The research which involves the evaluation of new tests, treatments and the effects of health related biomedical or behavioral outcomes, safety of medications or medical devices on one or group of human beings. Trials are carefully designed reviewed and completed, and need to be approved before they are about start. The results of clinical trials are often compared with existing interventions or combine the existing interventions. Different types of clinical trials done are:

• Treatment Trials: This trial includes investigating the newly developed treatments, medicines, new therapies, surgeries, new approaches to surgery.

• Diagnostic or Screening Trials: This trial includes evaluation of tests, procedures for diagnosing and detecting diseases or conditions.

• Prevention Trials: This trial includes testing new ways to prevent disease including medicines, vaccines, vitamins, or changes to diet, lifestyle or behavior.

Clinical trials proceed through four phases:

Phase I: Phase I clinical trial involves the testing of new biomedical intervention on small group of people of 20-80, to evaluate, drug safety, correct drug dosage, side effects and its safety.

Phase II: Phase II clinical trial involves testing to a larger group of people to monitor further safety and effects.

Phase III: Phase III clinical trial involves large no. of participants usually several hundred to thousand and the intervention will be compare with the other experimental interventions. Depending upon this interventions FDA will approve the experimental drug or device. As some of the effects may not be identified in Phase I and phase II that may be identifies in Phase III as it is done large group of people.

Phase IV: Phase IV clinical trial carried out after the drug is approved by FDA and marketed so the effectiveness and safety re monitored on the diverse population, as some of the drug effects show effects taken after longer period of time.