The development of new treatments usually progresses through levels of research, called phases, in the process of testing new drugs and procedures before they can be approved and released for general use.

• Phase 1 Trials
  Phase 1 trials evaluate the safety of a new agent or device. Before these compounds are tested in phase 1 trials, they are extensively studied in laboratory animals. A Phase 1 trial may involve different doses of a drug to learn about how well people tolerate it and to help determine what the most effective dose will be.
  
  
• Phase 2 Trials
  If the Phase 1 trial has shown that people tolerated the new agent well and did not experience serious side effects, the process moves forward to find out if the compound or device might be an effective treatment. Phase 2 trials usually include small groups of participants who have the disease/condition the new therapy is designed to treat. Phase 2 studies give researchers early information as to whether a treatment might be effective while continuing to confirm the safety of the treatment.
  
  
• Phase 3 Trials
  If the previous phases have successfully demonstrated that a new compound or device is safe and may potentially be effective,  a phase 3 study is performed.  Phase 3 studies are generally a comparison between the new compound or device and the current standard of care.  Results from a Phase 3 study can lead to approval from the Food and Drug Administration (FDA). 
  
  
• Phase 4 Trials
  After a compound or device is approved by the FDA and available for use, the FDA may require additional safety information be collected on the agent or device.