Effect of nifedipine on superior mesenteric artery impedance in humans

Objective: In a randomized, double-blind placebo-controlled study the acute effect of sublingual nifedipine (10 mg) on the superior mesenteric artery pulsatility index (PI) was studied over 60 min in 12 healthy subjects (Age 43 y). Methods: PI was considered as a parameter of vascular resistance and was calculated as the peak-to-peak amplitude of the waveform divided by the mean amplitude. PI measurements were performed with the subject resting and fasting and were made 5, 10, 15, 30, 45 and 60 min for 1 hour after nifedipine (10 mg) or placebo. Arterial blood pressure and heart rate were measured at the same times. Results: Placebo administration failed to change arterial blood pressure, heart rate or PI. 5 min after 10 mg sublingual nifedipine, PI had significantly decreased from 5.0 to 3.8, with a nonsignificant decrease in arterial blood pressure and an increase in heart rate. By 15 min after nifedipine administration PI had further decreased to 3.1, and there was a concomitant significant decrease in mean arterial blood pressure and increase in heart rate. Sixty minutes after drug intake PI and arterial blood pressure were still below baseline not significant but the heart rate remained significantly increased. Conclusion: Our data indicate that in healthy subjects sublingual administration of nifedipine had a vasodilator effect (decrease in PI) on the superior mesenteric vascular bed.