Summary of the National Institute of Child Health and Human Development-best pharmaceuticals for Children Act Pediatric Formulation Initiatives Workshop-Pediatric Biopharmaceutics Classification System Working Group

State of the art in pediatric nanomedicines

In recent years, the continuous development of innovative nanopharmaceuticals is expanding their biomedical and clinical applications. Nanomedicines are being revolutionized to circumvent the limitations of unbound therapeutic agents as well as overcome barriers posed by biological interfaces at the cellular, organ, system, and microenvironment levels. In many ways, the use of nanoconfigured delivery systems has eased challenges associated with patient differences, and in our opinion, this forms the foundation for their potential usefulness in developing innovative medicines and diagnostics for special patient populations. Here, we present a comprehensive review of nanomedicines specifically designed and evaluated for disease management in the pediatric population. Typically, the pediatric population has distinguishing needs relative to those of adults majorly because of their constantly growing bodies and age-related physiological changes, which often need specialized drug formulation interventions to provide desirable therapeutic effects and outcomes. Besides, child-centric drug carriers have unique delivery routes, dosing flexibility, organoleptic properties (e.g., taste, flavor), and caregiver requirements that are often not met by traditional formulations and can impact adherence to therapy. Engineering pediatric medicines as nanoconfigured structures can potentially resolve these limitations stemming from traditional drug carriers because of their unique capabilities. Consequently, researchers from different specialties relentlessly and creatively investigate the usefulness of nanomedicines for pediatric disease management as extensively captured in this compilation. Some examples of nanomedicines covered include nanoparticles, liposomes, and nanomicelles for cancer; solid lipid and lipid-based nanostructured carriers for hypertension; self-nanoemulsifying lipid-based systems and niosomes for infections; and nanocapsules for asthma pharmacotherapy.

Adult and pediatric physiologically-based biopharmaceutics modeling to explain lamotrigine immediate release absorption process

Physiologically-based biopharmaceutics modeling (PBBM) has potential to accelerate the development of new drug and formulations. An important application of PBBM is for special populations such as pediatrics that have pharmacokinetics dependent on the maturation process. Lamotrigine (LTG) is a Biopharmaceutics Classification System (BCS) II drug and is widely prescribed. Therefore, the goal of this study was to assess the biopharmaceutics risk of the low-soluble drug LTG when the ontogeny on gastrointestinal tract (GIT) physiological parameters are considered. An oral physiologically-based pharmacokinetic model and a PBBM were developed and verified using GastroPlus™ software for both adults and children (2-12 years old, 12-52 kg). The biopharmaceutics properties and GIT physiological parameters were evaluated by sensitivity analysis. High doses were simulated assuming a worst case scenario, that is, the dose of 200 mg for adults and 5 mg/kg (up to the maximum of 200 mg) for 2-year-old children. Although several authors have suggested that ontogeny may have an effect on gastrointestinal fluid volume, our study found no evidence of interference between fluid and dose volumes with in vivo dissolution of LTG. The most impactful parameter was found to be the gastric transit time. Therefore, the hypothesis is developed to examine whether LTG exhibits characteristics of a BCS II classification in vitro while showing BCS I-like behavior in vivo. This hypothesis could act as a base for conducting novel studies on model-informed precision dosing, tailored to specific populations and clinical conditions. In addition, it could be instrumental in assessing the influence of various release profiles on in vivo performance for both adult and pediatric populations.

Solubility of lamotrigine in age-specific biorelevant media that simulated the fasted- and fed-conditions of the gastric and intestinal environments in pediatrics and adults: implications for traditional, re-formulated, modified, and new oral formulations

BACKGROUND

Lamotrigine is an effective antiseizure medication that can be used in the management of focal and generalized epilepsies in pediatric patients. This study was conducted to quantify and compare the solubility of lamotrigine in age-specific biorelevant media that simulated the fasted and fed conditions of the gastric and intestinal environments in pediatrics and adults. Another aim was to predict how traditional, re-formulated, modified, and new oral formulations would behave in the gastric and intestinal environments across different age groups.

METHODS

Solubility studies of lamotrigine were conducted in 16 different age-specific biorelevant media over the pH range and temperature specified by the current biopharmaceutical classification system-based criteria. The age-specific biorelevant media simulated the environments in the stomach and proximal gastrointestinal tract in both fasted and fed conditions of adults and pediatric sub-populations. The solubility of lamotrigine was determined using a pre-validated HPLC-UV method.

RESULTS

Lamotrigine showed low solubility in the 16 age-specific biorelevant media as indicated by a dose number of > 1. There were significant age-specific variabilities in the solubility of lamotrigine in the different age-specific biorelevant media. Pediatric/adult solubility ratios of lamotrigine fell outside the 80-125% range in 6 (50.0%) and were borderline in 3 (25.0%) out of the 12 compared media. These ratios indicated that the solubility of lamotrigine showed considerable differences in 9 out of the 12 (75.0%) of the compared media.

CONCLUSION

Future studies are still needed to generate more pediatric biopharmaceutical data to help understand the performances of oral dosage forms in pediatric sub-populations.

Personalizing atomoxetine dosing in children with ADHD: what can we learn from current supporting evidence

PURPOSE

There is marked heterogeneity in treatment response of atomoxetine in patients with attention deficit/hyperactivity disorder (ADHD), especially for the pediatric population. This review aims to evaluate current evidence to characterize the dose-exposure relationship, establish clinically relevant metrics for systemic exposure to atomoxetine, define a therapeutic exposure range, and to provide a dose-adaptation strategy before implementing personalized dosing for atomoxetine in children with ADHD.

METHODS

A comprehensive search was performed across electronic databases (PubMed and Embase) covering the period of January 1, 1985 to July 10, 2022, to summarize recent advances in the pharmacokinetics, pharmacogenomics/pharmacogenetics (PGx), therapeutic drug monitoring (TDM), physiologically based pharmacokinetics (PBPK), and population pharmacokinetics (PPK) of atomoxetine in children with ADHD.

