Joumana Kmeid, Zeina A Kanafani

The emergence of resistance to glycopeptide antibiotics such as vancomycin and teicoplanin among Gram-positive bacteria has spurred the search for second-generation drugs of this class. Oritavancin, a promising novel, second-generation, semisynthetic lipoglycopeptide, is distinguished by two mechanisms of action: inhibition of cell wall synthesis and disruption of the cell membrane. This dual mechanism of action has increased the activity of oritavancin against vancomycin-resistant Gram-positive bacteria compared to other glycopeptides. Oritavancin has a concentration-dependent and rapid bactericidal activity against Gram-positive bacteria, particularly enterococci, contrary to vancomycin and teicoplanin, which exhibit bacteriostatic activity. It has a long half-life of about 195.4 hours and is slowly eliminated by the liver and kidneys, allowing once-daily dosing. Oritavancin has demonstrated preliminary safety and efficacy in Phase I and Phase II clinical trials. It was recently shown to be noninferior to vancomycin in a large Phase III randomized, double-blind clinical trial. To date, adverse events have been mild and limited, the most common being administration site complaints, headache, and nausea. Oritavancin appears to be a promising antimicrobial alternative to vancomycin with additional activity against Staphylococcus and Enterococcus isolates resistant to vancomycin and a more convenient way of administration.