Pfizer scored a big win on Thursday as a federal judge knocked out a large part of the multidistrict litigation over claims that it schemed to keep generic Lipitor off the market.

But some claims were left standing — namely that Pfizer violated antitrust law by paying off generic competitor Ranbaxy to delay entry under the guise of settling a patent suit, forcing the plaintiffs to pay as much as five times more for the brand-name drug.