EpistemisOxazolidinones
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 NamesLinezolid (Zyvoxid), tedizolid phosphate (Sivextro).
🔬 Pharmacological GroupOxazolidinones. Selective bacteriostatic inhibitors of bacterial translation at the initiation phase.
Mechanism of Action
Its selective mechanism targets the 70S initiation complex:
- Blockade of the 70S Initiation Complex: They selectively bind to the 23S ribosomal RNA of the bacterial 50S subunit, physically preventing it from associating with the mRNA, the initiator tRNA (fMet-tRNA), and the 30S ribosomal subunit. In this way, they early block the formation of the functional bacterial translation initiation complex, a unique molecular step that prevents the existence of cross-resistance with macrolides and lincosamides.
- Greater Potency of Tedizolid: Tedizolid is a next-generation derivative that possesses an additional lateral heteroaryl ring that interacts with additional binding sites on the bacterial ribosome, giving it 4- to 16-fold greater in vitro potency than linezolid and effectively circumventing common bacterial ribosomal methylation-mediated resistance mechanisms.
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 impairment.
- 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.
- System
- Antimicrobial and Infectious
- Group
- Protein Synthesis Inhibitors - Initiation Phase