Drug Interactions and Administration Precautions
Critical Drug Interactions
- Do NOT administer ofloxacin within 2 hours of antacids or medications containing divalent cations (calcium, magnesium, iron, aluminum), as these significantly decrease fluoroquinolone absorption 1
- Dairy products, calcium supplements, and iron should be avoided within 2 hours of ofloxacin dosing 1
Renal Dosing Adjustments
- Ofloxacin dosage must be adjusted if creatinine clearance is <50 mL/minute, as the drug is 80% renally cleared 1
- Supplemental doses are not necessary after hemodialysis 1
Monitoring Requirements
- Regular monitoring for adverse effects is mandatory, particularly with prolonged use 1
- Monitor for musculoskeletal complaints, tendon pain, or joint swelling 1
- Assess for gastrointestinal symptoms and central nervous system effects (headache, dizziness) 1
Common Pitfalls to Avoid
- Never use adult fixed-dose regimens (e.g., 400 mg twice daily) without adjusting for body weight in children, as this causes over-dosing in smaller children or under-dosing in heavier children 1
- Do not use ofloxacin as first-line therapy for community-acquired pneumonia or other common infections—safer alternatives like amoxicillin 90 mg/kg/day in 2 doses or azithromycin are preferred 1
- Avoid long-term fluoroquinolone therapy in children due to skeletal safety concerns 1
- Remember that pediatric dosing results in lower systemic exposure than adults (mean AUC₀₋₂₄ ≈ 66.7 µg·h/mL in children versus ≈ 103 µg·h/mL in adults), supporting the need for weight-based rather than fixed dosing 1, 3
Ophthalmic Ofloxacin (Separate Indication)
For bacterial conjunctivitis in children ≥1 year old, topical ofloxacin 0.3% ophthalmic solution is dosed as 1-2 drops in the affected eye(s) every 2-4 hours for the first two days, then 1-2 drops four times daily for days 3-5 4. Systemic toxicity is not a concern with topical therapy 4.