Linezolid
Linezolid is an oxazolidinone antibacterial with activity directed mainly against susceptible gram-positive organisms. Veterinary use is uncommon and extra-label, principally involving serious infections with resistant staphylococci, enterococci or selected Nocardia species. Its distinct ribosomal binding mechanism supports activity against some organisms resistant to other antibacterial classes.
Group
Oxazolidinone antibacterial
Mechanism of Action
Linezolid binds the 23S ribosomal RNA component of the bacterial 50S subunit and interferes with formation of a functional translation-initiation complex. Blocking this early step prevents new protein synthesis and suppresses bacterial growth. Activity is usually bacteriostatic against staphylococci and enterococci. Organism-specific susceptibility determines whether resistant gram-positive isolates or Nocardia species remain treatable.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Resistant gram-positive infection | 10 mg/kg | PO, IV | Every 12 h |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Resistant gram-positive infection | 10 mg/kg | PO, IV | Every 12 h |
Indications
- Specialist treatment of serious linezolid-susceptible methicillin-resistant staphylococcal infections in companion animals.
- Treatment of selected serious infections caused by susceptible resistant Enterococcus species.
- Treatment of selected susceptible Nocardia infections within a specialist antimicrobial plan; veterinary clinical evidence is limited.
Contraindications
- Do not use empirically for gram-negative infection.
- Avoid food-animal use.
Interactions
- MAO inhibition can interact with SSRIs, selegiline and adrenergic agents, including phenylpropanolamine.
- Rifampin may lower linezolid exposure.
- Flush IV lines between incompatible drugs.
Adverse effects
- Nausea and diarrhoea
- Thrombocytopenia, anaemia or leukopenia, especially with prolonged treatment
Toxicity
Stop treatment if significant cytopenia or serotonin toxicity develops and provide syndrome-directed care.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Linezolid 600 mg tablet | Tablet | 600 mg / tablet | PO |
| Linezolid 20 mg/mL reconstituted oral suspension | Oral Liquid | 20 mg / mL | PO |
| Linezolid 2 mg/mL injection | Injection | 2 mg / mL | IV |
Monitoring and Administration
Confirm susceptibility before use. Monitor CBC periodically, particularly beyond 2 weeks.
Do not mix IV formulation with other medicines. Reconstituted oral suspension is described as stable for 21 days at room temperature.