When I was in college, my roommate and I had a party where one of the guys that showed up was an off-duty police officer. He was the friend of one of the other guests, no one we knew directly. He relayed a story of an incident where he was on a "disturbance of the peace" call--some guy was "on drugs" and swinging around a tree branch, threatening his neighbors. This officer showed up on the scene to find a couple of other officers there, guns drawn, while the suspect was waving around a large branch and yelling. They tried to reason with him, and he only yelled back. Finally, he charged the officers, and was shot. He went down, then got back up, grabbed his branch, and came forward again. He got shot again. All in all, he wound up being shot multiple times. The autopsy showed he was running on an almost lethal dose of PCP.
May be urban legend, I dunno. I don't want to ever find out.
Dealing with people on drugs is different than those that are straight. Drugged people are MUCH more erratic and unpredictable. However, that can work in your favor, too. No, they may not feel things right away......but they DO feel things. Also, they are a bit easier to confuse. Finally, chances are, if you are dealing with a drugged person, you will be able to outlast them, whether running away or outfighting them.
I would say, best thing to do would be to act like you are one of them--offer to buy 'em a drink or something, whatever--and get the hell away from them.
My guess is that, if they are recreationally using drugs, they would rather enjoy their high than fight you.......but there's always that *one* jerk.....
Rambling again....sorry....
Peace--