Ambesyl

Amlodipine besilate.

Pharmacotherapeutic group: Calcium channel blockers, selective calcium channel blockers with mainly vascular effects, dihydropyridine derivatives. ATC code: CO8CA01.
Pharmacology: Pharmacodynamics: Amlodipine is a calcium ion influx inhibitor of the dihydropyridine group (slow channel blacker or calcium its antagonist) and inhibits the transmembrane influx of calcium ions into cardiac and vascular smooth muscle. The mechanism of the antihypertensive action of amlodipine is due to a direct relaxant effect on vascular smooth muscle. The precise mechanism by which amlodipine relieves angina has not been fully determined but amlodipine reduces total ischaemic burden by the following two actions: Amlodipine dilates peripheral arterioles and thus, reduces the total peripheral resistance (afterload) against which the heart works. Since the heart rate remains stable, this unloading of the heart redoes myocardial energy consumption and oxygen requirements.
The mechanism of action of amlodipine also probably involves dilatation of the main coronary arteries and coronary arterioles, both in normal and ischaemic regions. This dilatation increases myocardial oxygen delivery in patients with coronary artery spasm (Prinzmetal's or variant angina).
In patients with hypertension, once daily dosing provides clinically significant reductions of blood pressure in both the supine and standing positions throughout the 24 hour interval. Dots the slow onset of action, acute hypotension is not a feature of amlodipine administration.
In patients with angina, once daily administration of amlodipine increases total exercise time, time to angina onset, and time to 1 mm ST segment depression, and decreases both angina attack frequency and glyceryl trinitrate tablet consumption.
Amlodipine has not been associated with any adverse metabolic effects or changes in plasma lipids and is suitable for use in patients with asthma, diabetes, and gout.
Use in patients with coronary artery disease (CAD): The effectiveness of amlodipine in preventing clinical events in patients with coronary artery disease (CAD) has been evaluated in an independent, multicentre, randomised, double-blind, placebo-controlled study of 1997 patients; Comparison of Amlodipine vs. Enalapril to Limit Occurrences of Thrombosis (CAMELOT). Of these patients, 663 were treated with amlodipine 5-10 mg, 673 patients were treated with enalapril 10-20 mg, and 655 patients were treated with placebo, in addition to standard care of statins, beta-blockers, diuretics and aspirin, for 2 years. The key efficacy results are presented in the Table. The results indicate that amlodipine treatment was associated with fewer hospitalisations for angina and revascularisation procedures in patients with CAD. (See table.)

