Patient acceptability of a medicinal product is a key aspect in the development and prescribing of medicines. Children and older adults differ in many aspects from the other age subsets of population and require particular considerations in medication acceptability. This review highlights the similarities and differences in these two age groups in relation to factors affecting acceptability of medicines. New and conventional formulations of medicines are considered regarding their appropriateness for use in children and older people. Aspects of a formulation that impact acceptability in these patient groups are discussed, including, for example, taste/smell/viscosity of a liquid and size/shape of a tablet. A better understanding of the acceptability of existing formulations highlights opportunities for the development of new and more acceptable medicines and facilitates safe and effective prescribing for the young and older populations.Electronic supplementary materialThe online version of this article (doi:10.1007/s40265-014-0297-2) contains supplementary material, which is available to authorized users.

Introduction: Most conventional drug delivery systems are not acceptable for pediatric patients as they differ in their developmental status and dosing requirements from other subsets of the population. Technology platforms are required to aid the development of age-appropriate medicines to maximize patient acceptability while maintaining safety, efficacy, accessibility and affordability. Areas covered: The current approaches and novel developments in the field of age-appropriate drug delivery for pediatric patients are critically discussed including patient-centric formulations, administration devices and packaging systems. Expert opinion: Despite the incentives provided by recent regulatory modifications and the efforts of formulation scientists, there is still a need for implementation of pharmaceutical technologies that enable the manufacture of licensed age-appropriate formulations. Harmonization of endeavors from regulators, industry and academia by sharing learning associated with data obtained from pediatric investigation plans, product development pathways and scientific projects would be the way forward to speed up bench-to-market age appropriate formulation development. A collaborative approach will benefit not only pediatrics, but other patient populations such as geriatrics would also benefit from an accelerated patient-centric approach to drug delivery.

There is a significant need for research and development into paediatric medicines. Only a small fraction of the drugs marketed and utilized as therapeutic agents in children have been clinically evaluated. The majority of marketed drugs are either not labelled, or inadequately labelled, for use in paediatric patients. The absence of suitable medicines or critical safety and efficacy information poses significant risks to a particularly vulnerable patient population. However, there are many challenges associated with developing medicines for the paediatric population and this review paper is intended to highlight these. The paediatric population is made up of a wide range of individuals of substantially varied physical size, weight and stage of physiological development. Experimentation on children is considered by many to be unethical, resulting in difficulties in obtaining critical safety data. Clinical trials are subject to detailed scrutiny by the various regulatory bodies who have recently recognized the need for pharmaceutical companies to invest in paediatric medicines. The costs associated with paediatric product development could result in poor or negative return on investment and so incentives have been proposed by the EU and US regulatory bodies. Additionally, some commonly used excipients may be unsuitable for use in children; and some dosage forms may be undesirable to the paediatric population.

Multiparticulate formulations are composed of multiple solid dosage units which can be administered directly to the mouth or sprinkled on food. Oral grittiness (i.e. rough mouthfeel) may arise from the presence of particles in the mouth, limiting palatability. In this work, multiparticulate formulations were prepared by dispersion of spherical granules into orange flavoured vehicles thickened with hypromellose (HPMC) at different viscosities in order to assess oral perception of grittiness by a panel of thirty adults through direct scaling on a 100mm visual analogue scale. The effect of formulation factors such as particle size (90, 127, 263μm), amount of particles per 10ml (0.25, 0.50, 1.00g) and viscosity of the vehicle (0.08, 0.43, 2.80Pas) were investigated. Grittiness was increasingly perceived with increasing amount and size of particles. Increasing viscosity of the administration media had a masking effect on the perception of particles. Less gritty samples were generally regarded as 'more pleasant' by the participants of the study. However, samples dispersed in thickened vehicles seemed to be less preferred despite being less gritty; which could be ascribed to an unpleasant mouthfeel of the vehicle. In the design of multiparticulate formulations acceptable for a targeted patient group all these formulation factors will need to be considered and optimised.

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