AMLODIPINE BESYLATE

Amlodipine (Norvasc (Pfizer) and generics) (as besylate, mesylate or maleate) is a long-acting dihydropyridine-type (DHP) calcium channel blocker used to lower blood pressure and to treat anginal chest pain. Like other calcium channel blockers, amlodipine lowers blood pressure by relaxing arterial smooth muscles, which decreases total peripheral resistance and therefore reduces blood pressure. In angina, amlodipine increases blood flow to the heart muscle (although DHP-class calcium channel blockers are more selective for arteries than the muscular tissue of the heart (myocardium), as the calcium ion channels of the heart are not of the dihydropyridine-type).It is on the World Health Organization’s List of Essential Medicines, a list of the most important medication needed in a basic health system.

Adverse effects

Adverse side effects of the use of amlodipine may include:

• Common: peripheral edema in 8.3% of users, fatigue in 4.5% of users[5] dizziness; palpitations; stomach-pain, headache, dyspepsia, somnolence(sleepiness) and/or nausea in greater than 1%.
• Uncommon: blood disorders, development of breasts in men (gynecomastia), impotence, depression, insomnia, tachycardia, or gingival enlargement – in one in 1,000 users
• Rarely: erratic behavior, hepatitis, jaundice – in one in 10,000 users
• Very rarely: hyperglycemia, tremor, Stevens–Johnson syndrome – in one in 100,000 users

The acute oral toxicity (LD50) of amlodipine in mice is 37 mg/kg.

Cautions

• Hepatic impairment
• Pregnancy

Interactions

• In patients with severe coronary artery disease, amlodipine can increase the frequency and severity of angina or actually cause a heart attack on rare occasions.
• Excessive lowering of blood pressure during initiation of amlodipine treatment can occur, especially in patients already taking another medication for lowering blood pressure. In rare instances, congestive heart failure has been associated with amlodipine, usually in patients already on a beta blocker.
• Amlodipine is primarily metabolyzed by the liver, via the cytochrome P450 isoenzyme CYP3A4. As a result, serum levels can potentially be affected by drugs which inhibit or activate CYP3A4. Grapefruit juice can inhibit the cytochrome P450 system, but the predicted interaction risk with amlodipine is low.