====== Ketamine (treatment for depression) ======

The use of  [[https://en.wikipedia.org/wiki/Ketamine|Ketamine]] to treat [[content:psychology:disorders:depression]]  was formally investigated in a 2006  [[http://jamanetwork.com/journals/jamapsychiatry/fullarticle/668195|report]] for //JAMA Psychiatry//. A team based at the US National Institute of Mental Health (NIMH) in Bethesda, Maryland, found that :

>Robust and rapid antidepressant effects resulted from a single intravenous dose of an N-methyl-D-aspartate antagonist; onset occurred within 2 hours postinfusion and continued to remain significant for 1 week."

>To our knowledge, there has never been a report of any other drug or somatic treatment (ie, sleep deprivation, thyrotropin-releasing hormone, antidepressant, dexamethasone, or electroconvulsive therapy) that results in such a dramatic rapid and prolonged response with a single administration."

The mechanism of its action, however, is still unknown.

A new (2017) study, covered in //[[http://www.nature.com/news/party-drug-s-power-to-fight-depression-puzzles-scientists-1.21926|Nature]]// suggests that a previous theory (that it inhibits the brain's NMDA-receptors) may be incorrect.

>Their finding adds to recent studies contradicting a long-held idea that the drug works mainly by blocking proteins called NMDA receptors, on the surface of brain cells, which transmit signals between those cells."

A third (also as yet unproven) theory instead suggests that //breakdown chemicals// of the drug - rather than the drug itself - may be responsible for its anti-depressant effects.

//Note: //The 'enantiomer' (i.e. mirror image molecule) of Ketamine is called Esketamine (marketed under the name // Ketanest //and others) it has similar properties, and is also used to treat depression - also by an unknown mechanism.

//Update Oct 2018 :// //"Johnson & Johnson has submitted its esketamine for regulatory approval, but researchers still don't understand how the fast-acting antidepressant lifts moods." // [[https://www.nature.com/articles/nrd.2018.187|Nature Reviews Drug Discovery volume 17, pages 773–775 ]]

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Also see: [[content:medicine:drugs:lithium|Lithium]] and [[content:psychology:disorders:depression]] and [[content:medicine:drugs:gen_anaesthetics]]