DrugindexOnline^{2nd edition}

Pronouncation: (am-LOW-dih-PEEN)
Class: Calcium channel blocking agent

Trade Names:
Norvasc
- Tablets 2.5 mg
- Tablets 5 mg
- Tablets 10 mg

Mechanism of Action

Pharmacology

Inhibits movement of calcium ions across cell membrane in systemic and coronary vascular smooth muscle.

Pharmacokinetics

Absorption

T _max is 6 to 12 h.

Distribution

Bioavailability is 64% to 90%. About 93% is protein bound.

Metabolism

About 90% is converted to inactive metabolites in the liver.

Elimination

10% of the parent compound and 60% of the metabolites are excreted in the urine. Elimination is biphasic. T _½ is about 30 to 50 h.

Duration

24 h.

Special Populations

Hepatic Function Impairment

Clearance is decreased and AUC may increase about 40% to 60%. May require lower initial dose.

Elderly

Clearance is decreased and AUC may increase about 40% to 60%. May require lower initial dose.

Moderate to severe heart failure

Clearance is decreased and AUC may increase about 40% to 60%. May require lower initial dose.

Indications and Usage

Hypertension; chronic stable angina; vasospastic (Prinzmetal or variant) angina.

Contraindications

Sick sinus syndrome; second- or third-degree atrioventricular (AV) block, except with a functioning pacemaker.

Dosage and Administration

Adults

PO 5 to 10 mg every day.

Elderly

PO Initially 2.5 mg every day.

Hepatic Impairment

PO Initially 2.5 mg every day.

Storage/Stability

Store in tightly closed container in cool location at 59° to 86°F.

Drug Interactions

Beta-blockers

May cause increased adverse cardiac reactions as a result of myocardial depression.

Fentanyl

Severe hypotension or increased fluid volume requirements have occurred with similar drug.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Palpitations; peripheral edema; syncope; tachycardia; bradycardia; arrhythmias; ventricular asystoles.

CNS

Headache; dizziness; lightheadedness; fatigue; lethargy; somnolence.

Dermatologic

Dermatitis; rash; pruritus; urticaria.

GI

Nausea; abdominal discomfort; cramps; dyspepsia.

Respiratory

Shortness of breath; dyspnea; wheezing.

Miscellaneous

Flushing; sexual difficulties; muscle cramps, pain or inflammation.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Hepatic Function

Cautious use is required.

CHF

Cautious use is required with this condition.

Overdosage

Symptoms

Nausea, weakness, dizziness, drowsiness, confusion, slurred speech, hypotension, bradycardia, second- or third-degree AV block.

Patient Information

• Teach patient how to monitor pulse before taking medication. Tell patient not to take medication if pulse if less than 50 bpm and to call health care provider.
• Explain to patient how to monitor BP daily.
• Instruct patient not to stop taking this medication suddenly because doing so can cause chest pain and MI.
• Teach patient importance of good oral hygiene and frequent visits to dentist while taking medication.
• Inform patient that frequent follow-up appointments with health care provider are important to adjust medication dosage.
• Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.