||This article or section contains close paraphrasing of an external source, http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/019787s047lbl.pdf ( ). Ideas in this article should be expressed in an original manner. (November 2014)|
||This article may be too technical for most readers to understand. (March 2012)|
|Systematic (IUPAC) name|
|(RS)-3-ethyl 5-methyl 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methyl-1,4-dihydropyridine-3,5-dicarboxylate|
|Licence data||US FDA:|
|Bioavailability||64 to 90%|
|Half-life||30 to 50 hours|
|Mol. mass||408.879 g/mol|
|(what is this?)|
Amlodipine (Norvasc (Pfizer) and generics) (as besylate, mesylate or maleate) is a medication used to lower blood pressure and prevent chest pain. It belongs to a group of medications known as long-acting dihydropyridine-type calcium channel blockers. Like other medications in this group, amlodipine lowers blood pressure by relaxing the muscles controlling the diameter of blood vessels in the body. Widening of these blood vessels lowers blood pressure. In angina, amlodipine increases blood flow to the heart muscle to relieve pain due to angina.
It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system.
- Breast feeding
- Cardiogenic shock
- Unstable angina
- Systolic and diastolic blood pressure below 90/60 mmHg
- Aortic stenosis: Amlodipine causes vasodilation, which can result in reduced cardiac output in patients with severe aortic stenosis.
- Severe obstructive coronary artery disease
Adverse side effects of the use of amlodipine may include:
- Common: peripheral edema in 8.3% of users, fatigue in 4.5% of users dizziness; palpitations; stomach-pain, headache, dyspepsia, somnolence(sleepiness), dizziness, flushing and/or nausea in greater than 1%. Clinical trials showed edema, dizziness, flushing and palpitations to be dose-related side effects (higher incidence of the side effect at higher doses).
- Uncommon: blood disorders, development of breasts in men (gynecomastia), impotence, depression, insomnia, tachycardia, or gingival enlargement - in one in 1,000 users
- Rarely: erratic behavior, hepatitis, jaundice - in one in 10,000 users
- Very rarely: hyperglycemia, tremor, Stevens–Johnson syndrome - in one in 100,000 users
- In patients with severe coronary artery disease, amlodipine can increase the frequency and severity of angina or actually cause a heart attack on rare occasions.
- Excessive lowering of blood pressure during initiation of amlodipine treatment can occur, especially in patients already taking another medication for lowering blood pressure. This includes medications for erectile dysfunction, such as sildenafil, which can also lower blood pressure. In rare instances, congestive heart failure has been associated with amlodipine, usually in patients already on a beta blocker.
- Amlodipine is primarily metabolized by the liver, via the cytochrome P450 isoenzyme CYP3A4. As a result, serum levels can potentially be affected by drugs which inhibit or activate CYP3A4. Grapefruit juice can inhibit the cytochrome P450 system, but the predicted interaction risk with amlodipine is low. Eating pomegranate or drinking pomegranate juice might cause similar side effects.
Mechanism of action
Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the movement of calcium ions into vascular smooth muscle cells and cardiac muscle cells. Experimental data suggest amlodipine binds to both dihydropyridine and nondihydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular smooth muscle cells than on cardiac muscle cells. Negative inotropic effects, or decreased heart muscle contractility, can be detected in vitro, but such effects have not been seen in intact animals at therapeutic doses. Serum calcium concentration is not affected by amlodipine. Within the physiologic pH range, amlodipine is an ionized compound (pKa = 8.6), and its interaction with the calcium channel receptor is characterized by a gradual rate of association and dissociation with the receptor binding site, resulting in a gradual onset of effect.
Amlodipine is a peripheral arterial vasodilator that acts directly on vascular smooth muscle to cause a reduction in peripheral vascular resistance and reduction in blood pressure. Also, as a calcium channel blocker amlodipine is expected to inhibit the currents of L-type Cav1.3 channels in the zona glomerulosa of the adrenal cortex, reducing aldosterone production and corroborating to lower blood pressure.
The precise mechanisms by which amlodipine relieves angina are not fully understood, but are thought to include:
- Stable angina
- In patients with stable (exertional) angina, amlodipine reduces the total peripheral resistance (afterload) against which the heart works and reduces the rate pressure product, thereby lowering myocardial oxygen demand, at any given level of exercise.
- Prinzmetal's angina
- Amlodipine has been demonstrated to block spasm of the coronary arteries and restore blood flow in coronary arteries and arterioles in response to calcium, potassium, epinephrine, serotonin, and thromboxane A2 analog in experimental animal models and in human coronary vessels in vitro. This inhibition of coronary spasm is responsible for the effectiveness of amlodipine in Prinzmetal's angina.
Pharmacokinetics and metabolism
The metabolism and excretion of amlodipine have been studied in healthy volunteers following oral administration of 14C-labelled drug. amlodipine is well absorbed by the oral route with a mean oral bioavailability around 60%. It is extensively metabolized in the liver to inactive metabolites via CYP3A4. The half-life of amlodipine is about 30-50 hours, and steady-state plasma concentrations are achieved after 7 to 8 days of daily dosing. Renal elimination is the major route of excretion with about 60% of an administered dose recovered in urine, largely as inactive pyridine metabolites. However, renal impairment does not significantly influence amlodipine elimination. The major metabolite identified was 2-([4-(2-chlorophenyl)-3-ethoxycarbonyl-5-methoxycarbonyl-6-methyl- 2-pyridyl]methoxy) acetic acid, and this represented 33% of urinary radioactivity. Amlodipine concentrations in plasma declined with a mean half-life of 33 h, while elimination of total drug-related material from plasma was slower.
