Controlled-Release Nifedipine Effectively Inhibits Morning Hypertension: A Cross-Over Study with Doxazosin

Abstract

To examine the effect of controlled-release nifedipine (nifedipine CR) given at bedtime on morning hypertension and to compare its effect with that of α-adrenergic blocker, doxazosin, given at bedtime, we performed a cross-over study in ten (5 males, 5 females) hypertensive patients with morning hypertension. After control measurements, the patients were assigned to either nifedipine CR (20-40 mg) first or doxazosin (1-2 mg) first. After 4 weeks of the treatment, measurements were repeated and medication was switched to another drug for another 4 weeks. Systolic and diastolic blood pressure (BP) and heart rate were measured using a 24-hour ambulatory BP monitoring system. While BP at evening and early nighttime (16 : 00-3 : 00) were the same in the three conditions (control, nifedipine CR, and doxazosin), nifedipine CR significantly suppressed BP at the latest nighttime (5 : 00-6 : 00) (systolic BP/diastolic BP : control 128.4±12.0/85.1±10.6 mmHg, doxazosin 124.5±11.6/81.4±10.7 mmHg, nifedipine CR 111.2±16.0/77.7±11.2 mmHg, p<0.01 control vs nifedipine CR, p<0.05 doxazosin vs nifedipine CR). Nifedipine CR also suppressed BP at the morning (6 : 30-9 : 30) (control 144.2±11.2/92.2±12.2 mmHg, doxazosin 137.2±8.4/87.1±11.1 mmHg, nifedipine CR 123.9±10.8/83.1±12.1 mmHg, p<0.02 control vs nifedipine CR, p<0.01 nifedipine CR vs doxazosin). There was a significant increase in heart rate only in the doxazosin group during sleep time (control 64.7±5.2/min, doxazosin 68.5±8.8/min, nifedipine 64.5±5.7/min, p<0.05 doxazosin vs nifedipine). These results indicate that the dose of nifedipine CR that does not affect BP from evening through early morning, administered before sleep, is effective in the treatment of morning hypertension.