Amlodipine

Amlodipine (as besylate, mesylate or maleate) is a long-acting calcium channel blocker (dihydropyridine class) used as an anti-hypertensive and in the treatment of angina. Like 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 Dailyvasc in the Philippines by Xeno Pharmaceuticals, and by Pfizer as Norvasc in North America, Australia and some European countries, and as Istin in the United Kingdom. Generic brands (sold under names such as Perivasc in Australia) are also available.

Indications

• hypertension
• prophylaxis of angina

Cautions

• hepatic impairment
• pregnancy

Contraindications

• cardiogenic shock
• unstable angina
• significant aortic stenosis
• breast feeding

Side effects

Some side effects 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: 2.5 or 10 mg once daily (initial treatment can start as low as 2.5 mg per day).

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.