Propranolol

Propranolol

Definition

Propranolol is classified as a beta blocker. It is sold in the United States under the brand name Inderal. When combined with the diuretic, hydrochlorothiazide, it is sold under the brand name Inderide. Propranolol also is produced as a generic product by a number of generic manufacturers.

Purpose

Propranolol is approved by the Food and Drug Administration (FDA) for the treatment of hypertension (high blood pressure), angina, certain types of cardiac arrhythmias, certain types of cardiac output diseases, a sympathetic nervous system disorder known as pheochromocytoma, hyperthyroid conditions, migraine, heart attack, and tremors of a variety of origins. It is also used on occasion for the treatment of medication-induced movement disorders caused by antipsychotic drugs and certain anxiety states in people suffering from a specific form of social phobia . Beta blockers , such as propanolol, are not useful for people with general social phobia who are anxious in most social situations; instead, propanolol may be useful for people who are anxious about specific performance situations, such as presenting a speech before an audience.

Description

Propranolol falls into the broad pharmacologic category known as beta blockers. Beta blockers block specific sites in the central nervous system known as beta-adrenergic receptor sites. When these sites are blocked, heart rate and blood pressure are reduced and patients become less anxious. Because of this, propranolol is useful in treating chest pain, high blood pressure, and excessive nervousness. Unfortunately, propranolol often makes breathing disorders, such as asthma, worse because it tends to constrict breathing passages and sometimes causes fluid to build up in the lungs if it excessively depresses the heart.

In the treatment of anxiety, propranolol is usually not administered on a chronic basis but, rather, prior to stressful events such as public speaking or acting. In the treatment of certain types of tremors, especially tremors secondary to a drug, and movement disorders secondary to antipsychotic therapy, propranolol is administered throughout the day in divided doses. Propranolol is available in 10-, 20-, 40-, 60-, and 80-mg tablets; in long-acting capsules; and an injectable form containing 1 mg per mL. It is also combined with the diuretic hydrochlorothiazide in tablets and extended-release capsules.

Recommended dosage

For the treatment of performance anxiety or stage fright, a single dose of 10–40 mg may be administered 20–30 minutes before the event. For the treatment of tremors, especially tremors secondary to lithium, doses range from 20 to 160 mg per day administered in two or three divided doses. For the treatment of movement disorders secondary to antipsychotic drug therapy, doses range from 10 to 30 mg three times daily.

Precautions

Precautions should be taken when administering propranolol in the following situations:

• liver or renal (kidney) failure
• prior to screening tests for glaucoma
• a history of immediate allergic reaction (known as anaphylaxis) to a beta blocker of any kind

Side effects

The following side effects have been observed with propranolol. Most have been mild and transient (temporary) and rarely require the withdrawal of therapy:

• Cardiovascular: bradycardia, congestive heart failure, hypotension, Raynaud's syndrome.
• Central nervous system: light-headedness, mental depression, insomnia , vivid dreams, disorientation, memory loss.
• Gastrointestinal: nausea, vomiting, abdominal pain, cramping, diarrhea, constipation, bowel ischemia.
• Allergic: fever, rash, laryngospasm, thrombocytopenia.
• Respiratory: bronchospasm.
• Hematologic: bone marrow suppression, bleeding under the skin.

Interactions

• When drugs that deplete the body of epinephrine and norepinephrine (such as reserpine and guanethidine) are taken with propranolol, interactions have been reported. Some of these interactions include: fainting, hypotension, dizziness, and slow heart rate.
• Drugs known as calcium channel blockers may decrease the pumping ability of the heart and lead to the development of cardiac arrhythmias.
• Nonsteroidal anti-inflammatory agents (i.e., ibuprofen and naproxen) may blunt the blood pressure-lowering effects of propranolol.
• Aluminum hydroxide antacids greatly reduce the rate of intestinal absorption of propranolol.
• Alcohol slows the rate of propranolol absorption.
• Interactions have also been reported with phenytoin, rifampin, phenobarbital, chlorpromazine , lidocaine, thyroxin, cimetidine, and theophylline.

See also Alcohol and related disorders; Anxiety and related disorders

Resources

BOOKS

Medical Economics Staff. Physicians' Desk Reference. 56th edition, Montvale, N.J., 2002.

Springhouse Publishers Staff. Nursing 2002 Drug Handbook. Springhouse, PA: Lippincott, Williams and Wilkins, 2001.

Thomas, Clayton, MD, editor. Taber's Cyclopedic Medical Dictionary. 19th edition; Philadelphia: F. A. Davis Publishers, 2001.

Ralph Myerson, M.D.