What is the recommended linezolid dosing regimen and treatment duration for adults and children, including any adjustments for renal or hepatic impairment?

Linezolid Dosing Recommendations

For adults, administer linezolid 600 mg IV or PO every 12 hours for most serious Gram-positive infections; for children under 12 years, give 10 mg/kg IV or PO every 8 hours (maximum 600 mg per dose), and for children 12 years and older, use the adult dose of 600 mg every 12 hours. 1

Standard Adult Dosing

The recommended adult dose is 600 mg intravenously or orally every 12 hours for complicated skin and soft tissue infections, nosocomial pneumonia, community-acquired pneumonia, bacteremia, osteomyelitis, septic arthritis, and CNS infections. 2, 1, 3

• Linezolid exhibits 100% oral bioavailability, allowing the IV and oral formulations to be used interchangeably without dose adjustment. 1, 4
• The standard 600 mg every 12 hours dosing applies regardless of the route of administration. 1, 3
• Do not reduce dosing frequency to every 24 hours, as this fails to maintain adequate drug exposure for bactericidal activity. 1

Pediatric Dosing

Children under 12 years of age require 10 mg/kg IV or PO every 8 hours (not to exceed 600 mg per dose), while children 12 years and older should receive the adult dose of 600 mg every 12 hours. 2, 1

• The more frequent dosing interval in younger children (every 8 hours vs. every 12 hours) is necessary because children have higher linezolid clearance compared to adults. 5, 6
• For multidrug-resistant tuberculosis in children over 12 years, linezolid should be administered for as long as tolerated as part of a multidrug regimen. 1

Treatment Duration by Indication

Skin and Soft Tissue Infections

• Complicated skin and soft tissue infections: 10–14 days 2, 1, 3
• Uncomplicated infections may be treated for 7–10 days depending on clinical response. 1

Pneumonia

• Community-acquired or nosocomial pneumonia: 7–21 days, with most patients completing 10–14 days 1

Bacteremia

• Uncomplicated bacteremia: 7–14 days 1
• Complicated bacteremia: 4–6 weeks 2, 1

Bone and Joint Infections

• Osteomyelitis: minimum 8 weeks, with consideration for additional 1–3 months of oral therapy 1, 3
• Septic arthritis: 3–4 weeks 1

Central Nervous System Infections

• Meningitis: 2 weeks 1, 3
• Brain abscess, subdural empyema, or spinal epidural abscess: 4–6 weeks 1, 3

Endocarditis

• Infective endocarditis (native or prosthetic valve): 4–6 weeks 2, 3

Renal and Hepatic Impairment

No dose adjustment is required for linezolid in patients with mild to moderate renal or hepatic impairment, including those on dialysis. 1, 4, 6

• Linezolid is not removed by hemodialysis, so no supplemental post-dialysis dose is needed. 4
• In patients with severe renal impairment requiring hemodialysis, exposure to the two primary metabolites increases 7- to 8-fold, so use with caution and monitor for adverse effects. 5, 6
• Elderly patients achieve similar plasma concentrations to younger adults and do not require dose adjustment. 5, 6

Route of Administration Selection

Initiate IV linezolid for patients with severe sepsis, septic shock, or those requiring intensive hemodynamic support; transition to oral therapy once the patient can tolerate oral intake and has a functional gastrointestinal tract. 1

• The complete oral bioavailability allows seamless transition from IV to oral without changing the dose or frequency. 1, 4
• Oral linezolid provides efficacy comparable to IV vancomycin for most susceptible Gram-positive infections. 1

Monitoring and Precautions

Perform complete blood counts weekly in patients receiving linezolid, particularly those on treatment for longer than 2 weeks, as myelosuppression risk increases significantly with prolonged administration. 1

• Conduct visual acuity and color discrimination testing monthly in patients receiving extended linezolid treatment. 1
• Consider prophylactic pyridoxine (vitamin B6) in patients at risk for peripheral neuropathy, such as those with diabetes, alcohol abuse, or malnutrition. 1
• Monitor serum trough concentrations between 2–7 mg/L to assess efficacy and safety, particularly in populations vulnerable to under- or overexposure. 6

Important Drug Interactions and Contraindications

Avoid concomitant use of linezolid with monoamine oxidase inhibitors or within 2 weeks of taking such medications. 1

• Avoid linezolid in patients with uncontrolled hypertension, pheochromocytoma, carcinoid tumor, thyrotoxicosis, bipolar depression, schizophrenia, or acute confusional states. 1
• Linezolid is a mild, reversible inhibitor of monoamine oxidases A and B; coadministration with adrenergic agents (pseudoephedrine, phenylpropanolamine) may increase blood pressure. 5
• No pharmacokinetic interaction occurs when linezolid is coadministered with aztreonam, gentamicin, or warfarin. 5

Special Populations

Obese Patients

• Despite lack of sufficient data, dosing based on actual body weight or use of higher doses may be justified to prevent subtherapeutic concentrations. 6

Critically Ill Patients

• Although dose adjustment is not formally recommended, administration of linezolid as continuous intravenous infusion may be considered in critically ill patients with augmented renal clearance. 6
• Blood level monitoring should be considered in critically ill patients vulnerable to linezolid underexposure. 6

Pregnant Women

• Dose adjustment is not currently recommended for linezolid in pregnant women, though data are limited. 6

Common Pitfalls to Avoid

• Do not underdose pediatric patients: The full 10 mg/kg every 8 hours (up to 40 mg/kg/day) is essential for serious infections in children under 12 years; lower doses risk treatment failure. 1
• Do not use once-daily dosing: Linezolid pharmacokinetics do not support extended-interval dosing due to its relatively short half-life of 5–7 hours. 4, 5
• Do not empirically use linezolid for catheter-related bloodstream infections: Vancomycin or daptomycin are preferred first-line agents. 1