Amlodipine is a chiral calcium antagonist, currently on the market and in therapeutic use as a racemate [1:1 mixture of (R)-(+)- and (S)-(–)-amlodipine]. A method for the semipreparative chromatographic purification of the enantiomers (S)-(–)-amlodipine and (R)-(+)-amlodipine has been reported.
In the United Kingdom, tablets of amlodipine from different suppliers may contain different salts. The strength of the tablets is expressed in terms of amlodipine base, i.e., without the salt. Tablets containing different salts are therefore considered interchangeable.
The efficacy and tolerability of a fixed-dose combination of amlodipine 5 mg and perindopril 4 mg, an angiotensin converting enzyme inhibitor, have recently been confirmed in a prospective, observational, multicentre trial of 1250 hypertensive patients.
Combination therapies containing amlodipine:
- Exforge (amlodipine, valsartan)
- Exforge HCT (amlodipine, valsartan, hydrochlorothiazide)
- Tribenzor (amlodipine, olmesartan, hydrochlorothiazide)
- Twynsta (amlodipine, telmisartan)
- Azor (amlodipine, olmesartan)
- Amturnide (amlodipine, aliskiren, hydrochlorothiazide)
|This section does not cite any references or sources. (May 2010)|
Amlodipine is marketed as:
- Emadine in Nepal by Merck Kga'
- Aforbes by Merck Inc. Philippines
- Agen by Zentiva in the Czech Republic
- Aken in Mexico by Kendrick Farmaceutica
- Amcard in Bangladesh by Apex Pharma Ltd
- Amdepin by Cadila Pharmaceuticals in India
- Amlod in Nepal by Nepal Pharmaceuticals Laboratory Pvt. Ltd.
- Amdipin in Colombia by Laboratorios Lafrancol
- Amlodine by Dainippon Sumitomo Pharmaceuticals in Japan, and in Philippines by Westfield Pharmaceuticals, a division of InnoGen
- Amlodipin in Norway
- Amlodipine 5 in Indonesia by PT KALBE FARMA Tbk, Bekasi
- Amlodipin-Mepha 5/10 in Switzerland by Mepha Pharma AG, Basel
- Amlong in India by Micro Labs
- Amlopin by Lek
- Amlopin in Bangladesh by the Acme Laboratories Ltd
- Amlopine in Thailand by Berlin (Thailand) Pharmaceutical Industry Co Ltd
- Amlostin in the United Kingdom by Discovery Pharmaceuticals
- Amlosun in Bangladesh by Sun Pharmaceutical (Bangladesh) Ltd
- Amlovas in India by Macleods Pharmaceuticals Ltd
- Amlovasc in the United Kingdom by Dr. Reddy's Laboratories
- Amlozek in Poland by Adamed
- Asomex by Emcure Pharmaceuticals India
- Atecard-AM in India by Alembic Ltd
- Camlodin in Bangladesh by Square Pharmaceuticals Ltd
- Dailyvasc by Xeno Pharmaceuticals
- Hipril is a combination of lisinopril with amlodipine (5 mg each) in India
- Istin in the United Kingdom and Ireland 
- Lama in India by Stadmed Private Limited, Kolkata
- Lodopin in Pakistan by Merck Pakistan
- Lopin in Bangladesh by Edruc Ltd
- Lodip in Nepal by TIME Pharmaceuticals
- Nelod in Bangladesh by The Kemiko Pharmaceuticals Ltd
- Nopidin in Bangladesh by Ad-din Pharmaceuticals Ltd
- Norvasc by Pfizer in North America, some European countries, China, Japan, Philippines, and Pakistan
- Norvasc, Perivasc and Nordip in Australia
- Pharex Amlodipine in the Philippines by PHAREX HealthCorp
- Tenox by Krka
- Spidip 5 in India by Spiritus Pharmaceuticals Pvt Ltd
- "WHO Model List of EssentialMedicines". World Health Organization. October 2013. Retrieved 22 April 2014.
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- Source: Sandoz product information sheet
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- Zhang, Xiao-Ping ; Loke, Kit Ee ; Mital, Seema ; Chahwala, Suresh ; Hintze, Thomas H (February 2002). "Paradoxical Release of Nitric Oxide by an L-Type Calcium Channel Antagonist, the R+ Enantiomer of Amlodipine". Journal of Cardiovascular Pharmacology 39 (2): 208–214. doi:10.1097/00005344-200202000-00007.
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- Zentiva. "Zentiva: A Sanofi Company". http://www.zentiva.com/media-centre/downloads/Documents/Zentiva_site_brochure-EN.pdf.
- Pfizer Limited. "Istin Package Leaflet". http://www.medicines.org.uk/emc/PIL.2713.latest.pdf.
- Istin - Summary of Product Characteristics from the electronic Medicines Compendium
- U.S. National Library of Medicine: Drug Information Portal - Amlodipine