How quickly does amlodipine (calcium channel blocker) lower blood pressure in a patient with hypertension (high blood pressure) or coronary artery disease?

Onset of Blood Pressure Reduction with Amlodipine

Amlodipine begins lowering blood pressure within 6-12 hours after the first dose, with peak plasma concentrations and maximal blood pressure reduction occurring during this timeframe, though steady-state therapeutic effects require 7-8 days of consecutive daily dosing. 1

Pharmacokinetic Timeline

Absorption and Initial Effect:

• Peak plasma concentrations occur between 6-12 hours after oral administration 1
• The drug has a gradual onset of effect due to its slow rate of association with calcium channel receptors 1
• Absolute bioavailability ranges from 64-90% 1

Steady-State Achievement:

• Steady-state plasma levels are reached after 7-8 days of consecutive daily dosing 1
• The terminal elimination half-life is 30-50 hours, contributing to sustained blood pressure control 1

Clinical Blood Pressure Response

Short-Term Response (First 2 Weeks):

• In clinical trials, mean supine blood pressure decreased from 169/104 mmHg to 153/95 mmHg after just 2 weeks of amlodipine 5 mg daily 2, 3, 4
• After 6 weeks of treatment, blood pressure was further reduced to 146/92 mmHg 2, 3, 4

24-Hour Blood Pressure Control:

• Once daily administration produces statistically significant blood pressure reductions at 24 hours post-dose, averaging 12/6 mmHg in standing position and 13/7 mmHg in supine position 1
• Antihypertensive effectiveness is maintained for at least 24 hours with chronic once-daily oral administration 1
• Ambulatory monitoring studies demonstrate effective blood pressure reduction throughout the entire 24-hour period without altering the normal circadian pattern 2, 3, 4

Magnitude of Effect:

• Mean daytime blood pressure was reduced from 165/103 to 147/89 mmHg 2, 3
• Mean nighttime blood pressure was reduced from 137/79 to 121/69 mmHg 2, 3
• Systematic review of >5000 patients showed mean SBP decreased by 17.5 mmHg from baseline with amlodipine monotherapy 5

Important Clinical Considerations

Gradual Blood Pressure Lowering:

• Amlodipine's gradual onset of effect makes it particularly suitable for patients with coronary artery disease where rapid blood pressure reduction should be avoided 6
• In patients with elevated diastolic blood pressure who have CAD and evidence of myocardial ischemia, blood pressure should be lowered slowly 6

Dosing Strategy:

• Initial dose is typically 5 mg once daily 6
• Dose can be increased to 10 mg after at least 2 weeks if blood pressure control is inadequate 6, 2, 3
• The median daily dose in clinical trials was 5 mg (range 1.25-15 mg) 5

Patient-Specific Factors:

• Greater systolic blood pressure reduction occurs in elderly patients, likely due to higher baseline systolic pressures 1
• Patients with moderate hypertension (diastolic 105-114 mmHg) had approximately 50% greater response than those with mild hypertension (diastolic 90-104 mmHg) 1
• Elderly patients and those with hepatic insufficiency have decreased clearance with 40-60% increase in AUC, potentially requiring lower initial doses 1

Monitoring Timeline:

• Blood pressure should be reassessed after at least 2 weeks when initiating or adjusting amlodipine therapy 6
• For patients on bevacizumab or other cancer therapies, blood pressure should be measured before each treatment cycle 6