RESULTS

Some factors affecting the pharmacokinetics of atomoxetine were summarized, including food, CYP2D6 and CYP2C19 phenotypes, and drug‒drug interactions (DDIs). The association between treatment response and genetic polymorphisms of genes encoding pharmacological targets, such as norepinephrine transporter (NET/SLC6A2) and dopamine β hydroxylase (DBH), was also discussed. Based on well-developed and validated assays for monitoring plasma concentrations of atomoxetine, the therapeutic reference range in pediatric patients with ADHD proposed by several studies was summarized. However, supporting evidence on the relationship between systemic atomoxetine exposure levels and clinical response was far from sufficient.

CONCLUSION

Personalizing atomoxetine dosage may be even more complex than anticipated thus far, but elucidating the best way to tailor the non-stimulant to a patient's individual need will be achieved by combining two strategies: detailed research in linking the pharmacokinetics and pharmacodynamics in pediatric patients, and better understanding in nature and causes of ADHD, as well as environmental stressors.

Age and gender-specific reference intervals for a panel of lysophosphatidylcholines estimated by tandem mass spectrometry in dried blood spots

Background and objectives

Very long-chain fatty acyl-lysophosphatidylcholines (VLCFA-LysoPCs) are measured in dried blood spots (DBS) for identifying X-linked adrenoleukodystrophy (X-ALD) and other inherited peroxisomal disorders. Our study aimed to establish age- and gender-specific reference intervals for a panel of LysoPCs measured by tandem mass spectrometry in DBS.

Methods

LysoPCs (26:0-, 24:0-, 22:0- and 20:0-LysoPCs) were estimated by flow injection analysis-tandem mass spectrometry (FIA-MS/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods in 3.2 mm blood spots of 2689 anonymized, putative normal subjects (1375 males, and 1314 females) aged between 2 days and 65 years. Samples were divided into groups: Neonates (0-1month), Infants (>1m-1year), Children and Adolescents (>1-18years), and Adults (>18years). Reference intervals were determined using the percentile approach and represented as the median with the 1^st and 99^th percentile lower and upper limits.

Results

The percentage coefficient of variation (CV) for repeatability assays of internal and external quality control samples were within acceptable limits. Significant differences (P <0.0001, P <0.01) were observed in the concentrations of 26:0-, 24:0-, 22:0- and 20:0-LysoPCs and their ratios, 26:0/22:0-, 24:0/22:0-, 26:0/20:0-and 24:0/20:0-LysoPC in neonates and infants when compared to children, adolescents, and adults. Levels of 26:0-, 24:0- and 22:0-LysoPCs decreased, whereas 20:0-LysoPC increased with age. There were no significant gender-based differences in the concentration of LysoPCs.

Conclusion

We established age- and gender-specific reference intervals for a panel of LysoPCs in DBS. These reference values would be helpful when interpreting LysoPC values in DBS during screening for X-ALD and other peroxisomal disorders.

Oral drug delivery strategies for development of poorly water soluble drugs in paediatric patient population

Selecting the appropriate formulation and solubility-enabling technology for poorly water soluble drugs is an essential element in the development of formulations for paediatric patients. Different methodologies and structured strategies are available to select a suitable approach and guide formulation scientists for development of adult formulations. However, there is paucity of available literature for selection of technology and overcoming the challenges in paediatric formulation development. The need for flexible dosing, and the limited knowledge of the safety of many formulation excipients in paediatric subjects, impose significant constraints and in some instances require adaptation of the approaches taken to formulating these drugs for the adult population. Selection of the best drug delivery system for paediatrics requires an efficient, systematic approach that considers a drug's physical and chemical properties and the targeted patient population's requirements. This review is a step towards development of a strategy for the design of solubility enhancing paediatric formulations of highly insoluble drugs. The aim of this review is to provide an overview of different approaches and strategies to consider in order to assist development of paediatric formulation for poorly water-soluble drugs with the provision of examples of some marketed products. In addition, it provides recommendations to overcome the range of challenges posed by these strategies and adaptations of the adult approach/product presentation required to enable paediatric drug development and administration.

Manipulations and age-appropriateness of oral medications in pediatric oncology patients in Sweden: Need for personalized dosage forms

Due to the lack of age-appropriate formulations for children, healthcare professionals and caregivers frequently manipulate dosage forms to facilitate oral administration and obtain the required dose. In this study, we investigated drug manipulation and age-appropriateness of oral medications for pediatric oncology patients with the aim of identifying the therapeutic needs for personalized dosage forms. An observational study at a pediatric oncology ward, combined with analysis of the age-appropriateness of the oral medications, was performed. Nurses frequently manipulated solid dosage forms to administer them via enteral feeding tubes. Of the active pharmaceutical ingredients (APIs) assessed for age-appropriateness, 74% (29 of 39) were identified to need personalization, either because of lack of child-friendly dosage form, suitable dosage strength, or both. Most APIs, due to limited solubility, were sensitive to formulation changes, such as drug manipulation. This study demonstrates problems and therapeutic needs regarding oral dosage forms in treatment of children with cancer. Expertise in formulation design, new manufacturing technologies, and patient-centered information are needed to address age-appropriate formulations for children.

