Research and Drug Development for Huntington's Disease
Clinical Trials: Phase I:
A clinical trial is an important experimental technique for assessing the safety and effectiveness of a treatment. The most important purpose of a phase I clinical trial is to investigate the safety of a potential drug in humans, but it is also used to examine the pharmacokinetics and find the maximally tolerated dose.
For almost all phase I clinical studies, the participants should be healthy males and females from ages 18-40 who are not taking any additional medication. Usually, 20-100 participants are used in these studies. These trials are uncontrolled, meaning that all participants are given the drug. Each participant serves as their own control, because their health before and after the drug treatment is assessed and compared.
When beginning a phase I trial, researchers have to start with a certain dosage, look at its effects, and then slowly scale it up until they reach what they feel is the dose-limiting toxicity. This is the dosage at which side-effects are severe enough to prevent the participants from benefiting from the treatment. The dose previous to this one is considered the maximally tolerated dose, and is used in phase II clinical trials.
Furthermore, the toxicity of the drug and its effects on each of the major organs is carefully studied at each dose level. The pharmacokinetics of the drug- how much a change in dose affects the distribution, absorption, and elimination of the drug from the body- is examined as well. Participants are usually observed until several half-lives of the drug have passed. Essentially, by the end of a phase I clinical trial, researchers should have a recommended dose to use in phase II trials, a good idea of the pharmacokinetics of the drug, and notes as to any benefits they may have seen in the participants. Approximately 70% of drugs tested in phase I trials make it to phase II. Potential drugs that fail in phase 1 trials, usually do so because too many harmful side effects are produced that outweigh the benefits to justify using it as a kind of treatment.
HD and Phase I Clinical Trials
There are currently many clinical trials being conducted to study potential treatments for HD. Because the HD community is relatively small, it is possible to have good communication and coordination between researchers all over the world. The Huntington Study Group has been organizing and conducting clinical trials for HD since 1993. The HSG is a non-profit organization that is composed of physicians and health-care providers from around the world. They support open communication across the scientific community and full disclosure of all clinical trial results to the public.
Encouragingly, many clinical trials for potential HD therapies in progress at the time of writing have moved from phase I into phase II and III. As of March 2007 the University of Iowa is conducting a Phase I trial on a selective serotonin reuptake inhibitor (SSRI) called citalopram. For more information on this trial, please click here The National Center for Complementary and Alternative Medicine (NCCAM) has completed a phase I trial with an amino acid derivative called creatine for patients with HD. However, because it is thought that creatine will be more effective when used in combination with other drugs, additional research will first determine what other drugs it should be paired with before it is tested in phase III trials.
For information about clinical trials in every phase, the NIH runs a database that compiles all known trials in the country. For their list of trials related to HD, click here. Finally, there are ways for HD patients and their families to get involved with clinical trials for potential HD treatments. Huntington's Disease Drug Works is a program designed to facilitate communication between HD patients and their families, and the scientists and doctors conducting the latest research on Huntington's disease. Their hope is to speed up research and reduce the time it takes to set up a clinical trial. Through their website, you can find ways to enroll in a trial as a participant, or volunteer to help out those who do participate.
Last Modified: 05/22/2009
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