Preclinical studies refer to the testing of a drug, procedure or other medical treatment in animals before trials may be carried out in humans. During preclinical drug development, the drug’s toxic and pharmacological effects need to be evaluated through in vitro and in vivo laboratory animal testing. The FDA requires sponsoring companies to develop a pharmacological profile, determine toxicity in at least two species of animals and conduct short-term toxicity studies. Various preclinical requirements exist for different kinds of laboratory animals. Information gathered in preclinical studies are used as evidence and support in FDA applications for the approval of new drugs and medical procedures.