"B is a group of the formula --N(R6)(R7) or ##STR4## wherein R6, R7 and R8 are the same or different and each is a hydrogen atom, an alkyl, a cycloalkyl, an aralkyl, an aryl or a pyridyl, Ar is an aryl or a pyridyl and n is an integer of 0, 1 or 2 hereinafter referred to as dihydropyridine derivative (I)! or an acid addition salt thereof (generally a pharmacologically acceptable acid addition salt)" . . . .