Explain the three stages of drug testing.

First, drugs are tested on human cells and tissues, it is then tested on two different mammals. The final stage has two parts, the drug is initially tested on healthy human volunteers and they are given increasing doses of the drug in order to find the optimum dose. If this part is successfully, the drug is given to sick patients, one group of them is given the real drug and the other is given a placebo. This is a randomised double blind trail to test effectiveness of the drug