Slow Channel Inhibitors Verapamil and Nifedipine in the Management of Hypertension

Abstract

The "Oxford" system for continuous monitoring of the ambulatory blood pressure was used to assess the changes in blood pressure following therapy with the calcium ion antagonists verapamil and nifedipine in two separate groups of patients. In the first group 16 patients were studied on both no therapy and following a minimum of 6 weeks of verapamil therapy (dose range, 120-160 mg t.d.s.). During each study patients underwent standardized physiological tests including tilt, isometric handgrip, and dynamic bicycle exercise. A second group of nine patients followed the identical protocol but were prescribed nifedipine (20-60 mg b.d.). Both agents were demonstrated to produce a consistent reduction of blood pressure over most of the 24 h studied, but this was most marked during the day. Heart rate was lowered with verapamil but unaffected by nifedipine. There was no postural hypotension, and the absolute responses to dynamic and isometric exercise were reduced. The results demonstrate the antihypertensive efficacy of 'slow channel inhibitors' as represented by verapamil and nifedipine.