An inhibitor of L-type calcium channels (IC50s = 7.1 and 78.8 nM at -40 and -80 mV, respectively, in isolated guinea pig cardiomyocytes); preferentially inhibits L-type calcium channels in isolated rat portal vein over rat left ventricle (IC50s = 427 and 20,417 nM, respectively); decreases mean arterial pressure in anesthetized normotensive or spontaneously hypertensive rats (ED30s = 316 and 58 nmol/kg, respectively)