About Drug Development Process

Clinical trials involve the administration of an investigational pharmaceutical product to individuals under the supervision of qualified medical investigators. Clinical studies are conducted in accordance with protocols that detail the objectives of a study, the parameters to be used to monitor safety, and the efficacy criteria to be evaluated. Each protocol is submitted to the appropriate regulatory body and to a relevant IRB/REB prior to the commencement of each clinical trial. Clinical studies are typically conducted in three sequential phases which may overlap in time-frame.

In summary, the following steps must be completed prior to obtaining approval for marketing in Canada, the United States and Europe:

Nonclinical Animal Studies – These studies evaluate the safety and potential efficacy of a therapeutic product and form part of the application which must be reviewed by the appropriate regulatory authority prior to initiation of human clinical trials.

Phase 1 Clinical Trials – These trials test the product in a small number of healthy volunteers to determine toxicity (safety), maximum dose tolerance, and pharmacokinetic properties.

Phase 2 Clinical Trials – These trials are conducted in the intended patient population and include a larger number of subjects than in Phase 1. The primary goal is to determine the safety of a product in a larger number of patients and ultimately in the intended patient population. These trials may also provide early information on the potential effectiveness of a product.

Phase 3 Clinical Trials – These trials are conducted in an expanded patient population at multiple sites to determine longer-term clinical safety and efficacy of the product. It is from the data generated in these trials that the benefit/risk relationship of a product is established and the final drug labelling claims are defined.

In the course of conducting clinical trials for a drug candidate, a company may conduct more than one trial of a particular phase in order to evaluate the drug against a variety of indications or in different patient populations. In such a case, industry practice is to differentiate these trials by way of designations such as “Phase 2a” or “Phase 2b”.

A key factor influencing the rate of progression of clinical trials is the rate at which patients can be recruited to participate in the research program. Patient recruitment is largely dependent upon the incidence and severity of the disease and the alternative treatments available.

Even after marketing approval for a drug has been obtained, further trials may be required (referred to as Phase 4 trials). Post-market trials may provide additional data on safety and efficacy necessary to gain approval for the use of the product as a treatment for clinical indications other than those for which the product was initially tested. These trials may also be used for marketing purposes.