Abstract: A therapy of hyperlipemia or arteriosclerosis by using a pharmaceutical composition comprising (A) 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor or a salt thereof etc., and/or ezetimibe or a prodrug thereof or a salt thereof; and (B) a compound of the formula (I): wherein Ring A is a substituted or unsubstituted pyridine ring etc., Y is a substituted or unsubstituted aryl etc., R1 is a hydrogen atom, or a substituted or unsubstituted alkyl etc., R2 is a hydrogen atom or a lower alkyl group, R3 is a lower alkyl group, and Z is a hydroxy group or a amino group etc., or a salt thereof etc.; or a combination of (A) and (B), which is effective for a therapy of a patient who are not remedied by the current therapeutic agent, i.e. being not decreased to the desired level, in particular a patient having already suffered from a coronary heart disease etc.

Abstract: Naphthyridine derivative of the formula: ##STR1## wherein Ring A is substituted or unsubstituted pyridine, X is --N(R.sup.2)--CO--(R.sup.2 is H, alkyl, substituted alkyl, etc.), Z is a direct bond, --NH--, C.sub.1 -C.sub.2 alkylene, or --CH.dbd.CH--, Y is alkyl, substituted alkyl, aromatic group or substituted aromatic group, etc., B is alkyl, substituted alkyl, aromatic group or substituted aromatic group, or an acid addition salt thereof, these compounds having acyl-CoA: cholesterol acyl transferase inhibitory activity, and being useful as an agent for prophylaxis or treatment of hyperlipidemia, atherosclerosis, and related diseases thereof.