Factors affecting gentamicin pharmacokinetics in septic patients

Background: This prospective, comparative study was designed to estimate th e volume of distribution (V-d) and elimination rate constant (K-e) of genta micin and to determine the clinical factors affecting the pharmacokinetics of gentamicin in different stages of sepsis. Method: Seventy-seven critically ill patients treated with gentamicin for g ram-negative sepsis were included. These septic patients were divided into hyperdynamic septic and hypodynamic septic groups according to cardiac inde x. Twenty-seven patients who received postoperative prophylactic gentamicin were recruited as controls. Results: Fifty-two patients in the hyperdynamic septic group had a signific antly larger V-d than those in the hypodynamic septic and control groups. T he V-d was correlated significantly with both Acute Physiological Score (AP S) (r=0.340, P<0.01) and cardiac index (r=0.393, P<0.01). The K-e of gentam icin correlated significantly with both blood urea nitrogen (BUN) (r= 0.565 , P<0.01) and serum creatinine level (r=0.563, P<0.01). Conclusion: The increased V-d in the septic patients was related to the sev erity of illness and magnitude of cardiac output. The K-e of gentamicin was correlated with the serum creatinine level.