1. Phase I:
Safety and Dosage
Objective: Determine the safety of the drug or treatment and establish a safe dosage range.
Participants: Small number of healthy volunteers or sometimes patients (often 20-80).
Approach: Test various doses to observe side effects and how the body metabolizes and excretes the drug.
Outcome: Identify the maximum tolerated dose with minimal adverse effects.
2. Phase II:
Efficacy and Side Effects
Objective: Assess whether the drug has the intended effect on the condition it’s targeting and further evaluate its safety.
Participants: Larger group of people with the disease or condition (typically 100-300).
Approach: Conduct a controlled trial, often using randomization, to see if the drug is effective and to continue monitoring side effects.
Outcome: Provide preliminary data on whether the drug works in people who have a certain condition or disease.
3. Phase III:
Confirming Efficacy and Monitoring Adverse Reactions
Objective: Confirm effectiveness, monitor side effects, compare with commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Participants: Large groups of patients (from several hundred to several thousand).
Approach: Randomized and blind testing in large groups to confirm the treatment’s effectiveness, monitor side effects, compare it to standard or equivalent treatments, and collect data to ensure long-term safety.
Outcome: Complete the data collection needed for regulatory approval.
4. Phase IV:
Post-Marketing Surveillance
Objective: Monitor long-term effectiveness and impact on a patient’s quality of life and identify any additional side effects over extended use.
Participants: Several thousand individuals who use the drug/treatment after it has been marketed.
Approach: Conduct ongoing studies after the treatment is approved and marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
Outcome: Ensure long-term safety and effectiveness and detect any rare or long-term adverse effects.
