Removing barriers to accessing medical cannabis for paediatric patients.

Medical cannabis (MC) may offer therapeutic benefits for children with complex neurological conditions and chronic diseases. In Canada, parents, and caregivers frequently report encountering barriers when accessing MC for their children. These include negative preconceived notions about risks and benefits, challenges connecting with a knowledgeable healthcare provider (HCP), the high cost of MC products, and navigating MC product shortages. In this manuscript, we explore several of these barriers and provide recommendations to decision-makers to enable a family-centered and evidence-based approach to MC medicine and research for children.

From paediatric formulations development to access: Advances made and remaining challenges.

Developing suitable paediatric formulations and ensuring access to them by the greatest number of the 2.2 billion children worldwide are equally important to provide optimal pharmacotherapy. This review focuses on the progress made over the last two decades with paediatric oral formulations with respect to evidence for acceptability and dosing flexibility of liquid and solid oral dosage forms. It also discusses the clinical needs for, and the access to, paediatric formulations for existing authorised medicines. A significant body of new knowledge now supports the acceptability of solid oral dosage forms in children, resulting in an increasing number of medicines commercialised as multiparticulates, including minitablets that are starting to be brought to market. However, there are gaps with these formulations that deserve more research. Even though efforts have been made to identify medicines in need of age-appropriate formulations, there is no common priority list shared internationally. Such prioritisation would help to develop paediatric formulations with the greatest potential for providing a health benefit to children worldwide. In addition, available data highlight that paediatric formulation access is fragmented and unequal, with commercialisation of suitable paediatric formulations too often limited to some countries/regions. We propose actions to better align decisions during the development of paediatric formulations and promote a more globalised approach to facilitate registration pathways between different jurisdictions. Furthermore, discussions about alignment between approval, pricing and reimbursement processes should also happen, leaving working in siloes behind us. It is time for adults to start thinking outside the box for children.

Population Pharmacokinetics and Safety of Piperacillin-Tazobactam Extended Infusions in Infants and Children.

Piperacillin-tazobactam (TZP) is frequently used to treat severe hospital-acquired infections in children. We performed a single-center, pharmacokinetic (PK) trial of TZP in children ranging in age from 2 months to 6 years from various clinical subpopulations. Children who were on TZP per the standard of care were prospectively included and assigned to receive a dose of 80 mg/kg of body weight every 6 h infused over 2 h (ages 2 to 5 months) or a dose of 90 mg/kg every 8 h infused over 4 h (ages 6 months to 6 years). Separate population PK models were developed for piperacillin and tazobactam using nonlinear mixed-effects modeling. Optimal dosing was judged based on the ability to maintain free piperacillin concentrations above the piperacillin MIC for enterobacteria and Pseudomonas aeruginosa for ≥50% of the dosing interval. Any untoward event occurring during treatment was collected as an adverse event. A total of 79 children contributed 174 PK samples. The median (range) age and weight were 1.7 years (2 months to 6 years) and 11.4 kg (3.8 to 27.6 kg), respectively. A 2-compartment model with first-order elimination best described the piperacillin and tazobactam data. Both final population PK models included weight and concomitant furosemide administration on clearance and weight on the volume of distribution of the central compartment. The optimal dosing regimens in children with normal renal function, based on the piperacillin component, were 75 mg/kg/dose every 4 h infused over 0.5 h in infants ages 2 to ≤6 months and 130 mg/kg/dose every 8 h infused over 4 h in children ages >6 months to 6 years against bacteria with MICs up to 16 mg/liter. A total of 44 children (49%) had ≥1 adverse event, with 3 of these (site infiltrations) considered definitely associated with the extended infusions.

Incorporation of GSTA1 genetic variations into a population pharmacokinetic model for IV busulfan in paediatric hematopoietic stem cell transplantation.

