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amlodipine besylate tablet
----------Amlodipine Besylate 5 mg
Amlodipine besylate is the besylate salt of amlodipine, a long-acting calcium channel blocker.
Amlodipine besylate is chemically described as 3-Ethyl-5-methyl(±)-2- [(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6- methyl-3,5-pyridinedicarboxylate, monobenzenesulphonate. Its empirical formula is C20H25ClN2O5•C6H6O3S, and its structural formula is
Amlodipine besylate is a white crystalline powder with a molecular weight of 567.1. It is slightly soluble in water and sparingly soluble in ethanol. Amlodipine besylate tablets are formulated as white tablets equivalent to 2.5, 5, and 10 mg of amlodipine for oral administration. In addition to the active ingredient, amlodipine besylate, each tablet contains the following inactive ingredients: microcrystalline cellulose, dibasic calcium phosphate anhydrous, sodium starch glycolate, colloidal silicon dioxide and magnesium stearate.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggest that 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 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 kinetic 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.
The precise mechanisms by which amlodipine relieves angina have not been fully delineated, but are thought to include the following:
Exertional Angina: In patients with exertional angina, amlodipine reduces the total peripheral resistance (afterload) against which the heart works and reduces the rate pressure product, and thus myocardial oxygen demand, at any given level of exercise.
Vasospastic Angina: Amlodipine has been demonstrated to block constriction 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 vasospastic (Prinzmetal's or variant) angina.
Hemodynamics: Following administration of therapeutic doses to patients with hypertension, amlodipine produces vasodilation resulting in a reduction of supine and standing blood pressures. These decreases in blood pressure are not accompanied by a significant change in heart rate or plasma catecholamine levels with chronic dosing. Although the acute intravenous administration of amlodipine decreases arterial blood pressure and increases heart rate in hemodynamic studies of patients with chronic stable angina, chronic oral administration of amlodipine in clinical trials did not lead to clinically significant changes in heart rate or blood pressures in normotensive patients with angina.
With chronic once daily oral administration, antihypertensive effectiveness is maintained for at least 24 hours. Plasma concentrations correlate with effect in both young and elderly patients. The magnitude of reduction in blood pressure with amlodipine is also correlated with the height of pretreatment elevation; thus, individuals with moderate hypertension (diastolic pressure 105–114 mmHg) had about a 50% greater response than patients with mild hypertension (diastolic pressure 90–104 mmHg). Normotensive subjects experienced no clinically significant change in blood pressures (+1/–2 mmHg).
In hypertensive patients with normal renal function, therapeutic doses of amlodipine resulted in a decrease in renal vascular resistance and an increase in glomerular filtration rate and effective renal plasma flow without change in filtration fraction or proteinuria.
As with other calcium channel blockers, hemodynamic measurements of cardiac function at rest and during exercise (or pacing) in patients with normal ventricular function treated with amlodipine have generally demonstrated a small increase in cardiac index without significant influence on dP/dt or on left ventricular end diastolic pressure or volume. In hemodynamic studies, amlodipine has not been associated with a negative inotropic effect when administered in the therapeutic dose range to intact animals and man, even when co-administered with beta-blockers to man. Similar findings, however, have been observed in normal or well-compensated patients with heart failure with agents possessing significant negative inotropic effects.
Electrophysiologic Effects: Amlodipine does not change sinoatrial nodal function or atrioventricular conduction in intact animals or man. In patients with chronic stable angina, intravenous administration of 10 mg did not significantly alter A-H and H-V conduction and sinus node recovery time after pacing. Similar results were obtained in patients receiving amlodipine and concomitant beta-blockers. In clinical studies in which amlodipine was administered in combination with beta-blockers to patients with either hypertension or angina, no adverse effects on electrocardiographic parameters were observed. In clinical trials with angina patients alone, amlodipine therapy did not alter electrocardiographic intervals or produce higher degrees of AV blocks.
12.3 Pharmacokinetics and Metabolism
After oral administration of therapeutic doses of amlodipine, absorption produces peak plasma concentrations between 6 and 12 hours. Absolute bioavailability has been estimated to be between 64 and 90%. The bioavailability of amlodipine is not altered by the presence of food.
