From The Wall album. Not (supposedly) inspired by recreational drugs:
According to Rolling Stone the lyrics came from Roger Waters' experience when he was injected with tranquillizers for stomach cramps by a doctor prior to playing a Pink Floyd show in Philadelphia on the band's 1977 tour for the Animals album. "That was the longest two hours of my life," Waters said. "Trying to do a show when you can hardly lift your arm." The experience gave him the idea which became the lyrics to this song.Addendum: As Anthony points out in his comment, it would be more appropriate to feature the earlier version in which Roger Waters sings the lyrics. Here it is: