Amlodipine

Absorption

Amlodipine absorbed slowly and almost completely from the gastrointestinal tract. Peak plasma concentrations are achieved 6-12 hours after oral administration. The estimated bioavailability of amlodipine is 64-90%. Steady-state plasma amlodipine levels are achieved after 7-8 days of consecutive daily dosing. Absorption is not affected by food .

Toxicity

Acute oral toxicity (LD50): 37 mg/kg (mouse) .
Overdose
An overdose of amlodipine could result in a high degree of peripheral vasodilatation with a possibility of reflex tachycardia. Significant and prolonged hypotension leading to shock and fatal outcomes have been reported .
Carcinogenesis, mutagenesis, impairment of fertility
Rats and mice treated with amlodipine maleate in the diet on a long-term basis for up to 2 years demonstrated no evidence of a carcinogenic effect of the drug. For the mouse, the highest dose was comparable to the maximum recommended human dose of 10 mg amlodipine per day. For the rat, the highest dose was measured to be about twice the maximum recommended human dose .
Mutagenicity studies using amlodipine maleate showed no drug-related gene or chromosomal effects .
There was no impact on the fertility of rats given oral amlodipine maleate (males for 64 days and females for 14 days before mating) at doses up to 10 mg amlodipine/kg/day (8 times the maximum recommended human dose) .
Use in pregnancy
The safety of amlodipine in human pregnancy or lactation has not been proven. Amlodipine is therefore considered a pregnancy category C drug . Use amlodipine only if the potential benefit justifies the potential risk .
Use in nursing
Discontinue when administering amlodipine .

Description

Amlodipine is a dihydropyridine L-type calcium channel blocker that selectively inhibits calcium influx in cardiac and vascular smooth muscle. Acting as a vasodilator, amlodipine reduces blood pressure by relaxing the smooth muscle in the arterial wall, decreasing total peripheral resistance. It inhibits calcium-induced contractions in depolarized rat aorta with an IC₅₀ value of 1.9 nM, displaying a slow rate of association and dissociation in isolated vascular and cardiac tissues. Amlodipine also demonstrates actions independent of L-type calcium channel blockade by regulating membrane fluidity and cholesterol deposition, stimulating nitric oxide production, acting as an antioxidant, and regulating matrix deposition in vitro and in vivo. Formulations containing amlodipine have been used in the treatment of hypertension.

Chemical properties

Yellow Solid

The Uses of Amlodipine

A deuterated dihydropyridine calcium channel blocker.;Application of Labeled APIs: Labeled Amlodipine, intended for use as an internal standard for the quantification of Amlodipine by GC- or LC-mass spectrometry.

The Uses of Amlodipine

A dihydropyridine calcium channel blocker; activity resides mainly in the (-)-isomer.

The Uses of Amlodipine

anti-hypertensive;calcium channel blocker

What are the applications of Application

Amlodipine is an L-type calcium channel protein inhibitor and blocker

Background

Amlodipine, initially approved by the FDA in 1987, is a popular antihypertensive drug belonging to the group of drugs called dihydropyridine calcium channel blockers. Due to their selectivity for the peripheral blood vessels, dihydropyridine calcium channel blockers are associated with a lower incidence of myocardial depression and cardiac conduction abnormalities than other calcium channel blockers .
Amlodipine is commonly used in the treatment of high blood pressure and angina. Amlodipine has antioxidant properties and an ability to enhance the production of nitric oxide (NO), an important vasodilator that decreases blood pressure . The option for single daily dosing of amlodipine is an attractive feature of this drug .

Indications

Amlodipine may be used alone or in combination with other antihypertensive and antianginal agents for the treatment of the following conditions :
? Hypertension
? Coronary artery disease
? Chronic stable angina
? Vasospastic angina (Prinzmetal’s or Variant angina)
? Angiographically documented coronary artery disease in patients without heart failure or an ejection fraction < 40%

Definition

ChEBI: A fully substituted dialkyl 1,4-dihydropyridine-3,5-dicarboxylate derivative, which is used for the treatment of hypertension, chronic stable angina and confirmed or suspected vasospastic angina.

brand name

Norvasc (Pfizer).

General Description

Amlodipine, 2-[, for the treatment of hypertension. Amlodipineis also marketed as a combination therapy with atorvastatinunder the tradename Norvasc for the management of highcholesterol and high blood pressure.

Hazard

Human systemic effects.

