Ketamine -- can it reduce the effects of other drugs?

After some reading the other day into the way that Ketamine works on the brain I was left with a bit of a wonder.
Does Ketamine, in its act of blocking NP receptors (amongst others), reduce or nullify the acts of other drugs?
ie. Would some synergies with this particular chem not work or be of a reduced experience?
One such combination that comes to mind is the Ketamine + MDMA combination.
Ketamine can stop the rush of other neurotransmitters in the way it acts upon the brain thus can it perhaps, reduce the intense serotonin rush of MDMA or perhaps the dopamine rush of meth?

ive found that it reduces stimulants but amplifies depressants/psychedelics.

K kills a MDMA high faster the sound of nitrous excites raves.
I had railed half a pill recently, and was enjoying that nicely when someone offered me a line of K. I didn't know that the K would affect the roll, so I took it. Sure the K was nice, but I sure wasn't rolling after it.
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MDMA-4-ALL (Except if there is ketamine apparently)