Here is an article:

https://health.clevelandclinic.org/a-new-ketamine-nasal-spray-has-been-approved-for-depression-but-its-not-for-everyone/

snip:


Why it’s promising:

One potential benefit of the new drug is that it’s fast-acting. People may notice a relief in symptoms within just a few hours, and it could last for several days, Dr. Anand says. Most oral antidepressants, on the other hand, can take weeks to start working.

That’s because it works in a different way from other depression drugs. “Whereas most other available antidepressants work mainly on the serotonin, norepinephrine or dopamine systems, ketamine has major effects on glutamate, which is a different neurotransmitter that is much more prevalent in the brain,” Dr. Anand says.