Drug solubilization during simulated pediatric gastro-intestinal digestion

To increase the understanding of how drugs behave following oral administration to the pediatric population, the aim of the present study was to investigate the solubilization of fluconazole and ibuprofen during simulated gastro-intestinal (GI) digestion, using an immediate transfer model mimicking pediatric GI digestion. The effects of infant formula and digestion, on the drug solubilization, were studied using simulated fasted and fed state digestion media in the presence and absence of digestive enzymes. Additionally, the effect of digestion media viscosity on the solubilization process was investigated. It was found that the solubilization of fluconazole was unaffected by all tested parameters, as the entire estimated dose equivalent was solubilized in the aqueous phase throughout all digestion studies. In contrast, the solubilization of ibuprofen was affected by all the tested parameters, i.e. in the fasted state, the solubilization of ibuprofen was limited by its solubility in the aqueous phase of the simulated GI digestion media, whereas the solubilization in the fed state was affected by drug partitioning between the lipid and the aqueous phases, and therefore by the digestion of the lipid phase. Adding Nestlé Thicken Up™, containing xanthan gum as a thickening agent, to the digestion medium increased its viscosity, which in turn resulted in a reduced initial digestion rate, increased pH fluctuations, as well as high variability in all drug solubilization data as evident in large standard deviations. Furthermore, the increased digestion medium viscosity decreased the drug recovery from the combined pellet and aqueous phase. The observed viscosity effects might translate into a more variable and lower oral bioavailability.

Development of a Pediatric Relative Bioavailability/Bioequivalence Database and Identification of Putative Risk Factors Associated With Evaluation of Pediatric Oral Products

Generally, bioequivalence (BE) studies of drug products for pediatric patients are conducted in adults due to ethical reasons. Given the lack of direct BE assessment in pediatric populations, the aim of this work is to develop a database of BE and relative bioavailability (relative BA) studies conducted in pediatric populations and to enable the identification of risk factors associated with certain drug substances or products that may lead to failed BE or different pharmacokinetic (PK) parameters in relative BA studies in pediatrics. A literature search from 1965 to 2020 was conducted in PubMed, Cochrane Library, and Google Scholar to identify BE studies conducted in pediatric populations and relative BA studies conducted in pediatric populations. Overall, 79 studies covering 37 active pharmaceutical ingredients (APIs) were included in the database: 4 bioequivalence studies with data that passed BE evaluations; 2 studies showed bioinequivalence results; 34 relative BA studies showing comparable PK parameters, and 39 relative BA studies showing differences in PK parameters between test and reference products. Based on the above studies, common putative risk factors associated with differences in relative bioavailability (DRBA) in pediatric populations include age-related absorption effects, high inter-individual variability, and poor study design. A database containing 79 clinical studies on BE or relative BA in pediatrics has been developed. Putative risk factors associated with DRBA in pediatric populations are summarized.

Evaluating Solubility of Celecoxib in Age-Appropriate Fasted- and Fed-State Gastric and Intestinal Biorelevant Media Representative of Adult and Pediatric Patients: Implications on Future Pediatric Biopharmaceutical Classification System

Prediction of performance of traditional, reformulated, and novel oral formulations in adults and pediatrics is of great importance. This study was conducted to assess solubility of celecoxib in age-appropriate fasted- and fed-state gastric and intestinal biorelevant media, classify celecoxib into biopharmaceutical classification system (BCS), and assess the effects of age-related developmental changes in the composition and volume of gastrointestinal fluids on the solubility and performance of oral formulations containing celecoxib. Solubility of celecoxib was assessed at 37°C in the pH range specified by the BCS-based criteria in 13 age-appropriate biorelevant media reflective of the gastric and proximal small intestinal environment in both fasted and fed states in adults and different pediatric subpopulations. A validated HPLC-UV method was used to quantify celecoxib. Experimental and computational molecular descriptors and in vivo pharmacokinetic data were used to assign the permeability class of celecoxib. Celecoxib belonged to BCS class 2. The pediatric to adult solubility ratios were outside the 80-125% boundaries in 3 and borderline in 1 biorelevant media. Significant age-related variability could be predicted for oral formulations containing celecoxib intended for pediatric use. Findings of this study indicated that the criteria used in the adult BCS might not be directly applied to pediatric subpopulations.

Paediatric emergency department dog bite attendance during the COVID-19 pandemic: an audit at a tertiary children's hospital

BACKGROUND

Responses to the COVID-19 pandemic include strict public health measures, such as national lockdowns. During these measures, paediatric emergency department attendances have declined and the prevalence of presenting complaints has changed. This study sought to identify whether dog bite attendance and victim demographics changed during COVID-19 public health measures.

METHODS

An audit was conducted of emergency department attendance data from a UK tertiary paediatric hospital between January 2016 and September 2020. Dog bite attendance and victim demographics were explored using χ² tests and multivariable Poisson regression. The mean monthly percentage of attendance due to dog bites in 2020 was compared against predicted percentages based on previous years' data.

RESULTS

Dog bite attendance rose in conjunction with the introduction of COVID-19 public health measures and reached a peak in July 2020 (44 dog bites, 1.3% of all attendances were due to dog bites). This was a threefold increase in dog bite attendance. By September 2020, attendance had returned to normal. The demographic profile of child dog bite victims remained the same. Boys had the highest attendance rates in 7-12 year-olds, girls in 4-6 year-olds. Girls showed higher attendance rates in the summer, while boys' attendance rates were constant throughout the year. COVID-19 public health measures were associated with a 78% increase in attendance for boys and a 66% increase in girls.

CONCLUSIONS

COVID-19 national public health measures were associated with an increase in paediatric emergency department dog bite attendance, and may be due to increased child exposure to dogs via 'stay at home' orders and school closures. National lockdowns are likely to continue globally throughout the COVID-19 pandemic; this is likely to result in more dog bites. Urgent public health communication and injury prevention strategies are needed to help prevent these avoidable injuries.

