What are the peak and trough levels of Amlodipine (calcium channel blocker)?

Amlodipine Peak and Trough Levels

Amlodipine reaches peak plasma concentrations between 6 and 12 hours after oral administration, with trough levels occurring at 24 hours that maintain approximately 75-80% of peak concentrations due to its long half-life of 30-50 hours. 1, 2

Pharmacokinetic Profile

Peak Levels

• Peak plasma concentrations occur 6-12 hours after oral administration 1, 2, 3
• Absorption is gradual, which helps minimize rapid vasodilation-related side effects such as headache, flushing, and tachycardia 2, 3
• The slow absorption contributes to amlodipine's favorable side effect profile compared to other calcium channel blockers 3

Trough Levels

• Due to amlodipine's long elimination half-life (30-50 hours), there is minimal fluctuation between peak and trough levels 1, 2
• Fluctuation between peak and trough concentrations is only 20-25% with once-daily dosing 2
• This small peak-to-trough ratio allows for consistent blood pressure control throughout the 24-hour dosing interval 2, 3

Clinical Implications

Dosing Considerations

• Steady-state plasma levels are achieved after 7-8 days of consecutive daily dosing 1, 2
• The long half-life and small peak-to-trough fluctuation support once-daily dosing regimens 2, 3
• In some patients, blood pressure may take 4-8 hours to decrease after a dose, consistent with the time to peak concentration 2

Special Populations

• Elderly patients and those with hepatic insufficiency have decreased clearance of amlodipine with a resulting increase in AUC of approximately 40-60% 1
• Lower initial doses may be required in elderly patients and those with hepatic impairment 1
• The pharmacokinetics of amlodipine are not significantly influenced by renal impairment 1

Pharmacodynamic Correlation

• The gradual onset of antihypertensive effect (4-8 hours) correlates with the time to peak plasma concentration 2
• After discontinuation, blood pressure returns to baseline slowly over 7-10 days, without evidence of rebound hypertension 2
• The consistent plasma levels throughout the dosing interval provide stable blood pressure control with minimal fluctuations 2, 3

Common Pitfalls and Considerations

• Unlike some other calcium channel blockers, amlodipine does not require multiple daily dosing due to its favorable pharmacokinetic profile 2, 4
• When initiating therapy, clinicians should be aware that full therapeutic effect may not be seen for 1-1.5 weeks until steady state is achieved 2
• Drug interactions with strong CYP3A inhibitors (e.g., itraconazole, clarithromycin) may increase amlodipine plasma concentrations 1
• Bioavailability is high (60-90%) and is not affected by food intake 1, 4