Life Science Encyclopedia

Labetalol (Normodyne, Trandate, fixed combination with hydrochlorothiazide: Normozyde) is an alpha-1 and beta adrenergic blocker used to treat high blood pressure. It works by blocking these adrenergic receptors, which slows sinus heart rate, decreases peripheral vascular resistance.

It has a particular indication in the treatment of pregnancy-induced hypertension.

Administration

Labetalol is available in 100, 200, and 300 mg tablets and intravenously (only as Trandate) in 5 mg/ml solution. Adults taking tablets usually start with 100 mg two times a day, with a maximum of 2.4 g/day. In an emergency situation, this may be higher. By IV, the patient is usually started at 2 mg/minute or 20 mg, with a maximum of 300 mg.

Side effects

Side effects may include:

• Drowsiness
• Fatigue
• Weakness
• Difficulty sleeping
• Diminished sexual function
• Scalp tingling which passes after time.
• A rare but potentially lethal side effect is respiratory distress. If respiratory distress occurs after starting this drug, do not take additional dose; go to the emergency room and tell the clinician that you are having respiratory distress that you think may be due to the labetalol. Nurses: If your hospitalized patient on labetalol begins to have respiratory distress (may have no decrease in oximetry readings), stop the drug, initiate oxygen at 1-2 liters, and call the physician. Closely monitor the patient until all signs of respiratory distress are relieved.

Contraindications

Should not be used in patients that have asthma, congestive heart failure,
any degree of heart blocks, slow heart rates or those in cardiogenic shock

References

• Hodgson, Barbara B., and Kizior, Robert J. Saunders Nursing Drug Handbook 2006. St. Louis, MO: Elsevier, Saunders, 2006. bledsoe "prehospital emergency pharmacology" upper Saddle River, New Jersey: Pearson 2005