Lawyers in a bellwether case over Merck & Co.’s osteoporosis drug Fosamax drew a New Jersey appellate panel’s rebuke Wednesday for having waited four months to notify the court that the case had settled.

It was not until April 9—two days before the Appellate Division planned to release its opinion after review of a record with 5,300 pages of documents—that the lawyers let the court know of the settlement reached in January.