THE TRIP :
Before reaching the first line, fragmentation will occur- the world will begin to spin, but it won't be dizzying. Music will become fragmented. Chaos will ensue. At some point, you will find yourself complete removed from your surroundings and your body. Descriptions of the post-line experience vary substantially, but most include talk of alternate planes of existence, oneness, past and future revelations, and strange fabrics of all sorts. It will be very difficult to communicate at this point, and you probably will not be able to see or hear others in the room. Some revelations will be extremely heavy and some scary, but that fear does not seem to come back with you and is therefore difficult to describe as scary. You will probably find yourself coming back across the line again visibly, attempting to put an object in focus or define it. It is at this point that you will likely want to get in touch with your co-trippers. This is the "Wow" period. It is very important here that you do not try to move for awhile. The trip will continue mildly for an hour or so after this, with more conventional focuses.
PRECAUTIONS :
An overdose of Ketamine will knock you out as if in an operating room. This would prove to be a waste of a tripping experience, and will probably make you ill to your stomach. The danger dosage is much higher however, at 10 mg/lb. Interactively, Ketamine should not be used with respiratory depressants, primarily alcohol, barbituates, and Valium. Ketamine has been used with no ill interactive effects with dope, acid, nitrous, dextromethorphan, and MDMA, although no combinations are recommended and are highly unnecessary given the totality of ketamine. It does not have a build-on effect with halucinagins and will generally overpower other drugs. Nitrous in the up and down periods can be effective. Unpracticed trippers may be overpowered by the awesome revelations of Ketamine and may be somewhat overwhelmed, although in general fear seems to be unable to compound here (such as in an LSD trip or with other drug paranoias) and will probably be only episodic. Food should not be consumed within an hour and one-half before the trip, and should be avoided for longer periods of time if possible. A peculiar sort of loneliness can occur over the line, so it is a good idea to stay in close quarters with people you are close with, and best to have a sober monitor or experienced Ketter at hand.
www.erowid.org has a LOT of info on effecrs of drugs, dose etc...
Hope this helps