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Drug Reference

linezolid

oxazolidinone antibiotic· Brands: Zyvox, Linizol, Linospan, ZyvoxidIVPO

Mechanism of action
Linezolid inhibits bacterial protein synthesis by binding to the 23S rRNA of the 50S ribosomal subunit, preventing the formation of the 70S initiation complex. This action is bacteriostatic against most Gram-positive organisms, including staphylococci, streptococci, and enterococci, but may be bactericidal against some strains. It also suppresses bacterial toxin production and has activity against organisms resistant to other antibiotics.
Pharmacokinetics
It is metabolised by hepatic oxidation of the morpholine ring, which is not mediated by cytochrome P450 enzymes, to two inactive metabolites, and is excreted primarily in the urine as unchanged drug and metabolites.
Indications & dosing

Complicated skin and soft tissue infections (cSSTI), including diabetic foot infections

For suspected or confirmed MRSA. Continue for 7-14 days.

  • adult · IV,PO: 600 mg q12h · For suspected or confirmed MRSA. Continue for 7-14 days.

Community-acquired pneumonia (CAP)

For suspected or confirmed MRSA. Duration 10-14 days.

  • adult · IV,PO: 600 mg q12h · For suspected or confirmed MRSA. Duration 10-14 days.

Hospital-acquired pneumonia (HAP)

For suspected or confirmed MRSA. Duration 7-14 days.

  • adult · IV,PO: 600 mg q12h · For suspected or confirmed MRSA. Duration 7-14 days.

Vancomycin-resistant Enterococcus faecium (VRE) infections

Duration 14-28 days depending on site.

  • adult · IV,PO: 600 mg q12h · Duration 14-28 days depending on site.

Methicillin-resistant Staphylococcus aureus (MRSA) infectionsoff-label

Used for various MRSA infections, e.g. osteomyelitis, endocarditis. Seek specialist advice.

