Amlodipine; Uses, Dosage, Side Effects, Interactions, Pregnancy

Amlodipine
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Amlodipine is a synthetic dihydropyridine and a calcium channel blocker with antihypertensive and antianginal properties. Amlodipine inhibits the influx of extracellular calcium ions into myocardial and peripheral vascular smooth muscle cells, thereby preventing vascular and myocardial contraction. This results in a dilatation of the main coronary and systemic arteries, decreased myocardial contractility, increased blood flow and oxygen delivery to the myocardial tissue, and decreased total peripheral resistance. This agent may also modulate multi-drug response (MDR) activity through inhibition of the p-glycoprotein efflux pump.

Amlodipine is a long-acting 1,4-dihydropyridine calcium channel blocker. It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, amlodipine prevents calcium-dependent myocyte contraction and vasoconstriction.

Mechanism of Action of Amlodipine

Amlodipine decreases arterial smooth muscle contractility and subsequent vasoconstriction by inhibiting the influx of calcium ions through L-type calcium channels. Calcium ions entering the cell through these channels bind to calmodulin. Calcium-bound calmodulin then binds to and activates myosin light chain kinase (MLCK). Activated MLCK catalyzes the phosphorylation of the regulatory light chain subunit of myosin, a key step in muscle contraction. Signal amplification is achieved by calcium-induced calcium release from the sarcoplasmic reticulum through ryanodine receptors. Inhibition of the initial influx of calcium decreases the contractile activity of arterial smooth muscle cells and results in vasodilation. The vasodilatory effects of amlodipine result in an overall decrease in blood pressure. Amlodipine is a long-acting CCB that may be used to treat mild to moderate essential hypertension and exertion-related angina (chronic stable angina). Another possible mechanism is that amlodipine inhibits vascular smooth muscle carbonic anhydrase I activity causing cellular pH increases which may be involved in regulating intracelluar calcium influx through calcium channels.

The mechanisms by which amlodipine relieves angina are

  • Stable 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.
  • Variant angina: amlodipine blocks spasm of the coronary arteries and restores 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.
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Amlodipine has additionally been found to act as an antagonist of the mineralocorticoid receptor, or as an antimineralocorticoid.

Indications of Amlodipine

Contra Indications of Amlodipine

  • Extreme loss of body water
  • high amount of potassium in the blood
  • Renal artery stenosis
  • Liver problems
  • Blockage of a bile duct
  • Kidney disease with reduction in kidney function
  • Pregnancy
  • Second and third trimester of pregnancy
  • Biliary obstructive disorders.
  • Severe hepatic impairment.
  • Hypersensitivity to the active substance or to any of the excipients

Dosage of Amlodipine

Strength : 2.5, 5 mg and 10 mg Tablets

Initial dose: 2.5 mg orally once a day
Maintenance dose: 2.5 to 10 mg orally once a day
Maximum dose: 10 mg/day

Hypertension

  • Initial dose: 5 mg orally once a day
  • Maintenance dose: 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Angina Pectoris

  • Maintenance dose: 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Coronary Artery Disease

  • Maintenance dose: 5 to 10 mg orally once a day
  • Maximum dose: 10 mg/day

Pediatric Dose for Hypertension

  • Maintenance dose: 2.5 to 5 mg orally once a da
  • Maximum dose: 5 mg/day

Side Effects of Amlodipine

The most common

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Common

Rare

Drug Interactions of Amlodipine

Amlodipine may interact with following drugs, supplyments, & may change the efficacy of drugs

Amlodipine tablets may lower your blood pressure even more if you are already taking other medicines to treat your high blood pressure.

Pregnancy & Lactation of Amlodipine

Pregnancy

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This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding

It is not known if amlodipine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children

The safety and effectiveness of amlodipine have not been established for children under 6 years of age.

Combination therapy

Amlodipine can be given as a combination therapy with a variety of medications

  • Amlodipine/atorvastatin, where amlodipine is given for hypertension or CAD and atorvastatin prevents cardiovascular events, or if the person also has high cholesterol.
  • Amlodipine/aliskiren or amlodipine/aliskiren/hydrochlorothiazide if amlodipine alone cannot reduce blood pressure. Aliskiren is a renin inhibitor, which works to reduce primary hypertension (that with no known cause) by binding to renin and preventing it from initiating the renin-angiotensin system (RAAS) pathway to increase blood pressure. Hydrochlorothiazide is a diuretic and decreases overall blood volume.
  • Amlodipine/benazepril if either drug has failed individually, or amlodipine alone caused edema. Benazepril is an ACE inhibitor and blocks the conversion of angiotensin I to angiotensin II in the RAAS pathway.
  • Amlodipine/olmesartan or amlodipine/olmesartan/hydrochlorothiazide if amlodipine is insufficient in reducing blood pressure. Olmesartan is an angiotensin II receptor antagonist and blocks part of the RAAS pathway.
  • Amlodipine/perindopril if using amlodipine alone caused edema. Perindopril is a long-lasting ACE inhibitor.
  • Amlodipine/telmisartan, where telmisartan is an Angiotensin II receptor antagonist.
  • Amlodipine/valsartan or amlodipine/valsartan/hydrochlorothiazide, where valsartan is an angiotensin II receptor antagonist.

References

Amlodipine

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