Title Participants "Impact of disease on amikacin pharmacokinetics and dosing in children" "Xiu Liu, Anne Smits, Yuhuan Wang, Marleen Renard, Stephanie Wead, Richard Kagan, Daniel Healy, Pieter De Cock, Karel Allegaert, Catherine Sherwin" "Revisiting the loading dose of amikacin for patients with severe sepsis and septic shock" "Fabio Silvio Taccone, Pierre-François Laterre, Herbert Spapen, Thierry Dugernier, Isabelle K Delattre, Brice Layeux, Daniel De Backer, Xavier Wittebole, Pierre E Wallemacq, Jean-louis Vincent, Frédérique Jacobs" "Introduction: It has been proposed that doses of amikacin of >15 mg/kg should be used in conditions associated with an increased volume of distribution (Vd), such as severe sepsis and septic shock. The primary aim of this study was to determine whether 25 mg/kg (total body weight) of amikacin is an adequate loading dose for these patients.Methods: This was an open, prospective, multicenter study in four Belgian intensive care units (ICUs). All consecutive patients with a diagnosis of severe sepsis or septic shock, in whom amikacin treatment was indicated, were included in the study.Results: In 74 patients, serum samples were collected before (t = 0 h) and 1 hour (peak), 1 hour 30 minutes, 4 hours 30 minutes, 8 hours, and 24 hours after the first dose of amikacin. Blood amikacin levels were measured by using a validated fluorescence polarization immunoassay method, and an open two-compartment model with first-order elimination was fitted to concentrations-versus-time data for amikacin (WinNonlin). In 52 (70%) patients, peak serum concentrations were >64 μg/ml, which corresponds to 8 times the clinical minimal inhibitory concentration (MIC) breakpoints defined by EUCAST for Enterobacteriaceae and Pseudomonas aeruginosa (S16 μg/ml). Vd was 0.41 (0.29 to 0.51) L/kg; elimination half-life, 4.6 (3.2 to 7.8) hours; and total clearance, 1.98 (1.28 to 3.54) ml/min/kg. No correlation was found between the amikacin peak and any clinical or hemodynamic variable.Conclusions: As patients with severe sepsis and septic shock have an increased Vd, a first dose of ≥ 25 mg/kg (total body weight) of amikacin is required to reach therapeutic peak concentrations. However, even with this higher amikacin dose, the peak concentration remained below therapeutic target levels in about one third of these patients. Optimizing aminoglycoside therapy should be achieved by tight serum-concentration monitoring because of the wide interindividual variability of pharmacokinetic abnormalities." "A simple quantitative method analysing amikacin, gentamicin, and vancomycin levels in human newborn plasma using ion-pair liquid chromatography/tandem mass spectrometry and its applicability to a clinical study" "Yuma Bijleveld, Timo de Haan, Jan Toersche, Sona Jorjani, Johanna van der Lee, Floris Groenendaal, Peter Dijk, Arno van Heijst, Antonio W D Gavilanes, Rogier de Jonge, Koen P Dijkman, Henrica van Straaten, Monique Rijken, Inge Zonnenberg, Filip Cools, Debbie Nuytemans, Ron Mathôt" "Neuroprotective controlled therapeutic hypothermia is the standard of care for newborns suffering perinatal asphyxia. Antibiotic drugs, such as amikacin, gentamicin, and vancomycin are frequently administered during controlled hypothermia, which possibly alters their pharmacokinetic (PK) and pharmacodynamic (PD) profiles. In order to examine this effect an LC-MS/MS method for the simultaneous quantification of amikacin, the major gentamicin components (gentamicin C, C1a and C2), and vancomycin in plasma was developed. In 25μL plasma proteins were precipitated with trichloroacetic acid (TCA) and detection of the components was achieved using ion-pair reversed phase chromatography coupled with electrospray ionization tandem mass spectrometry. The chromatographic runtime was 7.5min per sample. Calibration standards were prepared over a range of 0.3-50mgL(-1) for amikacin and gentamicin and 1.0-100mgL(-1) for vancomycin. At LLOQ accuracy was between 103 and 120% and imprecision was less than 19%. For concentrations above LLOQ accuracy ranged from 98% to 102% and imprecision was less than 6%. Process efficiency, ionization efficiency, and recovery were acceptable. Samples and stock solutions were stable during the time periods and at the different temperatures examined. The applicability of the method was shown by analysing plasma samples from 3 neonatal patients. The developed method allows accurate and precise simultaneous quantification of amikacin, gentamicin, and vancomycin in a small volume (25μL) of plasma." "High level of cross-resistance between kanamycin, amikacin, and capreomycin among Mycobacterium tuberculosis isolates from Georgia and a close relation with mutations in the rrs gene" "Levan Jugheli, N Bzekalava, Pim De Rijk, Kristina Fissette, Françoise Portaels, Leen Rigouts" "In vitro activity of ciprofloxacin, sparfloxacin, ofloxacin, amikacin and rifampicin