Increased amikacin dosage requirements in burn patients receiving a once-daily regimen

Altered pharmacokinetics in burn patients may affect antibiotic plasma concentrations. Typical once-daily dosing (ODD) of 15 mg/kg amikacin (AMK) in burn patients does not always produce peak concentrations (Cmax) reaching the therapeutic objective of six to eight times the minimal inhibitory concentration (MIC). We recorded plasma concentrations following administration of 20 mg/kg AMK in burn patients and studied factors affecting pharmacokinetics. Mean Cmax was 48.3 ± 10.8 mg/L and the Cmax/MIC ratio was 6 ± 1.35. Statistical analysis demonstrated a relationship between Cmax and the area of the burn and Unit Burn Standard, and between AMK clearance and creatinine clearance (ClCR). We conclude that ODD regimens of AMK in patients with burns >15% body surface area and/or with ClCR >120 mL/min could require doses >20 mg/kg to reach adequate Cmax. In all cases, patient therapeutic drug monitoring is essential to ensure the safe usage of these dosing recommendations.