Clinical trials are typically conducted in four phases:
1. Phase I: This initial phase involves a small group of participants (20-80) and focuses on assessing the safety, dosage range, and side effects of a new treatment.
2. Phase II: This phase expands the study to a larger group (100-300) to further evaluate the treatment's efficacy and safety.
3. Phase III: Involving a much larger group (1,000-3,000), this phase compares the new treatment with the current standard treatment to confirm its effectiveness, monitor side effects, and collect information that will allow the treatment to be used safely.
4. Phase IV: After a treatment has been approved and is on the market, this phase involves post-marketing surveillance to gather additional information on the treatment's risks, benefits, and optimal use.
