2. Zetia

merck
Zetia's loss of exclusivity followed new data showing that the drug, combined with a statin as in Vytorin, could offer a cardiovascular benefit to some patients.

2. Zetia
Merck & Co.
2016 sales: $2.56 billion

Merck’s big-selling Zetia has a storied history that ended with a final boost to its reputation, if not its sales. A cholesterol-fighter that works differently from statin meds—it blocks cholesterol absorption in the blood rather than suppressing its production in the liver—it was expected to zoom right onto the market when Merck and its partner, Schering-Plough, launched it in 2002. And it did gin up sales quickly; by 2005, the partnership was reporting $1.5 billion from Zetia.

Sales kept growing. But then results from Enhance, a much-watched trial of its sister combo drug Vytorin compared with Zocor alone, were delayed, and in the end, the trial failed to show Vytorin beat the statin med at fighting atherosclerosis. In 2008, Zetia’s sales fell by 9%—to $2.2 billion—with 23% of its decline in the fourth quarter. The drug’s sales the final three years of its patent life hovered in the $2.5 billion range.

Ironically enough, Zetia's loss of exclusivity followed new data showing the drug, combined with a statin as in Vytorin, could offer a cardiovascular benefit to some patients. The Impact-It trial showed that Zetia, added to the Merck statin Zocor, could cut cardiovascular risks for patients with acute coronary syndrome.

RELATED: Zetia generics launch sets Merck up for $1.4B hit to 2017 cholesterol sales

The risk reduction wasn’t enough, however, to persuade the FDA to update the med’s label. An FDA advisory panel later voted against the change; ahead of the vote, FDA reviewers pointed out that the reduction in risk was small and limited to certain patients.

Plus, the risk-reduction finding showed that it’s overall cholesterol reduction, not the drug’s mechanism of action, that benefited patients, the trial investigators said at the time. And that supplies another twist: Zetia’s Impact-It results have left a legacy for other high-powered cholesterol meds and their case for slashing cholesterol levels.

What’s more, Zetia and its generics stand to benefit from the step therapy payers are requiring before patients can move on to pricey new competitors in the cholesterol field, Amgen’s Repatha and Sanofi and Regeneron’s Praluent.

2. Zetia