Firstly it depends on whether you're getting (-)MK-801, or dizocilpine [(+)MK-801].
The Ki for (+)MK-801 is about 10x less than (-)MK-801, which is about 2x less that PCP. The exact same ratios exsist for behavioural quantities.
So if you're average dose of PCP is 10mg, than your dose of (-)MK-801 should be 5mg, and your dose of (+)MK-801 should be .5mg (500µg).
But then, I would want to start low, so I would go for .1mg to start and work up.
Just to defend my logic here, although the Ki ahnd behavioural data is taken from mice, the dosage is not extrapolated directly from it. I believe it is safe to assume that if 10 times the dose of 20 times the dose of PCP is equal to a particular dose of (+)MK-801 in mice, then the
same would be true in humans, especailly when the behavioural quantities are proportional to the bindings ones; see:
http://bilz0r.orcon.net.nz/NMDA-antags.gif
Hope thats some help friend...
<EDIT> Oh and thats in reference to dizocilpine.... not dizocilpine melate </EDIT>