New York: Researchers have identified promising drug compounds that could successfully treat depression in less than 24 hours while minimizing side effects.

Although they have not yet been tested on people, the compounds could offer significant advantages over current antidepressant medications, the study said.

"Our results open up a whole new class of potential antidepressant medications," said lead researcher Scott Thompson, professor at the University of Maryland School of Medicine in the US.

"These compounds can relieve the devastating symptoms of depression in less than one day and can do so in a way that limits some of the key disadvantages of current approaches," Thompson said in the study published in the journal Neuropsychopharmacology.

These compounds, called GABA-NAMs, minimise unwanted side effects because they are precise: they work only in the parts of the brain that are essential for mood, the study said.

The compounds were tested in rats that were subjected to chronic mild stress and caused the animals to act in ways that resemble human depression.

Giving stressed rats GABA-NAMs successfully reversed experimental signs of a key symptom of depression, anhedonia, or the inability to feel pleasure.

Remarkably, the beneficial effects of the compounds appeared within 24 hours – much faster than the multiple weeks needed for most of the currently available antidepressants called selective serotonin re-uptake inhibitors, or SSRIs to produce the same effects.

"These compounds produced the most dramatic effects in animal studies that we could have hoped for."

"It will be exciting to find out whether they produce similar effects in depressed patients. If these compounds can quickly provide relief of the symptoms of human depression, such as suicidal thinking, it could revolutionise the way patients are treated," Thompson said.

No effects of the compound were detected in unstressed animals, raising hopes that they will not produce side effects in human patients.