Pharmacokinetics of amdinocillin in healthy adults

The pharmacokinetics of amdinocillin (mecillinam) were determined in 10 healthy volunteers. Single doses of 10 and 15 mg/kg of body weight were administered intravenously and intramuscularly in a crossover study. Plasma concentrations of amdinocillin were determined by microbiological assay. Mean peak plasma concentrations were 49 and 87 micrograms/ml after intravenous doses of 10 and 15 mg/kg, respectively. The terminal half-life value of 0.89 h was similar for both doses. After intramuscular injections, the mean concentration of drug in plasma was 26.2 micrograms/ml for the 10-mg/kg dose and 29.6 micrograms/ml for the 15-mg/kg dose, with terminal half-lives of 0.96 and 0.86 h, respectively. The mean apparent volumes of distribution at steady state were 18 and 16 liters/100 kg for the intravenous doses of 10 and 15 mg/kg, respectively. Drug concentrations in plasma at 4 h were above the minimal inhibitory concentrations for gram-negative organisms categorized as susceptible to this drug.