COLESTIPOL PLUS NIACIN THERAPY ELEVATES PLASMA HOMOCYST(E)INE LEVELS

The Cholesterol-Lowering Atherosclerosis Study (CLAS) was a randomized, placebo-controlled angiographic trial that tested the efficacy of colestipol plus niacin therapy for the reduction of blood low-density lipoprotein cholesterol level and the increase of blood high-density lipoprotein cholesterol level. One hundred sixty-two nonsmoking men from 40 to 59 years old who had undergone coronary bypass surgery were followed for 2 years and of these, 103 (57 drug treated, 46 placebo treated) were followed for 4 years. Average 4-year drug dose levels were niacin, 4.2 g/d, and colestipol, 30 g/d. Frozen plasma samples drawn during the fourth trial year and after cessation of therapy were assayed for homocyst(e)ine. There was a statistically significant difference between the drug and placebo groups with respect to on-trial homocyst(e)ine, (P < 0.01), with the drug group demonstrating higher levels. After therapy was withdrawn, there was a significant group difference in homocyst(e)ine change, (P < 0.001), with a median decrease of 5.99 nmol/mL in the drug group and a median increase of 0.98 nmol/mL in the placebo group. These results indicate that homocyst(e)ine levels are elevated by treatment with colestipol plus niacin.