Many medicines were first found in nature. Aspirin comes from willow bark and penicillin comes from a mould. Today many new drugs are designed and made in laboratories. Whatever the source, a new medicine must be tested thoroughly before it can be used on patients.
The first stage is preclinical testing. The drug is tested on cells and tissues grown in the laboratory and then on live animals. This checks that the drug is safe and effective, and helps to find a suitable dose.
If it passes, clinical trials begin on people. Healthy volunteers are given low doses first to check the drug is safe. Then patients are tested to find out whether it works and what the best dose is. Patients are often split into two groups, one given the new drug and one given a placebo, which contains no active drug. In a double blind trial, neither the patient nor the doctor knows who has the real drug, which stops bias in the results.
The results are then checked by other scientists in a process called peer review. In the school laboratory, you can investigate how antibiotics affect bacteria by growing bacterial cultures on agar using aseptic techniques, such as flaming the loop, so that unwanted microorganisms are kept out.