Amlodipine is extensively (about 90%) converted to inactive metabolites via hepatic metabolism with 10% of the parent compound and 60% of the metabolites excreted in the urine. Ex vivo studies have shown that approximately 93% of the circulating drug is bound to plasma proteins in hypertensive patients. Elimination from the plasma is biphasic with a terminal elimination half-life of about 30– 50 hours. Steady-state plasma levels of amlodipine are reached after 7 to 8 days of consecutive daily dosing.
The pharmacokinetics of amlodipine are not significantly influenced by renal impairment. Patients with renal failure may therefore receive the usual initial dose.
Elderly patients and patients with hepatic insufficiency have decreased clearance of amlodipine with a resulting increase in AUC of approximately 40–60%, and a lower initial dose may be required. A similar increase in AUC was observed in patients with moderate to severe heart failure.
12.4 Pediatric Patients
Sixty-two hypertensive patients aged 6 to 17 years received doses of amlodipine between 1.25 mg and 20 mg. Weight-adjusted clearance and volume of distribution were similar to values in adults.
Amlodipine besylate tablets are indicated for the treatment of hypertension. Amlodipine besylate tablets may be used alone or in combination with other antihypertensive agents.1.2 Coronary Artery Disease (CAD)
Chronic Stable Angina
Amlodipine besylate tablets are indicated for the symptomatic treatment of chronic stable angina. Amlodipine besylate tablets may be used alone or in combination with other antianginal agents.
Vasospastic Angina (Prinzmetal's or Variant Angina)
Amlodipine besylate tablets are indicated for the treatment of confirmed or suspected vasospastic angina. Amlodipine besylate tablets may be used as monotherapy or in combination with other antianginal agents.
Angiographically Documented CAD
In patients with recently documented CAD by angiography and without heart failure or an ejection fraction less than 40%, amlodipine besylate tablets are indicated to reduce the risk of hospitalization due to angina and to reduce the risk of a coronary revascularization procedure
Amlodipine besylate tablets are contraindicated in patients with known sensitivity to amlodipine.
6 ADVERSE REACTIONS6.1 Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Amlodipine has been evaluated for safety in more than 11,000 patients in U.S. and foreign clinical trials. In general, treatment with amlodipine was well-tolerated at doses up to 10 mg daily. Most adverse reactions reported during therapy with amlodipine were of mild or moderate severity. In controlled clinical trials directly comparing amlodipine (N=1730) at doses up to 10 mg to placebo (N=1250), discontinuation of amlodipine due to adverse reactions was required in only about 1.5% of patients and was not significantly different from placebo (about 1%). The most common side effects are headache and edema.
Overdosage might be expected to cause excessive peripheral vasodilation with marked hypotension and possibly a reflex tachycardia. In humans, experience with intentional overdosage of amlodipine is limited.
Single oral doses of amlodipine maleate equivalent to 40 mg amlodipine/kg and 100 mg amlodipine/kg in mice and rats, respectively, caused deaths. Single oral amlodipine maleate doses equivalent to 4 or more mg amlodipine/kg or higher in dogs (11 or more times the maximum recommended human dose on a mg/m2 basis) caused a marked peripheral vasodilation and hypotension.
If massive overdose should occur, initiate active cardiac and respiratory monitoring. Frequent blood pressure measurements are essential. Should hypotension occur, provide cardiovascular support including elevation of the extremities and the judicious administration of fluids. If hypotension remains unresponsive to these conservative measures, consider administration of vasopressors (such as phenylephrine) with attention to circulating volume and urine output. As amlodipine is highly protein bound, hemodialysis is not likely to be of benefit.
The usual initial antihypertensive oral dose of amlodipine besylate tablets is 5 mg once daily with a maximum dose of 10 mg once daily.
Small, fragile, or elderly patients, or patients with hepatic insufficiency may be started on 2.5 mg once daily and this dose may be used when adding amlodipine besylate tablets to other antihypertensive therapy.
Adjust dosage according to each patient's need. In general, titration should proceed over 7 to 14 days so that the physician can fully assess the patient's response to each dose level. Titration may proceed more rapidly, however, if clinically warranted, provided the patient is assessed frequently.
The recommended dose for chronic stable or vasospastic angina is 5–10 mg, with the lower dose suggested in the elderly and in patients with hepatic insufficiency. Most patients will require 10 mg for adequate effect [see Adverse Reactions (6)].
The recommended dose range for patients with coronary artery disease is 5–10 mg once daily. In clinical studies, the majority of patients required 10 mg [see Clinical Studies (14.4)].
