Population Pharmacokinetics of Gentamicin in Mexican Children With Severe Malnutrition.

BACKGROUND: To develop a population pharmacokinetic model of gentamicin in children with complicated severe malnutrition and to study the influence of covariates (weight and age) on pharmacokinetic indices. In addition, we use the model to perform Monte Carlo simulations to explore the efficacy of several dosage regimens. METHODS: Twenty-six children with severe complicated malnutrition were studied. Ninety-six samples of gentamicin plasma concentrations, obtained from 0.5 to 8 hours after intravenous dosing, were analyzed. Population pharmacokinetic models were built using the program Monolix 4.2 (Lixoft, Antony, France). Monte Carlo simulations were performed to evaluate optimal dosage regimens, using the final pharmacokinetic model, based on the probability of pharmacokinetic-pharmacodynamic target attainment. RESULTS: The concentration-time data were fitted best to 1-compartment model. The estimated population clearance was 1.1 L/h, and the volume of distribution was 2.23 L, with an interindividual variability of 47.2% and 35.6%, respectively. The final models for the clearance and volume of distribution were as follows: CL (L/h) = CL = 1.15 (age/median age) and V (L) = 2.33 (weight/median weight). In Monte Carlo simulations, gentamicin given in dosages of 7.5 to 15 mg/kg optical density was effective in achieving the pharmacodynamic target Cmax:minimal inhibitory concentration >10 for minimal inhibitory concentrations ≤2.5 mg/L, with a probability lower than 1% for Cmin >1 mg/L. CONCLUSIONS: Based on the available evidence, an intravenous dose of 7.5 to 15 mg/kg once daily in children with complicated severe malnutrition and normal renal function ensures high probability of efficacy and low risk of nephrotoxicity, which gives further support to the recommendations issued by the World Health Organization treatment for this patient population.

Effect of severity disease on the pharmacokinetics of cefuroxime in children with multiple organ system failure.

The aim of the present study was to investigate if the severity of illness affected the pharmacokinetics of cefuroxime in 11 children diagnosed with multiple organ system failure. The patients were assigned to a severely ill group (group 1), a very severely ill group (group 2), or a control group (group 0). Blood samples were taken and cefuroxime concentrations were measured in plasma by HPLC after the first intravenous infusion of 100 mg of cefuroxime per kg of body weight. The pharmacokinetic profile of cefuroxime exhibited both one and two compartmental distribution. Statistically significant differences between the pharmacokinetic parameters of the severe (group 1) and the very severe patients (group 2) were found, and significant differences (p<0.05) in the pharmacokinetic parameters between groups 1 and 2 vs. the control group were observed for most of the parameters analyzed. However, there was no statistical difference in clearance between group 1 and the control group. The data indicate that the pharmacokinetic differences determined by severity of disease are useful for establishing an individualized regimen dosage in children with multiple organ system failure.