A clinical trial scientifically evaluates the safety and efficacy of investigational or marketed medicine that may be available by prescription or over-the-counter at the pharmacy.

The drug development process consists of all stages on the evaluation and formulation of a new drug compound once the compound has been discovered and has undergone pre-clinical testing. This occurs before the new drug compound is made available in the market and broadly consists of:

Phase I

Study to evaluate the initial safety of the drug compound in a small number of healthy volunteers (20 to 100) and how their bodies handle the drug compound.

Phase II

Study to evaluate the efficacy and safety of the drug compound in selected patients (up to several hundreds) with the specific predetermined medical condition to be treated, diagnosed and prevented. The subjects may be randomly divided into 2 or more groups to receive the experimental treatment at varying doses, standard treatment or placebo. Usually, neither the patients nor the Investigators know who gets the experimental drug, i.e. the study is blinded. These studies will provide the regulatory authorities and pharmaceutical company with comparative information about the relative safety of the new compound and its efficacy.

Phase III

Study conducted in a large number of patients (several hundred to several thousands) to gather safety and efficacy data and to satisfy the registration requirements laid down by the regulatory authorities. This large-scale study provides the regulatory authorities and the pharmaceutical company with a more thorough understanding of the drug's effectiveness, benefits and possible adverse drug reactions.

Phase IV

Study conducted after the registered drug has been marketed and used in a large number of patients. This surveillance provides additional information on the safety and efficacy profiles of the marketed drug. It includes comparison with other drugs already in the market, on long-term effectiveness, impact on patients' quality of life and cost-effectiveness relative to traditional and new therapies.