Research and Drug Development for Huntington's Disease
Clinical Trials: Phase IV
Phase IV trials are conducted once a new drug has been approved for marketing and is available for prescription by doctors. Occasionally, government authorities (usually the FDA) may require a pharmaceutical company to do a phase IV study, while sometimes these studies are voluntarily conducted. A company might want to know more about the side effects and safety of the drug, or how the drug works in the long term. They also look at how the drug impacts the average participant's quality of life. Many phase IV trials are also used to determine the cost-effectiveness of the treatment, and compare it to any alternatives available.
Many drugs have very rare side effects that only appear in 1 of every 10,000 participants, or less frequently. Because phase III clinical trials have only a few thousand subjects and only last for a couple of years, these side effects may not show up in the earlier trials. Phase IV trials are particularly useful in helping to discover and monitor these rare side effects. They are also used to look at the effects of the drug in specific sub-categories of the participant population, such as children and the elderly. If many unexpected and severe side effects are detected in the phase IV trials, the drug can be withdrawn or restricted, despite its earlier approval from the FDA.
Additionally, phase IV trials might discover that the drug can be used to treat conditions other than the ones it was originally intended for. If the drug seems promising as a new treatment for a different condition, a pharmaceutical company can take the drug back to phase III clinical trials (called a new indication study) to get approval for multiple uses.
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-J. Seidenfeld, 5/19/07
For Further Reading:
What is a Clinical Trial? Online A useful site from the Huntington's Study Group that discusses the various phases of clinical trials in more detail.
Background Information for Clinical Research in Huntington's Disease. Online A resource from HD Drug Works discussing the types of clinical trials that are conducted for HD
Clinical Trials currently being conducted for HD. Click here. A service of the U.S. National Institutes of Health
Last Modified: 05/22/2009
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