Population Pharmacokinetics Of Gentamicin Research Articles

Population pharmacokinetics of gentamicin in acute lymphoblastic leukemia pediatric patients compared to non-oncology patients

Understanding the pharmacokinetics of gentamicin is essential in special populations, such as pediatric patients with acute lymphoblastic leukemia (ALL), in light of previous studies indicating that ALL patients have a lower volume of distribution than non-ALL patients. Furthermore, validation of such results is needed to ensure their clinical application. Accordingly, this single-center, retrospective, cross-sectional study compares the pharmacokinetic parameters of volume of distribution and clearance (Cl) of gentamicin between ALL and non-ALL patients. Inclusion criteria were pediatric patients aged between 1 and 14 years with or without ALL and receiving intravenous gentamicin for treatment courses > 72 h. Patients’ characteristics, such as age, sex, height, serum albumin, diagnosis, serum creatinine (Scr) concentration, dosing, and pharmacokinetic information, including peak and trough concentrations, were retrieved. The study scrutinized a total of 115 pediatric patients, comprising toddlers (15.7 %), children (76.5 %), and adolescents (7.8 %). All patients received gentamicin every 8 h, with an average dose of 2.50 (0.64) mg/kg. Patients were divided into two groups based on disease state, with 45.2 % (n = 52) in the non-ALL group and 54.8 % (n = 63) in the ALL group. Both groups had similar characteristics in terms of gender, weight, body surface area, and dose. The only significant covariates identified were weight and creatinine clearance (Clcr) for volume of distribution (Vd). A significant difference was found in Scr, Clcr, and blood urea nitrogen (BUN); however, no significant difference between ALL and non-ALL patients emerged in the volume of distribution or Cl. In conclusion, the study findings indicate that dosing requirements were similar between the two groups. Further prospective studies with larger sample sizes are warranted.

Population Pharmacokinetics of Gentamicin in Mexican Children With Severe Malnutrition

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. 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. 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. 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.

Population pharmacokinetics of gentamicin in premature newborns

To determine the pharmacokinetic parameters of gentamicin in a population of 200 premature newborns and to investigate the influence of several clinical and physiopathological covariates on the pharmacokinetics of the drug. To validate the pharmacokinetic analysis performed in another population of 50 premature newborns. A total of 200 premature newborns were evaluated at the neonatal intensive care unit of Severo Ochoa Hospital (Madrid, Spain). Four hundred and seventeen serum drug concentrations were included. Mean gestational age (GA) was 32.19+/-2.97 weeks, mean postnatal age (PNA) was 5.49+/-5.41 days and mean body weight (BW) was 1.68+/-0.63 kg. Fifty additional newborns were studied for validation (mean GA 32.62+/-3.07 weeks, mean PNA 5.17+/-3.77 days and mean BW 1.80+/-0.67 kg). Dosing, serum gentamicin concentrations and 15 covariates were collected. Data analysis was performed with NONMEM. One- and two-compartment open models were evaluated. Four parameters were analysed with the two-compartment open model: clearance (CL), central volume (Vc), peripheral volume (Vp) and intercompartmental clearance (Q). The two-compartment open model was found to significantly better describe gentamicin pharmacokinetics in the neonate. More than PNA or GA, creatinine clearance (CLCR) plays an important role in the elimination of gentamicin in premature newborns. Creatinine clearance is also related to GA. The appropriate dosing regimens given in accordance with the characteristics of the patients are 5 mg/kg/48 h and 4 mg/kg/24 or 36 h for neonates<32 weeks and >or=32 weeks of GA, respectively.

Pharmacokinetic basis for the use of extended interval dosage regimens of gentamicin in neonates.

To analyse the pharmacokinetic basis for the use of extended-interval dosage regimens of gentamicin in neonates using population pharmacokinetics. The population pharmacokinetics of gentamicin was studied retrospectively in a population of 113 neonates divided into two groups: one for computing the population model (n=97) and another for validation (n=36). A one-compartment pharmacokinetic model and non-linear mixed-effects modelling were used to assess the population pharmacokinetic model. Weight (W) and postnatal age (PA) were the covariates that influenced the pharmacokinetic parameters of gentamicin. The final population model obtained was: distribution volume, V (L)=0.636 x W (kg)0.852; clearance, Cl (L/h)=0.032 x W (kg)1.482+0.0024 x PA (days). The predictive performance of the model in the population validation was adequate for clinical purposes. The optimized population model allowed us to simulate gentamicin serum levels and their variability, in this kind of patient, when extended-interval dosage administration regimens were implemented. According to our pharmacokinetic population model, initial doses of gentamicin of 10 mg/kg, and dosage intervals between 36-48 h, appear to be appropriate to achieve target peak and trough serum levels of 15-20 and <0.5 mg/L, respectively, when extended-interval dosage regimens are implemented in newborns. The half-life of gentamicin in premature babies of very low weight and gestational age <31 weeks is long. Thus, to achieve serum concentrations in the 1-10 mg/L range, the use of dosage regimens of 5 mg/kg at 36-48 h dosage intervals seems suitable.

Population pharmacokinetics of gentamicin in preterm neonates: evaluation of a once-daily dosage regimen.

