Clinical trials are controlled research studies conducted in human volunteers to evaluate the safety, efficacy, dosage, and side effects of investigational drugs, biologics, or medical interventions. They are organized into sequential phases — Phase I (safety and dosing), Phase II (efficacy and side effects), Phase III (confirmatory efficacy and safety), and Phase IV (post-marketing surveillance) — and must comply with GCP (Good Clinical Practice) guidelines and receive authorization from regulatory agencies such as the European Medicines Agency (EMA) or Food and Drug Administration (FDA).
