Discovering New Drugs

Pharmaceutical discovery — like everything else — favors those who search in the right places. The drug discovery process at Lilly begins by focusing on specific diseases and patient needs. Lilly discovery scientists search for biological targets within the body that play a role in a given disease. They create or find unique molecules that might someday be medicines, and they screen millions of molecules against the targets to pick promising leads.

After the drug discovery process produces a promising lead, that compound is still a long way from being ready for testing in human subjects.

Developing Potential Medicines

In the development stage, Lilly scientists learn much more about how the new compound metabolizes in the body and intervenes in the disease. Is there a viable way to deliver the medical molecule to the biological target? How is this affected by chemical composition, the size of the molecule, and natural barriers within the body's tissues and organs? Should the delivery vehicle be an oral method, an injection, or something else? How fast is the drug released and distributed in the body?

Researchers probe further to determine what dosage will be required for the medicine to be effective, and at what level it might be toxic to the patient. They also explore practical issues like whether Lilly will be able to manufacture the compound on a large scale, and whether the compound will be stable enough to remain effective and safe in the patient's hands. All of this happens in preparation for the day when the first human dose can be administered.

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, preclinical trials are conducted to obtain initial proof of safety and effectiveness. This may include data from tests done in laboratory dishes or other devices — called in vitro research — or from limited animal studies. The point of preclinical 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 around the world and markets its medicines in 143 countries. That means we must work through regulatory approval processes in country after country in order to bring innovative cures to patients worldwide.