Phase 1 Clinical Trials

Phase 1 clinical trials are where the drug is first tested in humans. During this phase of clinical trials the main purpose is to determine what the highest yet safest dose of the drug is and also to determine the best route of administration, that is, the best way to give the drug e.g. liquid, tablet, capsule, injection, under the tongue, etc. Because any prior testing of the drug was done only on animals, this particular phase tends to pose the highest risk as researchers don't know what to expect when using the drug in humans. To minimize this though, the drug will initially be given in very small doses which will gradually be increased as long as the side effects from it remain minimal. This phase is usually done in healthy volunteers, or in the case of cancer and HIV, it is done in people who have the disease.

In addition to the optimal dose, researchers also try to determine what the best time of day to administer the medication is. Other key areas of research during this phase include:

• Drug bioavailability: this means basically how available the drug is within the body once it is ingested
• Drug bioequivalence: that is, are or can different forms of the drug be used
• Metabolism: how the drug is broken down in the body
• Pharmacodynamics: i.e. studying what the drug does to the body
• Pharmacokinetics: i.e. studying what the body does to a drug (how the body absorbs it, breaks it down, distributes it and then gets rid of it)

Phase 1 Clinical Trials Snapshot

• Goal: Is it safe?
• Number of Participants: ~20 to 80
• Duration: several months
• Outlook: about 70% of drugs advance successfully from phase I clinical trials to phase II clinical trials

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May 25, 2009

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