Linezolid: an oxazolidinone antimicrobial agent.

The pharmacology, antimicrobial activity, pharmacokinetics, clinical efficacy, and adverse effects of linezolid are reviewed. Linezolid, the only oxazolidinone antimicrobial approved for use in the United States, has significant activity against gram-positive bacteria, including penicillin-, cephalosporin-, and vancomycin-resistant species. Linezolid inhibits bacterial protein synthesis via binding to the 50S ribosomal subunit to prevent translation. The drug lacks cross-resistance with other antimicrobials. Linezolid is primarily excreted renally as unchanged drug. The measured plasma half-life of four to five hours permits twice-daily administration for all indicated infections. Virtually complete oral bioavailability allows for 1:1 conversion between the intravenous and oral dosage forms. Controlled comparative clinical trials demonstrate that linezolid is effective in the treatment of vancomycin-resistant Enterococcus faecium and methicillin-resistant Staphylococcus aureus (MRSA) infections, nosocomial and community-acquired pneumonia, and skin and skin-structure infections due to susceptible organisms. The recommended dosage is 600 mg i.v. or p.o. twice daily for all indications except uncomplicated skin and skin-structure infections (400 mg twice daily); adjustments for mild to moderate renal or hepatic impairment are not necessary. Clinically important interactions with monoamine oxidase inhibitors have not been observed. Reversible myelosuppression has been observed in a few patients. Linezolid has gram-positive activity comparable to that of vancomycin, is effective in a variety of infections, and is well tolerated, with diarrhea, headache, and nausea being the most frequently reported adverse effects. Linezolid provides a reasonable therapeutic alternative for patients with vancomycin-resistant E. faecium infections and patients infected with MRSA who cannot tolerate vancomycin.