This is the first PopPK for busulfan that successfully incorporated GSTA1 genotype in a paediatric population. Its use may contribute to better prediction of busulfan exposure in children and adolescents since the first dose, by tailoring the dose according to the individual metabolic capacity.

Intravenous linezolid was efficient and well tolerated in critically ill premature infants. PNA was the main determinant of clearance.

No dosage adjustments are required with any of the covariates tested. Clinical efficacy was associated with trametinib trough concentrations greater than 10 ng/mL.

OBJECTIVES The administration of acetaminophen via the oral and rectal routes may be contraindicated in specific clinical settings. Intravenous administration provides an alternative route for fever reduction and analgesia. This phase 1 study of intravenous acetaminophen (Ofirmev, Cadence Pharmaceuticals, Inc., San Diego, CA) in inpatient pediatric patients with pain or fever requiring intravenous therapy was designed to assess the safety and pharmacokinetics of repeated doses over 48 hours. METHODS Neonates (full-term to 28 days) received either 12.5 mg/kg every 6 hours or 15 mg/kg every 8 hours. Infants (29 days to <2 years), children (2 to <12 years) and adolescents (≥12 years) received either 12.5 mg/kg every 4 hours or 15 mg/kg every 6 hours. Both noncompartmental and population nonlinear mixed-effects modeling approaches were used. Urinary metabolite data were analyzed, and safety and tolerability were assessed. RESULTS Pharmacokinetic parameters of acetaminophen were estimated using a two-compartment disposition model with weight allometrically expressed on clearances and central and peripheral volumes of distribution (Vds). Postnatal age, with a maturation function, was a significant covariate on clearance. Total systemic normalized clearance was 18.4 L/hr per 70 kg, with a plateau reached at approximately 2 years. Total central and peripheral Vds of acetaminophen were 16 and 59.5 L/70 kg, respectively. The drug was well tolerated based on the incidence of adverse events. The primary and minor pathways of elimination were acetaminophen glucuronidation, sulfation, and glutathione conjugate metabolites across all age groups. CONCLUSIONS Intravenous acetaminophen in infants, children, and adolescents was well tolerated and achieved plasma concentrations similar to those achieved with labeled 15 mg/kg body weight doses by oral or rectal administration.

AIMSThe objectives of this study were to develop a population pharmacokinetic (PopPK) model for tacrolimus in paediatric liver transplant patients and determine optimal sampling strategies to estimate tacrolimus exposure accurately. METHODSTwelve hour intensive pharmacokinetic profiles from 30 patients (age 0.4-18.4 years) receiving tacrolimus orally were analysed. The PopPK model explored the following covariates: weight, age, sex, type of transplant, age of liver donor, liver function tests, albumin, haematocrit, drug interactions, drug formulation and time post-transplantation. Optimal sampling strategies were developed and validated with jackknife.

We currently calculate area under the busulfan concentration time curve (AUC) using 7 plasma busulfan concentrations (AUC7) drawn after the first of 16 i.v. busulfan doses given as a 2-hour infusion every 6 hours. The aim of this study was to develop and validate limited sampling strategies (LSSs) using 3 or fewer busulfan concentration values with which to reliably calculate AUC in children undergoing hematopoietic stem cell transplant (HSCT). Children in the development group (44) received i.v. busulfan at Sick Kids; the validation group consisted of 35 children who received care at CHU Ste-Justine. Busulfan doses given and subsequent plasma busulfan concentrations were recorded. LSSs using 1 to 3 concentration-time points were developed using multiple linear regression. LSS were considered to be acceptable when adjusted r(2) > 0.9, mean bias <15% and precision <15%. Extent of agreement between the AUC7 values and the LSS AUC was assessed by the intraclass correlation coefficient (ICC) and Bland-Altman (BA) analysis. Agreement was considered to be excellent when the lower limit of the 95% confidence limit of the ICC exceeded 0.9 and when the limits of agreement in the BA analysis were +/-15% for both AUC and dose. Administration of the theoretic adjusted busulfan doses based on each LSS was simulated and cases where the resulting AUC was >1500 or <900 microM x min were noted. LSSs using 1, 2, or 3 plasma busulfan concentrations were developed that showed excellent agreement with AUC7 and adjusted busulfan doses. In the validation sample, only the 2- and 3-point LSSs demonstrated acceptable precision and lack of bias. LSSs using 2 or 3 plasma busulfan concentrations can be used to reliably estimate busulfan AUC after IV administration in children undergoing HSCT.

bAlthough smallpox has been eradicated, the United States government considers it a "material threat" and has funded the discovery and development of potential therapeutic compounds. As reported here, the human efficacious dose for one of these compounds, ST-246, was determined using efficacy studies in nonhuman primates (NHPs), together with pharmacokinetic and pharmacodynamic analysis that predicted the appropriate dose and exposure levels to provide therapeutic benefit in humans. The efficacy analysis combined the data from studies conducted at three separate facilities that evaluated treatment following infection with a closely related virus, monkeypox virus (MPXV), in a total of 96 NHPs. The effect of infection on ST-246 pharmacokinetics in NHPs was applied to humans using population pharmacokinetic models. Exposure at the selected human dose of 600 mg is more than 4-fold higher than the lowest efficacious dose in NHPs and is predicted to provide protection to more than 95% of the population.

This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.