PHASE I TRIALS: Initial studies to determine what the body does to the drug in humans and vice versa in humans, the side effects associated with increasing doses, and to gain early evidence of effectiveness; may include healthy participants and/or patients.

PHASE II TRIALS: Controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study and to determine the common short-term side effects and risks.

PHASE III TRIALS: Expanded controlled and uncontrolled trials after initial evidence suggesting effectiveness of the drug has been obtained, and are intended to gather additional information to evaluate the overall benefit-risk relationship of the drug and provide adequate basis for physician labeling.

PHASE IV TRIALS: Post-marketing studies to gain additional information including the drug's risks, benefits, and optimal use.

MARKETING AND SALES: After a new drug is approved, the manufacturer must monitor the use of the drug and promptly report any additional, previously undetected side effects to regulatory agencies. On average, 1 in 10,000 molecules studied in the discovery phase make it to market and are able to recover their development costs.