A drug is a chemical that changes __________ processes in people's bodies. Drugs can be beneficial but may __________ the body.
Scientists are __________ new drugs all the time. Many drugs are derived from __________ substances have been known to __________ peoples for many years. Scientists seek to identify the key chemical in the __________ substances and then synthesis it into a drug that they can sell.
When new medical drugs are devised, they have to be extensively tested and __________ before being used. This is done through a multistage process:
New drugs are tested in the __________ to find out if they are toxic and to find out whether they work.
These tests often involve the use of __________. If a drug passes these tests, it is then tested on __________ in clinical trials.
Very __________ doses of the drug are given to __________ volunteers at the start of the trial. If the drug is found to be __________, further clinical trials are carried out to find the __________ dose for the drug.
During drug trials, some patients are given a __________ which does not contain the drug. Neither the doctors nor the patients know who has received a __________ and who has received the drug until the trial is complete. This is known as a 'double blind trial'.
Blind trials are important because even fake medicine makes you feel better. This is known as the '__________ effect'
Medicines must work better than a __________ to be worth using.