Abstract: A compound, in the form of a pure diastereoisomer or mixture thereof, which is a benzothiazepin-4-one derivative of formula (I): ##STR1## in which: R1 is hydrogen or a C.sub.2 -C.sub.4 alkanoyl group;R2 and R3 independently each is hydrogen, a linear or branched C.sub.1 -C.sub.4 alkyl group, a C.sub.3 -C.sub.5 cycloalkyl group, a phenyl group, a benzyl group or a phenethyl group, or R2 and R3 together form, with the nitrogen atom to which they are attached, a pyrrolidinyl, 2,2-dimethylpyrrolidinyl, piperidyl, 4-phenylpiperidyl, 4-(3-methoxyphenyl)piperidyl, 4-(4-fluorobenzoyl)piperidyl, 1,2,3,6-tetrahydropyridyl, perhydroazepinyl, perhydroazocinyl, 1,3-thiazolidinyl, thiomorpholinyl, morpholinyl, 2,3-dihydroindolyl, 1,2,3,4-tetrahydroisoquinolyl, 6-methoxy-1,2,3,4-tetrahydroisoquinolyl, 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolyl or 2,3,4,5-tetrahydro-1H-benz[b]azepinyl group; andX is hydrogen or chlorine;or a pharmacologically acceptable acid addition salt thereof.

Abstract: Compounds which are 1,5-benzothiazepine derivatives of general formula (I) ##STR1## in which R denotes hydrogen or C.sub.1 -C.sub.4 alkyl and R.sub.1 and R.sub.2 either separately denote C.sub.1 -C.sub.4 alkyl groups or together denote a tetramethylene or pentamethylene group and their acid addition salts are therapeutically active as calcium antagonists.