Labetalol

Brand names

• Normodyne
• Normozide [CD]
• Trandate
• Trandate HTC [CD]

Usage

To treat severe high blood pressure (hypertension).

How it works

Labetalol hydrochloride is a beta-blocker with alpha-blocker activity. Such medicaments work by preventing-or blocking-nerve impulses from exerting an accelerating or intensifying effect on specific parts of the body, especially the blood vessels and heart. Unlike other beta-blockers, this medicament does not significantly slow the heart rate.

Side effects

Serious

Shortness of breath, wheezing; chest pain or tightness; swelling of the ankles, feet, and lower legs; mental depression. If you experience such symptoms, seek medical help immediately.

Common

Dizziness or lightheadedness, especially when rising suddenly to a standing position; decreased sexual ability; unusual fatigue, weakness, or drowsiness; insomnia; scalp tingling, especially at the beginning of treatment.

Less common

Changes in taste; itching, numbness, or tingling; vivid dreams or nightmares; nausea or vomiting; irregular or slow heartbeat (50 beats per minute or less).

Possible interactions

Other medicaments:

Labetalol may increase the effects of:

• oral antidiabetic medicaments and prolong recovery from any hypoglycemia (low blood sugar) that may occur.
• other antihypertensive medicaments and cause excessive lowering of blood pressure. Dose adjustments may be necessary.

Labetalol taken concurrently with:

• amiodarone (Cordarone) may result in extremely slow heart rates and cardiac arrest.
• cimetidine (Tagamet) can cause elevated labetalol levels and low blood pressure or heart rate.
• clonidine (Catapres) must be closely watched for rebound high blood pressure if clonidine is withdrawn while labetalol is still being taken.
• digoxin's (Lanoxin) atrioventricular node conduction time extension may cause heart block and digoxin toxicity.
• dihydropyridine calcium channel blockers (nifedipine, others) may lead to impaired heart performance or excessively lowered blood pressure.
• epinephrine may result in severe increases in blood pressure.
• fluoxetine (Prozac) may increase labetalol effects.
• fluvoxamine (Luvox) may result in excessive lowering of blood pressure or excessive slowing of the heart.
• imipramine and other tricyclic antidepressants may result in increases in antidepressant blood levels and toxicity.
• insulin must be watched for development of hypoglycemia.
• NSAIDs may result in blunting of the therapeutic effects of labetalol.
• paroxetine (Paxil) may increase labetalol effects.
• phenothiazines may cause additive lowering of the blood pressure.
• ritodrine (Yutopar) may blunt the beneficial effects of ritodrine.
• venlafaxine (Effexor) may increase labetalol effects.
• zileuton (Zyflo) may increase labetalol effects.

Foods:

May increase the absorption of labetalol and result in a larger than expected blood level. Patients taking this medicine should also avoid excessive salt intake.

Herbal medicines or minerals:

Ginseng may increase blood pressure, blunting the benefits of these medicines. Hawthorn, saw palmetto, ma huang, goldenseal, yohimbe and licorice may also increase blood pressure. Calcium and garlic may help lower blood pressure. Indian snakeroot has a German Commission E monograph indication for hypertension-talk to your doctor. Eleuthero root and ma huang should be avoided by people living with hypertension.

Alcohol:

Alcohol may exaggerate this medicament's ability to lower blood pressure and may increase its mild sedative effect.

Tobacco smoking:

Nicotine may reduce this medicament's effectiveness.

Exposure to heat:

Hot environments can lower the blood pressure and exaggerate the effects of this medicament.

Exposure to cold:

Cold environments can increase blood flow problems in the extremities that may occur with beta-blocker medicaments. The elderly should take precautions to prevent hypothermia.

Heavy exercise or exertion:

It is prudent to avoid exertion that produces lightheadedness, excessive fatigue or muscle cramping. Use of this medicament may intensify hypertensive response to isometric exercise.

Occurrence of unrelated illness:

Fever can lower blood pressure and require decreased doses. Nausea or vomiting may interrupt scheduled doses. Ask your doctor for help.

Discontinuation:

If possible, gradual reduction of dose over a period of 2 to 3 weeks is recommended-otherwise rebound increases in blood pressure may occur. Ask your doctor for help.

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