BCS-based biowaivers: Extension to paediatrics

A BCS-based biowaiver allows extrapolation of drug product bioequivalence (when applicable) based on the BCS class of the drug and in vitro dissolution testing. Drug permeability and solubility considerations for adult BCS might not apply directly to paediatric subpopulations and bridging of adult and paediatric formulations should be undertaken with caution. The aims of this study were to: (i.) identify compounds which would change drug solubility classification in the paediatric population, and (ii.) to assess the risk of extending BCS-based biowaiver criteria into paediatric products of these compounds. Amoxicillin, prednisolone, and amlodipine were selected as the model compounds. Dissolution studies of IR formulations of these compounds were conducted with USP II (paddle) and mini-paddle apparatus, in media of three pHs (pH 1.2, 4.5 and 6.8). Three dissolution setups were tested: (1) 'typical' BCS-based biowaiver conditions, (2) "BE" setup derived from BE study protocols (volume: 250 mL), and (3) "paediatric" setup based on representative volume for the paediatric population (50 mL). Results revealed that extension of regulated BCS-based biowaiver criteria for paediatric application is not as simple as scaling down volumes. It was further shown that BCS-based biowaiver criteria should not be applied when there is the risk of change of the drug solubility class, from the adult to paediatric populations. A deeper knowledge of the paediatric gastrointestinal environment is still lacking and would assist in refining the biopharmaceutical tools needed to appropriately evaluate formulation performance across age groups. This would potentially reduce the number of clinical studies required and speed up formulation development.

A proposed pediatric biopharmaceutical classification system for medications for chronic diseases in children

Age-appropriate pediatric formulations for oral administration can be challenging to formulate. Development of such formulations is often time consuming, labor-intensive and costly. The Biopharmaceutical Classification System (BCS), developed more than two decades ago, is used to develop suitable oral drug formulations for adult use. In theory, some of the same principles could be applied to formulate pediatric oral liquid dosage forms. However, the present BCS system was developed using adult gastrointestinal physiologic factors. Direct extrapolation of this method to develop pediatric oral dosage forms is inappropriate due to differences in adult and pediatric gastrointestinal physiologic differences during development. To date age-appropriate BCS to guide pediatric oral liquid formulation development has not been developed for various pediatric subpopulations. The objective of this study was to provisionally classify oral liquid formulations of extemporaneously prepared drugs at our institution into an age-appropriate BCS class after elimination of any duplicate listing when matched with the most current World Health Organization's Essential Medicines List for Children available at the time of this study and other published studies that may have reported BCS classification of drugs used as extemporaneous oral liquid formulations in children to treat chronic or rare diseases. A total of 96 orally administered extemporaneously compounded liquid formulations were included in this classification. Dose numbers were calculated using age-appropriate initial gastric volume for neonates, 6-month-old infants, and children up to 6 years of age. Using age-appropriate initial gastric volumes and pediatric and neonatal Lexicomp® age-specific maximal dosing recommendations for calculation of dose numbers, the solubility classes shifted for 62.5% of the drugs studied. A significant number of currently used extemporaneously compounded oral liquid formulations for age groups of children included in this study may not provide formulations with predictable safety and efficacy. Factors used in development of adult BCS cannot be applied directly to pediatric subpopulations.

Availability of Authorizations from EMA and FDA for Age-Appropriate Medicines Contained in the WHO Essential Medicines List for Children 2019

Lack of age-appropriate commercially drug products availability is a common problem in pediatric therapeutics; this population needs improved and safer drug delivery. In addition, biopharmaceutic aspects, dosage requirements, and swallowing abilities demand pediatric forms different to adult formulations. The objective of this study was to evaluate the authorization availability from United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) of oral essential medicines for children and analyze its age-appropriateness for oral administration in children. All oral drugs from 7th List of Essential Medicines for Children by World Health Organization (WHO) were selected. Availability of commercial drug products was collected from OrangeBook, Spanish drug product catalogue, British electronic Medicines Compendium, and the International Vademecum. Tablets, effervescent tablets, and capsules were considered as not age-appropriate forms. Liquid forms, powder for oral suspension, mini tablets, granules, and soluble films were considered as age-appropriate forms due to their flexibility. More than 80% of the studied drugs possess a commercial authorization in oral forms in both EMA and FDA. Nevertheless, around 50% of these formulations are not age-appropriate for most pediatric groups. This study shows the lack of age-appropriate medicines for children. More efforts are needed to improve development and approval of pediatric medicines.

Classification of WHO Essential Oral Medicines for Children Applying a Provisional Pediatric Biopharmaceutics Classification System

The objective was using the Essential Medicines List for children by the World Health Organization (WHO) to create a pediatric biopharmaceutics classification system (pBCS) of the oral drugs included in the Essential Medicines List by the World Health Organization and to compare our results with the BCS for adults (aBCS). Several methods to estimate the oral drug dose in different pediatric groups were used to calculate dose number (Do) and solubility (high/low). The estimation of the gastrointestinal water volume was adapted to each pediatric group. Provisional permeability classification was done by comparison of each drug lipophilicity versus metoprolol as the model drug of high permeability. As a result, 24.5% of the included drugs moved from the favorable to unfavorable class (i.e., from high to low solubility). Observed changes point out potential differences in product performance in pediatrics compared to adults, due to changes in the limiting factors for absorption. BCS Class Changes 1 to 2 or 3 to 4 are indicative of drugs that could be more sensitive to the choice of appropriate excipient in the development process. Validating a pBCS for each age group would provide a valuable tool to apply in specific pediatric formulation design by reducing time and costs and avoiding unnecessary pediatric experiments restricted due to ethical reasons. Additionally, pBCS could minimize the associated risks to the use of adult medicines or pharmaceutical compound formulations.

