Objective: Clinical development of a drug product is a long and complex process, so it is rather impossible to capture all the aspects of this process in details in this article. Accordingly, the key objective of this article is to present an overview of how a new medicinal product undergoes clinical evaluation to ensure that ultimately quality medicine with proven safety and efficacy is delivered to the end user, i.e. patient who consumes it for health benefit. An attempt is also made to briefly cover clinical development of biological drugs, which can require a different approach to supporting the dose justification and assessing immunogenicity risks as compared to chemically synthesized drug products.

Method: The information covered in this article is based on personal experience in the area of clinical development for regulatory submissions worldwide, regulatory guidance documents and legislations, as well as extensive literature surveillance using key terms such as clinical research, phases of development, efficacy, safety, new drug product, new chemical entity, new therapeutic entity, generics, biologics and biosimilars, oncology trials, modeling, and simulation. Clinical development is a process driven not only by science and regulations but also significantly by cost and time. The interested reader is encouraged to review clinical trial guidelines on the Food and Drug Administration (FDA) website and websites of other regulatory authorities such as European Medicines Agency (EMA), Therapeutic Goods Administration (TGA), and Health Canada. Those with further interest may also visit Clinical Trial Registry websites including www.clinicaltrials.gov to get familiar to different types of clinical study designs across phases of development carried out by sponsors as research studies or in pursuance of their marketing authorization applications.