Now Wait For Last Year

Earth is trapped in the crossfire of an unwinnable war between two alien civilizations. Its leader is perpetually on the verge of death. And on top of it all, a new drug has just entered circulationa drug that whips its users back and forth across time.
In an attempt to escape his doomed marriage, Dr. Eric Sweetscent is caught up in all of it. But he has questions: is Earth on the right side of the war? Is he supposed to heal Earths leader or keep him sick? And can he change the harrowing future that the drug has shown him? Now Wait For Last Year plays with all of these questions in a way that only Philip K. Dick can.
Annotation
In a novel that makes our notions of politics, personality, and time seem terrifyingly provisional, Dick tells of a hapless doctor, whose planet is enmeshed in endless war, whose wife is addicted to a time control drug, and whose newest patient's demise could decide the fate of the world.