In a comparative study, 158 patients with type IIa or IIb primary hypercholesterolemia received either placebo, nicotinic acid extended-release 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 agents was permitted. During the short-term phase, low-density lipoprotein cholesterol levels were lower, in relation to baseline, with nicotinic acid treatment (-21%) than with placebo (P < or = 0.05), with pravastatin (-33%) than with either placebo (p < or = 0.001) or nicotinic acid (p < or = 0.05) and with combination therapy (-49%) than with the other 3 treatments (p < or = 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 < or = 0.05), pravastatin therapy (13%; p < or = 0.01) and combination therapy (16%; p < or = 0.01). Adverse events were less frequent in the pravastatin and placebo groups (p < or = 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 IIb primary hypercholesterolemia, and is superior to nicotinic acid in both efficacy and adverse event profile.(ABSTRACT TRUNCATED AT 250 WORDS)