AIMS: The aim of this study is to develop a population pharmacokinetic (PopPK) model for intravenous busulfan in children that incorporates variants of GSTA1, gene coding for the main enzyme in busulfan metabolism. METHODS: Busulfan concentration-time data was collected from 112 children and adolescents (median 5.4 years old, range: 0.1-20) who received intravenous busulfan during the conditioning regimen prior to stem cell transplantation. Weight, sex, baseline disease (malignant vs. non-malignant), age, conditioning regimen and GSTA1 diplotypes were evaluated as covariates of pharmacokinetic parameters by using nonlinear mixed effects analysis. The ability to achieve the target AUC24h (3600-6000 µM min-1 ) was assessed by estimating the first dose based on the present PopPK model and by comparing the results with other available models in children. RESULTS: A one-compartment model with first-order elimination best described the data. Allometric scaling of weight and a factor of busulfan metabolism maturation were included in the base model. GSTA1 diplotypes were found to be a significant covariate of busulfan clearance, which was 7% faster in rapid metabolizers and 12% slower in poor metabolizers, in comparison with normal ones. Busulfan doses calculated using the parameters of the proposed PopPK model were estimated to achieve the target AUC in 85.2% of the cases (95% CI 78.7-91.7%). CONCLUSION: 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.

Limited sampling strategies for estimating intravenous and oral cyclosporine area under the curve in pediatric hematopoietic stem cell transplantation.

BACKGROUND: The optimal monitoring strategy for cyclosporine (CsA) in pediatric hematopoietic stem cell transplantation (HSCT) patients remains unclear. Although there is a growing interest in the use of the area under the concentration-time curve (AUC), measurement of AUC in clinical settings is often impractical. The objective of this study was to identify and validate limited sampling strategies (LSSs) for the prediction of CsA AUC after intravenous (IV) and oral (PO) administration in this population. METHODS: Sixty-eight pediatric patients who underwent HSCT and received CsA were investigated. Twelve-hour pharmacokinetic profiles (n = 138) performed per standard of care were collected. Weighted multiple linear regression was used to investigate all possible LSSs consisting of 4 or less concentration-time points. Their predictive performance was evaluated by leave one out cross validation and external validation by measuring the root mean squared relative error (RMSE%) and the 95th percentile of the absolute relative error (AE%). Values less than 20% were considered clinically acceptable. RESULTS: Nine LSSs (4 IV and 5 PO) convenient for clinical application proved to have clinically acceptable performance. Notably, LSS based on C0, C2, and C4 was found to be accurate for estimation of CsA exposure after both IV and PO administration with the 95th percentile of AE% of 19.7% and 17.5%, respectively. CONCLUSIONS: LSSs using 3 or 4 concentration-time points obtained within 4 hours postdose provide a convenient and reliable method to estimate CsA exposure in this population. These LSSs may facilitate future research aiming at better defining the relationship between AUC and clinical outcomes.

Impact of sampling time deviations on the prediction of the area under the curve using regression limited sampling strategies.

The regression limited sampling strategy approach (R-LSS), which is based on a small number of blood samples drawn at selected time points, has been used as an alternative method for the estimation of the area under the concentration-time curve (AUC). However, deviations from planned sampling times may affect the performance of R-LSS, influencing related therapeutic decisions and outcomes. The aim of this study was to investigate the impact of different sampling time deviation (STD) scenarios on the estimation of AUC by the R-LSS using a simulation approach. Three types of scenarios were considered going from the simplest case of fixed deviations, to random deviations and then to a more realistic case where deviations of mixed nature can occur. In addition, the sensitivity of the R-LSS to STD in each involved sampling point was evaluated. A significant impact of STD on the performance of R-LSS was demonstrated. The tolerance of R-LSS to STD was found to depend not only on the number of sampling points but more importantly on the duration of the sampling process. Sensitivity analysis showed that sampling points at which rapid concentration changes occur were relatively more critical for AUC prediction by R-LSS. As a practical approach, nomograms were proposed, where the expected predictive performance of R-LSS was provided as a function of STD information. The investigation of STD impact on the predictive performance of R-LSS is a critical element and should be routinely performed to guide R-LSS selection and use.

Population pharmacokinetics and Bayesian estimation of tacrolimus exposure in paediatric liver transplant recipients.

