Back to the Conceptual Data Model.

The Approach :- 
Establish the Business Rules or FACTS
The Facts define what is known about the 'Things of Interest' in the area being studied. 
They establish an English-language version of the relationships between the 'Things of Interest' 
which can be understood and agreed to by the key people such as Users. 
This is very useful when the 'Things' become Entities or Tables in the Database.
The purpose of defining the Facts is to establish common understanding and agreement of the important 
terms and concepts involved in Clinical Drugs Trials. 
A. The Things of Interest are :- 
A.1 Drugs
A.2 Participants 
A.3 Trials 
B. Business Rules :-
B.1 Individuals take part in a Trial, when they become Participants. 
B.2 Individuals have identifiers, names and addresses
B.3 Trials have a Purpose, a Start date and a Completion Date.
B.4 Trials involve Participants and Drugs.
B.5 Participants have a Clinical Condition.