ABSTRACT
The objectives of this study were to: [1] derive equations for estimating gentamicin clearance [Clgent] and volume of distribution [Vd] based on the local population attending Al-Amiri Hospital, Kuwait; [2] independently evaluate these equations by comparison with other published methods in their predictive ability to estimate Clgent and Vd. Clgent and Vd were calculated in 47 patients [group 1] using the Sawchuk-Zaske method. Regression analysis was used to derive a correlation between creatinine clearance [Clcr] and Clgent, Vd and actual body weight [ABW]. Based on actual Clgent and Vd values, the predictive ability of the estimated parameters from the regression equations was validated and compared with 4 published methods using mean error [ME], i.e. bias, and mean squared error [MSE] and root mean squared error [RMSE], i.e. precision. All equations were also evaluated in an independent second group [group 2] of 23 patients. The mean +/- SD values of Clgent and Vd were 4.0 +/- 1.8 lúh-1 and 16.8 +/- 6.7 liters, respectively. The derived equations were: Clgent = [0.760] [Clcr] + 1.117 [r = 0.701] and Vd = [0.165] [ABW] + 5.604 [r = 0.532]. In comparison to the 4 published methods, the derived equations were less biased [ME = 0.00] and more precise [MSE = 1.68, RMSE = 1.02] in predicting Clgent [p < 0.05], and less biased [ME = -0.01] with no difference in precision [MSE = 36.22, RMSE = 4.59] in predicting Vd [p > 0.05]. This precision was confirmed in the second group of 23 patients, where the derived equations were less biased [ME = -0.1] and more precise [MSE = 3.22, RMSE = 1.48] in predicting Clgent [p < 0.05], whilst no difference was found for prediction of Vd [p > 0.05]. The equations developed in this study provided a reliable estimation of Clgent and Vd. It is planned to use them at Kuwait Hospitals to help provide more individualized patient dosing information to physicians