Demonstration of an add-on effect of probucol and cilostazol on the statin-induced anti-atherogenic effects.

Statins are often prescribed for treatment of cardiovascular diseases, although there are still many patients who cannot be effectively treated by statins alone. Both probucol and cilostazol exhibit anti-atherogenic effects. In the current study, we attempted to investigate whether a probucol and cilostazol combination had any add-on effects on atorvastatin. To examine this hypothesis, we fed Japanese white rabbits with a cholesterol-rich diet supplemented with atorvastatin alone (Statin group), probucol and cilostazol (PC group), atorvastatin, probucol and cilostazol (APC group), and compared their effects on plasma lipids and aortic atherosclerosis. All three drug-treated groups had lowered total cholesterol levels compared with the vehicle group but high-density lipoproteins cholesterol levels of the atorvastatin group were higher than other groups. Although aortic atherosclerosis was significantly reduced in all drug-treated groups, the most prominent atheroprotective effect was seen in APC group (APC: 67% reduction> PC: 43% reduction> Statin group: 42% reduction over the vehicle). Morphometric analysis revealed that the reduced aortic atherosclerosis in all three groups was mainly attributed to the reduction of intimal macrophages and smooth muscle cells. These results suggest that a combination of probucol and cilostazol with statin enhances statin's anti-atherogenic functions, which may be beneficial for those patients who are less responsive to statin therapy alone.