What is the recommended dose of Zyvox (linezolid) for adults?

Zyvox (Linezolid) Dosing for Adults

The standard adult dose of Zyvox (linezolid) is 600 mg every 12 hours (twice daily), administered either orally or intravenously, for most serious Gram-positive infections including MRSA. 1, 2, 3

Standard Dosing Regimen

• 600 mg PO or IV every 12 hours is the recommended dose for adults with normal renal and hepatic function for the following indications 1, 2, 3:

  • Complicated skin and soft tissue infections 4, 1
  • Pneumonia (community-acquired and hospital-acquired) 4, 1
  • Bacteremia 4
  • Osteomyelitis and septic arthritis 5, 2
  • CNS infections (meningitis, brain abscess, epidural abscess) 5

• Linezolid is 100% bioavailable orally, allowing equal dosing whether given IV or PO 6, 7

Duration of Therapy by Indication

The duration varies significantly by infection type 1, 5:

• 7-14 days for complicated skin/soft tissue infections 1
• 7-21 days for pneumonia 4, 1
• Minimum 6-8 weeks for osteomyelitis (some experts recommend additional 1-3 months for chronic infection or inadequate debridement) 1, 5
• 2 weeks for meningitis 5
• 4-6 weeks for brain abscess, subdural empyema, or spinal epidural abscess 5
• ≥6 weeks for infective endocarditis caused by resistant enterococci 4

Critical Dosing Distinction: MRSA vs. MDR-TB

Do not confuse MRSA dosing with MDR-TB dosing 2:

• MRSA infections: 600 mg twice daily (every 12 hours) 2
• MDR-TB: 600 mg once daily (different indication, different regimen) 2

This distinction is crucial as confusing these regimens can lead to either underdosing (ineffective treatment) or increased toxicity 2.

Renal and Hepatic Impairment

• No dose adjustment required for mild to moderate renal or hepatic impairment 6, 7
• Use with caution in severe renal insufficiency requiring hemodialysis, as metabolite accumulation occurs (7-8 fold higher exposure) 6

Monitoring Requirements

Monitor complete blood counts weekly in patients receiving linezolid for >14 days 8:

• Thrombocytopenia is duration-dependent, occurring primarily with treatment ≥2 weeks 3, 9, 8
• In Phase III trials, 2.4% of linezolid-treated adults developed substantially low platelet counts (vs. 1.5% with comparators) 3, 8
• Platelet counts typically return to normal after discontinuation 3, 8

Important Pharmacologic Considerations

• Elimination half-life: 5-7 hours, supporting twice-daily dosing 6
• Protein binding: Low (31%), allowing good tissue penetration 6
• Distribution: Approximately equivalent to total body water 6
• Linezolid is a weak, reversible monoamine oxidase inhibitor; avoid tyramine-rich foods and use caution with adrenergic/serotonergic agents 8

Common Pitfalls to Avoid

• Do not extend therapy beyond necessary duration without weekly CBC monitoring, as myelosuppression risk increases significantly after 2 weeks 3, 8
• Do not reduce the dose to 600 mg once daily for MRSA infections (this is the MDR-TB dose, not appropriate for acute MRSA) 2
• Do not assume dose adjustment is needed for renal impairment unless the patient requires hemodialysis 6, 7