Magnetic Resonance Imaging Quantification of Gastrointestinal Liquid Volumes and Distribution in the Gastrointestinal Tract of Children

The volume and localization of fluid in the paediatric gastrointestinal tract is crucial to the design of in vitro and in silico models that predict the absorption of oral drugs administered to children. Previous studies have used magnetic resonance imaging (MRI) to quantify fluid volumes and localization in the intestines of adults; this study is the first to undertake similar analysis of pediatric participants. This study quantified the amount and distribution of fluid in fasted and fluid-fed children using MRI data captured during the routine clinical assessment. Data from 32 fasted children (aged 0-16 years) and 23 fluid-fed children (aged 8-16 years) were evaluated. The gastric volume ranged from 0 to 9 mL in the fasted and 19-423 mL in the fluid-fed state. The small intestinal volume was recorded to be 0-51 mL in the fasted and 6-91 mL in the fluid-fed state with an average number of 7.7 and 22.4 fluid pockets, respectively. The data showed significant differences in gastric volumes and the number of fluid pockets in the small intestine for age-matched fasted and fluid-fed children (p < 0.05). Both the number and the volume of pockets reported in children are much lower than those previously reported in adults. This study is the first to report intestinal volumes and localization in children and provides new information to achieve the design of biorelevant in vitro models and real values to update in silico models. The data available from both fluid-fed and fasted children show the extremes of fluid volumes that are present in the gastro-intestinal tract which is useful to understand the variability associated with drug absorption in children.

Mind the Gaps: Ontogeny of Human Brain P-gp and Its Impact on Drug Toxicity

Available data on human brain P-glycoprotein ontogeny during infancy and childhood are limited. This review discusses the current body of data relating to maturation of human brain P-glycoprotein including transporter expression levels in post-mortem human brain samples, in vivo transporter activity using probe substrates, surrogate marker endpoints, and extrapolations from animal models. Overall, the data tend to confirm that human brain P-glycoprotein activity keeps developing after birth, although with a developmental time frame that remains unclear. This knowledge gap is a concern given the critical role of brain P-glycoprotein in drug safety and efficacy, and the vulnerable nature of the pediatric population. Future research could include the measurement of brain P-glycoprotein activity across age groups using positron emission tomography or central pharmacodynamic responses. For now, caution is advised when extrapolating adult data to children aged younger than 2 years for drugs with P-glycoprotein-dependent central nervous system activity.

Biopharmaceutical optimization in neglected diseases for paediatric patients by applying the provisional paediatric biopharmaceutical classification system

AIMS

Unavailability and lack of appropriate, effective and safe formulations are common problems in paediatric therapeutics. Key factors such as swallowing abilities, organoleptic preferences and dosage requirements determine the need for optimization of formulations. The provisional Biopharmaceutics Classification System (BCS) can be used in paediatric formulation design as a risk analysis and optimization tool. The objective of this study was to classify six neglected tropical disease drugs following a provisional paediatric BCS (pBCS) classification adapted to three paediatric subpopulations (neonates, infants and children).

METHODS

Albendazole, benznidazole, ivermectin, nifurtimox, praziquantel and proguanil were selected from the 5th edition of the Model List of Essential Medicines for Children from the World Health Organization. Paediatric drug solubility classification was based on dose number calculation. Provisional permeability classification was based on log P comparison versus metoprolol log P value, assuming passive diffusion absorption mechanisms and no changes in passive membrane permeability between paediatric patients and adults. pBCS classes were estimated for each drug, according to different doses and volumes adapted for each age stage and were compared to the adult classification.

RESULTS

All six drugs were classified into provisional pBCS in the three paediatric subpopulations. Three drugs maintained the same classification as for adults, ivermectin and benznidazole changed solubility class from low to high in neonates and proguanil changed from low to high solubility in all age stages.

CONCLUSION

Provisional pBCS classification of these six drugs shows potential changes in the limiting factors in oral absorption in paediatrics, depending on age stage, compared to the adult population. This valuable information will aid the optimization of paediatric dosing and formulations and can identify bioinequivalence risks when comparing different formulations and paediatric populations.

Biopharmaceutical considerations in paediatrics with a view to the evaluation of orally administered drug products - a PEARRL review

OBJECTIVES

In this review, the current biopharmaceutical approaches for evaluation of oral formulation performance in paediatrics are discussed.

KEY FINDINGS

The paediatric gastrointestinal (GI) tract undergoes numerous morphological and physiological changes throughout its development and growth. Some physiological parameters are yet to be investigated, limiting the use of the existing in vitro biopharmaceutical tools to predict the in vivo performance of paediatric formulations. Meals and frequencies of their administration evolve during childhood and affect oral drug absorption. Furthermore, the establishment of a paediatric Biopharmaceutics Classification System (pBCS), based on the adult Biopharmaceutics Classification System (BCS), requires criteria adjustments. The usefulness of computational simulation and modeling for extrapolation of adult data to paediatrics has been confirmed as a tool for predicting drug formulation performance. Despite the great number of successful physiologically based pharmacokinetic models to simulate drug disposition, the simulation of drug absorption from the GI tract is a complicating issue in paediatric populations.

SUMMARY

The biopharmaceutics tools for investigation of oral drug absorption in paediatrics need further development, refinement and validation. A combination of in vitro and in silico methods could compensate for the uncertainties accompanying each method on its own.

Effects of activated carbon N-acetylcysteine sustained-release microcapsule on dipeptidyl peptidase IV expression in young rats with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) in children has become the most common liver disease influencing adolescent health and one of the most influencing chronic liver diseases among children in Chinese wealthy families, particularly in coastal regions. However, the medicine available for the treatment of NAFLD is deficient. In order to solve this problem, our team studied the activated carbon N-acetylcysteine (NAC) sustained-release microcapsule, which improves the oxidation resistance, bioavailability and drug stability of acetylcysteine and reduces toxic and side effects. In addition, it accords with the characteristics of medication in infants and children. The present study mainly discusses whether the activated carbon NAC sustained-release microcapsule has effects on dipeptidyl peptidase IV (DPPIV) activity and protein in young rats with NAFLD, and whether it has the effect of an DPPIV inhibitor, hoping to provide new thoughts and methods with respect of basic studies on young rats with NAFLD/non-alcoholic steatohepatitis.

