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.

3D printing (3DP) in the pharmaceutical field is a disruptive technology that allows the preparation of personalised medicines at the point of dispensing. The paediatric population presents a variety of pharmaceutical formulation challenges such as dose flexibility, patient compliance, taste masking and the fear or difficulty to swallow tablets, all factors that could be overcome using the adaptable nature of 3DP. User acceptability studies of 3D printed formulations have been previously carried out in adults; however, feedback from children themselves is essential in establishing the quality target product profile towards the development of age-appropriate medicines. The aim of this study was to investigate the preference of children for different 3D printed tablets (Printlets™) as an important precursor to patient acceptability studies. Four different 3DP technologies; digital light processing (DLP), selective laser sintering (SLS), semi-solid extrusion (SSE) and fused deposition modeling (FDM) were used to prepare placebo printlets with similar physical attributes including size and shape. A single-site, two-part survey was completed with participants aged 4–11 years to determine their preference and opinions based on visual inspection of the printlets. A total of 368 participants completed an individual open questionnaire to visually select the best and worst printlet, and 310 participants completed further non-compulsory open questions to elaborate on their choices. Overall, the DLP printlets were the most visually appealing to the children (61.7%) followed by the SLS printlets (21.2%), and with both the FDM (5.4%) and SSE (11.7%) printlets receiving the lowest scores. However, after being informed that the SSE printlets were chewable, the majority of participants changed their selection and favoured this printlet, despite their original choice, in line with children’s preference towards chewable dosage forms. Participant age and sex displayed no significant differences in printlet selection. Printlet descriptions were grouped into four distinct categories; appearance, perceived taste, texture and familiarity, and were found to be equally important when creating a quality target product profile for paediatric 3D printed formulations. This study is the first to investigate children’s perceptions of printlets, and the findings aim to provide guidance for further development of paediatric-appropriate medicines using different 3DP technologies.

Acceptability of medicines in children and caregivers affects safety and effectiveness of medicinal treatments. The pharmaceutical industry is required to demonstrate acceptability of new paediatric formulations in target age groups as an integrated part of the development of these products (Kozarewicz, 2014). Two questions arise when trying to tackle this task: "which dosage form to choose for each target age group?" and "how to formulate it once the dosage form is decided?". Inevitably, both the regulator and the developer turn to scientific evidence for answers. Research has emerged in recent years to demonstrate age-appropriateness and patient acceptability of different dosage forms; however, such information is still fragmented and far from satisfactory to define efficient formulation development strategies for a diverse patient subset (Ranmal and Tuleu, 2013). This paper highlights how formulation factors affect the acceptability of different oral medicines in children (Table 1), and it is based on a more extensive review article by Liu et al. (Liu et al., 2014). Gaps in knowledge are highlighted in order to stimulate further research. In some areas, findings from studies conducted in adult populations may provide useful guidance for paediatric development and this is also discussed.

Background: Many medicines for children taste bitter and unpleasant, presenting a significant barrier to effective pharmacotherapy. Anecdotally, this issue is widely recognized; however, empirical evidence on the consequences of unpalatable medicines remains scarce and fragmented. The objective of this scoping review was to investigate the impact of poor tasting pediatric medicines on patient acceptability, medication adherence, and/or treatment outcomes.Methods: A literature search was performed in MEDLINE/PubMed, EMBASE and CINAHL from inception to June 2023. Eligibility criteria included interventional or observational studies conducted in children aged 0–18 years (population), administered an unpalatable oral medicine (exposure), with any reported impact on patient acceptability, medication adherence, and treatment effects (outcomes). Study screening and data extraction was completed using a standardized form on Covidence.Results: After searching 2,282 citations and reviewing 429 full-text papers, 225 articles were included in the final analysis. The impact of poor-tasting medicines was observed across 77 diseases or indications, with 156 different unpalatable medicinal products identified. Outcomes were most frequently linked to reduced patient acceptability, with 64% of articles reporting rejection responses, the need for strategies to aid administration (from positive reinforcement to physical restraint and forced administration), and impacts on prescribing practices (e.g., use of non-first line alternative therapies). Medication adherence impacts were reported in 27% of the reviewed studies, where poor taste was reported as a barrier to adherence in chronic diseases and correlated with incomplete dose administration in acute conditions. A small number of studies linked palatability with treatment outcomes, including viral suppression in HIV and seizure control in epilepsy.Conclusion: This review highlights the widespread adverse impact of poor-tasting pediatric medicines on patient experiences and outcomes, though the true extent of the issue may still be underreported. The problem affects children worldwide, across all age groups, and is frequently noted by parents, caregivers, and healthcare professionals in both clinical and domiciliary settings. These findings emphasize the need for the development and prescription of more palatable medicines for children, as well as the advancement of more universal taste-masking strategies to address this widespread problem.

Both researchers and practitioners have reached an influential period in the new era of developing pediatric medicines. Evolving regulatory reforms and guidance continue to serve as platforms steering research and development while distinctive opportunities and challenges in the field emerge. An advancing research need involves gaining a better understanding of end-user requirements and acceptability of formulations. This review considers solid oral forms to demonstrate the importance of such research to stakeholders in policy and practice.