The acute response to nifedipine is related to pre-treatment blood pressure.

The acute response to nifedipine 5 mg was studied in 11 young normotensive subjects and 18 older normotensive subjects who were age matched with 33 patients with uncomplicated essential hypertension. There was an immediate fall in blood pressure which was significantly greater in the hypertensive subjects--10.4%--compared to the normotensive subjects where it was only 4.7%. The best predictor of response both in the hypertensive and normotensive subjects was the pre-treatment mean blood pressure. Multiple regression analysis showed that the addition of age and plasma renin activity made little effect. These results clearly demonstrate that, at least acutely, nifedipine becomes more effective the higher the blood pressure. They are compatible with the idea that nifedipine is partly working on a mechanism which is responsible for the high blood pressure and therefore becomes more effective the higher the blood pressure.