Oxazolidinones: a new class of antibacterials.

The oxazolidinones represent the first truly new class of antibacterial agents to reach the marketplace in several decades. They have a unique mechanism of action involving inhibition of the initiation step of protein synthesis and are not cross-resistant to other classes of antibiotics. The first marketed member of that class, linezolid (Zyvox), shows good efficacy with an impressive antibacterial spectrum (including activity against gram-positive organisms resistant to other drugs), and a pharmacodynamic/pharmacokinetic relationship best characterized by time above the minimum inhibitory concentration. The agent is effective by both the intravenous and oral route of administration. Although technically classified as bacteriostatic against a number of pathogens in vitro, linezolid behaves in vivo like a bactericidal antibiotic.