Linezolid

Linezolid is a synthetic oxazolidinone antibacterial.  It is identified by CAS 165800-03-3 and has the molecular formula C16H20FN3O4. The Linezolid molecular weight is 337.35 g/mol.

Unlike beta-lactams or glycopeptides, linezolid targets bacterial protein synthesis. Its distinct mechanism supports research on susceptible and resistant Gram-positive organisms, while the defined stereochemistry helps confirm compound identity.

Application of Linezolid

Linezolid is used in antibacterial screening, minimum inhibitory concentration (MIC) assays, resistance studies, and analytical method development. As a well-characterized oxazolidinone, it also provides a comparator for evaluating new agents against clinically relevant Gram-positive bacteria.

Research applications include studies of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, streptococci, and selected mycobacteria. Linezolid is not indicated for Gram-negative infections, so organism selection and susceptibility controls are essential when planning experiments.

In Vitro

The Linezolid structure supports antibacterial activity primarily against Gram-positive organisms. In vitro data demonstrate activity against susceptible isolates of Staphylococcus aureus, Enterococcus faecium, Streptococcus pneumoniae, S. pyogenes, and S. agalactiae. Linezolid is generally bacteriostatic against staphylococci and enterococci but bactericidal against most streptococcal isolates. Susceptibility should still be determined for each tested strain.

In Vivo

Clinical pharmacokinetic data for Pfizer Linezolid show approximately 100% absolute oral bioavailability, with comparable systemic exposure after oral and intravenous administration. Myelosuppression has been reported during treatment, while peripheral and optic neuropathies have been reported primarily with treatment durations longer than 28 days. These effects should be considered when interpreting repeat-dose studies.

Biochemical and Physiological Actions

The Linezolid molecular structure enables binding within the peptidyl transferase center of the bacterial 50S ribosomal subunit, where it interacts with 23S rRNA. This prevents formation of a functional 70S initiation complex and blocks protein synthesis before peptide-chain elongation. Its binding mode differs from those of other major antibacterial classes, although resistance may still develop through 23S rRNA mutations, ribosomal protein changes, or transferable determinants.

Linezolid also acts as a weak, reversible, nonselective monoamine oxidase inhibitor. This off-target effect is relevant when studying interactions with serotonergic or adrenergic compounds.

Features and Benefits of Linezolid

• Defined Linezolid chemical structure and (S)-configuration for compound identification.
• Pfizer reference identifier PF-00184033 for study documentation.
• Activity against multiple clinically relevant Gram-positive organisms.
• Oral and intravenous pharmacokinetics characterized in humans.
• Established use as an assay control and comparator in antibacterial research.