What is the time to peak effect for amlodipine and losartan?

Time to Peak Effect for Amlodipine and Losartan

Amlodipine reaches peak plasma concentration at 6-8 hours after oral administration, while losartan achieves peak plasma levels at approximately 1-2 hours post-dose.

Amlodipine Pharmacokinetics

Peak Plasma Concentration Timing

• Amlodipine demonstrates a gradual absorption profile with peak plasma concentrations occurring 6-8 hours after oral administration 1
• Some studies report a slightly wider range of 6-12 hours to peak plasma levels 2
• This slow, gradual rise in plasma concentration is attributable to amlodipine's high degree of ionization and distinctive pharmacokinetic properties 1

Clinical Implications of Delayed Peak

• The gradual onset avoids dangerous rapid blood pressure drops that can occur with immediate-release formulations of other calcium channel blockers like nifedipine 3
• Bioavailability is 60-65% and remains unaffected by food consumption 1, 2
• The long elimination half-life of 40-50 hours (compared to 3-4 hours for other dihydropyridines) allows for once-daily dosing with sustained 24-hour blood pressure control 1, 2, 4

Steady-State Considerations

• At steady-state, amlodipine shows relatively small fluctuations in plasma concentrations across the dosage interval 1
• The American Heart Association considers amlodipine a first-line calcium channel blocker specifically due to its long duration of action 3
• Effective 24-hour blood pressure reduction is maintained throughout the entire dosing interval without altering normal circadian patterns 4

Losartan Pharmacokinetics

Peak Plasma Concentration Timing

• While the provided evidence does not explicitly state losartan's time to peak concentration, standard pharmacology indicates losartan reaches peak plasma levels at approximately 1-2 hours after oral administration
• Losartan undergoes first-pass metabolism to its active metabolite (E-3174), which has a longer half-life and contributes significantly to its antihypertensive effect

Comparative Clinical Efficacy

• In head-to-head trials, amlodipine demonstrated significantly greater reductions in both systolic (-16.1 vs -13.7 mmHg) and diastolic blood pressure (-12.6 vs -10.3 mmHg) compared to losartan 5
• After 12 weeks of treatment, amlodipine was significantly more effective than losartan in reducing 24-hour systolic blood pressure (-18.0 vs -10.8 mmHg) and diastolic blood pressure (-10.6 vs -8.0 mmHg) 6
• The superior blood pressure-lowering effect of amlodipine was maintained even after two missed doses during a drug holiday 6

Clinical Dosing Considerations

Amlodipine Administration

• Can be administered at any convenient time of day to improve adherence 7
• Initial dose: 5 mg once daily for adults 7
• Maximum dose: 10 mg once daily 7
• Pediatric dosing (ages 6-17): Start at 2.5 mg once daily, maximum 5 mg once daily 8, 7

Losartan Administration

• Initial dose: 0.7 mg/kg per day up to 50 mg/day 8
• Maximum dose: 1.4 mg/kg per day up to 100 mg/day 8
• Dosing interval: Once daily to twice daily 8