Click on icon to see table/diagram/image

Use in patients with heart failure: Haemodynamic studies and exercise based controlled clinical trials in NYHA Class 11-19 heart failure patients have shown that amlodipine did not lead to clinical deterioration as measured by exercise tolerance, left ventricular ejection fraction and clinical symptomatology.
A placebo controlled study (PRAISE) designed to evaluate patients in NYHA Class III-1V heart failure receiving digoxin, diuretics and ACE inhibitors has shown that amlodipine did not lead to an increase in risk of mortality or combined mortality and morbidity with heart failure.
In a follow-up, long-term, placebo-controlled study (PRAISE-2) of amlodipine in patients with NYHA III and IV heart failure without clinical symptoms or objective findings suggestive or underlying ischaemic disease, on stable doses of ACE inhibitors, digitalis, and diuretics, amlodipine had no effect on total cardiovascular mortality. In this same population amlodipine was associated with increased reports of pulmonary oedema.
Treatment to prevent heart attack trial (ALLHAT): A randomised double-blind morbidity-mortality study called the Antihypertensive and Lipid-Lowering Treatment. Prevent Heart Attack Trial (ALLHAT) was performed to compare newer drug therapies: amlodipine 2.5-10 mg/d (calcium channel blacker) or lisinopril 10-40 mg/d (ACE-inhibitor) as fist-line therapies to that of the thiazide-diuretic, chlorthalidone 12.5-25 mg/d in mild to moderate hypertension.
A total of 33,357 hypertensive patients aged 55 or older were randomised and followed for a mean of A.9 years. The patients had at least one additional CHD risk factor, including: previous myocardial infarction or stroke (>6 months prior to enrolment) or documentation of other atherosclerotic CVD (overall 51.5%), type 2 diabetes (36.1%), HDL-C <35 mg/di (0.6%), left ventricular hypertrophy diagnosed by electrocardiogram or echocardiography (20.9%), current cigarette smoking (21.9%).
The primary endpoint was a composite of fatal CHD or non-fatal myocardial infarction. There was no significant difference in the primary endpoint between amlodipine-based therapy and chlorthalidone-based therapy: RR 0.98 95% Cl (0.90-1.07) p=0.65. Among secondary endpoints, the incidence of heart failure (component of a composite combined cardiovascular endpoint) was significantly higher in the amlodipine group as compared to the chlorthalidone group (10.2% vs. 7.7%, RR 1.38, 95% Cl (1.25-1.52) p<0.001). However, there was no significant difference in all-cause mortality between amlodipine-based therapy and chlorthalidone-based therapy. RR 0.96 95% Cl [0.89-1.02] p=0.20.
Use in children (aged 6 years and older): Its study involving 268 children aged 6-17 years with predominantly secondary hypertension, comparison of a 2.5 mg dose, and 5 mg dose of amlodipine with placebo, showed that both doses reduced Systolic Blood Pressure significantly more than placebo. The difference between the two doses was not statistically significant.
The long-term effects of amlodipine on growth, puberty and general development have not been studied. The long-term efficacy of amlodipine on therapy in childhood to reduce cardiovascular morbidity and mortality in adulthood have also not been established.
Pharmacokinetics: Absorption, distribution, plasma protein binding: After oral administration of therapeutic doses, amlodipine is well absorbed with peak blood levels between 6.12 hours post dose. Absolute bioavailability has been estimated to be between 64 and 80%. The volume of distribution is approximately 21 /kg. In vitro studies have shown that approximately 975% of circulating amlodipine is bound to plasma proteins.
The bioavailability of amlodipine is not affected by food intake.
Biotransformation/elimination: The terminal plasma elimination half life is about 35-50 hours and is consistent with once daily dosing. Amlodipine is extensively metabolised by the liver to inactive metabolites with 10% of the parent compound and 60% of metabolites excreted in the urine.
Use in hepatic impairment: Very limited clinical data are available regarding amlodipine administration in patients with hepatic impairment. Patients with hepatic insufficiency have decreased clearance of amlodipine resulting in a longer half-life and an increase in AUC of approximately 40-60%.
Use in older patients: The time to reach peak plasma concentrations of amlodipine is similar in older and younger subjects. Amlodipine clearance tends to be decreased with resulting increases in AUC and elimination half-life in older patients. Increases in AUC and elimination half-life in patients with congestive heart failure were as expected for the patient age group studied.
Use in children: A population PK study has been conducted 1, 74 hypertensive children aged from 1 to 17 years (with 34 patients aged 6 to 12 years and 28 patients aged 13 to 17 years) receiving amlodipine between 1.25 and 20 mg given either once or twice daily. In children 6 to 12 years and in adolescents 13-17 years of age the typical oral clearance (CL/F) was 22.5 and 274 L/hr respectively in males and 16.4 and 21.3 L/hr respectively in females. Large variability in exposure between individuals was observed. Data reported in children below 6 years is limited.
Toxicology: Preclinical safety data: Reproductive toxicology: Reproductive studies in rats and mice have shown delayed date of delivery, prolonged duration of labour and decreased pup survival at doses approximately 50 times greater than the maximum recommended dose for humans based on mg/kg.
Impairment of fertility: There was no effect on the foray of rats treated with amlodipine (males for 64 days and females 14 days prior to mating) at doses up to 10 mg/kg/day (8 times* the maximum recommended human dose of 10 mg on a mg/m2 basis). In another rat study in which male rats were treated with amlodipine besilate for 30 days at a dose comparable with the human dose based on mg/kg, decreased plasma follicle-stimulating hormone and testosterone were found as well as decreases in sperm density and in the number of mature spermatids and Sertoli cells.
Carcinogenesis mutagenesis: Rats and mice treated with amlodipine in the diet for two years, at concentrations calculated to provide daily dose levels of 0.5, 1.25, and 2.5 mg/kg/day showed no evidence of carcinogenicity. The highest dose (for mice, similar to, and for rats twice* the maximum recommended clinical dose of 10 mg on a mg/m2 basis) was close to the maximum tolerated dose for mice but not for rats.
Mutagenicity studies revealed no drug related effects at either the gene or chromosome levels.
*Based on patient weight of 50 kg.

