The preclinical phase is the stage in drug development where the drug is tested in animals to determine safety and efficacy before moving on to human clinical trials. Synonyms for preclinical phase include animal testing, animal studies, preclinical testing, non-clinical testing, and preclinical research. These terms all refer to the same stage of drug development, highlighting the importance of thorough testing in animals before human trials. The preclinical phase is an essential step in drug development, allowing researchers to identify potential adverse effects and optimize dosing before testing in humans. This stage helps to ensure the safety and efficacy of drugs before they are given to humans, reducing the risk of harm or ineffectiveness.