Treating Coronary Heart Disease: Is Niaspan Better than Ezetimibe?
By Simeon Margolis
The media have given much attention to the results of a recent research study that looked at two drugs used to treat patients at high risk for coronary heart disease. The HALTS study, presented on November 16, 2009 at the annual meeting of the American Heart Association, appeared to show that Niaspan is more effective than ezetimibe.
Drugs that effect cholesterol levels
LDL cholesterol (LDL-C) is harmful because it deposits cholesterol into arterial walls to form the plaques which narrow the arteries that supply blood to the heart, brain, and other organs. Conversely, HDL cholesterol (HDL-C) is protective because it can remove cholesterol from arterial plaques.
Because ezetimibe interferes with cholesterol absorption from the intestine, this drug lowers blood levels of harmful LDL-C but has little effect on HDL-C. In contrast, Niaspan is the most effective drug for raising blood levels of beneficial HDL-C while also lowering LDL-C to some extent.
The HALTS study
The HALTS study measured wall thickness of the carotid artery, a major artery in the neck that supplies blood to the brain; the thickness indicates the amount of plaque buildup in the artery. The study included 208 men and women, divided into two groups: one group took a statin + Naispan, the other took a statin + ezetimibe. As one might then predict, after 14 months of treatment the average, harmful, LDL-C levels fell more in the ezetimibe group than in the Niaspan group. But the levels of protective HDL-C rose in those taking Niaspan and declined in the ezetimibe group. However, a small but significant reduction in carotid artery wall thickness (CAWT) in the Niaspan group but not in the ezetimibe group appeared to support the greater effectiveness of Niaspan. But is this really the case?
Too early to draw a conclusion
Given the relatively short time and small number of participants in this study, it is too early to decide whether Niaspan is more effective than ezetimibe when either drug is added to a statin. Also, CAWT is only one of a number of indirect measures of the extent of arterial narrowing by atherosclerotic plaques. Each of these measures is referred to as a “surrogate” for what we really need to know, that is, which drug combination is more likely to prevent undesirable clinical outcomes such as a heart attack, stroke, or death from a cardiovascular event. Surrogate measures are often used to gauge the possible value of a medication in trials that can be carried out in a short time in relatively few subjects. To be meaningful, however, such findings must be followed by more expensive and more time consuming research trials that determine true clinical outcomes.
A frequently used surrogate for the effectiveness of a drug is how much it lowers LDL-C. This surrogate can be misleading. For example, the combination of a statin and ezetimibe lowered LDL-C significantly more than a statin alone in several studies, but the combination was no more effective than the statin alone in reducing CAWT. This result would appear to be a second strike against ezetimibe, but it too is based on the same surrogate measure of clinical benefit that was used in HALTS.
Final judgments on the relative value of Niaspan versus ezetimibe combined with a statin must therefore await the future results of several ongoing, large, long-term studies comparing the effects of statins alone and the two combination regimens on cardiovascular events and/or mortality.
(Source: Yahoo)
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