Dihydropyridine derivatives and pharmaceutical composition thereof

DETAILED DESCRIPTION OF THE INVENTION This invention relates to dihydropyridine derivatives represented by the formula (I) ##STR2## wherein R.
sub.
1, R.
sub.
2 and R.
sub.
3 are the same or different and each is alkyl, cycloalkyl or alkoxyalkyl; R.
sub.
4 and R.
sub.
5 are the same or different and each is a hydrogen atom, halogen, nitro, halogenated alkyl, alkylsulfonyl, halogenated alkoxy, alkylsulfinyl, alkyl, cycloalkyl, alkoxy, cyano, alkoxycarbonyl or alkylthio (where both of R.
sub.
4 and R.
sub.
5 are not hydrogen atoms at the same time); X is a group represented by vinylene or azomethine; A is alkylene; and B is a group of the formula --N(R.
sub.
6).
sub.
2 or ##STR3## (wherein R.
sub.
6 and R.
sub.
7 are, independently, a hydrogen atom, alkyl, cycloalkyl, aralkyl, aryl or pyridyl, Ar is aryl or pyridyl, and n is an integer of 0 to 2) [hereinafter referred to briefly as dihydropyridine derivatives (I)], and nontoxic acid-addition salts thereof, which have an excellent calcium blocking action (Ca-antagonist), an antihypertensive action, a platelet aggregation-inhibiting action, a phosphodiesterase-inhibiting action and the like, and thus are useful as a medicine, such as a coronary vasodilator, a cerebral hyperkinemic; antihypertensive, thrombosis-preventing or -treating agents, phosphodiesterase-inhibitor or the like.
The dihydropyridine derivative (I) of the present invention has a unique structure as compared with dihydropyridine compounds which have been so far concretely known, and has a specific activity due to the unique structure.
Namely, the dihydropyridine derivatives (I) of the present invention and their acid-addition salts are characterized remarkably in that they show a high organ and tissue-selectivity in vasodilating activities particularly and that they are very low in acute toxicity and thus highly safe.
In the above formula, the alkyl represented by R.
sub.
1, R.
sub.
2 and R.
sub.
3 may be straight or branched, and particularly a lower alkyl (C.
sub.
1-6), such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, etc, is preferable; and C