Linezolid Hikma Farmacêutica (Portugal) (Linezolid)

Linezolid is indicated for bacterial infections affecting the skin, respiratory tract and resistant Gram‑positive organisms.

• Skin and soft tissue infections: effective against susceptible Staphylococcus aureus and Streptococcus species, reducing lesion size and bacterial load.
• Community‑acquired pneumonia: provides coverage for typical and atypical pathogens, improving clinical outcomes in adult patients.
• Hospital‑acquired (nosocomial) pneumonia: active against resistant strains, including MRSA, facilitating recovery in intensive care settings.
• Methicillin‑resistant Staphylococcus aureus (MRSA) infections: achieves bacterial eradication in skin and systemic MRSA infections.

• Linezolid inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. This binding prevents formation of the initiation complex, blocking the translation of essential proteins and halting bacterial growth. The action is bacteriostatic against most susceptible organisms and bactericidal at higher concentrations. It does not affect human mitochondrial ribosomes at therapeutic levels, contributing to its selective toxicity profile in clinical use.

Linezolid may be associated with a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea: mild gastrointestinal upset occurring in many patients.
• Diarrhea: loose stools that may be self‑limiting.
• Headache: transient cranial discomfort reported during therapy.

Serious or Rare Side Effects

• Thrombocytopenia: significant reduction in platelet count requiring monitoring.
• Peripheral or optic neuropathy: sensory changes or visual disturbances that may be irreversible.
• Lactic acidosis: metabolic disturbance presenting with hyperventilation and abdominal pain.
• Serotonin syndrome: risk when combined with serotonergic agents, characterized by agitation, hyperreflexia and fever.

Before initiating Linezolid therapy, clinicians should consider several safety precautions to minimize risks.

• Monitor blood counts: regular CBC testing to detect thrombocytopenia or anemia.
• Assess renal function: adjust therapy in patients with severe impairment.
• Evaluate hepatic status: caution in liver disease due to metabolism considerations.
• Avoid serotonergic drugs: concurrent MAO inhibitors or SSRIs increase serotonin syndrome risk.
• Use with caution in pregnancy: category B indicates no proven risk, but benefits must outweigh potential.
• Store at below 25°C: keep in original packaging, protect from moisture and light.

Linezolid interacts with several medicines, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): may precipitate severe serotonin syndrome.
• Selective serotonin reuptake inhibitors (SSRIs) and other serotonergic agents: increase risk of serotonin syndrome.

Moderate Interactions (Monitor Closely)

• Rifampin: induces hepatic enzymes, lowering linezolid plasma concentrations.
• Anticonvulsants such as phenytoin or carbamazepine: may reduce linezolid levels.
• Warfarin: linezolid can enhance anticoagulant effect, necessitating INR monitoring.