- High Blood Pressure Slideshow Pictures
- Take the Salt Quiz!
- Lowering Blood Pressure Exercise Tips Pictures
- What is labetalol, and how does it work (mechanism of action)?
- What brand names are available for labetalol?
- Is labetalol available as a generic drug?
- Do I need a prescription for labetalol?
- What are the side effects of labetalol?
- What is the dosage for labetalol?
- Which drugs or supplements interact with labetalol?
- Is labetalol safe to take if I'm pregnant or breastfeeding?
- What else should I know about labetalol?
What is labetalol, and how does it work (mechanism of action)?
Labetalol is a drug that is used for treating high blood pressure. And is related to carvedilol (Coreg). Nerves from the adrenergic nervous system travel from the spinal cord to arteries where they release norepinephrine. Norepinephrine attaches to adrenergic receptors on arteries and causes the arteries to contract, narrowing the arteries, and increasing blood pressure. Labetalol blocks receptors of the adrenergic nervous system. When labetalol attaches to and blocks the receptors, arteries expand, resulting in a fall in blood pressure. The FDA approved labetalol in August 1984.
What are the side effects of labetalol?
The most common side effects of labetalol are:
Postural hypotension (a rapid decrease in blood pressure when going from the lying or seated position to the standing position that may cause light-headedness or fainting) occurs rarely. Patients should be observed for this possible side effect within two to four hours of the first labetalol dose and after any changes in dose.
Other important side effects include:
What is the dosage for labetalol?
The recommended starting oral dose of labetalol is 100 mg twice daily and the dose can be increased by 100 mg twice daily every 2-3 days based on the response of the blood pressure. Usual maintenance doses are 200-400 mg twice daily. Patients with severely high blood pressure may require 1.2 to 2.4 g daily.
Side effects may be less if labetalol is given in three daily doses rather than two. Stopping or changing the dose of the drug should be directed by a physician because serious side effects may occur. The initial intravenous dose of labetalol is 20 mg injected over 2 minutes. Additional injections of 40 or 80 mg may be administered every 10 minutes as needed up to a total dose of 300 mg. Labetalol also may be administered by intravenous infusion at 1-2 mg/minute.
Which drugs or supplements interact with labetalol?
Labetalol can mask early warning symptoms of hypoglycemia (low blood sugar) such as tremors and increased heart rate which are the result of activation of the adrenergic nervous system. Therefore, people with diabetes taking medications that lower blood sugar such as insulin or oral antidiabetic medications may need to increase the frequency with which they monitor their blood sugar in order to prevent hypoglycemia.
Combining labetalol with tricyclic antidepressants such as amitriptyline (Elavil, Endep), imipramine (Tofranil), or nortriptyline (Pamelor) may lead to an increase in tremor which is a side effect of tricyclic antidepressants.
If combined with adrenergic stimulating drugs used for treating asthma, for example, albuterol (Proventil, Ventolin) or pirbuterol (Maxair), the adrenergic blocking effects of labetalol may counteract the effects of the stimulating drugs and reduce their effectiveness for treating asthmatic attacks. More of the adrenergic drug may be needed.
Glutethimide (Doriden) may decrease the effectiveness of labetalol by increasing its elimination. When both drugs are used together, more labetalol or less glutethimide may be needed.
Cimetidine (Tagamet) may increase the effectiveness of labetalol by blocking its elimination and increasing its levels in the blood. Therefore, less labetalol may be needed when cimetidine and labetalol are used together.
Halothane anesthesia may contribute to the blood pressure lowering effects of labetalol.
Is labetalol safe to take if I'm pregnant or breastfeeding?
There are no adequate studies of labetalol during pregnancy.
Labetalol is excreted in human breast milk. Therefore, it should be used cautiously in nursing mothers because of the risk that the infant may develop a slow heart rate.
Multimedia: Slideshows, Images & Quizzes
Heart Disease: Causes of a Heart Attack
Learn about heart disease and heart attack symptoms and signs of a heart attack in men and women. Read about heart disease...
Picture of Hypertension
High blood pressure, defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140...
Heart Disease: Symptoms, Signs, and Causes
What is heart disease (coronary artery disease)? Learn about the causes of heart disease. Symptoms of heart disease include chest...
Related Disease Conditions
Heart disease (coronary artery disease) occurs when plaque builds up in the coronary arteries, the vessels that supply blood to...
High Blood Pressure (Hypertension) Signs, Causes, Diet, and Treatment
High blood pressure (hypertension) is a disease in which pressure within the arteries of the body is elevated. About 75 million...
High Blood Pressure Treatment (Natural Home Remedies, Diet, Medications)
High blood pressure (hypertension) means high pressure (tension) in the arteries. Treatment for high blood pressure include...
Aortic dissection is a small tear in the large blood vessel that leads from the heart and supplies blood to the body. There are...
Atrial Fibrillation (AFib) Treatment Drugs
Atrial fibrillation (also called Afib or Afib) is heart rhythm disorder that causes irregular, and often, a rapid heartbeat. The...
Treatment & Diagnosis
- Drugs: Buying Prescription Drugs Online Safely
- How To Reduce Your Medication Costs
- Pharmacy Visit, How To Get The Most Out of Your Visit
- Indications for Drugs: Approved vs. Non-approved
- Drugs: The Most Common Medication Errors
- Medication Disposal
- Dangers of Mixing Medications
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
Prevention & Wellness
Heart Health Resources
Health Solutions From Our Sponsors
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
FDA Prescribing Information