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Systematic (IUPAC) name
CAS number 36894-69-6
ATC code C07AG01
PubChem 3869
DrugBank APRD01062
Chemical data
Formula C19H24N2O3 
Mol. mass 328.406 g/mol
Pharmacokinetic data
Bioavailability 90-100%
Protein binding 50%
Metabolism hepatic pass metabolism,
Half life Tablet: 6-8 hours; IV: 5.5 hours
Excretion Excreted in urine, not removed by hemodialysis
Therapeutic considerations
Pregnancy cat.

One of few drugs used for PIH

Legal status

Prescription only

Routes oral iv

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.



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.


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


  • 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
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Labetalol". A list of authors is available in Wikipedia.
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