Carried out by volunteers, FDA – Federal Drug Administration – clinical trials consists of a succession of tests, experiments and surveys with the purpose of gathering safety information concerning drugs and similar materials. It is an extended process and clinical trials are performed after a large number of tests have been conducted and plenty of information has been collected and considered as acceptable. From that point on, the Health Authority and Ethics Committee give the approval stamp to the country that performed the trials.

Nevertheless, a great deal of work is required before getting to the last final step. As FDA clinical trials are very expensive, in the first stage, only a reduced number of volunteers are selected to start the trials with. The number of people involved in the studies might vary because of certain factors, such as the product itself or the current development stage of the product. If the first set of trials goes well, the number of involved volunteers will rise as well, in order to match up the product in question to an already prescribed drug. The extent of FDA clinical trials might be different from case to case, varying from one single center to dozens.

Based on the United Stated National Institute of Health, there are currently five types of clinical trials, as they follow:

Treatment Trials - experimenting new drug combinations, radical methods regarding surgery and new treatments.

Screening Trials – experimenting health conditions and illnesses.

Supportive Care Trials – experimenting and searching ways to improve the quality of life of people with chronic diseases.

Prevention Trials – experimenting ways to stop some diseases from reappearing or stopping them for good through a different lifestyle and/or certain medications.

Compassionate Use Trials – being the last option with the FDA personally evaluating each case, one by one, to determine the necessity of these tests. In such case, patients who previously had undesirable or unsuccessful remedies will be provided with untried therapy.

In most cases, nearly all FDA clinical studies are conducted in connection with some experimental drug. Once the decision has been made, volunteers will go through three different phases, as they follow:

Phase I Clinical Studies. This is the first phase of the process and only deals with the first time the drug is used and how safe or unsafely the drug is. These studies are generally conducted in a hospital on a certain number of volunteers, varying from 20 to 100. The studies are conducted in a hospital because the involved volunteers can be easily monitored and can get proper treatment if something goes wrong.

Phase II Clinical Studies. This is an intermediary phase and it is carried out only after it has been confirmed that the drug is safe to use by any healthy individuals. The drug is now tested by volunteers suffering from the disease or medical condition the drug is anticipated to heal or improve. This phase is generally longer as the first phase, ranging from a couple of months to several years, while the number of volunteers involved in these trials might start at 200 and easily rising to even more. As soon as these are completed, FDA must evaluate the results to compare and contrast the data concerning the safety, dosage and efficiency of the drug. Regarding the success rate, statistics shows that roughly 1/3 of every tested experimental drug finishes Phase I and Phase II.

Phase III Clinical Studies. It is the last and final phase of the process lasting for several years with the drug tested on from 500 to 2,000 volunteers suffering from the disease or medical condition related to the drug in question. Similarly to Phase II clinical studies, these also require FDA evaluation for a better comprehension of the efficiency, benefits, disadvantages or any possible side effects of the drugs in question. In most cases, the rate of completed studies at this phase is about 70%-90%. For instance, flibanserin is one of these drugs.