The risk of coronary heart disease is increased for any given low-density lipoprotein (LDL) cholesterol level in patients with high levels of triglycerides because some triglyceride-rich lipoproteins are atherogenic. This paper reports the results of a pilot clinical trial aimed to evaluate a novel triglyceride-lowering drug in combination with pravastatin to treat combined hyperlipidemia. Twenty-six patients with type 2b hyperlipoproteinemia were randomized to receive pravastatin 40 mg/day or pravastatin 40 mg/day plus piperazine-sultosilate 1000 mg/day for 12 weeks if their cholesterol levels, but not triglyceride levels, had responded to therapeutic lifestyle changes and treatment with 40 mg/day of pravastatin. Concentrations of triglycerides, cholesterol and apolipoproteins A and B were measured in duplicate before and after the intervention. There were no significant differences between groups in the change from baseline in the concentration of serum triglycerides. Conversely, significant differences were found for LDL cholesterol, which increased slightly with pravastatin alone but decreased with the combination (12.605+/-22.777% vs. -6.396+/-13.157%, respectively; p=0.022). Apolipoprotein-B levels increased with pravastatin alone but remained stable with the combined treatment (10.464+/-8.446% vs. 0.767+/-12.335%; P=0.028). The increase in the pravastatin group was significant. Although sultosilate was not efficacious in reducing triglycerides, it helped to decrease the concentration of small, dense, atherogenic LDL particles that are less receptor-sensitive and which could accumulate during long-term statin therapy in patients with high levels of triglycerides.