Pharmacokinetics

General pharmacodynamic effects
Amlodipine has a strong affinity for cell membranes, modulating calcium influx by inhibiting selected membrane calcium channels. This drug's unique binding properties allow for its long-acting action and less frequent dosing regimen , .
Hemodynamic effects
After the administration of therapeutic doses of amlodipine to patients diagnosed with hypertension, amlodipine causes vasodilation, which results in a reduction of supine and standing blood pressure. During these blood pressure reductions, there are no clinically significant changes in heart rate or plasma catecholamine levels with long-term use. Acute intravenous administration of amlodipine reduces arterial blood pressure and increases heart rate in patients with chronic stable angina, however, chronic oral administration of amlodipine in clinical studies did not cause clinically significant alterations in heart rate or blood pressures in patients diagnosed with angina and normal blood pressure. With long-term, once daily oral administration, antihypertensive effectiveness is maintained for at least 24 hours .
Electrophysiologic effects
Amlodipine does not change sinoatrial (SA) nodal function or atrioventricular (AV) conduction in animals or humans. In patients who were diagnosed with chronic stable angina, the intravenous administration of 10 mg of amlodipine did not cause clinically significant alterations A-H and H-V conduction and sinus node recovery time after cardiac pacing. Patients administered amlodipine with concomitant beta-blockers produced similar results. In clinical trials in which amlodipine was given in combination with beta-blockers to patients diagnosed with hypertension or angina, no adverse effects on electrocardiographic parameters were noted. In clinical studies comprised of angina patients alone, amlodipine did not change electrocardiographic intervals or produce high degrees of AV block .
Effects on angina
Amlodipine relieves the symptoms of chest pain associated with angina. In patients diagnosed with angina, daily administration of a single amlodipine dose increases total exercise time, the time to angina onset, and the time to 1 mm ST-segment depression on ECG studies, decreases anginal attack frequency, and decreases the requirement for nitroglycerin tablets .

Clinical Use

Calcium-channel blocker:
Hypertension
Angina prophylaxis

Safety Profile

Human systemic effects. Whenheated to decomposition it emits toxic vapors of NOx andCl^-.

Drug interactions

Potentially hazardous interactions with other drugs
Aminophylline and theophylline: possibly increased aminophylline and theophylline concentration.
Anaesthetics: enhanced hypotensive effect.
Antibacterials: metabolism possibly inhibited by clarithromycin, erythromycin and telithromycin.
Antidepressants: enhanced hypotensive effect with MAOIs, concentration possibly reduced by St John’s wort.
Antiepileptics: effects probably reduced by phenobarbital and primidone.
Antifungals: negative inotropic effect possibly increased with itraconazole.
Antihypertensives: enhanced hypotensive effect; increased risk of first dose hypotensive effect of postsynaptic alpha-blockers.
Antivirals: concentration increased by telaprevir and possibly by ritonavir - reduce dose of amlodipine.
Ciclosporin: ciclosporin concentration may be increased by up to 40%.
Lipid lowering agents: possibly increased risk of myopathy - do not exceed 20 mg of simvastatin.1 Tacrolimus: possibly increased tacrolimus levels.

Metabolism

Amlodipine is heavily (approximately 90%) converted to inactive metabolites via hepatic breakdown with 10% of the parent compound and 60% of the metabolites found excreted in the urine. Ex vivo studies have shown that about 93% of the circulating drug is bound to plasma proteins in hypertensive patients . Characteristics that add to amlodipine's unique pharmacologic profile include nearly complete absorption, late-peak plasma concentrations, high bioavailability, and slow hepatic breakdown .

Metabolism

Amlodipine is extensively metabolised by the liver to inactive metabolites with 10% of the parent compound and 60% of metabolites excreted in the urine.

References

1) Mason et al. (2003), Novel vascular biology of third-generation L-type calcium channel antagonists: ancillary actions of amlodipine; Arterioscler. Thromb. Vasc. Biol., 23 2155 2) Asano et al. (2003), A calcium channel blocker activates both ecto-5(‘)-nucleotidase and NO synthase in HUVEC; Biochem. Biophys. Res. Commun., 311 625 3) Yu et al. (2003), Amlodipine modulates THP-1 cell adhesion to vascular endothelium via inhibition of protein kinase C signal transduction; Hypertension, 42 329 4) Zhou et al. (2004), Inhibition of oxidative stress and improvement of endothelial function by amlodipine in angiotensin II-infused rats; Am. J. Hypertension, 17 167 5) Ueda et al. (1993), A comparative assessment of the duration of action of amlodipine and nifedipine GITS in normotensive subjects; Br. J. Clin. Pharmacol., 36 561