Classification of natural products as sources of drugs according to the biopharmaceutics drug disposition classification system (BDDCS)

Natural products (NPs) are compounds that are derived from natural sources such as plants, animals, and micro-organisms. Therapeutics has benefited from numerous drug classes derived from natural product sources. The Biopharmaceutics Drug Disposition Classification System (BDDCS) was proposed to serve as a basis for predicting the importance of transporters and enzymes in determining drug bioavailability and disposition. It categorizes drugs into one of four biopharmaceutical classes according to their water solubility and extent of metabolism. The present paper reviews 109 drugs from natural product sources: 29% belong to class 1 (high solubility, extensive metabolism), 22% to class 2 (low solubility, extensive metabolism), 40% to class 3 (high solubility, poor metabolism), and 9% to class 4 (low solubility, poor metabolism). Herein we evaluated the characteristics of NPs in terms of BDDCS class for all 109 drugs as wells as for subsets of NPs drugs derived from plant sources as antibiotics. In the 109 NPs drugs, we compiled 32 drugs from plants, 50% (16) of total in class 1, 22% (7) in class 2 and 28% (9) in class 3, none found in class 4; Meantime, the antibiotics were found 5 (16%) in class 2, 22 (71%) in class 3, and 4 (13%) in class 4; no drug was found in class 1. Based on this classification, we anticipate BDDCS to serve as a useful adjunct in evaluating the potential characteristics of new natural products.

Paediatric Drug Development and Formulation Design-a European Perspective

The availability of licensed paediatric drugs is lagging behind those for adults, and there is a lack of safe formulations in suitable doses that children are able and willing to take. As a consequence, children are commonly treated with off-label or unlicensed drugs. As off-label and unlicensed drug use are associated with a greater risk for harm than on-label drug use, a range of global initiatives have been developed to realize "better" medicines for children. This review describes the challenges and achievements of the European Union to realize this goal, with a focus on paediatric drug development and formulation design. In 2007, a European Paediatric Regulation was installed enforcing companies to consider children in the early development of drugs with a new drug substance, for a new indication or with a new route of administration. The Regulation, e.g. requires companies to develop a paediatric investigation plan discussing the proposed clinical trials in children of different ages and the formulations for future marketing. Since 2013, the pharmaceutical design of any newly marketed paediatric drug should comply with the "Guideline on the Pharmaceutical Development of Medicines for Paediatric Use." Companies should, e.g. justify the route of administration, dosage form, formulation characteristics, safety of excipients, dosing frequency, container closure system, administration device, patient acceptability and user information. In this review, the guideline's key aspects are discussed with a focus on novel formulations such as mini-tablets and orodispersible films, excipients with a potential risk for harm such as azo dyes and adequate user instructions.

Medicines for Pediatric Patients-Biopharmaceutical, Developmental, and Regulatory Considerations

This commentary reflects current developments in pediatric medicine. The underpinning legislation in both Europe and the United States has led to the initiation of an increased number of clinical trials in the pediatric population, but there are still a number of outstanding issues within this field. These include the differences in the physiology between adults and the very heterogeneous nature of pediatric patients. There is an ongoing scientific debate on the applicability of a Pediatric Biopharmaceutical Classification System to define when waivers for bioequivalence studies can be supported by in vitro dissolution. However, a challenge is that in vitro models should adequately mimic the physiology of different pediatric age-groups and dose definition is another critical aspect. There is a tendency for off-label use of established adult medicines, resulting in increased adverse events and decreased efficacy in the target population. Recent advances in physiologically based pharmacokinetic modelling may be used to provide valuable input into these discussions, but there are currently still many knowledge gaps. It is encouraging that there is a global recognition of these deficiencies and substantial funding in the field of basic research is being provided, for example, within Europe the Innovative Medicines Initiative consortium.

A Physiologically Based Pharmacokinetic Model for Ganciclovir and Its Prodrug Valganciclovir in Adults and Children

A physiologically based pharmacokinetic (PBPK) model has been developed for ganciclovir and its prodrug valganciclovir. Initial bottom-up modeling based on physicochemical drug properties and measured in vitro inputs was verified in preclinical animal species, and then, a clinical model was verified in a stepwise fashion with pharmacokinetic data in adult, children, and neonatal patients. The final model incorporated conversion of valganciclovir to ganciclovir through esterases and permeability-limited tissue distribution of both drugs with active transport processes added in gut, liver, and kidney. A PBPK model which accounted for known age-related tissue volumes, composition and blood flows, and renal filtration clearance was able to simulate well the measured plasma exposures in adults and pediatric patients. Overall, this work illustrates the stepwise development of PBPK models which could be used to predict pharmacokinetics in infants and neonates, thereby assisting drug development in a vulnerable patient population where clinical data are challenging to obtain.

Children in clinical trials: towards evidence-based pediatric pharmacotherapy using pharmacokinetic-pharmacodynamic modeling

INTRODUCTION

In pediatric pharmacotherapy, many drugs are still used off-label, and their efficacy and safety is not well characterized. Different efficacy and safety profiles in children of varying ages may be anticipated, due to developmental changes occurring across pediatric life.

AREAS COVERED

Beside pharmacokinetic (PK) studies, pharmacodynamic (PD) studies are urgently needed. Validated PKPD models can be used to derive optimal dosing regimens for children of different ages, which can be evaluated in a prospective study before implementation in clinical practice. Strategies should be developed to ensure that formularies update their drug dosing guidelines regularly according to the most recent advances in research, allowing for clinicians to integrate these guidelines in daily practice. Expert commentary: We anticipate a trend towards a systems-level approach in pediatric modeling to optimally use the information gained in pediatric trials. For this approach, properly designed clinical PKPD studies will remain the backbone of pediatric research.

