The body has adapted defence mechanisms to protect itself against the entry of microorganisms.
Part ofCombined ScienceMicroorganisms and health
This first involves testing a drug in a lab on cells and tissues.
This is known as in-vitro testing.
The drugs are then tested on animals.
Animal testing allows scientists to check how well the drug works on an entire living organism.
Computer modelling is also carried out at this stage.
Preclinical trials are necessary to:
Clinical trials are needed to assess how the drug works in humans.
Any tests before this stage have only shown how effective it is in other species.
Clinical trials will occur if the preclinical trials prove that the drug works and has no harmful side effects.
Initially, small groups of healthy, human volunteers are used in these trials with the groups eventually becoming larger.
Participants are sometimes paid but some are willing to help medical research for free.
Patients who can potentially benefit from the drug can also volunteer to be involved in the research.
Clinical trials are necessary to determine the correct dosage required. If these trials are successful the drug can be licensed for use.
