Material and Method: Pharmacokinetic parameters of vancomycin in 12 septic shock patients were assessed. Then, the Monte Carlo simulation was performed to calculate the probabilities of target attainment (PTAs) to reach target AUC0-24/MIC of 400 and 450 mg•h/L.

Results: The total clearance (CL) and the volume of the central compartment (Vc) of vancomycin was 3.34±1.39 L/h and 0.14±1.43 L/kg, respectively. For Staphylococcal spp. with low MICs of 0.125 and 0.5 mg/L, the administration of vancomycin 30 mg/kg as the loading dose, followed by the maintenance dose of 20 mg/kg every six, eight, 12, and 24 hours achieved >90% PTAs to reach target AUC0-24/MIC. For pathogens with MIC of 1, and 1.5 mg/L, the vancomycin maintenance dose of 20 mg/kg every six, eight, and 12 hours and every six and eight hours respectively to achieve >90% PTA.

Conclusion: High dose of vancomycin is required to achieve PK/PD target for treatment of MRSA septic shock, especially if MRSA MIC is higher than 1 mg/L.

Keywords: Monte Carlo simulation, Vancomycin, septic shock, Pharmacokinetics/pharmacodynamics, Loading dose