WASHINGTON — Just two weeks after pleading guilty in a major federal fraud case, Amgen, the world’s largest biotech company, scored a largely unnoticed coup on Capitol Hill: Lawmakers inserted a paragraph into the fiscal cliff bill that did not mention the company by name but strongly ­favored one of its drugs.

The language buried in Section 632 of the law delays a set of Medicare price restraints on a class of drugs that includes Sensipar, an Amgen pill used by kidney dialysis patients.