against Ghanaian isolates of Mycobacterium ulcerans" "HS Thangaraj, O Adjei, BW Allen, Françoise Portaels, MRW Evans, DK Banerjee, MH Wansbrough-Jones" "Cerebrospinal fluid compartmental pharmacokinetics of amikacin in neonates" "Karel Allegaert, Erwin Adams, Veerle Cossey" "To describe and investigate the covariate effects of cerebrospinal fluid (CSF) amikacin pharmacokinetics in neonates, CSF samples were prospectively collected from neonates in whom amikacin had been initiated before a diagnostic lumbar puncture was performed. CSF analysis (amikacin concentration, white blood count [WBC], glucose content, and protein concentration) and amikacin therapeutic drug monitoring results (peak and trough concentrations) in serum were recorded. Correlations (Spearman rank) between the CSF amikacin concentration and the CSF WBC and glucose and protein concentration were investigated. There were 44 CSF amikacin concentrations and 83 serum samples available from 43 neonates (mean postmenstrual age, 36 weeks [range, 26 to 41 weeks]; mean weight, 2.43 kg [range, 0.87 to 3.86 kg]). The median time interval between initiation of amikacin administration and CSF sampling was 25 h (range, 2.5 to 93.7 h). The median amikacin concentration in the CSF was 1.08 mg/liter (range, 0.34 to 2.65 mg/liter), and the mean trough and peak amikacin concentrations in serum were 3.8 +/- 2.5 mg/liter and 35.7 +/- 5.9 mg/liter, respectively. A correlation between CSF amikacin and CSF protein contents (P < 0.01, r = 0.41, 95% confidence interval = 0.13 to 0.63) but not between CSF WBC and CSF glucose was documented. A two-compartment (central and CSF) linear disposition model was used to estimate population pharmacokinetics. The half time for equilibration (T-eq) between serum and CSF compartments was used as a measure of blood-brain barrier permeability. The T-eq was 7.58 h (coefficient of variation [CV] = 49.1%) with a partition coefficient of 0.103 (CV = 26.4%). There was no relationship between the T-eq and CSF WBC, CSF glucose content, or CSF protein content." "Quantification of amikacin in bronchial epithelial lining fluid in neonates" "Mohamed El-Attug, Erwin Adams, Ann Van Schepdael, Anne Debeer, Karel Allegaert, Anne Smits" "Amikacin efficacy is based on peak concentrations and the possibility of reaching therapeutic levels at the infection site. This study aimed to describe amikacin concentrations in the epithelial lining fluid (ELF) through bronchoalveolar lavage (BAL) in newborns. BAL fluid was collected in ventilated neonates treated with intravenous (i.v.) amikacin. Clinical characteristics, amikacin therapeutic drug monitoring serum concentrations, and the concentrations of urea in plasma were extracted from the individual patient files. Amikacin and urea BAL fluid concentrations were determined using liquid chromatography with pulsed electrochemical detection (LC-PED) and capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D), respectively. ELF amikacin concentrations were converted from BAL fluid concentrations through quantification of dilution (urea in plasma/urea in BAL fluid) during the BAL procedure. Twenty-two observations in 17 neonates (postmenstrual age, 31.9 [range, 25.1 to 41] weeks; postnatal age, 3.5 [range, 2 to 37] days) were collected. Median trough and peak amikacin serum concentrations were 2.1 (range, 1 to 7.1) mg/liter and 39.1 (range, 24.1 to 73.2) mg/liter; the median urea plasma concentration was 30 (8 to 90) mg/dl. The median amikacin concentration in ELF was 6.5 mg/liter, the minimum measured concentration was 1.5 mg/liter, and the maximum (peak) was 23 mg/liter. The highest measured ELF concentration was reached between 6 and 14.5 h after i.v. amikacin administration, and an estimated terminal elimination half-life was 8 to 10 h. The median and highest (peak) ELF amikacin concentrations observed in our study population were, respectively, 6.5 and 23 mg/liter. Despite the frequent use of amikacin in neonatal (pulmonary) infections, this is the first report of amikacin quantification in ELF in newborns." "Quantification and Explanation of the Variability of First-Dose Amikacin Concentrations in Critically Ill Patients Admitted to the Emergency Department: A Population Pharmacokinetic Analysis" "Erwin Dreesen, Pieter Annaert, Joost Wauters, Wouter Meersseman, Stefanie Desmet, Sandra Verelst, Willy Peetermans" "BACKGROUND: There may be a difference between the determinants of amikacin exposure in emergency department (ED) versus intensive care (ICU) patients, and the peak amikacin concentration varies widely between patients. Moreover, when the first dose of antimicrobials is administered to septic patients admitted to the ED, fluid resuscitation and vasopressors have just been initiated. Nevertheless, population pharmacokinetic modelling data for amikacin in ED patients are unavailable. OBJECTIVE: The aim of this study was to quantify