Study results may lead to antidepressants that act in hours not weeks

William Atkins
Saturday, 28 July 2007 19:47

Science - Health

National Institute of Medical Health (NIMH) medical studies with ketamine may lead the way for developing faster-acting antidepressant medications

NIMH scientists have performed two studies involving ketamine. The chemical ketamine was shown to successfully block a receptor called NMDA (N-methyl d-aspartate) in brain cells.
 

The NMDA receptor (NMDAR) is blocked, which directly results in another receptor, AMPA (α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid), to rapidly act to get antidepressant medicine into the system of people who need its fast actions to relieve their depressive symptoms.

In fact, ketamine has been found to provide relief in depressed patients within hours instead of the usual weeks or months from currently used antidepressant medicines. The speed that ketamine works is its most important feature.

AMPA imitates the effect of glutamate, which is a common and fast acting neurotransmitter in the nervous system. The AMPA receptor (AMPAR) is a common receptor in the nervous system, found in various parts of the brain.

Only recently has glutamate been found to be associated with depression.

According to Elias Zerhouni, director of the National Institutes of Health (NIH) “This new finding is a major step toward learning how to improve treatment for the millions of Americans with this debilitating disorder (and) toward eliminating the weeks of suffering and uncertainty they have to endure while they wait for their medications to work.”

Ketamine, according to another medical study published in the July 23 online edition of Biological Psychiatry, causes serious side effects such as hallucinations. In fact, ketamine is only used medically as a dissociative anesthetic (in humans and animals) on a limited basis due to this hallucinate nature. In addition, ketamine has been implicated as an illegal recreational (party) drug. It is included within the United States Controlled Substance Act, and is considered illegal or highly regulated in other countries such as Canada, the United Kingdom, and Hong Kong (China).

Consequently, it will not be used as an ingredient when these faster-acting antidepressants are developed. The studies with ketamine are only being used to understand how antidepressants work on the nervous system of mammals, such as humans.

According to NIMH, clinical depression--depression that is diagnosed by a medical profession--is thought to affect about 12% of women and about 6.5% of men in any given year. Over a lifetime, about 20% of women and 10% of men have clinical depression at least once. Millions of people in the United States suffer from depression. Major depression is considered one of the leading psychological problems in the industrialized countries the world. Its impact on society, along with its prevalence, is increasing, too.