|Principal Investigator (PI)||Prüfer|
|The investigator is responsible for conducting a clinical trial at their study site. In case several investigators are involved in conducting a trial at a single study site, a so called principal investigator (PI) must be appointed and all other investigators are referred to as subinvestigators in ICH‑GCP 1.56. The German Medicinal Products Act does not make this distinction. If several study sites are involved in a clinical trial, the sponsor appoints a so called coordinating investigator (CI).
Normally, a medical doctor will take on the role of principal investigator. Their experience in the conduct of clinical trials may be proven by a scientific curriculum vitae and certificates confirming the recent participation in investigator or GCP training (ICH‑GCP 4.1.1). The qualification of an investigator is evaluated by the competent ethics committee when reviewing the application for the conduct of a clinical trial.