What does “phase drug development” mean?

Author : first copy | Published On : 20 Aug 2026

Phase drug development” refers to the different stages used to study and evaluate a potential medicine before and after it becomes available to patients. The term is commonly used when discussing the phases of drug development, particularly the clinical phases that test a drug in humans. After discovery and preclinical research, a drug candidate may enter clinical development of drug programs, which are generally divided into Phase I, Phase II, and Phase III studies. Phase I mainly evaluates safety, tolerability, and suitable dosage; Phase II looks more closely at effectiveness and side effects in patients; and Phase III studies the medicine in larger patient groups to confirm its benefits and risks. After successful clinical phases, regulatory authorities review the available evidence before approval, followed by continued safety monitoring after the medicine reaches the market. Therefore, “phase drug development” is essentially a way of describing the structured stages within the new drug development process and the broader drug discovery and development process.