Norvasc |
Amlodipine (as besylate, mesylate or maleate) is a long-acting calcium channel blocker
(dihydropyridine) used as an anti-hypertensive and in the treatment of angina.
As other calcium channel blockers, amlodipine acts by relaxing the smooth
muscle in the arterial wall, decreasing peripheral resistance and hence reducing
blood pressure; in angina it increases blood flow to the heart muscle. Amlodipine is marketed as Norvasc® in North America and as Istin® in the United Kingdom by Pfizer as well as under various other names. Indications hypertension prophylaxis of angina Cautions hepatic impairment pregnancy Contra-indications cardiogenic shock unstable angina significant aortic stenosis breast feeding Side effects Some side effects[1] of the use of amlodipine may be: Very often: peripheral edema (feet and ankles) - in 1 of 10 users Often: dizziness, palpitations, muscle, stomach or headache, dyspepsia, nausea - in 1 in 100 users Sometimes: blood disorders, development of breasts in men (gynecomastia), impotence, depression, insomnia, tachycardia - in 1 in 1,000 users Rarely: erratic behavior, hepatitis, jaundice - in 1 in 10,000 users Very rarely: hyperglycemia, tremor, Stevens-Johnson syndrome - in 1 in 100,000 users Dose Hypertension or angina: 5 or 10 mg once daily. Salts In the United Kingdom tablets of amlodipine from different suppliers may contain different salts. The strength of the tablets is expressed in terms of amlodipine base. i.e. without the salt. Tablets containing different salts are therefore considered interchangeable. Drug Metabolism and Excretion Amlodipine is almost entirely metabolised to inactive metabolites. Ten per cent of the parent substance and 60% of the metabolites are excreted in urine. Patent loss Pfizer patent protection on Norvasc lasted until 2007. A number of generic versions are now available. Total patent expiration occurred later in 2007. |