The effectiveness of Merck’s (MRK) cholesterol lowering drug Zetia has been put to question following the release of data from a clinical trial comparing Abbott’s (ABT) Niaspan (niacin extended-release tablets) plus a statin with Merck’s Zetia. Although data are not encouraging for Merck, the company expressed its confidence recently at the American Heart Association meeting.

Results from the ARBITER 6 – HALTS study showed that patients at high cardiovascular risk showed significant reduction in atherosclerosis after 8 and 14 months of therapy with Abbott’s Niaspan plus a statin, the study’s primary endpoint. The study met its secondary endpoint too. It was observed that treatment with Niaspan plus statin resulted in significantly fewer major adverse cardiac events (or MACE, a composite endpoint consisting of heart attack, myocardial revascularization, admission to the hospital for an acute coronary syndrome, and death from coronary heart disease), as compared to Zetia.
However, the results are not very conclusive as the patient population has been very small (363). In addition, the study was stopped prematurely after just half the number of intended patients completed the full study period.

The results of the study may hamper the sales potential of Merck’s cholesterol drugs further. This is the third time in the last two years that negative results have lowered sales of the cholesterol drugs, Zetia and Vytorin. Earlier, the combined sales of these drugs came under pressure due to disappointing clinical trial outcomes and a potential cancer risk. Results from the ENHANCE and SEAS trials, released in 2008 have significantly depressed sales of both drugs.

Combined sales fell 12% in 2008 and were down 7% at $1 billion in the third quarter of 2009.
We believe the drugs will continue to struggle due to the unfavorable data as well as increased competition from generic and branded statins, especially following the Lipitor patent expiration in November 2011. We have a Neutral recommendation on Merck.

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