Population pharmacokinetic parameters of gentamicin in preterm neonates on a once-daily dosage regimen of 3.0 mg/kg given intravenously every 24 hours were established prospectively. In 34 preterm neonates with a mean gestational age of 32 +/- 4 (SD), 182 serum gentamicin levels (91 peak/trough pairs) were determined. Individual adjustments of dose or dosage interval were calculated by computer-aided Bayesian forecasting. The parameters Vd, ke, and CL for each patient were obtained by the nonparametric estimation of maximization method. The predictive power of the model was calculated and the pharmacokinetic estimates were statistically analyzed with SPSS/PC. Cluster analysis showed a division into 2 subpopulations (designated 1 and 2) on the basis of postnatal age. The mean +/- SD postnatal age of subpopulation 1 (n = 29) was 6 +/- 2 days (range 1-7) and of subpopulation 2 (n = 5) 15 +/- 4 days (range 12-24). The mean +/- SD gentamicin relative clearances of subpopulation 1 and subpopulation 2 were 0.0515 +/- 0.0128 and 0.1026 +/- 0.0102 L kg(-1) hr(-1), respectively (p < 0.05). The mean +/- SD values for Vd (Lkg(-1)) in both populations 1 and 2 were 0.6916 +/- 0.1670 and 0.7509 +/- 0.1961, respectively (not significantly different). For ke these data were 0.0744 +/- 0.0200 and 0.1366 +/- 0.0522 (p < 0.05). Statistics showed that the data for Vd and ke of subpopulation 1 were normally distributed (Vd and ke skewness 1.61 and 1.46; kurtosis 3.09 and 3.10 respectively). The model yielded a bias of -0.11 mg/L and a precision of 0.36 mg/L. It is recommended that gentamicin be started in a dosage of 3.5 mg/kg intravenously once-daily under close monitoring.

Population pharmacokinetics of aminoglycoside antibiotics in patients with cystic fibrosis.

The population pharmacokinetics of gentamicin and tobramycin were investigated in a group of 51 young adults with cystic fibrosis. Their ages ranged from 14-35 years, weights from 38-82 kg, and 27 of the patients were female. None of the patients had renal impairment, but 3 patients were treated in the intensive therapy unit (ITU) during one of their courses of therapy. Data comprised 219 courses of therapy and 544 concentrations (mean: 11 per patient). Concentration-time data were analyzed using a nonlinear mixed-effects model package (NONMEM) and were best described by a one-compartment model. Factors identified as potentially influencing aminoglycoside pharmacokinetics were added in a stepwise fashion and the best model found that drug clearance and volume of distribution were related to body surface area and admission to ITU. The mean population estimates were a clearance of 2.89 L/hr/m2 and a volume of distribution of 9.21 L/m2 with a 60% increase in patients who were admitted to ITU. Interpatient variability in clearance and volume were 14% and 8%, respectively. The results suggested that a dose of 120 mg/m2 should achieve an average 1 hour postdose peak of 10 mg/L and trough of <1 mg/L and that higher doses might be required in ITU patients.

Influence of diagnostic and treatment factors in the population pharmacokinetics of gentamicin.

Using the NONMEM program, the population kinetics of gentamicin were retrospectively studied in a series of 51 patients with different pathologies undergoing treatment (single or three daily doses) with gentamicin whose serum gentamicin levels were being monitored. Renal function, the type of treatment and cancer proved to be the covariates which affected drug clearance, while patient weight was found to govern the distribution volume. The distribution coefficient of gentamicin in the patients was 0.37 litres/kg, justifying gentamicin doses higher than those used conventionally. The optimized population model allowed us to simulate drug serum levels at 8 and 12h, as well as the area under the curve of gentamicin and its variability in patients with high distribution volumes when dosage regimens based on a single daily dose administration are implemented.

Population pharmacokinetics of gentamicin in premature infants.

The population kinetics of gentamicin were studied in 97 newborn patients with a gestational age ranging between 28 and 43 weeks and a postnatal age ranging between 2 and 30 days undergoing routine therapeutic monitoring of their serum gentamicin levels. The individual kinetic analysis of serum drug levels was performed using a single-compartment model. The clearance and apparent distribution volume were calculated in each patient. The population model employed assumes the existence of residual variability in the serum concentrations and interindividual variability in the pharmacokinetic parameters. The effects of demographic variables on the clearance, distribution volume, and optimum daily dose of gentamicin were established using multiple linear regression. Gestational age is the best predictive variable of the clearance and the optimum dose/day in the whole population studied. In the premature infant patients, the predictive capacity increases with postconceptional age. Weight is a good predictive variable of all of the parameters, especially of the apparent distribution volume in the overall population of newborns. Analysis of the population kinetic behavior and optimum dose/day in each subgroup recommends that the interval of drug administration should be increased, keeping the same dose/day ratio, due to the tendency of the drug to accumulate its long half-life, especially in premature babies.

Population pharmacokinetics of gentamicin in neonates.

The influence of a number of clinical characteristics on the population pharmacokinetics of gentamicin were examined using routine drug-monitoring data from a group of 113 neonates. The data were analyzed using the programme NONMEM. Clearance was 0.053 litres.h-1.kg-1 and was reduced in neonates with postconceptional age less than or equal to 34 weeks (X 0.83) and 5-min Apgar score less than 7 (X 0.82). Volume of distribution was 0.47 litres.kg-1. These population mean parameter estimates were used to generate dosage regimens to achieve concentrations within the therapeutic range.