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A haemodynamic dose finding study with a new slow-calcium channel blocker (amlodipine) in coronary artery disease
Insights
Amlodipine, a calcium channel blocker, effectively reduced blood pressure and afterload in patients with coronary heart disease. This drug also improved cardiac performance, showing promise for treating ischemic heart disease.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Coronary heart disease (CHD) poses significant cardiovascular risks.
- Long-acting calcium channel blockers are crucial in managing CHD.
- Amlodipine is a novel slow-calcium channel blocker with potential therapeutic benefits.
Purpose of the Study:
- To evaluate the hemodynamic dose-response effects of intravenous amlodipine.
- To assess amlodipine's impact on circulatory parameters at rest and during exercise in CHD patients.
- To determine the minimum effective intravenous dosage of amlodipine.
Main Methods:
- Twenty patients with confirmed coronary heart disease participated.
- Intravenous amlodipine was administered in escalating cumulative doses (1.25-10 mg, then 2.5-20 mg).
- Hemodynamic parameters were measured at rest and during constant-load bicycle exercise.
Main Results:
- Higher amlodipine doses significantly reduced resting systemic arterial pressure and vascular resistance.
- Resting heart rate, stroke volume index, and cardiac index increased.
- During exercise, amlodipine reduced mean arterial pressure and increased heart rate and cardiac index.
Conclusions:
- Amlodipine effectively reduces left ventricular afterload and enhances cardiac performance in stable coronary artery disease.
- The minimum effective intravenous dose of amlodipine was determined to be 10 mg.
- Amlodipine demonstrates potential for longer-term studies in ischemic heart disease management.
Abstract:
The haemodynamic dose-response effects of a new long-acting slow-calcium channel blocking agent, amlodipine were evaluated in 20 patients with angiographically confirmed coronary heart disease. At rest, following a control saline period, four i.v. doses of the drug (cumulative dosage 1.25, 2.5, 5 and 10 mg) were administered to ten patients and haemodynamics determined in the ten to 15 minutes following injection. Effects on circulatory parameters were only evident following the maximum cumulative dosage. Accordingly in a further ten patients, the regimen was doubled (cumulative i.v. dosage 2.5, 5, 10 and 20 mg). In each study the haemodynamic effects during constant load supine bicycle exercise were evaluated by comparison of values during the control exercise period and following the final cumulative dosage. On the higher regimen, amlodipine significantly reduced resting systolic, diastolic and mean (p less than 0.01) systemic arterial pressure and systemic vascular resistance index (p less than 0.01). Heart rate (p less than 0.01), stroke volume index (p less than 0.01) and cardiac index (p less than 0.01) increased; pulmonary artery occluded pressure was unchanged. During constant load bicycle exercise, the mean arterial pressure was significantly reduced (p less than 0.01), and the heart rate and cardiac index increased (p less than 0.01). Thus the immediate impact of amlodipine in stable coronary artery disease was to reduce left ventricular afterload and augment cardiac pumping performance. The minimum effective i.v. dosage appeared to be 10 mg. Amlodipine appears sufficiently promising to warrant longer-term studies in ischaemic heart disease.