Drug research begins with identifying a molecule with a therapeutic effect, the drug candidate. When a drug candidate has been shown to be sufficiently safe to investigate efficacy in humans, the clinical investigation phase begins. In the clinic, a drug is generally first tested in generally healthy people (phase 1). In phase 2-4, a drug is then tested in people who are ill. This of course takes place under strict conditions; drug testing must meet the guidelines for Good Clinical Practice (GCP). This international standard guarantees the rights, safety and well-being of the participants in the study.
Clinical research into the safety and effectiveness of a potential drug thus takes place in four phases:
- In phase 1, the drug is administered to people for the first time. In small groups (20-80 persons) of (usually healthy) volunteers, research is done into safe dosage and possible side effects.
- In phase 2, the efficacy of the drug is tested on patients who have the disease in question. This research phase usually lasts two years and concerns about 100 to 500 patients.
- Phase 3 is the most extensive clinical research phase. These studies can last more than four years. Several hundred to thousands of patients participate. Data on safety, efficacy and overall benefit-risk ratio of a potential drug are recorded in a comprehensive file. The drug is compared with a placebo (non-active substance) and/or with the current standard treatment. We do this to be able to answer the question whether the new drug is better and/or safer than the treatment that is already available.
- Phase 4 takes place after the drug is available to be prescribed. This phase is meant to carefully monitor the safety and effectiveness, now that the drug is used in daily practice by an extensive group of patients for a longer period of time.