Towards the development of a paediatric biopharmaceutics classification system: Results of a survey of experts

The aim of this research survey was to understand current global thinking around the need for and development of a paediatric biopharmaceutics classification system (pBCS) to be used for the development of paediatric medicines and regulatory purposes (e.g. Biowaivers). A literature review highlighted the paucity of data in this area and therefore a survey was developed to better understand this topic to identify areas of common thinking and highlight future research needs. Global experts in paediatric biopharmaceutics were identified from existing networks and public forums. An online survey was developed and circulated broadly to maximise participation. Sixty individuals (including academics, health care professionals, pharmaceutical industry scientists and regulators) completed the survey, bringing together their views on the need for a pBCS. The results highlighted that the area of greatest concern was the definition of BCS II and IV drugs within this population and additional research is required to generate evidence to underpin this issue. In questions relating to permeability and dissolution consensus was generally reached within the expert population suggesting that little additional research is required to define suitable criteria. More than 90% of those experts who participated agreed that a pBCS would be useful for paediatric populations with a greater need identified for the younger populations (newborn and infants compared to adolescents). The results presented will facilitate further discussion and research into the evidence to underpin a relevant pBCS. These results highlight the need for additional evidence and guidance in this area.

Pediatric Biopharmaceutical Classification System: Using Age-Appropriate Initial Gastric Volume

Development of optimized pediatric formulations for oral administration can be challenging, time consuming, and financially intensive process. Since its inception, the biopharmaceutical classification system (BCS) has facilitated the development of oral drug formulations destined for adults. At least theoretically, the BCS principles are applied also to pediatrics. A comprehensive age-appropriate BCS has not been fully developed. The objective of this work was to provisionally classify oral drugs listed on the latest World Health Organization's Essential Medicines List for Children into an age-appropriate BCS. A total of 38 orally administered drugs were included in this classification. Dose numbers were calculated using age-appropriate initial gastric volume for neonates, 6-month-old infants, and children aging 1 year through adulthood. Using age-appropriate initial gastric volume and British National Formulary age-specific dosing recommendations in the calculation of dose numbers, the solubility classes shifted from low to high in pediatric subpopulations of 12 years and older for amoxicillin, 5 years, 12 years and older for cephalexin, 9 years and older for chloramphenicol, 3-4 years, 9-11 and 15 years and older for diazepam, 18 years and older (adult) for doxycycline and erythromycin, 8 years and older for phenobarbital, 10 years and older for prednisolone, and 15 years and older for trimethoprim. Pediatric biopharmaceutics are not fully understood where several knowledge gaps have been recently emphasized. The current biowaiver criteria are not suitable for safe application in all pediatric populations.

Heteroaryl chalcone allied triazole conjugated organosilatranes: synthesis, spectral analysis, antimicrobial screening, photophysical and theoretical investigations

A series of heteroaryl tethered triazole conjoined organosilatranes were synthesized and studied for their solvatochromism experimentally and theoretically followed by antimicrobial screening.

An Algorithm to Identify Compounded Non-Sterile Products that Can Be Formulated on a Commercial Scale or Imported to Promote Safer Medication Use in Children

The lack of commercially-available pediatric drug products and dosage forms is well-known. A group of clinicians and scientists with a common interest in pediatric drug development and medicines-use systems developed a practical framework for identifying a list of active pharmaceutical ingredients (APIs) with the greatest market potential for development to use in pediatric patients. Reliable and reproducible evidence-based drug formulations designed for use in pediatric patients are needed vitally, otherwise safe and consistent clinical practices and outcomes assessments will continue to be difficult to ascertain. Identification of a prioritized list of candidate APIs for oral formulation using the described algorithm provides a broader integrated clinical, scientific, regulatory, and market basis to allow for more reliable dosage forms and safer, effective medicines use in children of all ages. Group members derived a list of candidate API molecules by factoring in a number of pharmacotherapeutic, scientific, manufacturing, and regulatory variables into the selection algorithm that were absent in other rubrics. These additions will assist in identifying and categorizing prime API candidates suitable for oral formulation development. Moreover, the developed algorithm aids in prioritizing useful APIs with finished oral liquid dosage forms available from other countries with direct importation opportunities to North America and beyond.

Risk assessment for extending the Biopharmaceutics Classification System-based biowaiver of immediate release dosage forms of fluconazole in adults to the paediatric population

OBJECTIVES

The paediatric population undergoes developmental changes in gastric pH, gastric emptying, intestinal transit time, membrane permeability, protein binding, body water, distribution and metabolism. It is widely recognised that changes in these parameters may result in an alteration of the plasma profile and thus in key bioequivalence parameters such as Cmax (maximum plasma concentration of drug) and area under the plasma concentration vs time profile curve. The aim of this work is to assess the risk of extending the biowaiver for immediate release dosage formulations of fluconazole from the adult to the paediatric population.

METHODS AND KEY FINDINGS

Fluconazole exhibits good solubility and very rapid dissolution characteristics in various pH media. The absorption of fluconazole in children is known to be complete (over 90%) and not impaired by elevated pH, which is prevalent during the early days of life. Dose numbers calculated using body surface area are less than 1. Therefore, the risk to drug absorption due to differences in gastric pH, gastric emptying, intestinal transit, membrane permeability and metabolising enzymes between adults and children is considered low.

CONCLUSIONS

Thus, it can be safely concluded that fluconazole meets highly soluble and highly permeable criteria in the paediatric population and can be allocated to class 1 of the Biopharmaceutics Classification System (BCS) for this population as well as in adults. Additionally, fluconazole has an excellent safety profile in children, similar to that in adults. The BCS-based biowaiver claimed in adults can be safely extended to the paediatric population provided that the requirements in excipient selection and dissolution profile comparison using BCS-based dissolution conditions as stated in the biowaiver monograph for fluconazole immediate release dosage forms in adults are fulfilled.

