I am often asked what the main stages of pharmaceutical Clinical Trials are.  In this post I will try and explain.  I should point out that I am not a Clinical Trials expert, but this is my understanding.

Discovery stage

A new chemical undergoes chemical and biological studies.

Preclinical stage

Testing on isolated organs, tissues and animal.

Phase I

Testing on a small number of healthy human subjects.  The aim is to assess chemical safety and how the body deals with the product.

Phase II

Drug is given to patients to see how effective the product is, usually over several weeks.  Usually given to people with the condition that the medicine is trying to treat.

Phase III

Large scale study (and very expensive) to gain further evidence of drug safety and efficacy.  This usually takes about a year and will include double-blind and multi-centre controlled trials.  This will include comparison with similar products if they exist.  Various dosages will also be tested to see which dose is the most effective.  If successful this may lead to the drug being approved and marketed.

Phase IV

Post market monitoring on the overall effectiveness (including negative effects) of the drug.