Fast-acting antidepressant shows continued relief in animals

A fast-acting antidepressant that provides a mood-lifting effect in mice within 24 hours and continues working for a sustained period may hold promise for use in humans.

For the more than one in 10 Americans taking antidepressants, fast-acting therapies would be preferable to those currently available, which can take weeks or months before alleviating symptoms. Antidepressants have proven themselves tricky for drug discovery and development because of the varying benefits the drugs provide to patients.

But a study presented at the Experimental Biology 2014 meeting last week of MI-4, also known as Ro-25-6981, backs up previous findings showing that the drug can cause a rapid antidepressant effect in animals by blocking a key signaling chemical in the brain. Previously, researchers were not aware of the full spectrum of MI-4's antidepressant properties.

Using standard tests designed to demonstrate antidepressant effects in rodents, the researchers found that MI-4 not only improves mood in mice with depression-like symptoms but works in the long term to provide sustained relief. It does this by using a three-pronged approach known as triple reuptake inhibition, which refers to a drug's ability to simultaneously increase the levels of dopamine, norepinephrine and serotonin, three chemicals in the brain associated with mood and feelings of pleasure. Most depression drugs target only one of these chemicals, which may explain the varied response among patients.

"What makes this study unique and exciting is that in the same drug we seem to have both of the properties you want in an antidepressant--both rapid and sustained effects," said study co-author Jeffery Talbot, director of the Research Center on Substance Abuse and Depression at Roseman University of Health Sciences in Nevada.

In addition, researchers concluded that it's unlikely that MI-4 would be addictive.

- read the press release
- see the study abstract