A clinical trial is a research study conducted to answer specific questions about new therapies, or new ways of using known treatments. Clinical trials are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work. Clinical trials are conducted in a series of steps, called phases – each phase is designed to answer a separate research question.
Phase I Trials
These are the earliest trials in the life of a new drug or treatment. They are usually small trials, recruiting anywhere between 20-80 patients. The study is designed to determine the effects of the drug on humans and the tolerability of the human body towards the drug. Determination is observed from the time the drug is absorbed, throughout the process of metabolism and until the drug is excreted from the body. This phase also investigates the side effects that occur as the dose is increased.
Phase II Trials
Not all treatments tested in phase I trials make it to phase II trials. The majority of phase II studies are categorized as random and blind studies, in which neither the patients nor the researchers are aware of who has received the experimental drug and who has received a “placebo”. This phase is executed for a comparative analysis between various doses and the effectiveness of the drug. The comparative data is provided for pharmaceutical companies, Food and Drug Administration (FDA), and Health Canada for evaluation.
Phase III Trials
These trials compare the undergoing trial drug with the best treatment that is currently available in the market, and provide a look at the benefits of the drug and the range of reactions caused by the drug. The number of subjects involved in these trials range from hundreds to thousands, and the duration can last up to several years. Of the total number of drugs that are initially used in the study, 70-90% of these drugs are successful once phase III is complete. The trials provide pharmaceutical companies, FDA, and Health Canada with additional safety information on the drug, and allow for the drug to undergo Phase III trials while having the drug on the market for consumers.