Peak Plasma Concentration Time for Amlodipine
Amlodipine reaches peak plasma concentration 6-12 hours after oral administration, with most patients achieving maximum levels between 6-8 hours post-dose. 1
Pharmacokinetic Profile
The FDA-approved drug label specifies that after oral administration of therapeutic doses, amlodipine absorption produces peak plasma concentrations between 6 and 12 hours 1. This timing is consistent across multiple research studies:
- Peak concentration timing: 6-8 hours is the most commonly observed timeframe in clinical studies 2, 3, 4
- Range of peak times: Individual studies have documented peaks occurring anywhere from 5.6 to 12 hours post-dose 5, 1
- Gradual absorption pattern: The intermediate rate of drug absorption contributes to the delayed peak, which occurs later than with other calcium channel blockers 2
Clinical Implications of Delayed Peak
The gradual onset of peak concentration provides therapeutic advantages by avoiding rapid vasodilation and associated reflex side effects. 2, 4
Key clinical considerations include:
- Hemodynamic effects: Blood pressure decreases gradually over 4-8 hours after single doses, with physiological reflexes not activated due to the slow onset 2
- Reduced side effects: The pharmacokinetic profile avoids sharp fluctuations in plasma levels that cause tachycardia, headache, and flushing seen with other calcium antagonists 4
- Bioavailability: Absolute bioavailability ranges from 60-90%, and food does not alter absorption 1, 2, 3
Steady-State Considerations
With once-daily dosing, steady-state plasma levels are reached after 7-8 days of consecutive administration. 1
- Accumulation period: The long elimination half-life (30-50 hours) requires 1-1.5 weeks to reach steady state 2, 4
- Dose interval fluctuation: Plasma concentration fluctuates only 20-25% between doses at steady state 2
- Sustained effect: The 24-hour antihypertensive effectiveness is maintained with once-daily dosing due to the prolonged half-life 1
Common Pitfalls
Clinicians should avoid expecting immediate blood pressure reduction after the first dose, as the gradual absorption and delayed peak mean therapeutic effects develop slowly over several hours 2. Additionally, when assessing treatment response, measurements should ideally occur at trough (just before the next dose) to ensure 24-hour control, though the minimal fluctuation at steady state makes timing less critical than with shorter-acting agents 6.