In a comparative study, 158 patients with type IIa or IIb primary hgpercholesterolemia received either placebo, nicotinic acid extended-relesase capsules (0.5 to 1.0 g twice daily), pravastatin;(40 mg at bedtime), or the combination for a short-term, 8-week period. A long-term, 88-week phase followed in which the addition of other lipid-lowering cents was permitted. During the short-term phase, low-density lipoprotein cholesterol levels were lower, in relation to baseline, with nicotinic add treatment (-21%) than with placebo (p less than or equal to 0.05), with pravastatin (-33%) than with either placebo (p less than or equal to 0.001) or nicotinic add (p less than or equal to 0.05) and with combination therapy (-49%) than with the other 3 treatments (p less than or equal to 0.05) at all weeks measured. At week 8, high-density lipoprotein cholesterol levels were increased, in relation to placebo, by nicotinic acid treatment (12%; p less than or equal to 0.05), pravastatin therapy (13%; p less than or equal to 0.01) and combination therapy (16%; p less than or equal to 0.01). Adverse events were less frequent in the pravastatin and placebo groups (p less than or equal to 0.05), In comparison with placebo, treatment with nicotinic acid resulted in significant increases in aspartate and alanine aminotransferase. The placebo and pravastatin groups did not differ significantly regarding adverse events or laboratory parameters. similar results were observed in the long-term phase. Therefore, pravastatin is very effective and well tolerated in the treatment of type IIa or II6 primary hypercholesterolemia, and is superior to nicotinic acid in both efficacy and adverse event profile. concomitant administration of pravastatin and nicotinic acid was even more effective and was generally well tolerated.