The effective antihypertensive oral dose in pediatric patients ages 6–17 years is 2.5 mg to 5 mg once daily. Doses in excess of 5 mg daily have not been studied in pediatric patients [see Clinical Pharmacology (12.4), Clinical Studies (14.1)].
16 HOW SUPPLIED/STORAGE AND HANDLING
16.1 2.5 mg Tablets
Amlodipine besylate tablets 2.5 mg (amlodipine besylate equivalent to 2.5 mg of amlodipine per tablet) are supplied as white to off white, round, flat-faced, beveled edge tablets ‘211’ debossed on one side and plain on the other side and supplied as follows:
NDC 51991-666-90 Bottle of 90
16.2 5 mg Tablets
Amlodipine besylate tablets 5 mg (amlodipine besylate equivalent to 5 mg of amlodipine per tablet) are white to off white, round, flat-faced, beveled edge tablets ‘210’ debossed on one side and plain on the other side and supplied as follows:
NDC 51991-667-90 Bottle of 90
16.3 10 mg Tablets
Amlodipine besylate tablets 10 mg (amlodipine besylate equivalent to 10 mg of amlodipine per tablet) are white to off white, round, flat-faced, beveled edge tablets ‘209’ debossed on one side and plain on the other side and supplied as follows:
NDC 51991-668-90 Bottle of 90
PATIENT PACKAGE INSERT
AMLODIPINE BESYLATE TABLETS 2.5 mg, 5 mg, and 10 mg
Read this information carefully before you start taking amlodipine besylate tablets and each time you refill your prescription. There may be new information. This information does not replace talking with your doctor. If you have any questions about amlodipine besylate tablets, ask your doctor. Your doctor will know if amlodipine besylate tablets is right for you.
What is amlodipine besylate?
Amlodipine besylate is a type of medicine known as a calcium channel blocker (CCB). It is used to treat high blood pressure (hypertension) and a type of chest pain called angina. It can be used by itself or with other medicines to treat these conditions.
High Blood Pressure (hypertension)
High blood pressure comes from blood pushing too hard against your blood vessels. Amlodipine besylate relaxes your blood vessels, which lets your blood flow more easily and helps lower your blood pressure. Drugs that lower blood pressure lower your risk of having a stroke or heart attack.
Angina is a pain or discomfort that keeps coming back when part of your heart does not get enough blood. Angina feels like a pressing or squeezing pain, usually in your chest under the breastbone. Sometimes you can feel it in your shoulders, arms, neck, jaws, or back. Amlodipine besylate can relieve this pain.
Who should not use amlodipine besylate?
Do not use amlodipine besylate if you are allergic to amlodipine (the active ingredient in amlodipine besylate tablets), or to the inactive ingredients. Your doctor or pharmacist can give you a list of these ingredients.
What should I tell my doctor before taking amlodipine besylate?
Tell your doctor about any prescription and non-prescription medicines you are taking, including natural or herbal remedies.
Tell your doctor if you:
How should I take amlodipine besylate?
What should I avoid while taking amlodipine besylate?
What are the possible side effects of amlodipine besylate?
Amlodipine besylate may cause the following side effects. Most side effects are mild or moderate:
It is rare, but when you first start taking amlodipine besylate or increase your dose, you may have a heart attack or your angina may get worse. If that happens, call your doctor right away or go directly to a hospital emergency room.
Tell your doctor if you are concerned about any side effects you experience. These are not all the possible side effects of amlodipine besylate. For a complete list, ask your doctor or pharmacist.
How do I store amlodipine besylate tablets?
Keep amlodipine besylate tablets away from children. Store amlodipine besylate tablets at 20° to 25°C (68° to 77°F), excursions permitted to 15° to 30°C (59° to 86°F) (see USP Controlled Room Temperature). Keep amlodipine besylate out of the light. Do not store in the bathroom. Keep amlodipine besylate in a dry place.
General advice about amlodipine besylate
Sometimes, doctors will prescribe a medicine for a condition that is not written in the patient information leaflets. Only use amlodipine besylate the way your doctor told you to. Do not give amlodipine besylate to other people, even if they have the same symptoms you have. It may harm them.
You can ask your pharmacist or doctor for information about amlodipine besylate.
Revised: 11/2010 Lake Erie Medical DBA Quality Care Products LLC
Reproduced with permission of U.S. National Library of Medicine
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