How do researchers test new treatments?

Phases in drug development

Phase I

A newly developed, an experimental drug is tested in the laboratory during the preclinical phase of research. Drug safety and efficacy may be tested in both animal and human cells and/or animal models. If laboratory tests show promising results, the drug advances to the clinical phase of the study.

Phase II 

Human clinical trials investigate dosing levels, safety, and efficacy of an experimental drug in a small number of normal people and in patients who have the disease or condition under study. If these trials show beneficial results – with a good balance between efficacy and side effects – the drug progresses to the next phase of the study.

Phase III 

In the final stage of the investigation, human clinical trials study the safety and efficacy of an experimental drug in large numbers of patients who have the disease or condition. If these trials show beneficial results, the manufacturer applies to health authorities worldwide for marketing approval in their specific countries. Health Canada reviews these applications to decide whether the drug will or will not be approved for use in Canada.

Learn more at https://en.wikipedia.org/wiki/Drug_development