Role of Clinical Trials When Developing New Pharmaceutical Drugs

Clinical trials are medical research studies that are usually conducted by scientists, doctors, hospitals, universities, and the pharmaceutical industry itself. Participants (subjects) in a clinical trial have met the strict eligibility criteria defined by the study and have given informed consent to partake after the investigator has explained carefully the risks, benefits and alternatives to the study treatment. The FDA carefully reviews the results of clinical trials in many phases before approving a newly developed drug for commercial availability and use in the general population.

Phase 1 Trials

• Phase One clinical trials are the earliest studies of a new drug. These are usually very small studies because the primary aims are to determine if the new drug is even safe to give to humans and to start to determine a safe dosage range. Very little is known about the drug in this phase, although it may have gone through animal or laboratory testing.

Phase 2 Trials

• Phase Two clinical trials are larger, often with several hundred or even thousands of participants. In these trials, the drug is tested for effectiveness in the specific conditions being studied in the trial. Study subjects are also carefully monitored for side effects and adverse events due to the new medication.

Phase 3 Trials

• Phase Three clinical trials use the study drug in even larger groups, often thousands of subjects, to further test and confirm effectiveness as well as side effects and toxicities. In some conditions, the new study drug may be compared to older, standard medications to see if the new drug is as effective as, or possibly more effective than, the current standard therapies. Also, in some trials, a placebo drug may be given to some patients and results compared to the new study drug in other patients. Subjects will not know whether they are getting a placebo or the investigational drug.

FDA approval

• The FDA uses the results of clinical trials, particularly Phase Three trials, to determine whether they will approve the drug and for what indications. FDA approval is required for marketing and selling the drug in the United States. The FDA may also recommend that Phase Four trials, also known as post-marketing trials, be conducted in order to further confirm the side effects and effectiveness of the new drug. Post-marketing studies can be used to define the labeled risks and warnings, to expand indications for the medication, and in rare cases, to remove an indication when the drug is found to be more toxic or less effective than initial trials suggested.