AMLODIPINE

Medical Diagnosis and Drugs, Medications
AMLODIPINE
(am-lo'di-peen)
Norvasc
Classifications: calcium channel blocker; antihypertensive agent;
Therapeutic: antihypertensive
; calcium channel blocker
Prototype: Nifedipine
Pregnancy Category: C

Availability

2.5 mg, 5 mg, 10 mg tablets

Action

Amlodipine is a calcium channel blocking agent that selectively blocks calcium influx across cell membranes of cardiac and vascular smooth muscle without changing serum calcium concentrations. It reduces coronary vascular resistance and increases coronary blood flow. Additionally, amlodipine decreases peripheral vascular resistance, increases oxygen delivery to myocardial tissue, and increases cardiac output.

Therapeutic Effect

Amlodipine reduces systolic, diastolic, and mean arterial blood pressure. It also decreases pain due to angina.

Uses

Treatment of mild to moderate hypertension and angina.

Contraindications

Hypersensitivity to amlodipine; hypotension; severe obstructive coronary artery disease; severe aortic stenosis; pregnancy (category C).

Cautious Use

Liver disease; concomitant use with hypotension; CHF, ventricular dysfunction; lactation; older adults; children <6 y, GERD; hepatic disease.

Route & Dosage

Hypertension
Adult: PO 5–10 mg once daily
Geriatric: Start with 2.5 mg, adjust dose at intervals of not less than 2 wk

Hepatic Impairment
Start with 2.5 mg, adjust dose at intervals of not less than 2 wk

Administration

Oral
  • Give drug without regard to meals.
  • Prescribed initial dosages of 2.5 mg daily are common if added to a regimen including other antihypertensive drugs.
  • Note: Doses are usually titrated over a period of 14 d or more rapidly if warranted.
  • Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

CV: Palpitations, flushing tachycardia, peripheral or facial edema, bradycardia, chest pain, syncope, postural hypotension. CNS: Light-headedness, fatigue, headache. GI: Abdominal pain, nausea, anorexia, constipation, dyspepsia, dysphagia, diarrhea, flatulence, vomiting. Urogenital: Sexual dys- function, frequency, nocturia. Respiratory: Dyspnea. Skin: Flushing, rash. Other: Arthralgia, cramps, myalgia.

Interactions

Drug: Adenosine may increase the risk of bradycardia; bosentan may decrease efficacy of amlodipine; additive hypotensive effects with other antihypertensive agents; azole antifungals (e.g., fluconazole, itraconazole) may inhibit metabolism of amlodipine; itraconazole may increase edema. Food: Grapefruit juice may increase amlodipine levels. Herbal: Ephedra, ma huang, melatonin may antagonize antihypertensive effects.

Pharmacokinetics

Absorption: >90% absorbed from GI tract. Onset: Gradual. Peak: 6–9 h. Duration: 24 h. Distribution: >95% protein bound. Metabolism: Extensively in the liver to inactive metabolites; via CYP3A4. Elimination: Inactive metabolites primarily excreted in urine (<5–10% excreted unchanged), 20–25% in feces. Half-Life: <45 y: 28–69 h; >60 y: 40–120 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor BP for therapeutic effectiveness. BP reduction is greatest after peak levels of amlodipine are achieved 6–9 h following oral doses.
  • Monitor for S&S of dose-related peripheral or facial edema that may not be accompanied by weight gain; rarely, severe edema may cause discontinuation of drug.
  • Monitor BP with postural changes. Report postural hypotension. Monitor more frequently when additional antihypertensives or diuretics are added.
  • Monitor heart rate; dose-related palpitations (more common in women) may occur.

Patient & Family Education

  • Report significant swelling of face or extremities.
  • Take care to have support when standing & walking due to possible dose-related light-headedness/dizziness.
  • Report shortness of breath, palpitations, irregular heartbeat, nausea, or constipation to physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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