Brand-name drug manufacturers risk antitrust violations by slowing generic production through patent layering.

Patents on many blockbuster drugs will expire in the near future, opening up the doorways for generic production. Brandname drug companies lose an estimated half of their U.S. sales during the first six months of generic production alone. In an effort to forestall large sales declines, some brand-name pharmaceutical companies are scrambling to delay generic production. One measure brand-name pharmaceutical companies often take to extend their monopolies is patenting additional features of the drug products or purified forms of the drugs. A patent gives a pharmaceutical company the exclusive right to make, use, or sell the patented drug for twenty years. When the patent expires generic companies are free to market the same drug, creating competition in the marketplace and lowering prices. Although antitrust law prohibits anti-competitive behavior, patents are an exception to the rule against monopolies. Patent holders are given a legally enforceable monopoly for the twenty-year