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What Are the Phases of Drug Development?

The process of taking a new medicine through discovery and development, and delivering it to the market is a lengthy, expensive, research intensive and high-risk venture where failure looms at every point within the process. In the U.S., the process is estimated to take 10-15 years at a cost that has risen from $800 million in 2000 to over $1.3 billion in 2006. One drug is brought to market for every 5,000-10,000 compounds screened during discovery. Thirty one drugs and biologics were approved in 2008 while there were 2,900 compounds in development at the beginning of 2009.

  1. Discovery Phase:

    • With the identification of an unmet medical need, the process begins with the identification and validation of a target molecule within the body. Compounds are then screened and the lead compound is optimized for effectiveness against the target.

    Preclinical Phase:

    • The lead compound undergoes extensive toxicology testing in laboratory and animal studies to determine if it should proceed onto testing in humans. (3-6 years)

    IND Submission:

    • At the conclusion of preclinical studies, the research data is filed as an Investigational New Drug Submission (IND) with the FDA (Food and Drug Administration) in the U.S. (or comparable agencies in other countries). An FDA approval allows the new medicine to proceed into human trials.

    Clinical Trials, Phases I-III:

    • Trials in humans begin with Phase I Clinical trials where studies are conducted, usually in 20-100 healthy volunteers, to determine how well the drug candidate is tolerated. (safety). (6 mos. - 1 year)

      Phase II "Proof of concept" trials move into 100-500 patient volunteers to determine efficacy and optimal dosage, and to further study drug safety. (1 year)

      In Phase III, expanded testing for verification of efficacy and monitoring of adverse events in long-term use of the drug is conducted in 1,000-5,000 patient volunteers. (1 - 4 years)

    NDA Submission and FDA Approval Review

    • At the conclusion of Phase III trials, the Drug Company assembles and analyzes all data it has generated during the process and presents their findings to the U.S. FDA in a New Drug Application (NDA). This government agency reviews the submitted information and makes a determination whether or not a drug has been proven safe and effective for marketing in the U.S. (6 mos. - 2 years)

    Phase IV:

    • The FDA will sometimes require a company to conduct additional “post-marketing studies” to monitor the long-term safety or to generate data in a specific group of patients (e.g., the elderly). The cost of one study can be $20-$30 million. These studies may be used to submit a Supplemental NDA seeking use of the medicine for additional disease indications.

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