It goes without much discussion that bondage play while either or both is on a strong drug-induced high is a no-no. Of course we all have our lines of bodily tolerance to drugs - I don't do the stuff at all, but wouldn't bash friends or other people for smoking joints or trying something other - but the idea to take on stuff which might cloud your powers of instant observation and drastically change how you respond in the play-out of the scenario (or cause vomiting into a tight gag, physical cramps etc) is a risk to anything sensible in bdsm.

I agree with master & slave 327-834-200 that you can't stash away your ability to break the scenario or change it if the bound/silenced sub is in danger.