Development of a Pediatric Physiologically Based Pharmacokinetic Model for Sirolimus: Applying Principles of Growth and Maturation in Neonates and Infants

This study describes the maturation of sirolimus clearance in a cohort of very young pediatric patients with vascular anomalies. The relationship between allometrically scaled in vivo clearance and age was described by the E_max model in patients aged 1 month to 2 years. Consistent with the observed increase, in vitro intrinsic clearance of sirolimus using pediatric liver microsomes showed a similar age-dependent increase. In children older than 2 years, allometrically scaled sirolimus clearance did not show further maturation. Simulated clearance estimates with a sirolimus physiologically based pharmacokinetic model that included CYP3A4/5/7 and CYP2C8 maturation profiles were in close agreement with observed in vivo clearance values. In addition, physiologically based pharmacokinetic model-simulated sirolimus pharmacokinetic profiles predicted the actual observations well. These results demonstrate the utility of a physiologically based pharmacokinetic modeling approach for the prediction of the developmental trajectory of sirolimus metabolic activity and its effects on total body clearance in neonates and infants.

Ethics of pharmacological research involving adolescents

Pharmacological research in the adolescent population is not meeting adolescents' needs. Medication is still frequently prescribed off label, and studies especially in sensitive areas of adolescent health care are underrepresented. Adolescents did not benefit from the new knowledge gained in cancer research, and their outcome has essentially not improved during the last two decades in comparison to younger children and adults. There are many obstacles that make it challenging to enroll adolescents in pharmacological research. Access can be difficult. Confidentiality plays an essential role for minors and may be a hindrance, notably to studying sexual and mental health matters. Pharmaceutical companies may exclude the adolescent patient because of a lack of profit and in fear of a complex study design. Research concepts should be explained to the adolescent in a comprehensive manner, and assent and consent forms should be clear and understandable. New laws and incentives have been developed to encourage pharmaceutical companies to engage adolescents in their research projects. Centralization and collaboration of all parties involved may make the whole approach to adolescent research more efficient and uniform. The mature minor doctrine has facilitated the enrollment process. Parental consent may be waived for low-risk medical trials to promote recruitment. Ethics committees therefore play a major role in protecting the adolescent from harm from participating in research. In conclusion, pharmacological research in adolescents has to be encouraged. This will increase the safety of current medical treatment regimens and will allow this population to benefit from therapeutic advancements.

Persistent pharmacokinetic challenges to pediatric drug development

The development of new therapeutic agents for the mitigation of pediatric disorders is largely hindered by the inability for investigators to assess pediatric pharmacokinetics (PK) in healthy patients due to substantial safety concerns. Pediatric patients are a clinical moving target for drug delivery due to changes in absorption, distribution, metabolism and excretion (ADME) and the potential for PK related toxicological (T) events to occur throughout development. These changes in ADMET can have profound effects on drug delivery, and may lead to toxic or sub-therapeutic outcomes. Ethical, economical, logistical, and technical barriers have resulted in insufficient investigation of these changes by industrial, regulatory, and academic bodies, leading to the classification of pediatric patients as therapeutic orphans. In response to these concerns, regulatory agencies have incentivized investigation into these ontogenic changes and their effects on drug delivery in pediatric populations. The intent of this review is to briefly present a synopsis of the development changes that occur in pediatric patients, discuss the effects of these changes on ADME and drug delivery strategies, highlight the hurdles that are still being faced, and present some opportunities to overcome these challenges.

Paediatric oral biopharmaceutics: key considerations and current challenges

The complex process of oral drug absorption is influenced by a host of drug and formulation properties as well as their interaction with the gastrointestinal environment in terms of drug solubility, dissolution, permeability and pre-systemic metabolism. For adult dosage forms the use of biopharmaceutical tools to aid in the design and development of medicinal products is well documented. This review considers current literature evidence to guide development of bespoke paediatric biopharmaceutics tools and reviews current understanding surrounding extrapolation of adult methodology into a paediatric population. Clinical testing and the use of in silico models were also reviewed. The results demonstrate that further work is required to adequately characterise the paediatric gastrointestinal tract to ensure that biopharmaceutics tools are appropriate to predict performance within this population. The most vulnerable group was found to be neonates and infants up to 6 months where differences from adults were greatest.

Considerations for a Pediatric Biopharmaceutics Classification System (BCS): application to five drugs

It has been advocated that biopharmaceutic risk assessment should be conducted early in pediatric product development and synchronized with the adult product development program. However, we are unaware of efforts to classify drugs into a Biopharmaceutics Classification System (BCS) framework for pediatric patients. The objective was to classify five drugs into a potential BCS. These five drugs were selected since both oral and intravenous pharmacokinetic data were available for each drug, and covered the four BCS classes in adults. Literature searches for each drug were conducted using Medline and applied to classify drugs with respect to solubility and permeability in pediatric subpopulations. Four pediatric subpopulations were considered: neonates, infants, children, and adolescents. Regarding solubility, dose numbers were calculated using a volume for each subpopulation based on body surface area (BSA) relative to 250 ml for a 1.73 m(2) adult. Dose numbers spanned a range of values, depending upon the pediatric dose formula and subpopulation. Regarding permeability, pharmacokinetic literature data required assumptions and decisions about data collection. Using a devised pediatric BCS framework, there was agreement in adult and pediatric BCS class for two drugs, azithromycin (class 3) and ciprofloxacin (class 4). There was discordance for the three drugs that have high adult permeability since all pediatric permeabilities were low: dolasetron (class 3 in pediatric), ketoprofen (class 4 in pediatric), and voriconazole (class 4 in pediatric). A main contribution of this work is the identification of critical factors required for a pediatric BCS.