Clinical Trial [Syn. clinical investigation, clinical study] is any systematic and carefully designed study on medicinal products in human subjects whether in patients or non-patient volunteers; the aim of a clinical trial is to discover or verify the effects of, and identify any adverse reaction to (investigational) products and to study their absorption, distribution, metabolism and excretion in order to ascertain the efficacy and safety of the product.
A clinical trial can be either prospective (nonrandomized observational cohort, randomized controlled – frequently double-blind –, withdrawal, rechallenge, etc.) or retrospective (historical control, case control study, cross-sectional study); activities concerning clinical trials are usually divided into 4 stages: a planning or set-up phase, requiring about a few weeks to several months for protocol and case record form preparation, packaging, labelling and regulatory review incl. by an ethical committee, a patient treatment or monitoring phase (including follow-up) and finally the analysis as well as the reporting phase, requiring also a few weeks to several months for data clean-up, quality assurance, statistical analysis and report writing.