What is the recommended dosage of linezolid (oxazolidinone antibiotic) for pediatric patients?

Linezolid Dosing in Pediatric Patients

For children under 12 years of age, administer linezolid 10 mg/kg every 8 hours (IV or oral), while children 12 years and older should receive 600 mg every 12 hours, matching adult dosing. 1

Age-Based Dosing Recommendations

Neonates (Birth to 7 Days)

• Full-term neonates <7 days: 10 mg/kg every 8 hours 1
• Preterm neonates <7 days (gestational age <34 weeks): Start with 10 mg/kg every 12 hours due to lower systemic clearance 1
• All neonates ≥7 days of life: Transition to 10 mg/kg every 8 hours regardless of gestational age 1

Infants and Children (>7 Days to 11 Years)

• Standard dosing: 10 mg/kg every 8 hours (IV or oral) 2, 3, 1
• Maximum single dose: Do not exceed 600 mg per dose 3
• This more frequent dosing (compared to adults) is necessary because children have 2-3 fold higher clearance rates than adults, resulting in lower drug exposure and shorter elimination half-lives 1, 4

Adolescents (≥12 Years)

• Standard dosing: 600 mg every 12 hours (IV or oral) 2, 3, 1
• Pharmacokinetic parameters in this age group approximate adult values, justifying the same dosing interval 3, 1

Duration of Treatment by Indication

• Uncomplicated skin/soft tissue infections: 10-14 days 3, 1
• Complicated skin/soft tissue infections: 10-14 days 3, 1
• Community-acquired or nosocomial pneumonia: 10-14 days 3, 1
• Vancomycin-resistant Enterococcus faecium infections: 14-28 days 1
• Osteomyelitis: Minimum 8 weeks 3
• Septic arthritis: 3-4 weeks 3
• CNS infections (meningitis, brain abscess): 2-6 weeks 3
• Multidrug-resistant tuberculosis: As long as tolerated as part of multi-drug regimen; for children <12 years: 10 mg/kg twice daily, for children ≥12 years: 10 mg/kg once daily 5

Critical Monitoring Requirements

Hematologic Monitoring

• Complete blood counts weekly, particularly for treatment exceeding 2 weeks, due to risk of bone marrow suppression 2, 3
• Myelosuppression is reversible upon drug cessation 5

Neurologic Monitoring

• Monthly screening for peripheral neuropathy in patients on extended treatment 3
• Monthly visual acuity and color discrimination testing for prolonged therapy 2, 3
• Peripheral neuropathy may not be fully reversible even after drug cessation 5

Cardiac Monitoring

• Baseline and monthly ECGs to assess QTc interval, especially when using multiple QTc-prolonging agents 3
• Avoid linezolid if baseline QTc >450 ms that does not correct with medical management 3

Important Clinical Considerations

Route of Administration

• Linezolid has 100% oral bioavailability, allowing seamless transition from IV to oral without dose adjustment 1
• May be administered without regard to meals, though high-fat food delays time to maximum concentration by approximately 40 minutes and reduces peak concentration by 17% without affecting total exposure 1

Special Populations Requiring Dosage Adjustment

• Critically ill children with bacteria MIC ≥2 mg/L: Consider increasing dose to 15 mg/kg every 6-8 hours to achieve pharmacodynamic target (AUC/MIC >80) 6, 7
• Children with elevated AST (>40 U/L): May require dosage reduction due to significantly higher drug exposure 6
• Renal insufficiency: No dose adjustment needed for parent drug, though metabolites accumulate; give after hemodialysis if applicable 1

Drug Interactions and Contraindications

• Avoid concomitant use with MAO inhibitors or within 2 weeks of discontinuing MAO inhibitors due to serotonin syndrome risk 3
• Consider prophylactic pyridoxine in patients at risk for peripheral neuropathy (diabetes, alcohol abuse, malnutrition) 2

Common Pitfalls to Avoid

• Do not reduce dosing frequency to every 24 hours in children <12 years, as this fails to maintain adequate drug exposure 2
• Do not use adult dosing intervals (every 12 hours) in children <12 years, as their faster clearance necessitates every 8-hour dosing 1, 4
• The currently approved 10 mg/kg every 8 hours dosing may be insufficient for bacteria with MIC ≥2 mg/L; consider dose escalation to 15-20 mg/kg every 8 hours in these cases 8, 7
• Preterm neonates <7 days require special consideration with initial every 12-hour dosing due to immature clearance mechanisms 1