Step 4

Clinical trials

The real challenge for drug candidates begins once they pass the initial tests. They have to show in clinical trials that the potential medicine is effective and well tolerated.

Clinical testing proceeds in four phases. Only when a drug candidate has successfully passed one phase it can move on to the next.

Phase I:

Tolerability and safety

Drug candidates are first tested for safety and tolerability in studies with healthy volunteers. These studies are conducted in dedicated clinical facilities that ensure participants the best possible care.
Researchers can see how the new agent behaves in the human body and obtain preliminary information about its effects and the most appropriate dosage.

Phase II:

Clinical efficacy

The next step is to confirm the drug’s presumed mechanism of action, i.e. to prove it’s effective.
Researchers work with carefully defined groups of patients, giving them a range of dosages. This provides the information needed to identify the ideal treatment dose.
Patients enrolled in phase II studies are cared for by physician investigators and are observed closely in an effort to identify potential risks as early as possible.

Phase III:

Documenting treatment outcomes

Only now does the developer test the drug in large-scale trials involving up to several thousands of patients, under conditions that closely resemble the clinical setting the drug is intended for.
This provides a realistic picture of how the drug will perform in clinical use. The information gained in this phase will also be important for marketing the drug when the time comes.

Phase IV:

Ongoing Surveillance

Even after a drug is approved, it remains under expert surveillance. All side effects observed in patients taking a drug must be recorded and listed in the package leaflet.