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Oxazolidinone Antibiotic Pregnancy: Avoid — no human data; animal studies showed fetal toxicity

Linezolid (MRSA Osteomyelitis)

Brand names: Zyvox

Adult dose

Dose: 600 mg twice daily
Route: Oral or Intravenous (bioequivalent — oral preferred when possible)
Frequency: Twice daily
Max: 1200 mg/day
Oral bioavailability is 100% — switch to oral early; no need for prolonged IV. Duration in MRSA osteomyelitis: typically 4–6 weeks. Reserve for MRSA osteomyelitis and PJI where glycopeptides are not appropriate or failed — antimicrobial stewardship essential.

Paediatric dose

Dose: 10 mg/kg
Route: Oral or IV
Frequency: Every 8 hours (<12 years); every 12 hours (12+ years)
Max: 600 mg per dose
Paediatric MRSA osteomyelitis — restricted use; serotonin syndrome risk with concurrent SSRIs

Dose adjustments

Renal

No dose adjustment required for renal impairment; metabolites accumulate in severe CKD but not clinically significant

Hepatic

No dose adjustment for mild-moderate impairment; limited data in severe hepatic impairment

Paediatric weight-based calculator

Paediatric MRSA osteomyelitis — restricted use; serotonin syndrome risk with concurrent SSRIs

Clinical pearls

  • 100% oral bioavailability: unique among antibiotics with bone penetration — allows complete OPAT or community-based treatment without IV access; bone concentrations approximately equal to serum (excellent biofilm penetration)
  • Myelosuppression: FBC must be checked weekly — thrombocytopenia occurs in 2–3% and is dose/duration dependent; stop if platelets fall <100 × 10⁹/L
  • Optic neuropathy and peripheral neuropathy: both are irreversible if not detected early — vision assessment and neurological examination monthly for courses >28 days; any visual change = STOP immediately
  • Tyramine interaction: linezolid inhibits MAO-A and MAO-B — patients must avoid tyramine-rich foods (aged cheeses, cured/smoked meats, Marmite, red wine, tap beer, some fermented foods) to prevent hypertensive crisis
  • Serotonin syndrome with SSRIs: a very common co-prescription trap in orthopaedic patients — review all medications before prescribing linezolid; SSRIs are extremely prevalent in this patient population

Contraindications

  • Concurrent serotonergic drugs (SSRIs, SNRIs, MAOIs, triptans) — serotonin syndrome risk
  • Uncontrolled hypertension
  • Carcinoid syndrome
  • Phaeochromocytoma
  • Concurrent vasopressor agents (relative)

Side effects

  • Myelosuppression — thrombocytopenia (most important; monitor weekly), anaemia, leucopenia
  • Serotonin syndrome — with serotonergic drugs; potentially fatal
  • Optic neuropathy — prolonged use (>28 days); irreversible if not detected
  • Peripheral neuropathy — prolonged use
  • Lactic acidosis — mitochondrial toxicity with prolonged use
  • GI effects — nausea, diarrhoea

Interactions

  • SSRIs (fluoxetine, sertraline, citalopram) — serotonin syndrome; avoid concurrent use; wash out SSRIs 2 weeks before if possible
  • MAOIs — contraindicated; severe serotonin syndrome
  • Tyramine-rich foods — linezolid is a weak MAO inhibitor; avoid aged cheese, cured meats, Marmite, red wine, tap beer — hypertensive crisis risk
  • Adrenergic agents (dopamine, epinephrine) — enhanced pressor response

Monitoring

  • FBC weekly (especially platelets)
  • Visual acuity and colour vision monthly (>28 days use)
  • Peripheral neurological assessment monthly
  • Serotonin syndrome symptoms
  • Blood pressure

Reference: BNFc; BNF 90; IDSA MRSA Guidelines 2011; NICE Antimicrobial Prescribing Guidelines; MHRA Linezolid Safety Update; SPC Zyvox. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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