Can Amlodipine (calcium channel blocker) cause a fall in diastolic blood pressure?

Amlodipine's Effect on Diastolic Blood Pressure

Yes, amlodipine (Amlo press) can cause a significant fall in diastolic blood pressure as part of its mechanism of action as a calcium channel blocker. 1

Mechanism of Action and Hemodynamic Effects

• Amlodipine is a dihydropyridine calcium channel blocker that inhibits calcium ion influx across cell membranes, with a greater effect on vascular smooth muscle cells than cardiac muscle cells 1
• It acts as a peripheral arterial vasodilator, directly affecting vascular smooth muscle to reduce peripheral vascular resistance and blood pressure 1
• Following therapeutic dosing in hypertensive patients, amlodipine produces vasodilation resulting in reduction of both systolic and diastolic blood pressures in both supine and standing positions 1

Clinical Evidence of Diastolic BP Reduction

• In the FACET trial, patients treated with amlodipine showed better systolic blood pressure control compared to fosinopril, while diastolic blood pressure was similarly reduced in both treatment groups 2
• In a study comparing amlodipine to felodipine, amlodipine demonstrated more effective nighttime systolic and diastolic BP reduction, likely due to its longer elimination half-life (35-50 hours) 3
• In patients with mild to moderate hypertension, amlodipine treatment reduced mean diastolic blood pressure from 88.85 mmHg at baseline to 81.56 mmHg after 3 months of treatment 4

Pharmacological Properties Contributing to Diastolic BP Effects

• Amlodipine has a long half-life (30-50 hours) and duration of action, allowing it to sustain its antihypertensive effect for more than 24 hours following a single dose 1, 5
• The magnitude of blood pressure reduction with amlodipine correlates with the height of pretreatment elevation; individuals with moderate hypertension (diastolic pressure 105-114 mmHg) had about 50% greater response than those with mild hypertension (diastolic pressure 90-104 mmHg) 1
• Unlike some other calcium channel blockers, amlodipine does not cause significant changes in heart rate with chronic oral administration 1

Special Considerations and Cautions

• In patients with pulmonary hypertension, high-dose calcium channel blocker testing (including amlodipine) has been associated with systemic hypotension in some patients 2
• In patients with heart failure, dihydropyridine calcium channel blockers like amlodipine are generally considered safe, unlike non-dihydropyridine calcium channel blockers (verapamil, diltiazem) which should be avoided due to negative inotropic effects 2
• Amlodipine appears to have renoprotective effects in chronic kidney disease patients, likely due to reduction in renal artery smooth muscle contraction leading to higher renal flow, even while systemic blood pressure (including diastolic) is reduced 2

Clinical Implications

• The diastolic blood pressure lowering effect of amlodipine makes it particularly useful in patients with isolated systolic hypertension or combined systolic/diastolic hypertension 5
• When switching from other calcium channel blockers to amlodipine, continued monitoring of both systolic and diastolic blood pressure is important, as the magnitude of effect may differ 4
• In some patient populations, excessive lowering of diastolic blood pressure may be a concern, particularly in elderly patients with coronary artery disease who require adequate coronary perfusion pressure 2

Potential Side Effects Related to BP Lowering

• Side effects of amlodipine related to its vasodilatory effects include edema, palpitations, dizziness, and flushing, which are more common with higher doses (10 mg) 5
• In some patients with advanced heart failure, the hypotensive effect may be associated with an increase in right atrial pressure and a decrease in cardiac output, suggesting direct negative inotropic effects 2