AIMS: The 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. METHODS: Twelve 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. RESULTS: A two-compartment model with first-order absorption and elimination and lag time described the data. Weight was included on all pharmacokinetic parameters. Typical apparent clearance and central volume of distribution were 12.1 l h(-1) and 31.3 l, respectively. The PopPK approach led to the development of optimal sampling strategies, which allowed estimation of tacrolimus pharmacokinetics and area under the concentration­time curve (AUC) on the basis of practical sampling schedules (three or four sampling times within 4 h) with clinically acceptable prediction error limit. The mean bias and precision of the Bayesian vs. reference (trapezoidal) AUCs ranged from -2.8 to -1.9% and from 7.4 to 12.5%, respectively. CONCLUSIONS: The PopPK of tacrolimus and empirical Bayesian estimates represent an accurate and convenient method to predict tacrolimus AUC(0-12) in paediatric liver transplant recipients, despite high between-subject variability in pharmacokinetics and patient demographics. The developed optimal sampling strategies will allow the undertaking of prospective trials to define the tacrolimus AUC-based therapeutic window and dosing guidelines in this population.

Bayesian approach for the estimation of cyclosporine area under the curve using limited sampling strategies in pediatric hematopoietic stem cell transplantation.

BACKGROUND: The optimal marker for cyclosporine (CsA) monitoring in transplantation patients remains controversial. However, there is a growing interest in the use of the area under the concentration-time curve (AUC), particularly for cyclosporine dose adjustment in pediatric hematopoietic stem cell transplantation. In this paper, we develop Bayesian limited sampling strategies (B-LSS) for cyclosporine AUC estimation using population pharmacokinetic (Pop-PK) models and investigate related issues, with the aim to improve B-LSS prediction performance. METHODS: Twenty five pediatric hematopoietic stem cell transplantation patients receiving intravenous and oral cyclosporine were investigated. Pop-PK analyses were carried out and the predictive performance of B-LSS was evaluated using the final Pop-PK model and several related ones. The performance of B-LSS when targeting different versions of AUC was also discussed. RESULTS: A two-compartment structure model with a lag time and a combined additive and proportional error is retained. The final covariate model does not improve the B-LSS prediction performance. The best performing models for intravenous and oral cyclosporine are the structure ones with combined and additive error, respectively. Twelve B-LSS, consisting of 4 or less sampling points obtained within 4 hours post-dose, predict AUC with 95th percentile of the absolute values of relative prediction errors of 20% or less. Moreover, B-LSS perform better for the prediction of the 'underlying' AUC derived from the Pop-PK model estimated concentrations that exclude the residual errors, in comparison to their prediction of the observed AUC directly calculated using measured concentrations. CONCLUSIONS: B-LSS can adequately estimate cyclosporine AUC. However, B-LSS performance is not perfectly in line with the standard Pop-PK model selection criteria; hence the final model might not be ideal for AUC prediction purpose. Therefore, for B-LSS application, Pop-PK model diagnostic criteria should additionally account for AUC prediction errors.

A specific and sensitive HPLC-MS/MS micromethod for milrinone plasma levels determination after inhalation in cardiac patients.

BACKGROUND: Milrinone administered through inhalation is an emerging method aimed at specifically reducing pulmonary hypertension without affecting systemic pressures. Its administration has been shown to be useful both in patients undergoing cardiac surgery and for persistent pulmonary hypertension of the newborn. These populations are prone to receive many concomitant medications and/or blood sampling may require a low volume quantification method. To address these issues in view of pharmacokinetic studies, this article aims to develop and validate a specific and sensitive analytical assay using high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) detection for the quantification of milrinone plasma concentrations after inhalation in patients undergoing cardiac surgery. METHODS: Plasma samples (50 µL) were extracted using ethyl acetate. Milrinone was separated on a C18 analytical column at 50°C. The mobile phase consisted of methanol and 10 mM ammonium acetate (45:55 vol/vol). The electrospray was operated in the negative ionization mode and monitored the following mass transitions: m/z 212.1 → 140.0 at 36 eV for milrinone and m/z 252.1 → 156.1 at 32 eV for olprinone. RESULTS: Calibration curves followed a quadratic regression in the concentration range of 0.3125-640 ng/mL. The lower limit of quantification is 0.3125 ng/mL and is based on a low plasma volume of 50 µL. Mean drug recovery and accuracy were ≥72.3% and 96.0%, respectively. Intraday and interday precision coefficient of variation (%) was ≤7.4% and ≤11.5%, respectively. The specificity allowed milrinone quantification in the multidrug administration conditions of cardiopulmonary bypass. CONCLUSIONS: This validated micromethod proved to be highly sensitive and specific while using a low volume of plasma. Its low volume and its lower limit of quantification indicate that this approach is suitable for further characterization of milrinone pharmacokinetics in both adults (inhalation) and neonates.

