Differential effects of nicotinic acid in subjects with different LDL subclass patterns

Twenty-six subjects (20 male, 6 female) at high risk for CAD events were treated with moderate doses of nicotinic acid to investigate whether there was a differential lipoprotein response in patients with different LDL subclass patterns. Subjects were selected to have either pattern A (predominance of large LDL, peak particle diameter > 262 Å, n = 9) or pattern B (predominance of small LDL, peak particle diameter < 255 Å, n = 17) as assessed by 2–16% gradient gel electrophoresis of plasma. Nicotinic acid dose was similar in pattern A (2111 ± 651 mg/day) and pattern B subjects (1875 ± 698 mg/day). Total cholesterol and LDL cholesterol decreased by similar amounts in pattern A (-41 ± 26 mg/dl and −37 ± 18 mg/dl) and pattern B (−51 ± 44 mg/dl and −44 ± 45 mg/dl) subjects. Triglycerides tended to be reduced more in pattern B subjects (−100 ± 175 mg/dl) compared to pattern A subjects (−23 ± 34 mg/dl) although this difference was not statistically significant ( P = 0.08 for triglycerides log transformed). HDL cholesterol increased significantly more in the pattern B group (11.9 ± 14.2 mg/dl) compared to pattern A subjects (0.7 ± 8.5 mg/dl), ( P < 0.04). Similarly, LDL particle diameter increased significantly more in the pattern B subjects (9.8 ± 6.9 Å) compared to the pattern A subjects (3.6 ± 3.0 Å), ( P < 0.02). All pattern B subjects who achieved a plasma triglyceride < 140 mg/dl converted to pattern A. The differential effect of nicotinic acid in individuals with differing LDL subclass profiles may contribute to intraindividual variation in response to this drug and its effect on coronary atherosclerosis.