Using Monte Carlo simulation to determine optimal dosing regimen for cefetamet sodium for injection

The objective of the study was to use Monte Carlo simulation to determine the optimal treatment dosing regimen of the cefetamet sodium for injection by analysing the pharmacokinetics (PK) parameters in healthy Chinese volunteers, and antibacterial activity in vitro was also examined. A three-cross Latin square single-dose PK study was designed. Twelve healthy volunteers were randomized to receive 500, 1000, and 2000 mg of cefetamet sodium for IV infusion over 30 minutes in three periods sequentially; and the washout time in between periods was 3 days. The drug concentrations in plasma were analysed by high-performance liquid chromatography, and the PK parameters were calculated using DAS2.0 PK software. The peak concentrations (Cmax) at 0.5 hours were 37.78±7.29, 76.18±12.81, and 149.32±29.94 mg/l, the areas under concentration-time curve (AUC0-t) were 69.75±14.44, 139.06±22.62, and 278.54±53.12 mg h/l, and the elimination half-life (t1/2) were 1.69±0.19, 1.69±0.27, and 1.81±0.23 hours for 500, 1000, and 2000 mg of cefetamet sodium for injection, respectively. The disposition of cefetamet was appear to fit a two-compartment model with linear kinetics. Antibacterial activity in vitro showed that most Gram-negative bacteria, including non-extended-spectrum beta-lactamases (ESBL)-producing Enterobacter, Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae, were sensitive to cefetamet. The result of Monte Carlo simulation showed that the probability of target attainment for bactericidal response (%fT>MIC≧50%) for susceptible bacteria was reached at all three dosing regimens of 500 mg, q6h, 1000 and 2000 mg, q8h and q6h. Considering the efficacy, safety, and pharmacoeconomy comprehensively, we recommended the dosing regimen of 500 mg, q6h for further clinical treatment based on the principle of minimum daily dosage.