Amlodipine pharmacokinetics
Pro Research Analysisby 
Searched over 200M research papers for "amlodipine pharmacokinetics"
Amlodipine Pharmacokinetics: Absorption, Bioavailability, and Half-Life
Amlodipine is a dihydropyridine calcium channel blocker with a unique pharmacokinetic profile compared to other drugs in its class. It is almost completely absorbed after oral administration, with a high absolute bioavailability of about 64%—significantly higher than most other dihydropyridines, which typically have bioavailability between 10% and 30%Abernethy1989Faulkner1986Pa1994+1 MORE. Amlodipine is characterized by a slow onset of action and a long elimination half-life, ranging from 34 to 50 hours, allowing for once-daily dosing and a prolonged therapeutic effectAbernethy1989Faulkner1986Pa1994+1 MORE.
Distribution and Metabolism of Amlodipine
Amlodipine has a large apparent volume of distribution (about 21 L/kg), indicating extensive distribution into tissues. It is predominantly present in the ionized form at physiological pH, which contributes to its strong affinity for cell membranes and slow hepatic metabolism. The drug is extensively metabolized in the liver, and hepatic excretion is the dominant route of eliminationAbernethy1989Jl1988.
Pharmacokinetics in Special Populations
In elderly patients, the elimination half-life of amlodipine is significantly prolonged, suggesting decreased clearance or increased bioavailability. Patients with liver cirrhosis also experience a much longer half-life (up to 60 hours), indicating greater drug accumulation due to impaired hepatic metabolism. In contrast, patients with renal dysfunction do not show significant changes in amlodipine pharmacokinetics, reinforcing the importance of hepatic rather than renal elimination.
Genetic Variability and Drug Interactions
Genetic polymorphisms can significantly affect amlodipine pharmacokinetics. Variations in the CYP2D6, SLC22A1, ABCB1, and CYP3A5 genes have been shown to influence drug clearance, plasma concentrations, and half-lifeSoria-Chacartegui2023Kim2006Kim2006. For example, CYP2D6 poor metabolizers have a longer half-life, while certain ABCB1 and CYP3A5 genotypes are associated with lower plasma concentrations and higher oral clearanceSoria-Chacartegui2023Kim2006Kim2006. These genetic differences may explain some of the interindividual variability in response to amlodipine.
Drug interactions can also alter amlodipine pharmacokinetics. Co-administration with triptolide in animal studies increased amlodipine plasma concentrations and prolonged its half-life, likely by inhibiting hepatic metabolism. However, common co-administered antihypertensive drugs such as telmisartan and hydrochlorothiazide do not significantly affect amlodipine pharmacokinetics in humans. Food, digoxin, and cimetidine have also been shown to have no significant impact on amlodipine’s pharmacokinetic parameters.
Clinical Implications and Therapeutic Monitoring
Amlodipine’s long half-life and high bioavailability make it suitable for once-daily dosing in the management of hypertension and anginaAbernethy1989Faulkner1986Pa1994+1 MORE. Therapeutic drug monitoring may be useful in certain populations, such as those with hepatic impairment or genetic variations affecting drug metabolism, to optimize efficacy and minimize adverse effects. Most patients achieve therapeutic plasma concentrations, but a notable proportion may have levels above or below the therapeutic range, highlighting the value of individualized therapy.
Conclusion
Amlodipine stands out among calcium channel blockers for its high oral bioavailability, slow absorption, and long elimination half-life, supporting its use as a once-daily antihypertensive agent. Its pharmacokinetics are influenced by age, liver function, genetic factors, and certain drug interactions, but are generally stable across most patient populations. Understanding these factors can help clinicians optimize amlodipine therapy for individual patients.
Sources and full results
Most relevant research papers on this topic