Evaluating palatability in young children: a mini-review of relevant physiology and assessment techniques.

The palatability of pediatric pharmaceutical products plays a crucial role of influencing medication compliance. Rejection of unpalatable medications can potentially lead to treatment failure which can have immediate and delayed consequences. With advances in both the food and pharmaceutical industries, the systematic assessment of palatability has gained importance. Various methods such as visual analogue scales, facial hedonic scales, and facial recognition software, have been employed to assess palatability. While proven to be useful, these methods have significant limitations and may not be workable for young children. Despite these advancements, a universally accepted "gold standard" for assessing pediatric mediation palatability, recognized by drug regulatory agencies, is yet to be established.

Utility of the 13 C-pantoprazole breath test as a CYP2C19 phenotyping probe for children.

The 13 C-pantoprazole breath test (PAN-BT) is a safe, noninvasive, in vivo CYP2C19 phenotyping probe for adults. Our objective was to evaluate PAN-BT performance in children, with a focus on discriminating individuals who, according to guidelines from the Clinical Pharmacology Implementation Consortium (CPIC), would benefit from starting dose escalation versus reduction for proton pump inhibitors (PPIs). Children (n = 65, 6-17 years) genotyped for CYP2C19 variants *2, *3, *4, and *17 received a single oral dose of 13 C-pantoprazole. Plasma concentrations of pantoprazole and its metabolites, and changes in exhaled 13 CO2 (termed delta-over-baseline or DOB), were measured 10 times over 8 h using high performance liquid chromatography with ultraviolet detection and spectrophotometry, respectively. Pharmacokinetic parameters of interest were generated and DOB features derived using feature engineering for the first 180 min postadministration. DOB features, age, sex, and obesity status were used to run bootstrap analysis at each timepoint (Ti ) independently. For each iteration, stratified samples were drawn based on genotype prevalence in the original cohort. A random forest was trained, and predictive performance of PAN-BT was evaluated. Strong discriminating ability for CYP2C19 intermediate versus normal/rapid metabolizer phenotype was noted at DOBT30 min (mean sensitivity: 0.522, specificity: 0.784), with consistent model outperformance over a random or a stratified classifier approach at each timepoint (p < 0.001). With additional refinement and investigation, the test could become a useful and convenient dosing tool in clinic to help identify children who would benefit most from PPI dose escalation versus dose reduction, in accordance with CPIC guidelines.

Peppermint oil effects on the gut microbiome in children with functional abdominal pain.

Peppermint oil (PMO) is effective in the treatment of functional abdominal pain disorders, but its mechanism of action is unclear. Evidence suggests PMO has microbicidal activity. We investigated the effect of three different doses of PMO on gut microbiome composition. Thirty children (7-12 years of age) with functional abdominal pain provided a baseline stool sample prior to randomization to 180, 360, or 540 mg of enteric coated PMO (10 participants per dose). They took their respective dose of PMO (180 mg once, 180 mg twice, or 180 mg thrice daily) for 1 week, after which the stool collection was repeated. Baseline and post-PMO stools were analyzed for microbiome composition. There was no difference in alpha diversity of the gut microbiome between the baseline and post-PMO treatment. Principal coordinate analysis revealed no significant difference in overall bacterial composition between baseline and post-PMO samples, as well as between the PMO dose groups. However, the very low abundant Collinsella genus and three operational taxonomic units (one belonging to Collinsella) were significantly different in samples before and after PMO treatment. The Firmicutes/Bacteroidetes ratio was lower in children who received 540 mg of PMO compared to the 180 mg and 360 mg dose groups (p = 0.04). Network analysis revealed separation between pre- and post-PMO fecal samples with the genus Collinsella driving the post-PMO clusters. PMO administration appeared to impact only low abundance bacteria. The 540 mg PMO dose differentially impacted the Firmicutes/Bacteroidetes ratio. A higher dose and/or longer duration of treatment might yield different results.

Randomised trial: Peppermint oil (menthol) pharmacokinetics in children and effects on gut motility in children with functional abdominal pain.

