...People participate in clinical research for a variety of reasons. People who volunteer for phase II and phase III trials can gain access to promising drugs long before these compounds are approved for the marketplace. They typically  get excellent care from the physicians during the course of the study. 

... There are a several reasons why clinical trials are important. First, the participant may have a positive response to the study medication, and their disease or condition may improve. In addition, participants receive laboratory and medical testing at no charge. More often than not, the study medication is in development because it works differently than other drugs on the market, and therefore, it may present an alternative course of treatment for the patient. Second, participation in a clinical trial helps manufacturers make informed decisions about whether to pursue getting a particular drug approved,Finally, data from one patient (who completes the entire study) can be an important part of a drug development program. In the best case scenarios, this  data can help get an exciting new drug approved and ultimately, continue the industry's efforts in developing medications that are safer, more effective, and work faster than any before them.

Independent Institutional Review Boards (IRB)  review  study-related documents, such as protocols, Informed Consent forms, physician credentials and eligibility, and patient recruitment materials.

...There are three primary phases an investigational drug has to go through before it can be approved and a fourth phase that an approved drug may enter.

Phase I  In this phase of a clinical trial, the manufacturer wants to find out how the drug works in healthy study participants. Mode of action (how the drug exerts its effects), safety, and side effects -- these are some of the main issues that are of the utmost concern to drug makers at this stage of the clinical trial process. It is important to note that in Phase I studies, the overall safety of the medication in patients has not been established.

 

Phase II  A drug reaches Phase II only when the Phase I data has been reviewed and concluded that the drug is safe for patients and  its clinical activity may be beneficial against a particular disease or condition. At this point, a larger group of patients are enrolled and condition- or disease-specific rating scales are used to record data.

 

Phase III  This is an important turning point for drug manufacturers. The medication has already passed the rigorous testing and review process required and now it's ready to be studied in an  larger patient population, with  more advanced rating scales and clinical measures. In recent years, there has been a growing industry trend to not only measure clinical effectiveness at this phase, but also measure "real world" results. For example, if a patient shows clinical improvement after entering the study, how are their activities of daily living improving (e.g., the patient can work in the garden more often or attend their child's games on a regular basis)? Most medications that reach Phase III will at least be considered for approval.

 

Phase IV  At this phase in development, the drug has already been granted approval. Phase IV studies are often performed to either identify an additional use for an already approved drug, or to gather additional safety information from a larger group of patients. In some cases, Phase IV studies are implemented to establish effectiveness in a subgroup of patients, for example, patients over age 65.

...After a study is complete the information is reviewed and decision is made whether to continue or halt the drug's development. If it remains in development, the manufacturer may build in a "compassionate use" extension for the study. This means that eligible patients may receive the study drug for a predefined amount of time without having to undergo any typical study procedures, such as blood tests or clinical ratings. This usually occurs in later studies, such as Phase III and Phase IV (post-marketing surveillance). In some cases, a study doctor may dispense approved medication samples and provide additional care at no charge.