Clinical trials are conducted before a drug or a medicinal products get marketing authorization by the corresponding regulatory authority. Clinical trials are planned by sponsor companies who has developed the new Medicine or Medical device etc. The sponsor companies conducts Clinical trials with different purposes.
Clinical trials can be divided into five basic categories depending on the purposes for which they are conducted. The categories are
1. Treatment trial
2. Prevention trial
3. Diagnostic trial
4. Screening  trial
5. Quaility of life trial ( also known as supportive care trial)