In the United States, before clinical trials with new drugs can proceed, an Investigational New Drug (IND) application must be submitted to the Food and Drug Administration. Applications for drugs intended for the treatment of HIV-related diseases are reviewed by the Division of Anti-Viral Drug Products (DAVDP) within the Center for Drug Evaluation and Research. IND applications must contain adequate preclinical studies to support the safety of the proposed clinical trials. Essential for demonstrating safety are animal toxicology studies in which the drug has been administered in doses, by the route(s) of administration, and over a length of time equivalent to the corresponding parameters proposed for clinical trials. Reproductive toxicology/teratology studies should be conducted early in the development of the drug. Other nonclinical toxicology studies, such as carcinogenicity bioassays, are usually conducted concurrently with clinical trials. The DAVDP has developed a Pre-IND program to assist sponsors in preparing the best preclinical research to support the development of new drugs.