| pA2 online © Copyright 2004 The British Pharmacological Society |
220P
GKT, University of London Winter Meeting December 2003 |
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Vascular
effects of amlodipine in essential hypertension |
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Print abstractArterial stiffness is recognised as an important determinant of outcome in the hypertensive population. The effects of anti-hypertensive drugs on arterial stiffness are complex and vary with time, the vascular territory and blood pressure (BP). Some of the dihydropyridine group of calcium channel blockers reduce pulse wave velocity (PWV), although their effect on arterial wave reflection measured as the augmentation index (AIx) is not very well documented. Amlodipine is the most common dihydropyridine currently used in the hypertensive population but there is no data on its effect on large arterial properties.
The aim of our study was to examine the effects of amlodipine 5 mg on PWV and AIx in patients with essential hypertension, using hydrochlorthiazide (HTCZ) as a comparator, which is generally regarded to have no effects on arterial stiffness.
We randomised 23 patients (mean age 55±2 years, 12 male) with essential hypertension to either amlodipine 5 mg (n=12) or HTCZ 12.5 mg per day (n=11) in a single-blind parallel group design for one month. BP and heart rate were measured with an oscillometric device (Omron). Carotid-femoral PWV was measured with the foot-to-foot method using the Complior®. The AIx was measured using radial applanation tonometry with the SphygmoCorTM. All the measurements were performed in a quiet room in the supine position with the patients having. abstained from alcohol, smoking or caffeine containing beverages in the 12 hours preceding the study.
The statistical analysis was done with JMP version 3(SAS for Windows, Cary, USA). Results expressed as mean±SEM,*p<0.05 was considered significant.
Both drugs reduced BP (mm Hg) significantly (Table) and the reduction in aortic systolic BP was greater with amlodipine. There was no change in PWV with either of the two drugs. However, there was a significant reduction in AIx with amlodipine (p<0.05) but not with hydrochlorthiazide.
| Variable |
Amlodipine
|
HTCZ
|
||
|
Before
|
After
|
Before
|
After
|
|
| Brachial SBP |
169±4
|
150±5*
|
167±4
|
156.5±3*
|
| Brachial DBP |
96.6±2
|
90±2*
|
93.4±3
|
88±3*
|
| Aortic SBP |
160±4
|
140±5*†
|
158±5
|
151±4*
|
| Aortic DBP |
98±2
|
91±2*
|
94±2
|
89±2*
|
| HR(bpm) |
69±3
|
73±2
|
68±2
|
70±3
|
| AIx(%) |
36±3
|
31±2*†
|
34±2
|
34±1
|
| PWV(m/sec) |
10.77±0.3
|
10.5±0.3
|
11.5±0.6
|
11.7±0.7
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*p<0.05 from baseline, †p<0.05 between treatments
This short-term study suggests that amlodipine reduces arterial wave reflection and aortic systolic BP, suggesting that the vascular effects of amlodipine are seen primarily on muscular rather than elastic arteries.