The wonderful things about humans is our individuality. The lottery that is our genetic make-up means that
we are all unique, and this means we can react differently to medications.
It is not possible to test every new treatment on every person before approval, so researchers try to
understand how a medicine works through testing in a clinical trial on only a sample of people. Researchers
hope a sample will reflect how well and safe the intervention may be in general population, but it is not
always perfect because of genetic variability, and human factors.
The size of the sample tested in clinical trials depend on how frequent, serious or chronic the condition being
treated. For example, a medicine used to be used to treat high blood pressure, which lots of people have,
will be tested on more people than a treatment for a rare disease for which there might only be 1000 people
in the world affected. Or, there may be less people tested if there is thought to be an urgent need for a
treatment, for example because people die from the condition and there is no other treatment. By the time a
treatment is approved, it may have only been tested on 5,000-10,000 people worldwide.
Clinical trials are run under strict conditions with close medical monitoring in only a fraction of the population
that may eventually receive the medicine. “Real-life” use of a medicine after it is approved can therefore
uncover safety issues that were not previously found, or recognised as issues, in clinical trials. Clinical trials
will continue after a medicine is marketed to collect further safety data. The new safety information collected
can result in regulators sometimes taking approved medicines off the market.