Oxazolidinones

Protein Synthesis Inhibitors - Initiation Phase

Linezolid and tedizolid are synthetic broad-spectrum bacteriostatic oxazolidinones against multidrug-resistant Gram-positive pathogens. Its action uniquely blocks the initiation of ribosomal translation.

Mechanism

💊 Generic and Commercial Names

Linezolid (Zyvoxid), Tedizolid Fosfato (Sivextro).

🔬 Pharmacological Group

Oxazolidinonas. Inhibidores bacteriostáticos selectivos de la traducción bacteriana en fase de iniciación.

Mechanism of Action

Su mecanismo selectivo se localiza en la diana del complejo iniciador 70S:

Bloqueo del Complejo de Iniciación 70S: Se unen de forma selectiva al ARN ribosomal 23S de la subunidad dural 50S bacteriana, impidiendo de forma física que se asocie con el ARNm, el ARNt iniciador (fMet-ARNt) y la subunidad ribosomal 30S. De este modo, bloquean de forma temprana la formación del complejo funcional de iniciación de la traducción bacteriana, un paso molecular único que evita la existencia de resistencia cruzada con macrólidos y lincosamidas.
Mayor Potencia de Tedizolid: Tedizolid es un derivado de última generación que posee un anillo lateral adicional de heteroarilo que interactúa con sitios de unión adicionales del ribosoma bacteriano, confiriéndole una potencia in vitro entre 4 y 16 veces superior a la de linezolid y eludiendo de forma eficaz los mecanismos de resistencia mediados por metilación ribosomal bacteriana comunes.

Pharmacokinetics

Key Pharmacokinetics

Parameter	Linezolid	Tedizolid (Phosphate - Prodrug)
Routes of Administration	Oral and IV. Extraordinary oral bioavailability of 100%. Allows direct therapeutic switch without modifying dose.	Oral and IV. It is dosed as a 1-hour infusion. Prodrug rapidly hydrolyzed in plasma by nonspecific phosphatases.
Distribution and Tissues	Moderate to high (0.6 - 0.8 L/kg). Excellent penetration into lung, bone and CSF.	Very high (~1.5 L/kg). Excellent tissue distribution in fatty and bone tissues.
Protein Binding	Low (~31%).	Very high (~85-90%).
Metabolism	Non-enzymatic hepatic through oxidation at the inactive plasma level (60%). No relevant CYP450 inhibitor.	Suffers hepatic metabolism by inactive sulfation. No relevant cytochrome inducer.
Excretion and Half-Life	Mixed glomerular renal excretion. Elimination half-life of 5.0 to 7.0 hours.	Majority fecal and biliary excretion. Prolonged half-life of 12 hours, allowing once-daily dosing.

Antimicrobial Spectrum

High Potency Multidrug-Resistant Gram-Positives: Excellent activity against methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Streptococcus pneumoniae, coagulase-negative staphylococci, and vancomycin-resistant Enterococcus faecium and Enterococcus faecalis (ERV). They lack activity against Gram-negatives.

Indicators and dose

Dosage and Adjustment

Linezolid: 600 mg every 12 hours orally or IV. No adjustment required in moderate renal or hepatic insufficiency.
Tedizolid: 200 mg every 24 hours orally or IV. It does not require adjustment in renal or hepatic failure with a mild to severe clinical course.

Security

Contraindications and ADRs

Contraindications: Patients who consume Monoamine Oxidase Inhibitors (MAOI) or serotonergic type in the 14 days prior to the start of treatment.
Adverse Effects (ADR):
- Reversible Cumulative Myelotoxicity: Linezolid interferes with the synthesis of mitochondrial proteins in eukaryotic cells in treatments longer than 14 days of clinical course, inducing cellular depletion of the bone marrow. It is manifested by isolated severe thrombocytopenia, anemia and reversible leukopenia.
- Optic and Peripheral Neuropathy: Neuropathy with a painful course, predominantly distal, that is associated with treatments of more than 28 days of cumulative duration.
- Hyperlactatemia and Lactic Acidosis: Secondary to mitochondrial toxicity due to uncoupling of the cellular respiratory chain of mitochondrial origin.

Critical Interaction of Linezolid with Serotoninergics

Linezolid is a weak reversible non-selective inhibitor of the enzyme Monoamine oxidase type A (MAO-A). Its coadministration with agents that increase serotonergic or adrenergic transmission (such as SSRIs, SNRIs, Tramadol, tricyclic antidepressants, triptans or sympathomimetics) can precipitate an acute condition of Serotoninergic Syndrome characterized by severe hyperthermia, diaphoresis, muscle clonus, hyperreflexia and dural hemodynamic instability. Tedizolid has a lower MAO inhibition potency, significantly reducing this risk.

Epistemis is educational review material. It is not a medical device, does not diagnose or prescribe treatment, and does not replace formal medical training, current clinical guidelines, or professional clinical judgment.

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System: Antimicrobial and Infectious
Cluster: Protein Synthesis Inhibitors - Initiation Phase

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