Several years ago, the Schering-Plough cholesterol absorption inhibitor (Zetia, ezetimibe) and its combination pill with simvastatin (Vytorin) were the subject of a lot of puzzled controversy. A clinical trial (ENHANCE) looking at arterial wall thickness in patients with familial hypercholesteremia had unexpectedly shown little or no benefit, although statins themselves had worked in this population. This led to plenty of (still unresolved) speculation about the drug's mechanism of action, whether it really was going to be of benefit to the wider patient population, what this meant for the surrogate endpoint of LDL lowering (which the drug does accomplish), and so on.
Sales of both Zetia and Vytorin took a hit, naturally. But a new editorial in JAMA wonders why they're selling at all, and particularly, why they're doing so well in Canada. A new paper in the American Heart Journal shows that ezetimibe sales in the US went down 47% over the next year after the ENHANCE results came out. But in Canada, it just kept rolling along. (Even after the decline, though, it's still used more in the US).
What's causing this? Quite likely, an over-focus on cholesterol levels themselves:
Krumholz, one of the coauthors on the study with Jackevicius, remains perplexed as to the continuing popularity of ezetimibe. “The drug continues to defy gravity, and that’s probably a result of really strong marketing and the singular focus on cholesterol numbers,” he said.
Krumholz said heart health campaigns urging patients to “know your numbers” and treatment goals based on cholesterol measurements, such as getting asymptomatic individuals’ LDL-C levels below 130 mg/dL, have worked in ezetimibe’s favor at the expense of evidence-based medicine. “Is this the drug that lowers your LDL-C and helps you? We don’t know that,” he said. “The comfort of hitting a target offers little benefit if you don’t know that it is really protecting you.”
The funny thing is, all that emphasis on LDL assay numbers was supposed to be "evidence-based medicine". But that's the funny thing about science - the evidence keeps leading you in new directions.