Contrasting effects of nifedipine, captopril, and propranolol in normotensive and hypertensive subjects.
Nifedipine was given to 15 patients with essential hypertension for 6 weeks and to 8 normotensive subjects for 5 days. In the hypertensives, 30 min after the first dose of nifedipine (5-mg capsule), there was a 13.9% fall in mean blood pressure (p less than 0.001), and, at the 6th week of treatment at the maximum dose of 20 mg t.d.s., a 20.6% fall in mean blood pressure (p less than 0.001). In the normotensive subjects, 30 min after the first dose of 5 mg of nifedipine, there was a 2.3% fall in mean blood pressure (NS), and on the 5th day with the maximum dose of 20 mg t.d.s., the fall was 2.2% (NS). In view of the difference in age between these normotensive and hypertensive subjects, a larger group of patients with essential hypertension and older normotensive subjects were also studied acutely after a single 5-mg capsule of nifedipine. Thirty minutes after the first dose of nifedipine in the larger group of hypertensives, there was a significant fall in mean blood pressure (10.4%; p less than 0.001, n = 33). In the normotensive subjects, there was also a significant fall in mean blood pressure (4.7%; p less than 0.01, n = 29). This was significantly less than in the hypertensives (p less than 0.001). In both the normotensive and hypertensive subjects, there was a significant correlation between pretreatment blood pressure and percentage decrease in blood pressure with nifedipine. Nifedipine, therefore, has a greater blood pressure-lowering effect the higher the initial blood pressure. This finding is compatible with the idea that nifedipine reveals a functional abnormality of vascular smooth muscle that becomes greater the higher the blood pressure.
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002216:Captopril / Q000494:pharmacology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D009543:Nifedipine / Q000494:pharmacology*; D011187:Posture; D011392:Proline / Q000031:analogs & derivatives*; D011433:Propranolol / Q000494:pharmacology*; D011674:Pulse / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D012083:Renin / Q000097:blood
D002121:Calcium Channel Blockers; D011725:Pyridines; D011392:Proline; D002216:Captopril; D011433:Propranolol; D012083:Renin; D009543:Nifedipine