3. Vytorin

After the Enhance trial, which showed Vytorin didn’t beat Zocor alone at fighting atherosclerosis, sales of Vytorin and Zetia took a hit.

3. Vytorin
Merck & Co.
2016 sales: $1.14 billion

Merck’s cholesterol drugs Zetia and Vytorin are a franchise, but they’re also distinct meds with different marketing points. Zetia can be added on to any statin. Vytorin combines Zetia with Merck’s off-patent statin Zocor. Adding Zetia means more than one pill; Vytorin puts both meds in one.

That convenience factor added enough oomph to the Vytorin brand to push it, albeit briefly, above its single-agent counterpart. In 2008, Vytorin brought in $2.4 billion in sales worldwide for Merck and its then-partner (now subsidiary) Schering-Plough, compared with Zetia’s $2.2 billion. Both of those results were a decline from 2007; after the Enhance trial, which showed Vytorin didn’t beat Zocor alone at fighting atherosclerosis, the meds took a sales hit.

But the Vytorin edge dwindled. By 2011, Zetia was outperforming its peer, with Vytorin turning in $1.8 billion to Zetia’s $2.4 billion. And as 2016 sales figures show, Vytorin continued to slide.

RELATED: Merck's Vytorin set for massive sales slide as generics hit

Though it was approved two years after Zetia, it lost its exclusivity just months after Zetia did. As of April, the combo drug was facing multiple generic competitors.

Analysts expect Vytorin to quickly cede sales to cheap knockoffs now. Providing data on patent losses this year, life science commercial intelligence firm Evaluate in August predicted the drug’s sales will sharply fall to $177 million in 2022.

3. Vytorin