Essential hypertension.
Chronic stable and vasospastic angina pectoris.

Dosage: Adults: For both hypertension and angina the usual initial dose is 5 mg amlodipine once daily which may be increased to a maximum dose of 10 mg depending on the individual patient's response.
In hypertensive patients, amlodipine has been used in combination with a thiazide diuretic, alpha blocker, beta blocker, or an angiotensin converting enzyme inhibitor. For angina, amlodipine may be used as monotherapy or in combination with other antianginal medicinal products in patients with angina that is refractory to nitrates and/or to adequate doses of beta blockers.
No dose adjustment of amlodipine is required upon concomitant administration of thiazide diuretics, beta blockers, and angiotensin-converting enzyme inhibitors.
Special populations: Older patients: Amlodipine used at similar doses in older or younger patients is equally well tolerated. Normal dose regimens are recommended in older patients, but increase of the dose should take place with care (see Precautions and Pharmacology: Pharmacokinetics under Actions).
Hepatic impairment: Dose recommendations have not been established in patients with mild to moderate hepatic impairment; therefore dose selection should be cautious and should start at the lower end of the dosing range (see Precautions and Pharmacology: Pharmacokinetics under Actions).
Renal impairment: Changes in amlodipine plasma concentrations are not correlated with degree of renal impairment, therefore the normal dose is recommended. Amlodipine is not dialysable.
Paediatric population: Children and adolescents with hypertension from 6 years to 17 years of age: The recommended antihypertensive oral dose in paediatric patients ages 6-17 years is 2.5 mg once daily as a starting dose, up-titrated to 5 mg once daily if blood pressure goal is not achieved after 4 weeks. Doses in excess of 5 mg daily have not been studied in paediatric patients (see Pharmacology: Pharmacodynamics and Pharmacokinetics under Actions).
Doses of amlodipine 2.5 mg are not possible with this medicinal product.
Children under 6 years old: No data are available.
Method of administration: For oral administration.

In humans experience with intentional overdose is limited.
Symptoms: Available data suggest that gross overdose could result in excessive peripheral vasodilatation and possibly reflex tachycardia. Marked and probably prolonged systemic hypotension up to and including shock with fatal outcome have been reported.
Treatment: Clinically significant hypotension due to amlodipine overdose calls for active cardiovascular support including frequent monitoring of cardiac and respiratory function, elevation of extremities and attention to circulating fluid volume and urine output.
A vasoconstrictor may be helpful 6 restoring vascular tone and blood pressure, provided that there is no contraindication to its use. Intravenous calcium gluconate may be beneficial in reversing the effects of calcium channel blockade.
Gastric lavage may be worthwhile in some cases. In healthy volunteers the use of charcoal up to 2 hours after administration of amlodipine 10 mg has been shown to reduce the absorption rate of amlodipine.
Since amlodipine is highly protein-bound, dialysis is not likely to be of benefit.

Amlodipine is contraindicated in patients with: hypersensitivity to dihydropyridine derivatives, amlodipine or to any of the excipients; severe hypotension; shock (including cardiogenic shock); obstruction of the outflow tract of the left ventricle (e.g., high grade aortic stenosis); haemodynamically unstable heart failure after acute myocardial infarction.

