Linezolid (Zyvox)

The first example of a new class of antibiotics called the oxazolidinones. It is a reversible, non-selective MAOI. It is highly effective against all Gram + ve organisms including MRSA, penicillin-resistant pneumococci and VRE (vancomycin-resistant enterococci). Emergence of resistance during therapy has been uncommon to date. Linezolid is a useful alternative to the glycopeptides (teicoplanin and vancomycin) in patients with renal impairment as it is not known to be nephrotoxic, and does not require therapeutic dosage monitoring.The oral route (tablets or suspension) has good bioavailability and is therefore given at the same dose as the IV formulation.

Uses
Community-acquired pneumonia
Nosocomial pneumonia (combined with antibiotic active against
Gram ~ ve organisms)
Severe infections due to MRSA
Complicated skin and soft tissue infections
Infections due to VRE
Contraindications
Concurrent use of MAOIs (Types A or B) or within two weeks of taking such drugs

Administration
Recommended duration of treatment is 10–14 consecutive days. Safety and effectiveness of linezolid when administered for periods longer than 28 days have not been established.

Oral: 600 mg 12 hourly
Also available as suspension (100 mg/5 ml) 30 ml 12 hourly
IV: 600 mg (300-ml bag containing 2 mg/ml solution) 12 hourly infused over 30–120 min
Monitor FBC weekly (risk of reversible myelosuppression)

How not to use linezolid
Currently licensed for up to 14 days therapy only (risk of myelosuppression may increase with longer duration)

Adverse effects
Oral and vaginal candidiasis
Diarrhoea
Nausea
Reversible myelosuppression
Headaches

Cautions
Severe renal failure
Unless close BP monitoring possible, avoid in uncontrolled hypertension, phaeochromocytoma, carcinoid tumour, thyrotoxicosis and patients on SSRIs, tricyclic antidepressants, pethidine, buspirone or sympathomimetics or dopaminergic drugs

Organ failure
Renal: no dose adjustment required
Hepatic: no dose adjustment required