By Miriam Vishio and Nicholas Cheolas (November 29, 2017, 4:13 PM EST) -- Brand-name pharmaceutical companies employ a variety of strategies to preserve and extend their branded drug products' monopolies. Challenges by generic drug manufacturers and consumers to those efforts as allegedly manipulative of regulatory and administrative processes have met with varying degrees of success. This article focuses on the antitrust implications of three such strategies that have the effect of blocking or delaying lower-priced generic drugs from entering the market: (1) using citizen petitions to inhibit final approval of generics, (2) introducing a reformulated version of a patented drug that effectively prevents generic substitution (a strategy referred to as "product hopping"); and (3) transferring drug patents to entities with sovereign immunity — like Native American tribes — to foreclose certain patent challenges....