SOLVED. Junkie ex-pharmacist searching for his missing child [s]

[Jmjharrison]

I read this in 1989, a hardcover from a library. It was a very dark thriller/mystery. I believe it had a one word title. The main character was a pharmacist who became an addict and was fired/lost his medical license. He is searching for his missing daughter while robbing various pharmacies for drugs along the way. As the novel progresses, so does his delusions and drug psychosis. The novel ends on an ambiguous note and the possibility that the narrator was actually the one who did something to the child. I am sure the last sentence loosely says "The car disappeared into the traffic of the highway." Looking back, the book had a Chuck Palahniuk Fight-Club feel; that being the unreliable narrator. I'm pretty sure it was a one word title, "Denial" and "Delusion" pop in my head, but I have had zero luck searching those words. This has become my Holy Grail.

[Lobstergirl, au gratin]

Disappearance?

An unusual hero--a drug-addicted pharmacologist--carries Cohen's (coauthor, Mindbender, 1989 paperback) otherwise mundane snatch-and-search tale into the realm of fierce and memorable nightmare. "Fifty milligrams of pentobarbital, and the town of Calverton turned into a blur of concrete"--but no matter how many drugs Adam Druit swallows, snorts, or shoots, he can't quite bury the pain of a broken life. Once a top pharmacologist and happy family man, his drug addiction had driven him into exile as a pharmacist in a small Rhode Island town--and his wife Casey and young daughter Sherry into another man's arms. When Sherry is kidnapped, however, Adam learns that the same drugs that have scourged his life can be potent weapons in the search for his daughter. By feeding a dangerous hallucinogen to a witness to the snatch, Adam digs out a thin description of the kidnapper; by slipping poison to a recalcitrant pawnshop owner and then to a seedy Hells Angel-like drag-dealer, he forces out clues about the kidnapper--identifying him as a serial killer of young girls who's been working his way north through New England. Finally tracking him to a tranquil town, Adam stalks the kidnapper stalking--and then grabbing--a young girl at the local public school; but all of his drug-taking takes its toll, and hallucinating Adam nearly kills the wrong man before he at last comers the kidnapper and his latest victim at a sleazy hotel.....

[Lobstergirl, au gratin]

Jmjharrison, are you still looking for this or was it "Disapppearance?"

[Lobstergirl, au gratin]

Given that the OP was a drive-by, it's doubtful we'll hear back from him or her. But the title and description match extremely well so let's call this solved.