The safety and efficacy of amlodipine in hypertensive crisis has not been established.
Patients with cardiac failure: Patients with heart failure should be treated with caution. In a long-term, placebo-controlled study in patients with severe heart failure (NYHA class III and IV) the reported incidence of pulmonary oedema was higher in the amlodipine treated group than in the placebo group (see Pharmacology: Pharmacodynamics under Actions).
Calcium channel blockers, including amlodipine, should be used with caution in patients with congestive heart failure, as they may increase the risk of future cardiovascular events and mortality.
Patients with hepatic impairment: The half-life of amlodipine is prolonged and AUC values are higher in patients with impaired liver function; dose recommendations have not been established. Amlodipine should therefore be initiated at the lower end of the dosing range and caution should be used, both on initial treatment and when increasing the dose. Slow dose titration and careful monitoring may be required in patients with severe hepatic impairment.
Patients with renal impairment: Amlodipine may be used in such patients at normal doses. Changes in amlodipine plasma concentrations are not correlated with degree of renal impairment. Amlodipine is not dialysable.
Effects on ability to drive and use machines: Amlodipine can have minor or moderate influence on the ability to drive and use machines. If patients taking amlodipine suffer from dizziness, headache, fatigue or nausea the ability to react may be impaired. Caution is recommended especially at the start of treatment.
Use in the elderly: In older patients increase of the dose should take place with care (see Dosage & Administration and Pharmacology: Pharmacokinetics under Actions).

Pregnancy: Pregnancy The safety of amlodipine in human pregnancy has not been established.
In animal studies, reproductive toxicity was observed at high doses (see Pharmacology: Toxicology: Preclinical safely data under Actions).
Use in pregnancy is only recommended when there is no safer alternative and when the disease itself carries greater risk for the mother and foetus.
Breast-feeding: It is not known whether amlodipine is excreted in breast milk. A decision on whether to continue/discontinue breast-feeding or to continue/discontinue therapy with amlodipine should be made taking into account the benefit of breast-feeding to the child and the benefit of amlodipine therapy to the mother.
Fertility: Reversible biochemical changes in the head of spermatozoa have been reported in some patients treated by calcium channel blockers. Clinical data are insufficient regarding the potential effect of amlodipine on fertility. In one rat study, adverse effects were found on male fertility (see Pharmacology: Toxicology: Preclinical safely data under Actions).

Summary of the safely profile: The most commonly reported adverse reactions during treatment are somnolence, dizziness, headache, palpitations, flushing, abdominal pain, nausea, ankle swelling, oedema and fatigue.
List of adverse reactions: The following adverse reactions have been observed and reported during treatment with amlodipine with the following frequencies: Very common (61/10); common (61/100 to <1/10); uncommon (61/1,000 to <1/100); rare (61/10,000 U <1/1,000); very rare (<1/10,000).
Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness.
Blood and lymphatic system disorders: Very rare: Leukocytopenia, thrombocytopenia.
Immune system disorders: Very rare: Allergic reactions.
Metabolism and nutrition disorders: Very rare: Hyperglycaemia.
Psychiatric disorders: Uncommon: Depression, mood changes (including anxiety), insomnia. Rare: Confusion.
Nervous system disorders: Common: Somnolence, dizziness, headache (especially at the beginning of the treatment). Uncommon: Tremor, dysgeusia, syncope, hypoaesthesia, paraesthesia. Very rare: Hypertonia, peripheral neuropathy. Not known: Extrapyramidal disorder.
Eye disorders: Common: Visual disturbance (including diplopia).
Ear and labyrinth disorders: Uncommon: Tinnitus.
Cardiac disorders: Common: Palpitations. Uncommon: Arrhythmia (including bradycardia, ventricular tachycardia and atrial fibrillation). Very rare: Myocardial infarction.
Vascular disorders: Common: Flushing. Uncommon: Hypotension. Very rare: Vasculitis.
Respiratory, thoracic and mediastinal disorders: Common: Dyspnoea. Uncommon: Cough, rhinitis.
Gastrointestinal disorders: Common: Abdominal pain, nausea, dyspepsia, altered bowel habits (including diarrhoea and constipation). Uncommon: Vomiting, dry mouth. Very rare: Pancreatitis, gastritis, gingival hyperplasia.
Hepatobiliary disorders: Very rare: Hepatitis, jaundice, hepatic enzyme increased*.
Skin and subcutaneous disorders: Uncommon: Alopecia, purpura, skin discolouration, hyperhidrosis, pruritus, rash, exanthema, urticaria. Very rare: Angioedema, erythema multiforme, exfoliative dermatitis, Stevens-Johnson syndrome, Quincke oedema, photosensitivity.
Musculoskeletal and connective tissue disorders: Common: Ankle swelling, muscle cramps. Uncommon: Arthralgia, myalgia, back pain.
Renal and urinary disorders: Uncommon: Micturition disorder, nocturia, increased urinary frequency.
Reproductive system and breast disorders: Uncommon: Impotence, gynaecomastia.
General disorders and administration site conditions: Very common: Oedema. Common: Fatigue, asthenia. Uncommon: Chest pain, pain, malaise.
Investigations: Uncommon: Weight increased, weight decreased mostly consistent with cholestasis.

