Linezolid Dosing for Pediatric Patients
For pediatric patients under 12 years of age, linezolid should be dosed at 10 mg/kg every 8 hours (not every 12 hours), with a maximum single dose not exceeding 600 mg. For children 12 years and older, use the adult dosing of 600 mg every 12 hours 1, 2.
Age-Based Dosing Algorithm
Children Under 12 Years
- Dose: 10 mg/kg every 8 hours (PO or IV) 1, 3
- Maximum single dose: 600 mg 1
- Rationale: Children have 2-3 fold higher clearance rates than adults, resulting in lower drug exposure and shorter elimination half-lives, necessitating the shorter dosing interval 2, 4
Children 12 Years and Older
- Dose: 600 mg every 12 hours (PO or IV) 1, 3
- Rationale: Pharmacokinetic parameters in this age group approximate adult values 2, 4
Special Consideration for Neonates
- Full-term neonates <7 days: 10 mg/kg every 12 hours 2
- Full-term neonates ≥7 days: 10 mg/kg every 8 hours 2
- Preterm neonates <7 days: 10 mg/kg every 12 hours 2
Critical Pharmacokinetic Considerations
The every-8-hour dosing in younger children is essential because:
- Clearance is most rapid in children aged >1 week to 11 years 2
- Single-dose systemic exposure (AUC) is lower and half-life is shorter compared to adults 2
- The every-8-hour regimen produces similar daily AUC values in children as the every-12-hour regimen does in adults 2
Duration of Treatment by Indication
MRSA Infections
- Uncomplicated skin/soft tissue infections: 10-14 days 1
- Complicated skin/soft tissue infections: 14 days 1
- Pneumonia: 10-14 days 1
- Osteomyelitis: Minimum 8 weeks, with consideration for additional 1-3 months of oral therapy 3
- Septic arthritis: 3-4 weeks 1
- CNS infections (meningitis, brain abscess): 2-6 weeks depending on specific infection 3
Multidrug-Resistant Tuberculosis
- Children >12 years: 10 mg/kg once daily for entire treatment course 1
- Children <12 years: 10 mg/kg twice daily for entire treatment course 1
Monitoring Requirements
Hematologic Monitoring
- Complete blood counts weekly, particularly for treatment exceeding 2 weeks 3
- Risk increases significantly with prolonged administration beyond 2 weeks 3
- Avoid in children with baseline significant anemia, leukopenia, or thrombocytopenia 1
Neurologic Monitoring
- Monthly screening for peripheral neuropathy 1, 3
- Monthly visual acuity and color discrimination testing for extended treatment 3
- Avoid in children with significant baseline peripheral neuropathy 1
Cardiac Monitoring
- Baseline and monthly ECGs to assess QTc interval 1
- Avoid if baseline QTc >450 ms that does not correct with medical management 1
Common Pitfalls and Caveats
Dosing Errors
The most critical error is using the adult every-12-hour dosing interval in children under 12 years, which results in subtherapeutic drug exposure 2, 4. The FDA label explicitly states that pediatric patients up to 11 years require every-8-hour dosing 2.
Underdosing Risk
Recent pharmacokinetic studies suggest that the standard 10 mg/kg every 8 hours may be inadequate for bacteria with MIC ≥2 mg/L 5, 6. In critically ill children or when treating organisms with MIC of 2 mg/L, consider escalating to 15 mg/kg every 8 hours or even 15 mg/kg every 6 hours 7, 6.
Drug Interactions
- Contraindicated: Concomitant use with MAO inhibitors or within 2 weeks of discontinuing MAO inhibitors 3
- Avoid in patients with: Uncontrolled hypertension, pheochromocytoma, carcinoid tumor, thyrotoxicosis 3
Renal Impairment
No dose adjustment is required for renal insufficiency, as linezolid clearance is not significantly altered 2. However, metabolites accumulate in severe renal impairment, though clinical significance remains unclear 2. Linezolid should be administered after hemodialysis, as approximately 30% is removed during a 3-hour session 2.
Hepatic Impairment
Patients with elevated AST (>40 U/L) have significantly higher AUC values and may require dosage adjustment to avoid toxicity 7.