Azelnidipine is a dihydropyridine calcium channel antagonist being jointly developed by Daiichi Sankyo Inc (formerly Sankyo) and Ube Industries. Azelnidipine is a L-type calcium channel antagonist. Azelnidipine was approved by Pharmaceuticals and Medicals Devices Agency of Japan (PMDA) on Jan 31, 2003. Azelnidipine is indicated for the treatment of hypertension. Its trend name is Calblock. Azelnidipine has two enantiomers (R-(−)- and S-( )-enantiomers) due to an asymmetric carbon at the 4-position, and the (R)-(−) enantiomer of dihydropyridine calcium antagonists is considered to possess intrinsic pharmacological activity. The pharmacological action of azelnidipine resides in the (R)-enantiomer. This is in marked contrast to other calcium channel blocker (CCB) in which the (S)-enantiomer is responsible for the biological activity. There were no significant differences in the inhibitory effects on TGF-b1-induced expression of COL1A1 mRNA among vitamin E - pretreated LX-2 cells treated with azelnidipine (racemate), (R)-(-)-azelnidipine or (S)-( )-azelnidipine, although the L-type voltage-operated calcium channel blocking activity of (R)-(-)- enantiomer was more potent than that of the (S)-( )- enantiomer.