The 3 Stigmata of Palmer Eldritch by Philip K. Dick

1977 mass-market paperback from Bantam Science Fiction in good condition with some mild spine creasing. A very cool find. 
 
In the overcrowded world and cramped space colonies of the late 21st century, tedium can be endured through the drug Can-D, which enables users to inhabit a shared illusory world. When industrialist Palmer Eldritch returns from an interstellar trip, he brings with him a new drug, Chew-Z. It is far more potent than Can-D, but threatens to plunge the world into a permanent state of drugged illusion controlled by the mysterious Eldritch.