Drug Groups

approved; investigational

Description

Linezolid is a synthetic antibiotic, the first of the oxazolidinone class, used for the treatment of infections caused by multi-resistant bacteria including streptococcus and methicillin-resistant Staphylococcus aureus (MRSA). The drug works by inhibiting the initiation of bacterial protein synthesis.

Indication

For the treatment of bacterial infections caused by susceptible strains of vancomycin resistant Enterococcus faecium, Staphylococcal aureus (methicillin resistant and susceptible strains), Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae.

Pharmacology

Linezolid is a synthetic antibacterial agent of a new class of antibiotics, the oxazolidinones, which has clinical utility in the treatment of infections caused by aerobic Gram-positive bacteria. The in vitro spectrum of activity of linezolid also includes certain Gram-negative bacteria and anaerobic bacteria. Susceptible organisms include methicillin- and vancomycin-resistant staphylococci, vancomycin-resistant enterococci, penicillin-resistant pneumococci and anaerobes. Oxazolidinones inhibit protein synthesis by binding at the P site at the ribosomal 50S subunit. Resistance to other protein synthesis inhibitors does not affect oxazolidinone activity, however rare development of oxazolidinone resistance cases, associated with 23S rRNA alterations during treatment have been reported. Linezolid inhibits bacterial protein synthesis through a mechanism of action different from that of other antibacterial agents; therefore, cross-resistance between linezolid and other classes of antibiotics is unlikely.

Toxicity

Clinical signs of acute toxicity lead to decreased activity, ataxia, vomiting and tremors.

Affected Organisms

Biotransformation

Linezolid is primarily metabolized by oxidation of the morpholine ring, which results in two inactive ring-opened carboxylic acid metabolites: the aminoethoxyacetic acid metabolite (A), and the hydroxyethyl glycine metabolite

Absorption

Linezolid is rapidly and extensively absorbed after oral dosing. Maximum plasma concentrations are reached approximately 1 to 2 hours after dosing, and the absolute bioavailability is approximately 100%.

Half Life

4.5-5.5 hours

Protein Binding

31%

Distribution

* 40 to 50 L [healthy adult volunteers]

References

External Links