Outer space, at least as we encounter it in science fiction, is basically a drug free-for-all. If character's aren't piloting starships on Melange or Somec, then they're playing with dolls on Can-D or pumping their brains full of Merge Nine, Semuta and whatever passes for rave music 20,000 years from now.
But let's steer clear of the fictional space drugs and consider the buffet of pharmaceuticals that real astronauts might indulge themselves in.
Booze: While coffee continues to be readily available in space, alcohol is more of a gray area. In 1969, Buzz Aldrin consumed communion wine on the moon and, if you believe some of the stories, the Russian MIR space station was practically swimming in vodka. While the ISS is technically a dry operation, NASA came under scrutiny in 2007 amid reports of astronauts hitting the bottle before takeoff. It's hard to argue drinking in orbit is a good idea, but that hasn't stopped scientists from developing space brews. According to New Scientist, a University of Colorado student, with a little help from Coors, actually sent a miniature brewing kit into orbit as part of her thesis on fermentation in space. The results were reportedly rather foul, but it's just as well. Without gravity, you can't get a good head on a pint anyway.