To provide a compound which inhibits the kinetic cell death of cardiac muscles without inhibiting cardiac functions. A 1,4-benzothiazepine derivative represented by general formula (I) and a pharmaceutically acceptable salt thereof, wherein R represents H or C₁ to C₃ lower alkoxy; X represents O or H₂; n represents 1 or 2; R¹ represents H, substituted phenyl (wherein the substituent is OH or C₁ to C₃ lower alkoxy), (a), C₁ to C₃ lower alkoxy, or (b) wherein R² represents C₁ to C₃ acyl; and ph represents phenyl.
An object of the invention is to provide compounds having a myocardial KD (Kinetic cell death)-inhibiting effect without being accompanied by a cardiodepressant effect. A 1,4-benzothiazepine derivative represented by the following Formula [I]: ##STR1## wherein each of substituent groups is defined as follows: R represents H or a C.sub.1 -C.sub.3 lower alkoxy group; X represents O or H.sub.2 ; n represents 1 or 2; R.sup.1 represents H, a substituted phenyl group wherein the substituent group is OH or a C.sub.1 -C.sub.3 lower alkoxy group, ##STR2## a C.sub.1 -C.sub.3 lower alkoxy group, ##STR3## wherein R.sup.2 represents a C.sub.1 -C.sub.3 acyl group, and ph represents a phenyl group, or a pharmaceutically acceptable salt thereof.