AIMS: Little is known regarding the pharmacokinetics and pharmacodynamics of menthol, the active ingredient in peppermint oil (PMO). Our aim was to investigate the pharmacokinetics of menthol at 3 dose levels in children and determine their effects on gut motility and transit. METHODS: Thirty children ages 7-12 years with functional abdominal pain underwent wireless motility capsule (WMC) testing. Approximately 1 week later they were randomized to 180, 360 or 540 mg of enteric coated PMO (10 participants per dose). Menthol pharmacokinetics were determined via blood sampling over 24 hours. They then took their respective dose of PMO (180 mg once, 180 mg twice or 180 mg thrice daily) for 1 week during which time the WMC test was repeated. RESULTS: Evaluable area under the plasma concentration vs. time curve (AUClast ) data were available in 29 of 30 participants. A direct linear relationship (apparent dose-proportionality for systemic menthol exposure) was observed between PMO dose and menthol systemic exposure with mean elimination half-life 2.1, 3.5 and 4.6 hours for the 180, 360 and 540 mg doses, respectively. WMC technical issues precluded complete motility data in all participants. Colonic transit time was inversely related to AUClast (P = .003); transit time in other regions was not affected. In contrast, stomach, small bowel and whole gut (but not colonic) contractility positively correlated with menthol AUClast (P < .05). CONCLUSION: Pharmacokinetics and pharmacodynamics of menthol derived from PMO demonstrated apparent dose-proportionality. A higher dose of PMO may be needed to achieve maximal gut response. www.clinicaltrials.gov NCT03295747.

Clearance of buprenorphine during pregnancy and neonatal outcomes.

Buprenorphine is emerging as the preferred pharmacologic treatment for opioid use disorder during pregnancy. We examined the relative plasma clearance of buprenorphine (BUP) across pregnancy. Pregnant women with opioid use disorder participating in a prospective, observational study from 2013 to 2016 on stress in pregnancy who were receiving BUP for opioid use disorder were included. Women with an active eating disorder or suicidal ideation were excluded. Research visits occurred at 4-6-week intervals across pregnancy and the early postpartum period and included medication exposure history and blood samples. All assays for BUP serum concentrations at steady state were completed. Relative weight-adjusted clearance (Cl) was calculated using Cl = (daily dose [mg]/ body weight [kg])/serum concentration [ng/ml]. We collected 112 maternal blood samples from 29 women throughout pregnancy and the postpartum period. Serum concentrations for BUP ranged from < 0.2 to 15.8 ng/ml. Eleven women, with greater than three collected samples, increased their daily dose of BUP during pregnancy; however, there were no significant differences in relative clearance of BUP across this same period. This data suggests that women with opioid use disorder receiving BUP did not demonstrate a significant increase in BUP clearance across pregnancy despite increase in dosages during pregnancy. When selecting an appropriate BUP dosage for management of perinatal opioid use disorder, gestational stage appears not to be an important covariate and should be based on an individualized approach.

A Pilot Comparison of High- Versus Low-Tech Palatability Assessment Tools in Young Children.

BACKGROUND: Medication refusal in children is largely driven by aversive taste profiles, which in turn influence adherence and therapeutic outcomes. However, there are no standardized methods for evaluating taste in young children. This study compares facial recognition technology with three hedonic visual scales in this population. METHODS: Children, 3-7 years of age, were enrolled with informed parental permission into an institutional review board-approved, double-blind, randomized investigation. Each child received three test articles: prednisone (bitter), simple syrup (sweet), and filtered water (neutral), with an appropriate washout. Facial recognition software (Noldus FaceReader 7) recorded facial expression and intensity for 30-60 s after administration. Participants subsequently rated taste using three hedonic scales (5-point Sjövall and 5- and 3-point TASTY) and responded to simple questions on their perception of the test article. Repeated measures analysis of variance and multiple regression analysis were used to explore associations between palatability measures. RESULTS: Twelve children (seven males: ten white and two black) completed the study without adverse effects. There were no significant differences in participant characteristics by randomization sequence. The three hedonic scales tracked similarly for each test substance, with correlations between the 5-point scales (r = 0.899) comparable to those between the 3- and 5-point scales (r = 0.860-0.903). Hedonic scales appeared more reliable in assessing taste response than facial recognition, which did not effectively discriminate positive and negative responses. CONCLUSIONS: Our experience suggests that the TASTY scales appear to offer the greatest promise for assessing palatability in future clinical use.

Bioavailability testing of a newly developed clindamycin oral suspension in a pediatric porcine model.

Background: Clindamycin's bitter taste and odor is known to affect treatment adherence in children. Recently, a formulation of clindamycin HCl complexed with ion exchange resin IRP 69 was shown to mask the bitter taste. Because of the potential benefit of this formulation for children, a pilot study using a porcine model was conducted to evaluate its relative bioavailability. Methods: A randomized two-way crossover study design using six (n = 6) healthy male piglets 10-12 kg was used to evaluate the absorption profiles and pharmacokinetic parameters of clindamycin from the resinate complex formulation (Test) compared to a commercialized reference suspension. A dose of 15 mg/kg was administered orally by gastric gavage to each piglet followed by repeated blood sampling over 12 h. A wash-out period of 48 h occurred between treatments. Plasma concentration vs. time data was analyzed by non-compartmental analysis. Results: The mean relative bioavailability of clindamycin from the resinate formulation was 78.8%. A two-tailed, paired Student t test yielded a p < 0.05 for AUC∞ and Tmax parameters. A two one-sided test (TOST) suggested a difference in AUC∞ and Cmax for the Test formulation compared to the reference formulation according to the FDA's criteria for bioequivalence. Conclusion: The bioavailability of clindamycin from this novel oral formulation supports continued evaluation of the drug in humans for potential pediatric applications.