Effects of other medicinal products on amlodipine: CYP3A4 inhibitors: Concomitant use of amlodipine with strong or moderate CYP3A4 inhibitors (protease inhibitors, azole antifungals, macrolides like erythromycin or clarithromycin, verapamil or diltiazem) may give rise to significant increase in amlodipine exposure resulting in an increased risk of hypotension. The clinical translation of these PK variations may be more pronounced in older people. Clinical monitoring and dose adjustment may thus be required.
CYP3A4 inducers: There is no data available regarding the effect of CYP3A4 inducers on amlodipine. The concomitant use of CYP3A4 inducers (e.g., rifampicin, Hypericum perforatum) may give a lower plasma concentration of amlodipine. Amlodipine should be used with caution together with CYP3A4 inducers. Administration of amlodipine with grapefruit or grapefruit juice is not recommended as bioavailability may be increased in some patients resulting in increased blood pressure lowering effects.
Dantrolene (infusion): In animals, lethal ventricular fibrillation and cardiovascular collapse are observed in association with hyperkalaemia after administration of verapamil and intravenous dantrolene. Due to risk of hyperkalaemia, it is recommended that the co-administration of calcium channel blockers such as amlodipine be avoided in patients susceptible to malignant hyperthermia and in the management of malignant hyperthermia.
Effects of amlodipine on other medicinal products: The blood pressure lowering effect of amlodipine adds to the blood pressure-lowering effects of other medicinal products with antihypertensive properties.
Tacrolimus: There is a risk of increased tacrolimus blood levels when co-administered with amlodipine but the pharmacokinetic mechanism of this interaction is not fully understood. In order to avoid toxicity of tacrolimus, administration of amlodipine in a patient treated with tacrolimus requires monitoring of tacrolimus blood levels and dose adjustment of tacrolimus when appropriate.
Clarithromycin is an inhibitor of CYP3A4. There is an increased risk of hypotension in patients receiving clarithromycin with amlodipine. Close observation of patients is recommended when amlodipine is co-administered with clarithromycin.
Ciclosporin: No drug interaction studies have been conducted with ciclosporin and amlodipine in healthy volunteers or other populations with the exception of renal transplant patients, where variable trough concentration increases (average 0%-40%) of ciclosporin were observed. Consideration should be given for monitoring ciclosporin levels in renal transplant patients on amlodipine, and ciclosporin dose reductions should be mode as necessary.
Simvastatin: Co-administration of multiple doses <6 10 mg of amlodipine with 80 mg simvastatin resulted in a 77% increase in exposure to simvastatin compared to simvastatin alone. Limit the dose of simvastain in patients on amlodipine to 20 mg daily.
In clinical interaction studies, amlodipine did not affect the pharmacokinetics of atorvastatin, digs-Us, or warfarin.

Incompatibilities: Not applicable.

Store at room temperature not exceeding 25°C.

Calcium Antagonists / Anti-Anginal Drugs

C08CA01 - amlodipine ; Belongs to the class of dihydropyridine derivative selective calcium-channel blockers with mainly vascular effects. Used in the treatment of cardiovascular diseases.

Rx