Molecular Absorbent Recirculating System therapy (MARS®) in pediatric acute liver failure: a single center experience.

BACKGROUND: Supportive care as a bridge to transplant or recovery remains challenging in children suffering from acute liver failure (ALF). We report our experience in children using the Molecular Absorbent Recirculating System (MARS(®)). METHODS: Retrospective data from children receiving therapy using MARS(®) from October 2009 to October 2012 were included in this single-center retrospective study. Patient characteristics, clinical presentation and complications of ALF, clinical and biological data before and after each MARS(®) session, technical modalities and adverse events were recorded. RESULTS: A total of six children underwent 17 MARS(®) sessions during the study period. Two adolescents were treated with the adult filter MARSFLUX(®) and four infants were treated with the MiniMARS(®) filter. The mean PEdiatric Logistic Dysfunction (PELOD) score at admission was 19 (range 11-33). All patients were mechanically ventilated, and four had acute kidney injury. The neurological course improved in one case, judged as stable in two cases and worsened in one case; data were unavailable in two cases. Mean serum ammonia levels decreased significantly following treatment with MARS(®) from an initial 89 ± 29 to 58 ± 35 mcmol/L (p = 0.02). No other significant biological improvement was observed. Hemodynamic status improved/remained unchanged in the adolescent group, but in the infants four of the seven sessions were poorly tolerated and two sessions were aborted. Three patients died, two were successfully transplanted and one recovered without transplantation. CONCLUSION: In our experience, treatment with MARS(®) is associated with encouraging results in adolescents, but it needs modification for very sick infants to improve tolerance.

Conversion from twice- to once-daily tacrolimus in pediatric kidney recipients: a pharmacokinetic and bioequivalence study.

BACKGROUND: The objectives of this study were to investigate pharmacokinetic and pharmacogenetic parameters during the conversion on a 1:1 (mg:mg) basis from a twice-daily (Prograf) to once-daily (Advagraf) tacrolimus formulation in pediatric kidney transplant recipients. METHODS: Twenty-four-hour pharmacokinetic profiles were analyzed before and after conversion in 19 stable renal transplant recipients (age 7-19 years). Tacrolimus pharmacokinetic parameters [area under the concentration-time curve (AUC0-24), minimum whole-blood concentration (Cmin), maximum whole-blood concentration (Cmax), and time to achieve maximum whole-blood concentration (tmax)] were compared between Tac formulations and between CYP3A5 and MDR1 genotypes after dose normalization. RESULTS: Both AUC0-24 and Cmin decreased after conversion (223.3 to 197.5 ng.h/ml and 6.5 to 5.6 ng/ml; p = 0.03 and 0.01, respectively). However, the ratio of the least square means (LSM) for AUC0-24 was 90.8 %, with 90 % CI limits of 85.3 to 96.7 %, falling within bioequivalence limits. The CYP3A5 genotype influences the dose-normalized Cmin with the twice-daily formulation only. CONCLUSIONS: Both tacrolimus formulations are bioequivalent in pediatric renal recipients. However, we observed a decrease in AUC0-24 and Cmin after the conversion, requiring close pharmacokinetic monitoring during the conversion period.

Drug Prescriptions Requiring Compounding at a Canadian University Affiliated Pediatric Hospital: A Cross-Sectional Study.

