Developing new drugs is a long and expensive process that takes 10-12 years and costs $500 million on average. Potential drugs are first tested in laboratories and then on animals to test safety and effectiveness before clinical trials begin with human volunteers. Clinical trials involve three phases of testing on increasing numbers of patients to further evaluate safety and efficacy. If a drug successfully completes all phases of clinical trials and regulatory approval, it can then be licensed and prescribed by doctors, while continued monitoring occurs after market release.