NEW YORK (CNN/Money) - Vytorin, a relatively new cholesterol-blocking drug from Merck and Schering-Plough, has outpaced sales of a blockbuster rival, according to a report Monday from Friedman, Billings, Ramsey & Co.

Vytorin, a combination of Zetia, a Schering-Plough (up $0.11 to $20.84, Research) drug that stops cholesterol absorption into the liver and intestine, and Zocor, Merck's (up $0.16 to $30.90, Research) cholesterol-cutting statin, has become the No. 3 best-seller since it debuted last summer, according to the FBR report.

In the most recent figures available, more than 66,000 new prescriptions were filled for Vytorin in the week ending July 15 and the drug had 7.5 percent market share of cholesterol blockers, or statins, according to the report, which was authored by David Moskowitz and other FBR analysts.

The prescription numbers are significant, because Vytorin managed to outpace the best-seller Pravachol and the aspiring blockbuster Crestor, both statins, the report said. Bristol-Myers Squibb's (up $0.18 to $24.97, Research) Pravachol totaled $2.6 billion in 2004 sales and AstraZeneca's (down $0.23 to $40.71, Research) Crestor made $908 million.

FBR analysts were not immediately available for comment, but past reports have attributed Vytorin's success to a "very high" efficacy in lowering cholesterol with a good safety profile. This is partly because Zetia and Zocor have been tested in the marketplace for years, in addition to the required clinical testing.

Pfizer's Lipitor is still the No. 1 cholesterol blocker, as well as the top-selling drug of all time. Lipitor sales totaled $10.8 billion in 2004.

With $5.2 billion in 2004 sales, Zocor is the second most profitable statin. However, the drug's patent is set to expire June 2006. Drug sales generally plummet when a name brand goes generic, but Merck hopes to continue making revenue from Zocor by including it in Vytorin.

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