PHARMACOLOGY
Amlodipine is a dihydropyridine calcium antagonist that inhibits the trans-membrane influx of calcium ions into the vascular smooth muscle and cardiac muscle. The mechanism of the antihypertensive action is due to a direct relaxant effect on vascular smooth muscle. The precise mechanism by which Amlodipine relieves angina may be due to the following two actions:
1. Amlodipine dilates peripheral arterioles and thus reduces the total peripheral resistance against which the heart works. Since there is no associated reflex tachycardia, this unloading of the heart reduces myocardial energy consumption and oxygen requirements and probably accounts for the effectiveness of Amlodipine in myocardial ischaemia.
2. The mechanism of action of Amlodipine probably involves dilation of the main coronary arteries and coronary arterioles, both in normal and ischaemic regions.
PHARMACOKINETICS :
Amlodipine is well absorbed following oral administration of the therapeutic doses with peak blood concentrations occurring after 6 to 12 hours. The bioavailability is about 60 to 65%. It is reported to be about 97.5% bound to plasma proteins. It has a prolonged terminal elimination half-life of 35 to 50 hours and steady-state plasma concentrations are not achieved until 7 to 8 days of administration. Amlodipine is extensively metabolised to inactive metabolites in the liver; metabolites are mostly excreted in urine together with less than 10% of a dose as unchanged drug.
INDICATIONS :
Amlodipine is a dihydropyridine calcium-channel blocker and it is used in the management of hypertension and angina pectoris.
DOSAGE AND ADMINISTRATION:
In hypertension the usual initial dose is 5 mg once daily, increased, if necessary, to 10 mg once daily. Similar doses are given in the treatment of stable angina and Prinzmetal’s angina. Or as prescribed by the physician.
CONTRAINDICATION :
Amlodipine is contraindicated in patients with known hypersensitivity to Amlodipine.
ADVERSE EFFECTS:
The most commonly observed side effects were dizziness, flushing, headache, hypotension, peripheral oedema, tachycardia, and palpitations. Nausea and other gastrointestinal disturbances, increased micturition frequency, lethargy, eye pain, and mental depression have also occurred. A paradoxical increase in ischaemic chest pain may occur the start of treatment and in few patients excessive fall in blood pressure has led to cerebral or myocardial ischaemia or transient blindness.
DRUG INTERACTIONS:
Amlodipine has been safely administered with thiazide diuretics, beta-adrenoceptor blocking drugs, angiotensin converting enzyme inhibitor, long acting nitrates, sublingual glyceryl nitrate, non-steroidal anti-inflammatory drugs, antibiotics and oral hypoglycaemic agents. Co-administration of Cimetidine did not alter the pharmacokinetics of Amlodipine. In vitro data from studies with human plasma indicate that Amlodipine has no effect on protein binding of Digoxin, Phenytoin, Warfarin, or Indomethacin.
PRECAUTIONS:
Should be used with caution in patients with hypotension, in patients whose cardiac reserve is poor, and in those with heart failure since deterioration has been noted. It should not be used in cardiogenic shock, in patients who have recently suffered myocardial infarction, or in acute unstable angina.
AVAILABILITY
Amlodipine Besilate 5 mg Tablet alu-alu blister foil by 10’s ( Box of 100’s )
Amlodipine Besilate 10 mg Tablet alu-alu blister foil by 10’s ( Box of 100’s)
CAUTION :
Foods, Drugs, Devices, and Cosmetics Act prohibits dispensing without presc ription.
STORE AT TEMPERATURES NOT EXCEEDING 30° C.
DAILYvasc is a trademark of XENO Pharmaceuticals Phils. Inc.
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