It is intended to provide a drug which has an excellent effect of inhibiting the secretion of apoB-related lipoproteins and enhances the lipid-lowering effect of another lipid-lowering agent, i.e., an agent enhancing lipid-lowering effect. It is found out that a derivative having tetrahydropyran represented by the following general formula (I): (I) wherein each symbol is as defined in the description; has a potent activity of inhibiting the secretion of apoB-related lipoproteins and can enhance the lipid-lowering effect of another lipid-lowering agent, when used together with such an agent. When used together with another lipid-lowering agent, the above drug is useful as an agent enhancing lipid-lowering effect for familial hypercholesterolemia and a remedy for intractable hyperlipemia with the coincidence of diabetes.