  • adult · IV,PO: 600 mg q12h · Used for various MRSA infections, e.g. osteomyelitis, endocarditis. Seek specialist advice.
Contraindications & precautions
  • Known hypersensitivity to linezolid or any component of the formulation · Avoid in patients with a history of immediate or severe reactions. Cross-reactivity with other oxazolidinones is possible.
  • Concomitant use of MAO inhibitors (within 14 days) · Increased risk of hypertensive crisis or serotonin syndrome. Wait at least 14 days after stopping MAOIs.
  • Concomitant use of serotonergic agents (e.g., SSRIs, SNRIs, tricyclic antidepressants, triptans) · Risk of serotonin syndrome. Use only if urgent and monitor closely; consider alternative therapy.
  • Uncontrolled hypertension, thyrotoxicosis, or pheochromocytoma · Linezolid has MAOI activity and can cause hypertensive episodes; use with caution.
  • Monitor full blood count (FBC) weekly, especially in patients receiving linezolid for more than 14 days, as myelosuppression (thrombocytopenia, anaemia, leukopenia) can occur.
  • Watch for signs of serotonin syndrome (e.g., agitation, confusion, myoclonus, hyperreflexia) in patients receiving serotonergic drugs concurrently; consider alternative agents or dose adjustment.
  • Advise patients to avoid tyramine-rich foods (e.g., aged cheese, cured meats, fermented foods) to prevent hypertensive crisis.
  • Use with caution in patients with uncontrolled hypertension, thyrotoxicosis, or pheochromocytoma due to the MAOI action.
  • Monitor for peripheral or optic neuropathy (visual acuity, colour perception) if treatment exceeds 28 days; discontinue if symptoms develop.
  • Linezolid is a weak MAOI; avoid concurrent co-administration with MAOIs and wait at least 14 days after stopping them.
Adverse effects
  • Nausea
  • Diarrhoea
  • Headache
  • Thrombocytopeniaserious
  • Anaemiaserious
  • Peripheral neuropathy (sensory or motor)serious
  • Optic neuropathy (visual impairment)serious
  • Serotonin syndromeserious
  • Lactic acidosisserious
Interactions
  • sertralinecontraindicatedDo not co-prescribe linezolid and sertraline. If linezolid is essential, withhold sertraline for at least 5 half-lives before starting linezolid, and resume at least 24 hours after the last dose of linezolid (or longer for long-acting formulations). If urgent concomitant use is unavoidable, closely monitor for signs of serotonin syndrome and consider alternative antibiotics when clinically feasible.
  • fluoxetinecontraindicatedAvoid concomitant use. If linezolid is essential for a severe infection, stop fluoxetine and allow a washout period of at least 5 to 6 weeks due to its long half-life and active metabolite. If urgent co-administration is unavoidable, monitor closely in a hospital setting for signs of serotonin syndrome and be prepared for supportive care including benzodiazepines, active cooling and discontinuation of both agents. Consult current formularies and specialist guidance.
  • escitalopramcontraindicatedConcomitant use is contraindicated. If linezolid is essential, discontinue escitalopram at least 5 half-lives (approximately 1 week) before starting linezolid. After stopping linezolid, wait at least 1 week (or the product label's advised interval) before resuming escitalopram. Monitor for symptoms of serotonin syndrome if the interaction is unavoidable. Consider alternative antibiotics or alternative antidepressants with no serotonergic activity.
  • tramadolmajorAvoid co-prescription. If co-administration is considered essential, use the lowest possible doses and monitor frequently for early signs of serotonin syndrome. Consider alternative analgesic agents with no serotonergic activity. If serotonin syndrome is suspected, stop both drugs immediately and provide supportive care.
Renal & hepatic adjustment
  • eGFR 0+: No dose adjustment required in renal impairment. For patients on haemodialysis, administer linezolid after the dialysis session.
  • Hepatic impairment (mild): No dose adjustment required.
  • Hepatic impairment (moderate): No dose adjustment required.
  • Hepatic impairment (severe): No dose adjustment required. Use with caution due to limited data.
Monitoring, pregnancy & toxicity
  • Full blood count with differential (including platelets) · Baseline and weekly if therapy exceeds 10 days, in haematologically at-risk patients, or when signs of myelosuppression occur.
  • Blood pressure · Regularly during treatment, especially in patients with hypertension or receiving pressor agents.
  • Visual function (visual acuity, colour vision, visual fields) · At baseline and if prolonged therapy (>28 days) or if visual symptoms develop.
  • Signs and symptoms of serotonin syndrome · Monitor when linezolid is used with serotonergic agents or in patients with signs of toxicity.
  • Serum lactate or acid-base status · If lactic acidosis is suspected.
  • Pregnancy: Linezolid should be used in pregnancy only if the potential benefit outweighs the risk. Limited data are available; alternative antimicrobials with more established safety should be considered if appropriate.
  • Toxicity: Myelosuppression (thrombocytopenia, anaemia, leukopenia) · Monitor full blood count frequently; discontinue linezolid if counts fall significantly. Supportive care, including transfusion if severe.
  • Toxicity: Serotonin syndrome · Discontinue linezolid and the offending serotonergic agent. Provide supportive care, including cooling and benzodiazepines for agitation. Severe cases may require cyproheptadine.
  • Toxicity: Peripheral and optic neuropathy · Assess visual and neurological symptoms, especially with prolonged therapy. Discontinue linezolid if neuropathy develops. Symptoms may be reversible on discontinuation.
  • Toxicity: Lactic acidosis · Discontinue linezolid and provide supportive care; correct acidosis with sodium bicarbonate if severe. Monitor serial lactate.
Clinical notes
Linezolid is reserved for the treatment of serious infections caused by resistant Gram-positive bacteria, including MRSA, vancomycin-resistant enterococci (VRE), and penicillin-resistant pneumococci. It is also used in skin and soft tissue infections, pneumonia, and osteomyelitis. Monitor blood counts weekly, as prolonged use is associated with thrombocytopenia, anaemia, and leucopenia. Linezolid is a weak monoamine oxidase inhibitor, so avoid concurrent use with serotonergic agents, such as SSRIs and MAOIs, to prevent serotonin syndrome. It is also contraindicated in patients with pheochromocytoma, carcinoid syndrome, and uncontrolled hypertension.

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BNF; local formulary