A new study, demonstrating the benefits of ketamine, claims that the drug may prove to be the fastest treatment for depression. The horse tranquilliser, according to research, works within 40 minutes.
This compares with the weeks, even months, it takes with traditional antidepressants, reports the Daily Mail.
Two small studies have found that 70 per cent of patients with manic depression responded positively to the horse drug ketamine, with the effects lasting for at least three days.
A number of clinical trials are under way, investigating the benefits of the drug.
Manic depression - also known as bipolar disorder - is characterised by mood swings ranging from extreme happiness to extreme sadness. These episodes of highs and lows can often last for several weeks or more - they may be interspersed by periods of normal mood.
Many people can also suffer episodes of recurrent depression without the extreme highs. The condition is thought to be a result of imbalances in brain chemicals such as norepinephrine, serotonin and dopamine.
Ketamine has a reputation as an illegal party drug but it has also long been used as an anaesthetic. It works in a different way from traditional medicine for treating depression.
The drug targets the activity of the brain chemical glutamate. One of glutamate's jobs is to boost the electrical flow among brain cells.
Studies have shown that when this is interrupted, depression can result. Ketamine helps by blocking a brain protein, which affects glutamate signals.
It also improves the working of another brain protein, which is involved in regulating brain cells' electrical flow.