Current treatments for major depressive disorder and bipolar depression have major limitations with many patients not responding to available antidepressant drugs. Even for those who do respond, it takes several weeks before symptoms improve.
‘Ketamine, a general anesthetic agent could produce an anti-depressant response in two hours rather than weeks compared to other drugs. The finding offers a new approach to treating severe depression.’
Ketamine, an anesthetic, is one of several glutamatergic drugs affecting neurotransmitters in the central nervous system.
Several studies have reported "rapid, robust, and relatively sustained antidepressant response" to ketamine, injected intravenously at low, subanesthetic doses, the researchers said.
Ketamine and related drugs may represent a "paradigm shift" in the treatment of major depressive disorder and bipolar depression -- especially in patients who do not respond to other treatments, according to Carlos A.
Zarate, from the National Institute of Mental Health, National Institutes of Health, in Maryland, US.
Another study led by Cristina Cusin, from Massachusetts General Hospital, showed that ketamine-induced changes in several brain areas involved in the development of depression.
The two studies on ketamine and other glutamatergic drugs for depression were published in the journal Harvard Review of Psychiatry.
Ketamine may also rapidly reduce suicidal thoughts. It has also produced rapid antidepressant effects in patients with treatment-resistant bipolar depression.
However, since the drug is FDA-approved only as an anesthetic, use of ketamine in depressive disorders is "off-label", unregulated, and not standardised.
"Efforts are underway to bring ketamine to market, standardise its use, and determine its real-world effectiveness," Zarate said.
Independent of how ketamine works or its ultimate role in clinical treatment, antidepressant response to glutamatergic drugs points to an exciting conclusion: "that rapid antidepressant effects are indeed achievable in humans".