Three dihydropyridine compounds with 2-carbamoyl groups, NPK-1868, NPK-1867 and NPK-1886, were studied comparatively for their cardiovascular effects. In three experimental models in hypertensive rats, the hypotensive potency of these three compounds, given p.o., was almost the same as that of nifedipine and felodipine. However, in anesthetized beagle dogs, the effect of i.v. NPK-1886 was longer-lasting and more selective on vertebral blood flow than that of the other compounds. In pharmacokinetic studies, NPK-1868, given p.o., showed the highest Cmax, and NPK-1868 and NPK-1886 showed a longer half-life than felodipine. These data suggest that NPK-1886 is a potent hypotensive substance that has a longer-lasting effect on cerebral blood flow.