Drugs (eg. antibodies and antivirals) are substances that cause changes to the body.

New medical drugs have to be tested to ensure that they work, and are safe, before they can be prescribed. There are three main stages of testing.

The drugs are tested using computer models and human cells grown in a laboratory. Many substances fail this test because they damage cells or do not seem to work.
Drugs that pass the first stage are tested on animals. In the UK, new medicines have to undergo these tests. But it is illegal to test cosmetics and tobacco products on animals. A typical test involves giving a known amount of a substance to the animals, then monitoring them carefully for any side-effects.
Drugs that have passed animal tests are used in clinical trials. They are tested on healthy volunteers to check that they are safe. Very low doses of the drug are given to begin with. If there are no problems, further clinical trials are done to find the optimum dose for the drug.

Clinical trials are not without risk. Sometimes severe and unexpected side-effects occur. Most substances do not pass all of the tests and trials, so drug development is expensive and takes a long time.

	Created by Carina C almost 9 years ago

	Copied by Sarah Egan almost 9 years ago

GCSE GCSE Note on B1c: Staying healthy, created by Sarah Egan on 04/04/2016.