Introduction

The drug development process includes multiples phases of pre-clinical work, clinical trials, Food and Drug Administration (FDA) approval and post-approval clinical trials.  Before a pharmaceutical or biotechnology company can initiate testing in humans, it must conduct extensive pre-clinical or laboratory research.  This research typically involves years of experimentation in animal and human cells as well as in animals.  If this stage of testing is successful, a pharmaceutical/biotechnology company provides this data to the FDA and requests approval to begin testing the drug compound in humans.  This is the beginning of the clinical trial process.  Clinical trials allow companies to independently evaluate the safety and effectiveness of new drug compounds so that the investigational drug can move through the FDA approval process and be marketed to the public.  

The clinical testing process is normally done in three phases with each successive phase involving a larger number of people.  Once the FDA has approved a new drug, pharmaceutical/biotechnology companies also conduct post-approval clinical trials.  The different phases of clinical trials are:

Phase I Trials - Phase I trials are the first human trials.  These trials evaluate the safety of an investigational drug, how a drug is absorbed, metabolized and excreted in the human body, the best way to give a drug and the proper dosage to cause the fewest side effects.  Phase I trials have a small number of participants, often 20-100, who are typically healthy volunteers that do not have the medical condition that the drug is intended to treat. 

Phase II Trials - Phase II trials are conducted with volunteers who have the medical condition the drug is intended to treat.  While safety continues to be a focus of the trials, the efficacy of the drug begins to be studied in order to evaluate if the drug works and whether there are any common side effects.  These trials are often randomized and "blinded" - neither the participants nor the researchers know who is getting the experimental drug and who is receiving the placebo.  Phase II trials have more participants, often one hundred to several hundred.

Phase III Trials - Phase III trials test drugs that have been shown to help some patients and usually compares the safety and efficacy of the drug with the standard or best known treatment for the medical condition the drug intends to treat.  Phase III trials have much larger numbers of participants, often several hundred to several thousand across a diverse patient population.  This large scale testing provides the pharmaceutical companies and the FDA with a more thorough understanding of the drug's effectiveness, benefits and the range of possible adverse reactions.  Once a Phase III trial is successfully completed, a company can request FDA approval for marketing the drug. 

Post-Approval Clinical Trials (Phase IV) - Phase IV trials are post-FDA approval and continue to study the various attributes of the drug, such as side effects, how the drug compares to competitive drugs or the ability of the drug to treat other diseases.   

Clinical trials that are well-designed and well-executed are the best approach for eligible participants to:

• Play an active role in their own health care.
• Gain access to new research treatments before they are widely available.
• Obtain expert medical care at leading health care facilities during the trial.
• Help others by contributing to medical research.