TRENTON, N.J. (AP) — Five large drug and grocery chains are suing Pfizer Inc. and a second drugmaker, alleging they conspired to delay sales of cheap generic versions of the blockbuster cholesterol drug Lipitor.

Lipitor, the world’s top-selling drug ever, had peak sales of nearly $13 billion a year several years ago. Sales dropped sharply after it got U.S. generic competition on Nov. 30.