In the past, dosage regimens authorized for adults were extrapolated to children relying mainly on empirical dosage adjustments. However, children are not small adults, but a distinct and heterogeneous group in terms of physiology, disease occurrence, pharmacokinetics, pharmacodynamics and also psychological, cognitive, and behavioral aspects. Even though it would be helpful to know the physiological changes and the special drug treatment needs in children, this task could not be performed due to ethical reasons. Important issues to consider for the development of paediatric drug products refer to the administration of the accurate dose, the use of the appropriate excipients, and acceptability. The latter is crucial and taste-screening methods (like electronic tongues) have been developed. A new era in paediatric medicines started with the entry into force of paediatric regulations. In the early '80s, the FDA started the set-up of a regulatory framework by authorizing issues like the Paediatric Rule, the Best Pharmaceuticals for Children Act, the Paediatric Research Equity Act, and the Food and Drug Administration Safety and Innovation Act. Similar efforts have been made in the EU, mainly through the entry into force of the Paediatric Regulation and the establishment of the Paediatric Committee, the Paediatric Investigation Plan, the Paediatric Use Marketing Authorization, and the European Paediatric Research Network. Other efforts to bridge the gap, between knowledge in adults and the children's special requirements, include the extrapolation concept of safety/efficacy aspects, the application of modeling/simulation approaches in paediatric drug development, and the development of a paediatric Biopharmaceutics Classification Scheme.
Regulatory guidelines are necessary to standardize the evaluation procedure in bioequivalence. Revisions in the guidelines occur in order to resolve any previously unclear issues and to address new needs. In this paper, the authors discuss the major regulatory requirements for bioequivalence assessment before and after the EMA guidelines of 2010 and unveil their differences. The authors compiled this review following the critical exploration of literature articles and regulatory guidance documents. This was achieved through searching MEDLINE, Scopus, and the official EMA site. The authors found, in the post-2010 era, that the major differences in the regulatory framework refer to: the choice of clinical designs, the assessment of highly variable drugs, biowaivers, the pharmacokinetics parameters used, and the explicit definition for the use of metabolite data, enantiomers, and endogenous substances. Also, product-specific guidelines have started to be issued, while recommendations are now provided for some special formulations like orodispersible tablets. Other issues were elucidated like studies in the fasting or fed state and the dissolution assessment. The EMA regulatory framework on bioequivalence changed significantly in the post-2010 era. Many issues are now defined more explicitly, while others are newly introduced. However, some issues remain unresolved.
Dried blood spot (DBS) microsampling is extensively employed in newborn screening (NBS) and neonatal studies. However, the impact of variable neonatal hematocrit (Ht) values on the results can be a source of analytical error, and the use of fixed Ht for calibration (Htcal) is not representative of all neonatal subpopulations. A computational approach based on neonatal demographics was developed and implemented in R® language to propose a strategy using correction factors to address the Ht effect in neonatal DBS partial-spot assays. A rational “tolerance level” was proposed for the Ht effect contribution to the total analytical error and a safe Ht range for neonatal samples, where the correction of concentrations can be omitted. Furthermore, an “alert zone” for a false positive or negative result in NBS was proposed, where the Ht effect has to be considered. Results point toward the use of Htcal values closely representative of populations under analysis and an acceptable level of percentage relative error can be attributed to the Ht effect, diminishing the probability of correction. Overall, the impact of the Ht effect on neonatal studies is important and future work may further investigate this parameter, correlated to other clinical variables potentially affecting results.
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