Probucol further lowers the serum cholesterol of colestipol-treated patients with hypercholesterolemia.

When probucol in therapeutic doses is added to the therapeutic regimen of patients previously treated with colestipol and diet, total and HDL cholesterol levels fell. LDL-C/apo B and apo AI/apo AII ratios also fell. One can conclude from these findings that probucol works by different mechanism than does colestipol, and that in addition to lowering levels of lipoproteins it also produces changes in the compositions of both LDL and HDL. The significance of these findings for the prevention or treatment of atherosclerosis is unknown.