• Phase I usually includes short studies involving 8-60 subjects and is designed to determine the drug's basic safety profile, pharmacokinetics, and sometimes pharmacodynamics.
• Phase II trials, which involve administering the drug to roughly 50-250 patients, strive to determine efficacy, side effects, and clinically relevant dose ranges.
• Phase II studies are designed to refine dosing and provide evidence of safety and efficacy in more diverse and greater number (usually 300 to 1000+) of patients.

General guidance for clinical trials can be found at http://www.fda.gov/cder/guidance/959fnl.pdf

An IND (Investigational New Drug) application seeks the FDA's authorization for the first administration of an experimental human drug. The subsequent filing is the New Drug Application (NDA). The FDA web site offers information on the form and content of an IND and well as other relevant documents. See http://www.fda.gov/cder/regulatory/applications

New biotech firms or existing ones developing new compounds should have a clinical development plan. Many companies may not wish to take their compound(s) through the complete clinical development cycle since this process requires considerable capital and expertise. A possible exit strategy is to license the development rights to a large pharmaceutical company after a successful Phase I study or after proof-of- concept is established.