Multicenter, Randomized Study of the Efficacy and Safety of Intravenous Iclaprim in Complicated Skin and Skin Structure Infections

Iclaprim is a novel antibacterial agent that is currently in development for the treatment of complicated skin and skin structure infections (cSSSI). Iclaprim specifically and selectively inhibits bacterial dihydrofolate reductase, a critical enzyme in the bacterial folate pathway, and exhibits an extended spectrum of activity against various resistant pathogens, including methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). The objective of this randomized, double-blind phase II study was to compare the efficacy and safety of iclaprim to those of vancomycin in patients with cSSSI. Patients were randomized to receive 0.8 mg iclaprim/kg of body weight, 1.6 mg/kg iclaprim, or 1 g vancomycin twice a day for 10 days. Clinical cure rates for the 0.8- and 1.6-mg/kg-iclaprim treatment groups were comparable to that for the vancomycin treatment group (26/28 patients [92.9%], 28/31 patients [90.3%], and 26/28 patients [92.9%], respectively). Iclaprim also showed high microbiological eradication rates. Iclaprim exhibited an eradication rate of 80% and 72% versus 59% observed with vancomycin for S. aureus, the pathogen most frequently isolated at baseline. Five MRSA cases were observed, four in the 0.8-mg/kg-iclaprim arm and one in the vancomycin arm, and all were both clinically and microbiologically cured. Iclaprim exhibited a safety profile similar to that of vancomycin, an established drug for the treatment of cSSSI. Results from this study indicate that iclaprim is a promising new therapy for the treatment of cSSSI, in particular those caused by S. aureus, including MRSA.