ARBITER 6-HALTS Results Not Good for Zetia

Houston, TXResults of the ARBITER 6-HALTS trial of Zetia (ezetimibe) and Niaspan (niacin) show that Niaspan is more effective than Zetia as a cholesterol treatment. This news has caused some doctors to question whether or not to use Zetia to treat patients with high cholesterol. The results were published along with two editorials in the New England Journal of Medicine on November 15.

ARBITER 6

The results of the ARBITER 6-HALTS study (Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol 6–HDL and LDL Treatment Strategies) reveal that Niaspan, made by Abbott Laboratories Inc., is more effective than Zetia as a supplementary cholesterol treatment.

The study tested the effect of Niaspan or Zetia on the thickness of the carotid artery's wall. Niaspan works by raising levels good HDL cholesterol while Zetia decreases the amount of bad LDL cholesterol. Both drugs are used in combination with other medications to slow artherosclerosis.

Researchers also found that the rate of major adverse cardiac events was one percent with niacin (Niaspan) compared with five percent for ezetimibe (Zetia). However, researchers cautioned that the study was not designed to investigate major adverse cardiac events and that the information should only be used as a hypothesis generator. Furthermore, although the percentage differences appear significant, they actually involved two patients taking niacin and seven patients taking ezetimibe.

New England Journal of Medicine Zetia Editorials

An editorial published in the New England Journal of Medicine claimed that the trial was ended prematurely and the small sample size should have prevented researchers from concluding that Niaspan is more effective than Zetia. Only 208 patients had completed the full 14 months of the trial, compared with the 363 patients who had enrolled.

One of the authors of a second editorial that accompanied the results of the ARBITER 6 trial was a lead investigator on the ENHANCE trial, which also measured the effectiveness of ezetimibe in slowing the progression of plaque. The ENHANCE trial found that Vytorin and Zetia did not provide any significant benefit over the drug Zocor in slowing down the clogging of the arteries. The lead investigator in that trial, John J.P. Kastelein, Md, PhD., agreed in his editorial with the ARBITER 6 investigators that niacin was more effective than ezetimibe.

Merck's Response

Merck has responded to the ARBITER 6 trial by affirming its support of ezetimibe products. "The results of the small ARBITER 6 study do not, in any way, change our view of Zetia and Vytorin as effective medicines for fighting LDL cholesterol," said Peter S. Kim, PhD, president of Merck Research Laboratories.

However, some doctors, including the past president of the American College of Cardiology, said that ezetimibe and Vytorin, "should be drugs of last resort." They argued that doctors should not use ezetimibe as frequently as they have been.

The ARBITER 6 study was funded by Abbot, maker of Niaspan, according to MedPageToday (November 15, 2009).