he's on midazolam, it comes up in episode 3, or 4, cant quite remember. he buys it off some kid and the kid starts asking him some qquestions about an old case, and mahone says "listen kid, i only need one thing from your, midazolam, 1500 miligrams every 30 days, got it" i had to rewind and watch it several times befor ei could underdstand what he was saying, cause he says "midazolam" really fast.