Getting acquainted with Clinical Trials

A Clinical Trial is a medical experiment during which a therapeutic regimen is tried on a specific number of volunteers, in order to test its efficacy and identify its toxicity (tolerance - safety). Strategic trials are carried out to determine the optimal administration mode of a drug in combination with other substances.

Progress in Medicine is based on Research. The research and development of a drug requires a long-term investment  of 10 to 13 years in duration, while it presupposes the conduction of large and costly clinical trials. The overall cost of Research & Development (R&D) has become today even higher because, besides proving the safety and efficacy of each drug, there is also need to prove its added value to the patients' quality of life. The discovery and development of new drugs becomes more and more difficult, since out of the 10.000 molecules that are investigated it is only 1 that will end up as a new drug in the market. 

According to the 2007 Report of the European Federation of Pharmaceutical Industries and Associations (EFPIA), the average cost for the research and development of a new chemical substance amounts to approximately 1 billion Euros. However, the most costly and time-consuming stage in pharmaceutical R&D is the conduction of Clinical Trials (Phases I, II and III) which investigate the action of a substance on humans. Therefore, the Pharmaceutical Industry is the worldwide largest R&D investor of all other industrial sectors. 


What are Clinical Trials?

A Clinical Trial is a medical experiment during which a therapeutic regimen is tried on a specific number of volunteers , in order to test its efficacy and identify its toxicity (tolerance - safety). Strategic trials are carried out to determine the optimal administration modes of a drug in combination with other substances.

What is the aim of a Clinical Trial?

Clinical Trials are carried out to ensure safety and efficacy of drugs, before these are approved to enter the market.


How is a Clinical Trial conducted?

In general terms, Clinical Trials are conducted in 3  mandatory phases: Phases I, II and III.

Preclinical studies

This is the stage of Basic Research on experimental animals before the initiation of a Clinical Trial. Preclinical Studies can be either pharmacological or toxicological.

Phase Ι 

This is the first step testing a new drug in a group of people to evaluate its safety, determine a safe dosage range and identify side-effects. Given there is potential risk of unknown side-effects, the number of volunteers is small and the duration of this phase is short (2-3 weeks). 


Phase ΙΙ

The primary aim of this phase is to check the efficacy of the drug formulation. This phase may involve thousands of patients and last several months or years. 

Phase ΙΙΙ

Researchers collect information to identify the most favorable conditions that will allow the drug to be optimally effective, monitor secondary side-effects and compare it to commonly used treatments. This phase involves thousands of people and lasts 2-4 years. 

Phase II and III Clinical Trials are called 'Controlled Studies' , for they compare the efficacy of the drug under investigation with some pharmaceutical regimens that serve as reference points. Sometimes, in case there are no other approved regimens to compare with, the comparator drug may be placebo (inactive agent) or partially placebo.


In order to avoid subjective factors that may potentially affect the result s of Phase II and III Trials, volunteers should not be aware which drugs they are given (Blind Study). In some Trials, even the competent physician may ignore which drug is administrated to patients (Double-Blind Study). 

In general, the time needed for every tested drug to complete its determined trial process is 7 to 10 years, depending on how difficult it is to draw clear conclusions with regard to its efficacy and tolerance. 


Phase ΙV

Studies are conducted after the drug has been introduced to the market, in order to gather information on its optimal mode of administration (e.g. when one should start taking it, when to switch to another drug, when to discontinue it).



The Multinational Clinical Trials in which Greece participates, concern the development of innovative drugs for specific therapeutic categories. Given the approval of the National Drug Organization (Ε.Ο.Φ.) and the National Ethics Committee (Ε.Ε.Δ.),  Public and Private Hospital Departments participate in these Clinical Trials. The Department of Clinical Trials -integrated to the Pharmaceutical Research Directorate of  the National Drug Organization- is responsible for the approval and control of every Clinical Trial. 

According to the Ministerial Decree ΔΥΓ3/89292, ΦΕΚ Β1973/31-12-2003 (harmonized with Directive 2001/20/EC), Clinical Trials are divided in 2 categories:

·  Interventional Clinical Trials

· Non-interventional Clinical Trials


All Clinical Trials conducted wordlwide are registered to a database, that can be used by anyone who wishes to seek information:

The Registry of Clinical Trials conducted in E.U. countries can be found on: