Study Finds Extended Release Niacin, but not IHN, Effective in Lowering Cholesterol Levels

Evidence from a study published in the January issue of Journal of Clinical Lipidology, reports inositol hexanicotinate (IHN) ineffective in managing high cholesterol. The study, which published clinical results comparing an extended-release form of niacin to IHN and a placebo, simultaneously confirms a wax-matrix form of extended release niacin can help lower cholesterol.

6 Feb 2013 --- Conducted by Joseph M. Keenan, MD, and a team of researchers from the University of Minnesota, the study examined 120 subjects with high cholesterol at the University’s Clinical Research Center. Subjects received instruction for a heart-healthy diet, and were monitored for diet, medication side effects, blood chemistries, blood lipids and dosing compliance throughout the study. Five subjects from each group were randomly selected for a pharmaco-kinetic substudy in the research center. Blood tests over eight hours were used to measure the absorption rate and metabolism of the subjects’ first 500 mg dose of wax-matrix, extended release niacin in the form of Niamax (also known by the brand name Endur-Acin) and IHN.

Results showed IHN and placebo produced no significant improvement in blood lipids. Conversely, wax-matrix niacin, demonstrated positive lipid benefits, reducing total cholesterol 11 percent, LDL cholesterol 18 percent, non-HDL cholesterol 15 percent and triglycerides nine percent. It also promoted an increase in HDL cholesterol by 12 percent. “IHN has been a popular choice for niacin therapy, especially by alternative health providers because of its ‘no flush’ claim. However, there has never been a controlled study of IHN conducted on a United States population, and several European studies using IHN were combination interventions making it difficult to measure the contribution of IHN to lipid benefits,” said principal investigator Joseph Keenan, MD. “This clinical trial was a six-week placebo controlled comparison of 1500 mg/day of the two niacin products, which also included a pharmaco-kinetic sub-study designed to give health professionals a scientific basis for making their choice in niacin therapy.”

Previous studies with wax-matrix niacin have shown that about 15 percent of subjects are especially sensitive to niacin, and instead utilize a lower than typical therapeutic dose. Six subjects in the wax-matrix niacin arm of this study completed the study on a reduced dose (500 to 1000 mg/day) and had comparable lipid benefits to the full dose subjects. Blood chemistry monitoring showed a modest rise in liver enzymes within the range of normal, which was not considered clinically significant.

“IHN was well tolerated, and subjects were compliant with dosing and study protocols, but there were essentially no lipid benefits at all and the IHN results were the same as placebo,” said Dr. Keenan. “The pharmaco-kinetic sub-study was helpful in explaining these results since the blood assays showed no evidence of nicotinic acid rise after a 500 mg dose nor any nicotinic acid metabolites.” “This study concluded that the nicotinic acid in IHN is not bio-available, and there’s no evidence that it reaches the therapeutic levels needed to alter lipids. Therefore it has no place in the management of high cholesterol,” continued Dr. Keenan. “In fact this study raises the ethical issue of whether IHN has any benefit at all even as a vitamin supplement.” For over 40 years, Lonza has been the global leader in niacin production. Niacin is used as a dietary supplement and maintains good cholesterol within the normal range.