Amlodipine, a long-acting calcium channel blocker, attenuates morning blood pressure rise in hypertensive patients

1, The effects of once-daily calcium channel blockers with different plasma half-lives on diurnal blood pressure changes were examined in hypertensive patients. 2, Patients with essential hypertension nine men and 13 women aged 61+/-2 y ears, were treated with amlodipine or nitrendipine in a random cross-over d esign for 12-16 weeks each, The study drugs were given once daily as monoth erapy (n = 8) or in combination with other classes of antihypertensive drug s (n = 14), The plasma half-life of amlodipine is as long as 36 h, while th at of nitrendipine is 10 h, At the end of each treatment period, 24 h ambul atory blood pressure and pulse rate were monitored. 3, Average office blood pressure was comparably controlled below 140/90 mmH g by either amlodipine or nitrendipine, both in the monotherapy and the com bination therapy groups; however, pulse rate was greater in nitrendipine th an in amlodipine either in the monotherapy (by 6 b.p.m., P < 0.05) or in th e combination therapy (by 5 b.p.m., P < 0.01), 4. In 24 h blood pressure monitoring, morning (05.30-09.00 h) blood pressur e was higher in nitrendipine than in amlodipine by 6/4 mmHg in the monother apy (P < 0.05) and by 7/5 mmHg in the combination therapy (P < 0.03) althou gh the blood pressure in the remainder of the 24 h did not differ between t he two treatment periods. In addition, pulse rate in the daytime (09.30-18. 00 h) was greater in nitrendipine than in amlodipine by 6 b.p.m. in the mon otherapy (P< 0.01) and by 7 b.p.m. in the combination therapy (P < 0.02) 5, These results suggest slow pharmacokinetics of amlodipine provides an ad vantage in controlling morning blood pressure and mitigating reflex activat ion of the sympathetic nervous system.