Despite ongoing international efforts, many drugs administered to children must be compounded from dosage forms designed for adults because they remain unavailable in commercial formulations that suit their needs. Even though oral drug compounding is common in pediatrics, the extent of this practice has not been well described in recent years. This cross-sectional and retrospective study was conducted at a Canadian university-affiliated, 484-bed, tertiary care pediatric hospital and its rehabilitation centre on two randomly selected days. A total of 606 hospitalized children with 5465 prescriptions were included. Overall, compounded drugs for enteral administration (CDEA) represented 13% of all prescriptions (enteral and parenteral) and 23% of prescriptions for enteral administration. Of the 390 prescribed drugs, 122 required compounding. CDEA were mostly liquids (n = 478 [67%]) and mainly included drugs of the central nervous (35%), cardiovascular (21%), and gastro-intestinal (12%) systems. Nearly half (N = 298 [49%]) of children had at least one CDEA prescribed in their medical file. Many CDEA are available as commercial products in other jurisdictions. Collaboration is needed between all stakeholders to make these drugs available to Canadian children.

An Integrated Clinical and Genetic Prediction Model for Tacrolimus Levels in Pediatric Solid Organ Transplant Recipients.

BACKGROUND: There are challenges in achieving and maintaining therapeutic tacrolimus levels after solid organ transplantation (SOT). The purpose of this genome-wide association study was to generate an integrated clinical and genetic prediction model for tacrolimus levels in pediatric SOT. METHODS: In a multicenter prospective observational cohort study (2015-2018), children <18 years old at their first SOT receiving tacrolimus as maintenance immunosuppression were included (455 as discovery cohort; 322 as validation cohort). Genotyping was performed using a genome-wide single nucleotide polymorphism (SNP) array and analyzed for association with tacrolimus trough levels during 1-y follow-up. RESULTS: Genome-wide association study adjusted for clinical factors identified 25 SNPs associated with tacrolimus levels; 8 were significant at a genome-wide level (P < 1.025 × 10-7). Nineteen SNPs were replicated in the validation cohort. After removing SNPs in strong linkage disequilibrium, 14 SNPs remained independently associated with tacrolimus levels. Both traditional and machine learning approaches selected organ type, age at transplant, rs776746, rs12333983, and rs12957142 SNPs as the top predictor variables for dose-adjusted 36- to 48-h posttacrolimus initiation (T1) levels. There was a significant interaction between age and organ type with rs776476*1 SNP (P < 0.05). The combined clinical and genetic model had lower prediction error and explained 30% of the variation in dose-adjusted T1 levels compared with 18% by the clinical and 12% by the genetic only model. CONCLUSIONS: Our study highlights the importance of incorporating age, organ type, and genotype in predicting tacrolimus levels and lays the groundwork for developing an individualized age and organ-specific genotype-guided tacrolimus dosing algorithm.

Impact of blood volume monitoring on fluid removal during intermittent hemodialysis of critically ill children with acute kidney injury.

BACKGROUND: In chronic pediatric patients treated with intermittent hemodialysis (IHD), blood volume monitoring (BVM) is commonly used to assess and manage volume status during the dialysis session. Minimal data exists on its use during IHD in critically ill children with acute kidney injury (AKI). In these cases, fluid removal may be limited by hemodynamic instability. METHODS: We present a retrospective study conducted in our pediatric intensive care unit. For eligible patients, demographic data and IHD treatment characteristics were recorded including BVM use, ultrafiltration (UF) volume per session, hypotensive episodes and intradialysis interventions. Hypotensive episodes and UF per IHD session were compared between IHD sessions with BVM (BVM group) and IHD sessions without BVM (control group). RESULTS: Twenty-three AKI patients with a median age of 11 years (1.8-18) and body weight of 36 kg (10-85) received 134 IHD sessions (70 with BVM and 64 without BVM). Hypotensive episodes occurred in 34% of all sessions with no significant difference between the BVM group and the control group: (95% CI: 22%, 44%) and 36% (95% CI: 24%, 48%), respectively, but UF per session was higher in the BVM group as compared to control (48 ± 27 mL/kg and 33 ± 26 mL/kg, respectively, P = 0.0001). The mean decrease in BVM did not exceed 13% over an entire dialysis session in patients without hypotension. CONCLUSION: In conclusion, in our experience of IHD sessions in critically ill children with AKI, the use of BVM allowed a higher UF in those with BVM without influencing the frequency of hypotensive episodes. Applying specific guidelines on BVM use may decrease hypotensive episodes during IHD treatment in critically ill patients.

