MedicalResearch.com Interview with:
Dr. Richard L. Dunbar MD MS
Assistant Professor of Medicine, Attending Physician, Preventive Cardiovascular Medicine Clinic, Member, Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of MedicineMember, Institute for Diabetes, Obesity and Metabolism,
University of Pennsylvania School of Medicine and
Dr. Harsh Goel
WellSpan Academic Hospitalists
Department of Medicine, York Hospital, PA
MedicalResearch.com: What is the background for this analysis?
Response: Niacin is the first cholesterol lowering treatment to prevent heart attacks and lower long term mortality. It thus provided the first proof that lowering cholesterol reduces cardiovascular risk. However, it is generally poorly tolerated due to almost universal flushing, limiting use. The better-tolerated statin drugs overshadowed niacin, rightly dominating hyperlipidemia therapy. Despite their advantages, statins are far from perfect, leaving important gaps. Firstly, at least 10% of patients simply don’t tolerate statins. Secondly, about 40% of patients have insufficient cholesterol lowering, leaving them far from their target LDL-cholesterol levels. Finally, even though statins lower cardiovascular risk, they by no means eliminate it and significant residual risk remains even in patients who respond to them.
The relatively poor tolerance of niacin motivated development of an extended-release alternative which was dosed very differently from the established cardioprotective regimen used in the Coronary Drug Project (CDP) and the Stockholm Ischemic Heart Disease Study (SIHDS), the two landmark trials that proved niacin’s benefits. These trailblazing trials used 3 grams of niacin divided throughout the fed portion of the day as 1 gram thrice daily with meals. In sharp contrast, the alternative regimen was severely handicapped by a profoundly lower dose of only 2 grams per day. Perhaps worse, the alternative regimen dosed all of the niacin at one sitting, at bedtime before the overnight fast, rather than three times a day before meals. We believe these were critical departures from the established cardioprotective niacin regimen, insofar as they severely undermined the alternative regimen’s efficacy. Accordingly, when added to statins, the alternative regimen failed to recapitulate the benefits seen with the established cardioprotective regimen in two recent large clinical trials, the AIM-HIGH trial and the HPS2-THRIVE trial. Besides the inherent flaws of the alternative regimen, there were also major issues with the trial designs which likely contributed to null results.
From a practice standpoint, this is worrisome, because clinicians may draw erroneous conclusions from the trials of the alternative regimen, and thereby deny a significant population of hyperlipidemic patients the benefits of a well-proven cardioprotective therapy, i.e. the population which does not tolerate or does not respond adequately to statins (almost 50% of at risk patients). Hence, we embarked on a critical analysis and review of the alternative regimen with a special focus on the AIM-HIGH and HPS2-THRIVE trials to bring to light the pitfalls of comparing radically different regimens of what is nominally the same drug.