Linezolid: The First Oxazolidinone Antimicrobial

Linezolid is the first of a new class of antimicrobial agents, the oxazolidinones, to be approved for clinical use in the United States and elsewhere. The drug is a totally synthetic compound, which lessens the likelihood of naturally occurring resistance mechanisms. It has excellent activity against virtually all important gram-positive pathogens, including methicillin-resistant staphylococci, penicillin-resistant pneumococci, macrolide-resistant streptococci, and vancomycin-resistant enterococci. Development of resistance to the compound has been infrequent thus far. Linezolid is 100% bioavailable, so it can be given in equal doses orally or parenterally. Its elimination half-life allows dosing twice per day, and alteration of drug dosage is not required in patients with impaired renal or hepatic function. Linezolid has approved indications for skin and soft tissue infections; lower respiratory tract infections; and vancomycin-resistant Enterococcus faecium infections, including cases with concurrent bacteremia. The drug has an acceptable profile of adverse events, but reversible myelosuppression has occurred in patients receiving high doses for more than 2 weeks.