Pharmacokinetic analysis investigating gentamicin dosing in a major burned patient complicated by septic shock

Profound pharmacokinetic alterations involving volume of distribution and clearance may impair the achievement of adequate antimicrobial serum concentrations in major burn patients. Gentamicin pharmacokinetic analysis was performed in a major burn victim with 90% of total body surface area affected and complicated by septic shock due to Serratia marcescens (minimum inhibitory concentration [MIC] = 2 mg/L). Gentamicin 240 mg was administered as a 30-min intravenous infusion, and plasma samples were obtained at 0-, 0.5-, 1-, 3- and 6-hour time points after the start of infusion. Gentamicin peak concentrations (C_MAX) were 11.9 mg/L, providing for the achievement of an inadequate C_MAX/MIC target. Volume of distribution was more than double as compared to healthy volunteers (0.44 vs. 0.18 L/Kg), while clearance was quite similar (5.21 vs. 5.42 L/h). Higher dosage (7-10 mg/Kg) coupled with adaptive therapeutic drug monitoring should be implemented in order to maximize gentamicin dosing schedule in critical challenging situations.