the interindividual variability (IIV) in the pharmacokinetics of amikacin in patients admitted to the ED and to identify the patient characteristics that explain this IIV. METHODS: Patients presenting at the ED with severe sepsis or septic shock were randomly assigned to receive amikacin 25 mg/kg or 15 mg/kg intravenously. Blood samples were collected at 1, 6 and 24 h after the onset of the first amikacin infusion. Data were analysed using nonlinear mixed-effects modelling. RESULTS: A two-compartment population pharmacokinetic model was developed based on 279 amikacin concentrations from 97 patients. The IIV in clearance (CL) and central distribution volume (V1) were 71% and 26%, respectively. Body mass index (BMI), serum total protein level, serum sodium level, and fluid balance 24 h after amikacin administration explained 30% of the IIV in V1, leaving 18% of the IIV unexplained. BMI and creatinine clearance according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation 24 h after amikacin administration explained 46% of the IIV in CL, and 39% remained unexplained. CONCLUSION: The IIV of amikacin pharmacokinetics in ED patients is large. Higher doses may be considered in patients with low serum sodium levels, low total protein levels, or a high fluid balance. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT02365272." "Covariates of amikacin disposition in a large pediatric oncology cohort" "Karel Allegaert, Annouschka Laenen, Anne Smits" "OBJECTIVE: Amikacin pharmacokinetics (PK) in children display large variability due to maturational and disease-related covariates. The objective was to explore amikacin PK in a large pediatric oncology cohort, taking into account within-patient changes. MATERIALS AND METHODS: Clinical data and amikacin therapeutic drug monitoring (TDM) observations were collected retrospectively from children with an oncology diagnosis receiving amikacin during febrile neutropenia. Individual amikacin PK parameters were calculated using a 1-compartment model with instantaneous input and first-order output. This approach was selected based on a pragmatic study design using TDM from routine clinical care, with availability of 2 TDM samples per treatment episode. To explore covariates of clearance (Cl) and volume of distribution (Vd), linear mixed models were used, modelling a random effect for patient to account for clustering due to repeated measurements. RESULTS: Based on 188 amikacin treatment episodes in 114 patients, median (interquartile range) amikacin Cl was 1.37 (1.05; 2.46) L/h and Vd 7.98 (5.66; 12.73) L. Height and creatinemia were significant covariates for Cl (marginal R2 71.1%), while weight, height, and creatinemia determined Vd (marginal R2 59.5%). CONCLUSION: We described extensive variability of amikacin PK in a large cohort of pediatric oncology patients, including within-patient changes across treatment episodes. Maturational covariates and creatinemia determined amikacin Cl and Vd, while primary non-maturational covariates were not significant. Our observations, based on combined clinical and PK data in children with oncology diagnoses, can be useful to feed dosing software programs to improve drug exposure in special populations." "Amikacin pharmacokinetics to optimize dosing in neonates with perinatal asphyxia treated with hypothermia" "Anne Smits, Karel Allegaert" "Aminoglycosides pharmacokinetics (PK) is expected to change in neonates with perinatal asphyxia treated with therapeutic hypothermia (PATH). Several amikacin dosing guidelines have been proposed to treat neonates with (suspected) septicemia, however, none provide adjustments in the case of PATH. Therefore, we aimed to quantify the differences in amikacin PK between neonates with and without PATH to propose suitable dosing recommendations.Based on amikacin therapeutic drug monitoring data collected retrospectively from neonates with PATH, combined with a published dataset, we assessed the impact of PATH on amikacin PK using population modelling. Monte Carlo and stochastic simulations were performed to establish amikacin exposures in neonates with PATH after dosing according to the current guidelines and according to proposed model-derived dosing guidelines.Amikacin clearance was decreased by 40.6% in neonates with PATH, with no changes in volume of distribution. Simulations showed that, increasing the dosing interval with 12 hours results in a decrease in percentage of neonates reaching toxic trough levels (> 5 mg/L) from 40-76% to 14-25%, while still reaching efficacy targets, compared to current dosing regimens.Based on this study, a 12-hour increase in amikacin dosing interval in neonates with PATH is proposed to correct for the reduced clearance, yielding safe and effective exposures. As amikacin is renally excreted, further studies into other renally excreted drugs may be required as their clearance may also be impaired."