Correlation between Amikacin and Ceftazidime pharmacoknetic parameters

Abstract

Aim: Ceftazidime and amikacin are usually prescribed together for the treatment of suspected or documented gram-negative bacilli infection. Similar physicochemical properties of ceftazidime and amikacin may contribute to good relationship of their pharmacokinetic parameters. This study was conducted to prove this hypothesis and create predictive pharmacokinetic parameter equations for each other. Method: Prospective observative pharmacokinetic study was performed in nineteen patients who received ceftazidime and amikacin as part of therapy at Phramongkutklao Hospital. Two plasma concentrations at steady state of both antibiotics were used for calculating the pharmacokinetic parameters. Regression analysis were performed to determine a correlation and predictive equation between ceftazidime and amikacin pharmacokinetic parameters. Results: Regression analysis showed a significant linear with high correlation between total drug clearance (Cl), elimination rate constant (K[subscript e]) and elimination half life (t[subscript 1/2]) of ceftazidime and amikacin (r = 0.966, 0.942, 0.891 for Cl, K[subscript e] and t[subscript 1/2], respectively). The correlation between clearance of amikacin and ceftazidime was better than the correlation between either drug clearance and creatinine clearance. A fair correlation was found between the volume of distribution (L/kg) of the two drugs (r = 0.671). Conclusion: A high correlation between pharmacokinetic parameters of ceftazidime and amikacin in this study indicated that ceftazidime pharmacokinetic parameters could be accurately predicted from those of amikacin and vice versa. This will help in modification of drug dosage regimen for individual patient in order to maximize therapeutic effect and minimize antimicrobial-resistant bacteria.