Evaluating metronidazole as a novel, safe CYP2A6 phenotyping probe in healthy adults.

AIMS: CYP2A6 is a genetically polymorphic enzyme resulting in differential substrate metabolism and health behaviours. Current phenotyping probes for CYP2A6 exhibit limitations related to procurement (deuterated cotinine), toxicity (coumarin), specificity (caffeine) and age-appropriate administration (nicotine, NIC). In vitro, CYP2A6 selectively forms 2-hydroxymetronidazole (2HM) from metronidazole (MTZ). The purpose of this study was to evaluate MTZ as a CYP2A6 phenotyping probe drug in healthy adults against the well-established method of measuring trans-3-hydroxycotinine (3HC)/cotinine (COT). METHODS: A randomized, cross-over, pharmacokinetic study was completed in 16 healthy, nonsmoking adults. Separated by a washout period of at least 2 weeks, MTZ 500 mg and NIC gum 2 mg were administered and plasma was sampled over 48 hours and 8 hours, respectively. Correlations of plasma metabolite/parent ratios (2HM/MTZ; 3HC/COT) were assessed by Pearson coefficient. CYP2A6 genotyping was conducted and incorporated as a variable of plasma ratio response. RESULTS: Correlations between the plasma ratio 2HM/MTZ and 3HC/COT were ≥ 0.9 at multiple time points (P < 0.001), demonstrating a wide window during which 2HM/MTZ can be queried post-MTZ dose. CYP2A6 genotype had significant impacts on both MTZ and NIC phenotyping ratios with decreased activity predicted phenotypes demonstrating 2HM/MTZ ratios ≤58% and 3HC/COT ratios ≤56% compared with extensive activity predicted phenotypes at all time points examined in the study (P < 0.05). No adverse events were reported in the MTZ arm while 38% (n = 6) of participants reported mild adverse events in the NIC arm. CONCLUSIONS: Metronidazole via 2HM/MTZ performed well as a novel, safe phenotyping probe for CYP2A6 in healthy adults.

How to Conduct Clinical Trials in Children: A Tutorial.

Despite a growing interest in, and commitment to, implementing pediatric clinical trials, approximately one in every five trials in children fails because of inappropriate study design, suboptimal experiment planning, or inadequate participant enrollment. This tutorial, presented from the perspectives of seasoned pediatric investigators, an experienced research coordinator, and an established pediatric clinical trials network, is designed to provide practical guidance for successfully implementing pediatric clinical trials at an academic center or another comparable institution.

Developmental Changes in Pharmacokinetics and Pharmacodynamics.

Effective drug therapy to optimally influence disease requires an understanding of a drug's pharmacokinetic, pharmacodynamic, and pharmacogenomic interrelationships. In pediatrics, age is a continuum that can and does add variability in drug disposition and effect. This article addresses the many important factors that influence drug disposition and effect relative to age. What is known about the influence of maturation on the processes of drug absorption, distribution, metabolism, excretion, and drug receptor dynamics are outlined. Our state of understanding of many of these factors remains in flux, however, and only with additional study will we be able to better anticipate and model drug-response relationships across the age continuum. Being able to continuously improve our care of the ill pediatric patient while simultaneously being able to accurately determine the utility of new drugs and chemical entities in this population requires our enhanced understanding of these disposition characteristics.

A Population-Based Pharmacokinetic Model Approach to Pantoprazole Dosing for Obese Children and Adolescents.

