Proving Safety and Effectiveness

Drug trials and approval processes aim to prove that a new drug candidate is safe for human patients and effective in treating the target disease.

Before any human ever takes a new drug candidate, pre-clinical trials are conducted to obtain initial proof of safety and effectiveness. This may include data from tests done in laboratory dishes or other devices — so called in vitro research — or from limited animal studies. The point of pre-clinical trials is to demonstrate that it is reasonable to proceed to the next step.

Next come three phases of clinical trials with humans. Phase I is intended to confirm the safety of the drug, how it behaves inside the human body, and possible side effects. The subjects in this phase are healthy volunteers (rather than people who have the target disease), and they usually number between 20 and 80.

Phase II marks the beginning of controlled testing with patients who actually have the disease, in order to demonstrate the medicine's effectiveness. The total number of patients is still small — perhaps several hundred people. This phase also produces additional information about short-term side effects and risks associated with the drug.

Phase III seeks to provide definitive proof of effectiveness and safety with larger numbers of patients — from several hundred to several thousand — who suffer from the disease. This extensive data provides a basis for extrapolating results to the general population and for the labeling information that will be provided with the product.

Lilly conducts clinical trials in more than 30 countries and markets its medicines in 159 countries. That means we must work through regulatory approval processes in country after country in order to bring innovative cures to patients worldwide.