The role of pharmaceutical formulation development in clinical trials of new medicinal products

The discovery and development of new active pharmaceutical ingredients (APIs) is a complex and resource-intensive process characterized by high attrition rates and significant translational uncertainty. While advances in computational chemistry and AI have accelerated early-stage candidate identification, successful clinical translation depends not only on pharmacological activity but also on appropriate pharmaceutical formulation. This review examines the critical role of formulation development in bridging molecular discovery with clinical evaluation, emphasizing physicochemical characterization, enabling formulation strategies for poorly soluble compounds, and integration of mechanistic tools such as physiologically based pharmacokinetic (PBPK) and physiologically based biopharmaceutics modeling (PBBM). Particular attention is given to modified-release systems, amorphous solid dispersions, and long-acting injectable formulations, highlighting how formulation design directly influences systemic exposure, variability, and clinical reliability. Case studies of posaconazole and long-acting injectable aripiprazole demonstrate how rational reformulation and process optimization can significantly improve pharmacokinetic consistency and therapeutic performance while introducing technological and regulatory complexity. Emerging trends indicate a paradigm shift toward formulation-informed and model-integrated drug development, where AI, mechanistic modeling, and Quality by Design (QbD) principles are increasingly used to predict formulation performance and support clinical and regulatory decision-making. Integration of formulation science with predictive modeling and data-driven approaches enables earlier identification of translational risks, improves development efficiency, and enhances the probability of clinical success. Overall, formulation development should be regarded as a central determinant of clinical outcomes and regulatory success, rather than a downstream technical activity, supporting more predictive and efficient pharmaceutical development.