BACKGROUND AND AIMS: Pharmacokinetic data for proton pump inhibitors (PPIs), acid-suppression drugs commonly prescribed to children, are lacking for obese children who are at greatest risk for acid-related disease. In a recent multi-center investigation, we demonstrated decreased, total body weight adjusted, apparent clearance (CL/F) of the PPI pantoprazole for obese children compared with their non-obese peers. Subsequently, we developed a population-based pharmacokinetic (PopPK) model to characterize pantoprazole disposition and evaluated appropriate pantoprazole dosing strategies for obese pediatric patients, using simulation. METHODS: Pharmacokinetic data from the only prospective study of PPIs in obese children (aged 6-17 years; n = 40) included 273 pantoprazole and 256 pantoprazole-sulfone plasma concentrations, after single oral-dose administration, and were used for pantoprazole model development and covariate analysis (NONMEM®). Model evaluation was performed via bootstrapping and predictive checks, and the final model was applied to simulate systemic pantoprazole exposures for common dosing scenarios. RESULTS: A two-compartment PopPK model, which included CYP2C19 genotype and total body weight, provided the best fit. Resultant, typical, weight-normalized pantoprazole parameter estimates were different than previously reported for children or adults, with significantly reduced pantoprazole CL/F for obese children. Of the dosing scenarios evaluated, the weight-tiered approach, approved by the US Food and Drug Administration, achieved pantoprazole exposures [area under the curve (AUC0-∞)] within ranges previously reported as therapeutic, without over- or under-prediction for obese children. CONCLUSIONS: Our data argue against empiric dose escalation of PPIs for obese children and support current FDA-approved pediatric weight-tiered dosing for pantoprazole; however, 3- to 5-fold inter-individual variability in pantoprazole AUC0-∞ remained using this dosing approach.

Obese Children Require Lower Doses of Pantoprazole Than Nonobese Peers to Achieve Equal Systemic Drug Exposures.

OBJECTIVE: To assess appropriate pantoprazole dosing for obese children, we conducted a prospective pharmacokinetics (PK) investigation of pantoprazole in obese children, a patient population that is traditionally excluded from clinical trials. STUDY DESIGN: A total of 41 obese children (6-17 years of age), genotyped for CYP2C19 variants *2, *3, *4, and *17, received a single oral dose of pantoprazole, ~1.2 mg/kg lean body weight (LBW), with LBW calculated via a validated formula. Ten post-dose pantoprazole plasma concentrations were measured, and PK variables generated via noncompartmental methods (WinNonlin). Linear and nonlinear regression analyses and analyses of variance were used to explore obesity, age, and CYP2C19 genotype contribution to pantoprazole PK. PK variables of interest were compared with historic nonobese peers treated with pantoprazole. RESULTS: Independent of genotype, when normalized to dose per kg total body weight, pantoprazole apparent clearance and apparent volume of distribution were significantly lower (P < .05) and systemic exposure significantly higher (P < .01) in obese vs nonobese children. When normalized per kg LBW, these differences were not evident in children ≥12 years of age and markedly reduced in children <12 years of age. CONCLUSIONS: LBW dosing of pantoprazole led to pantoprazole PK similar to nonobese peers. Additional factors, other than body size (eg, age-related changes in CYP2C19 activity), appear to affect pantoprazole PK in children <12 years of age. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02186652.

Palatability of a novel oral formulation of prednisone in healthy young adults.

OBJECTIVES: Prednisone is a widely used anti-inflammatory for a variety of conditions. While oral liquid formulations of prednisone enable weight-based dosing, children frequently find them to be objectionable due to bitter taste. This limitation of prednisone can adversely impact patient acceptance and may result in non-compliance. Efforts to mask flavours often result in poorly controlled, heterogeneous particle distributions and can provide ineffective taste masking. The present work utilized a novel drug delivery technology developed by Orbis Biosciences, Inc., to create an oral taste-masked formulation of prednisone. METHODS: The study examined the palatability of Orbis' microsphere prednisone formulation in healthy young adults (n = 24). Four test articles were used in the study including a reference formulation (Roxanne Laboratories), a control and the test formulation (Orbis) prepared in two different ways. Study participants were randomized in a crossover design. KEY FINDINGS: Results indicated that the test prednisone formulation was indistinguishable from the control, and both were preferable to the reference formulation in every category of palatability assessed using a validated 9-point Hedonic Scale. The data also suggested that preparing the microsphere suspension immediately before administration results in the most ideal palatability properties. CONCLUSIONS: In conclusion, the novel microsphere formulation technology was effective in taste-masking prednisone.

Pharmacokinetics of two 6-mercaptopurine liquid formulations in children with acute lymphoblastic leukemia.

