Linezolid

# Linezolid ## Overview - **Classification**: Oxazolidinone antibiotic - **Mechanism**: Inhibits bacterial protein synthesis by binding to the 23S ribosomal RNA of the 50S ribosomal subunit, preventing the formation of the 70S initiation complex. ## Primary Indications 1. **Vancomycin-resistant *Enterococcus faecium* (VRE) infections** - including bacteremia. 2. **Nosocomial pneumonia (NP)** - caused by *Staphylococcus aureus* (methicillin-sensitive & -resistant strains). 3. **Complicated skin and skin structure infections (cSSSI)** - caused by susceptible gram-positive bacteria. 4. **Community-acquired pneumonia (CAP)** - caused by *Streptococcus pneumoniae* or methicillin-sensitive *Staphylococcus aureus*. ## Adult Dosing ### Standard Dosing **VRE Infections, Nosocomial Pneumonia, Complicated Skin and Skin Structure Infections** - **Dose**: **600 mg** - **Frequency**: Every 12 hours (q12h) - **Route**: Oral (PO) or Intravenous (IV) - **Duration**: 10 to 28 consecutive days **Community-Acquired Pneumonia** - **Dose**: **600 mg** - **Frequency**: Every 12 hours (q12h) - **Route**: PO or IV - **Duration**: 10 to 14 consecutive days ### Dose Adjustments - **Renal Impairment**: No dose adjustment required. Administer after hemodialysis. - **Hepatic Impairment**: No dose adjustment required. - **Elderly Patients**: No dose adjustment required. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: **10 mg/kg/dose** - **Frequency**: Every 12 hours (q12h) - **Maximum**: Do not exceed **600 mg/dose**. - **Special Notes**: Consider q8h dosing in neonates > 7 days old with suboptimal response due to increased clearance. IV or PO. ### Infants (1-12 months) - **Dose**: **10 mg/kg/dose** - **Frequency**: Every 8 hours (q8h) - **Maximum**: Do not exceed **600 mg/dose**. - **Special Notes**: IV or PO. ### Children (1-12 years) - **Dose**: **10 mg/kg/dose** - **Frequency**: Every 8 hours (q8h) - **Maximum**: **600 mg/dose** (do not exceed adult single dose). - **Special Notes**: IV or PO. ### Adolescents (13-18 years) - **Dose**: **600 mg** - **Frequency**: Every 12 hours (q12h) - **Maximum**: **600 mg/dose** (standard adult dosing). - **Special Notes**: IV or PO. ## Safety Information ### Contraindications - **Absolute**: Concomitant use of MAO inhibitors (e.g., phenelzine, selegiline) or within 2 weeks of MAOI use. - **Absolute**: Hypersensitivity to linezolid or any component. - **Relative**: Caution with serotonergic drugs (SSRIs, SNRIs, TCAs, meperidine) due to serotonin syndrome risk. - **Relative**: Caution with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis, or carcinoid syndrome. ### Common Adverse Effects - **Very Common (>10%)**: Headache, nausea, diarrhea. - **Common (1-10%)**: Vomiting, constipation, taste perversion, dizziness, insomnia, anemia, thrombocytopenia, elevated LFTs. - **Serious but Rare**: Serotonin syndrome, optic neuropathy, peripheral neuropathy, myelosuppression (anemia, leukopenia, pancytopenia), lactic acidosis, *Clostridioides difficile*-associated diarrhea (CDAD). ### Key Drug Interactions - **MAO Inhibitors**: Risk of severe hypertension and serotonin syndrome. **Absolutely contraindicated**. - **Serotonergic Drugs (e.g., SSRIs, TCAs, meperidine, tramadol)**: Increased risk of serotonin syndrome. Avoid if possible; monitor closely if combined. - **Adrenergic Drugs (e.g., pseudoephedrine, vasopressors, dopamine)**: Potentiates vasopressor effect, increasing blood pressure. Monitor BP closely. - **Tyramine-rich Foods**: May cause hypertensive crisis. Counsel patients to limit intake. ## Monitoring & Follow-up - **Before Treatment**: Complete blood count (CBC) with platelet count. Baseline visual acuity if prolonged treatment expected. - **During Treatment**: CBC with platelet count **weekly** (especially if >2 weeks therapy or pre-existing myelosuppression). - **During Treatment**: Monitor for signs/symptoms of serotonin syndrome, lactic acidosis, and visual changes. - **Clinical Signs**: Watch for vision changes, numbness/tingling, severe headache, confusion, fever, rash, unexplained bleeding/bruising. ## Clinical Pearls - 💡 **Tip 1**: Administer IV infusions over 30 to 120 minutes. Do not mix with other IV medications. - 💡 **Tip 2**: Myelosuppression and neuropathy (optic, peripheral) risks increase with treatment durations exceeding **2 weeks**. - 💡 **Tip 3**: Counsel patients to avoid large quantities of tyramine-containing foods (e.g., aged cheeses, fermented meats, tap beers) to prevent hypertensive reactions. - 💡 **Tip 4**: Linezolid is bacteriostatic against staphylococci and enterococci, but bactericidal against most streptococci. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.