The History of Clinical Drug Trials in Turkey The history of clinical trials in Turkey dates back to the beginning of the 20th century, but many years had passed with studies done with no compliance to the Good Clinical Practice (GCP) guidelines. This was not due to the lack of legal documents. On the contrary, the first mention of clinical trials in a legal document occurred in 1926; “The Code of Pharmaceutical Products and Preparations No. 1262” law carried the statement: “Experimental drugs can be used in a patient only by his/her permission.”