What are the 3 main Stages of Drug Testing?

1) STAGE 1: Drugs are tested in Laboratories using computer models and skin cells grown using human stem cells. Tests: efficacy and possible side effects. Many substances fail this first test of a preclinical drug trial because they damage cells or do not seem to work 2) STAGE 2: New medicines tested on animals (In UK), illegal to test cosmetics and tobacco products on animals. Typically involves giving a known amount of substance and monitoring carefully for any side-effects 3) STAGE 3: Human clinical trials. Tested on healthy volunteers to check that they are safe, then tested on people with the illness to ensure that they are safe and that they work. Low doses of the drug are used initially, and if this is safe the dosage increases until the optimum dosage is identified