BACKGROUND: A liquid formulation of 6-mercaptopurine (6-MP) was recently approved by the Food and Drug Administration (Purixan®) based on bioavailability (BA) data from healthy adults. We examined the pharmacokinetics (PK) and BA of 6-MP in children with acute lymphoblastic leukemia (ALL) comparing a marketed tablet, two extemporaneously prepared liquid formulations, and data from the approved liquid formulation. METHODS: Twenty-two children (6-17 years) participated in a randomized two-way, crossover study of two cohorts. Group 1 (n = 11; five males) received a 5 mg/ml liquid formulation and the marketed 50 mg 6-MP tablet on separate occasions, and Group 2 (n = 11; five males) received a 50 mg/ml liquid formulation and the marketed tablet. The usual prescribed 6-MP dose (25-115 mg/m2 ) was given after an 8-hr fast. Serial blood samples were collected over 8 hr postdose. Plasma 6-MP concentrations were determined using a good laboratory practice (GLP)-validated liquid chromatography-tandem mass spectrometry method. PK parameters were calculated using noncompartmental analysis and compared within and between cohorts, and thiopurine methyltransferase (TPMT) genotype was analyzed. RESULTS: No patient had a TPMT genotype reflective of a poor metabolizer phenotype. Comparison of PK parameters between 5 and 50 mg/ml treatments revealed significant differences (P <0.05) in AUCN (where AUC is area under the curve), CmaxN , and Tmax . Comparisons within each group revealed significant differences in AUC0-∞ and Tmax in the 5 mg/ml group. CONCLUSIONS: Pharmacokinetic profiles of 6-MP established in healthy adults with the approved liquid formulation may not reflect the PK profile in children with ALL. Formulation-specific differences in PK may significantly impact the dose-exposure profile in these children and must be considered.

Decreased Pregnane X Receptor Expression in Children with Active Crohn's Disease.

Expression of the pregnane X receptor (PXR) has been reported to be decreased in animal models of inflammatory bowel disease (IBD). To investigate the differential expression of PXR in children with Crohn's disease, a type of IBD, RNA was extracted from archived intestinal biopsies from 18 children with Crohn's disease (CD) and 12 age- and sex-matched controls (aged 7-17yrs). The aim of this investigation was to compare the relative mRNA expression of PXR, cytochrome p450 3A4 (CYP3A4), and villin 1 (VIL1) (a marker of epithelial cell integrity) in the inflamed terminal ileum (TI) versus noninflamed duodenum of children with CD. Relative expression was determined via reverse transcription real-time quantitative polymerase chain reaction, data normalized to glyceraldehyde 3-phosphate dehydrogenase, and differences in gene expression explored via paired t tests. PXR expression was decreased in the inflamed TI versus noninflamed duodenum (TI = 1.88 ± 0.89 versus duodenum = 2.5 ± 0.67; P < 0.001) in CD, but not controls (TI = 2.11 ± 0.41 versus duodenum = 2.26 ± 0.61; P = 0.52). CYP3A4 expression was decreased in CD (TI = -0.89 ± 3.11 versus duodenum = 1.90 ± 2.29; P < 0.05), but not controls (TI = 2.46 ± 0.51 versus duodenum = 2.60 ± 0.60; P = 0.61), as was VIL1 (CD TI = 3.80 ± 0.94 versus duodenum = 4.61 ± 0.52; P < 0.001; controls TI = 4.30 ± 0.35 versus duodenum = 4.47 ± 0.40; P = 0.29). PXR expression correlated with VIL1 (r = 0.78, P = 0.01) and CYP3A4 (r = 0.52, P = 0.01) expression. In conclusion, PXR, CYP3A4, and VIL1 expression was decreased only in the actively inflamed small intestinal tissue in children with CD. Our findings suggest that inflammation has the potential to influence expression of genes, and potentially intestinal proteins, important to drug disposition and response. The observed differential patterns of gene expression support further investigation of the role of PXR in the pathogenesis and/or treatment of pediatric Crohn's disease.

Clinical and Pharmacologic Considerations for Guanfacine Use in Very Young Children.

OBJECTIVE: Guanfacine, in the immediate release form, remains a commonly used medication for the treatment of clinically significant hyperactivity, impulsivity, or disruptive behaviors. This article reviews the available literature regarding guanfacine use in very young children (<6 years of age), and explores some of the factors that may uniquely impact the clinical pharmacology of guanfacine in very young children and that deserve consideration when it is used in this patient population. METHODS: The authors performed electronic literature searches in PubMed through October 2015 using the terms attention-deficit/hyperactivity disorder, guanfacine, and alpha agonists. We also performed an informal review of the literature and used selected articles from relevant reference lists. The result was a broad, qualitative review of the literature, with a focus on specific factors regarding guanfacine use in very young children. RESULTS: Despite the fact that guanfacine is commonly used in very young children, there is a paucity of published studies that looked specifically at its use in this population. In reviewing the pharmacology of guanfacine, there are specific factors that may play a unique role in its disposition in very young children. CONCLUSIONS: Guanfacine is an important medication option in very young children; however, there is a significant pharmacologic "information gap," and further research is needed to help establish appropriate, safe, and effective dosing of guanfacine in this population.