DHP-218, also known as PAK-9, is a calcium channel antagonist potentially for the treatment of hypertension and myocardia ischemia. Calcium-induced contraction of the rat aorta in high K+ solution was inhibited by DHP-218 with the pA2 value of 9.11. The IC50 value for the inhibitory effects of this compound in high K+-induced and phenylephrine-induced contraction was 6.3 nmol/l and 66 nmol/l, respectively.