Children are often treated as small adults—not as the special patients they are. Regulations exist to encourage the development of drugs and formulation for children. However, off-patent drugs are often administered to children without appropriate formulations or systematic investigations. Therefore, the paediatric use marketing authorisation (PUMA) has been designed.The EMA Paediatric Working Party has prioritized the unmet need for the cardiovascular off-patent drug enalapril in the European paediatric population. Enalapril is an ACE inhibitor commonly used for cardiac failure in children under 1 year of age, although it is not labelled for any condition in patients <20 kg in European countries.Current problems with the use of enalapril in children include: no appropriate formulation and insufficient stability of the liquid soluble formulation for young paediatric patients; insufficient paediatric pharmacokinetic (PK) data for any formulation; insufficient safety data in neonates, infants, and young children; and limited pharmacodynamics (PD) and efficacy data for paediatric cardiological indications.The aim of the LENA (Labeling of Enalapril from Neonates up to Adolescents) project is to address these shortcomings and provide a basis for a future PUMA of enalapril by developing an age-appropriate solid oral formulation suitable for all paediatric subsets; generating PK and PD data; collecting data on the safety of enalapril in young paediatric patients; and providing dose recommendations based on PK/PD modelling and bridging from adult data.The international collaboration of the LENA investigators will provide the required expertise to develop and evaluate drug formulation, investigate dosing, and recruit paediatric patients for clinical trials while respecting current legislation, regulatory considerations, and ethical aspects, with the aim of applying for a PUMA.