Limited sampling strategies for monitoring tacrolimus in pediatric liver transplant recipients.

OBJECTIVE: To develop and validate limited sampling strategies (LSSs) for tacrolimus in pediatric liver transplant recipients. METHODS: Thirty-six 12-hour pharmacokinetic profiles from 28 pediatric liver transplant recipients (0.4-18.5 years) were collected. Tacrolimus concentrations were measured by immunoassay and area under the curve (AUC0-12) was determined by trapezoidal rule. LSSs consisting of 1, 2, 3, or 4 concentration-time points were developed using multiple regression analysis. Eight promising models (2 per category) were selected based on the following criteria: r2 ≥ 0.90, inclusion of trough concentration (C0), and time points within 4 hours postdose. The predictive performance of these LSSs was evaluated in an independent set of data by measuring the mean prediction error and the root mean squared prediction error. RESULTS: Five models including 2-4 time points predicted AUC0-12 with a ±15% error limit. Bias (mean prediction error) and precision (root mean squared prediction error) of LSS involving C0, C1, and C4 (AUCpredicted = 9.30 + 3.69 × C0 + 2.19 × C1 + 4.69 × C4) were -4.98% and 8.29%, respectively. Among single time point LSSs, the model using C0 had a poor correlation with AUC0-12 (r2 = 0.53), whereas the one with C4 had the highest correlation with tacrolimus exposure (r2 = 0.84). CONCLUSIONS: Trough concentration is a poor predictor of tacrolimus AUC0-12 in pediatric liver transplant recipients. However, LSSs using 2-4 concentration-time points obtained within 4 hours postdose provide a reliable and convenient method to predict tacrolimus exposure in this population. The proposed LSSs represent an important step that will allow the undertaking of prospective trials aiming to better define tacrolimus target AUC in pediatric liver transplant recipients and to determine whether AUC-guided monitoring is superior to C0-based monitoring in terms of efficacy and safety.

Efficacy and safety of low-dose versus high-dose hydrocortisone to treat hypotension in neonates: a protocol for a systematic review and meta-analysis.

BACKGROUND: Impaired adrenal function is a well-described entity in critically ill term and preterm neonates with systemic hypotension. The standard treatment for neonatal hypotension includes volume expanders and vasopressors. Recent evidence supports the use of glucocorticoids for the primary or rescue treatment of neonatal hypotension associated with impaired adrenal function. However, inconsistency regarding the prescribed dosing regimen to provide the best balance between efficacy and safety in this vulnerable population remains an area of concern. METHODS: We will conduct a systematic review and meta-analysis to evaluate low-dosing compared with high-dosing regimens of hydrocortisone for the treatment of hypotension in critically ill term, preterm and very low birth weight neonates. Ovid MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and Web of Science will be searched from inception to November 2021. Study screening and selection will be completed as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. Our primary outcomes will be (1) an improvement in end-organ perfusion, defined as an increase in blood pressure along with an increase in urine output or a reduction in serum lactate and (2) mortality prior to discharge. Our secondary outcomes will be the development of (1) major neurosensory abnormality, (2) bronchopulmonary dysplasia and (3) the occurrence of adverse events. DISCUSSION: Hydrocortisone may be beneficial in the treatment of hypotension associated with impaired adrenal function among critically ill neonates. However, its optimal dosing to balance desired efficacy with the risk of adverse events is yet to be determined. Our systematic review and meta-analysis aims to address this evidence gap, providing valuable knowledge for a large audience, including guideline developers, policy-makers and clinicians. PROSPERO REGISTRATION NUMBER: This protocol is submitted for registration to the international database of prospectively registered systematic reviews (PROSPERO, awaiting registration number).