FIGURE 2. In vitro and in vivo properties of plectasin.

a, Kinetics of bacterial killing in vitro. S. pneumoniae serotypes 2 (D39), 3 (68034) and 6A (6A) were incubated in the presence of medium alone (Med.), or in the presence of either plectasin (Plec.) at 1 , 5 or 10 MIC, vancomycin (Vanc.) at 1 and 10 MIC, or penicillin (Pen.) at 1 and 8 MIC at 35 °C. Data are shown for strain D39 only. Concentrations of viable bacteria were measured as described in the Methods and Supplementary Methods sections, and the colony counts are shown as the mean and range. CFU, colony-forming units. b, The pharmacokinetic behaviour of plectasin in vivo was investigated in mice after a single dose of 14 mg per kg, using two mice at each time point. The serum concentrations were determined for intravenous, subcutaneous and intraperitoneal administration, respectively, at the time points indicated. The maximum observed mean concentrations for intravenous, subcutaneous and intraperitoneal dosing were 95 mg l^-1 after 5 min, and 55 mg l^-1 and 34 mg l^-1 after 30 min, respectively. The terminal half-life was estimated to 49–54 min and the concentration–time data following intravenous bolus administration showed two-compartment behaviour.