Nifedipine tablets for systemic hypertension: a study using continuous ambulatory intraarterial recording.

The action of nifedipine tablets was examined in 17 patients with essential hypertension focusing particularly on the profile of blood pressure (BP) reduction over 24 hours resulting from both twice-daily and once-daily therapy (dose range 40 to 120 mg daily). This new formulation of nifedipine has a more prolonged and lower peak plasma level than an equivalent dose of nifedipine capsules. Our patients were fully ambulant and studied by continuous intraarterial recording techniques. BP responses during isometric and dynamic exercise testing were also observed. Within-patient comparisons of consecutive mean hourly systolic and diastolic BP showed a highly significant effect from twice-daily therapy (p less than 0.001) for nearly the entire day. Also, significantly lower BP was maintained during isometric and dynamic exercise. Mean hourly heart rates were not significantly altered. The profile of action of the single morning dose was initially similar, but its efficacy diminished from 6 P.M. to 8 A.M. on the following day. Side effects were not unduly troublesome and did not cause any patient withdrawals. Four patients developed mild ankle edema. Two others had facial flushing. Nifedipine given twice daily in tablet form, therefore, is an effective antihypertensive drug capable of lowering BP consistently over 24 hours in ambulant patients and during formal exercise testing. We suggest that this agent may be useful as initial therapy for systemic hypertension, although the tablets are not as yet widely available.