Effects of nipradilol on venous hemodynamics: evaluation with a Doppler blood flow method.

Nipradilol is a newly synthesized beta-blocker which has a propranolol-like structure and contains a nitrate moiety. To examine the effect of nipradilol on venous blood flow, a single oral dose of nipradilol (6 mg) and propranolol (20 mg) was administered in the same 15 normal volunteers on separate days. Peak flow velocities, flow velocity integrals, and the diameter of the right brachiocephalic vein were measured before and 2 h after drug administration using Doppler echocardiography. These two beta-blockers significantly decreased systolic blood pressure to the same extent as they did heart rate. Nipradilol dilated the venous diameter by 8% and decreased peak flow velocity by 8% during systole and 9% during diastole. The flow velocity integral in one cardiac cycle also decreased significantly by 14%. Propranolol, however, failed to modify these parameters. These results suggest that nipradilol decreased venous return through its nitroglycerin-like direct vasodilating action.