Anesthesia Pharmacology Chapter 14:  General Anesthesia

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Labetalol (Trandate, Normodyne) (alpha1 and beta Adrenoceptor Antagonist 

  • Labetalol is a competitive antagonist at both α1 and β1-adrenergic receptors. It also has an intrinsic sympathomimetic effect at β2 receptors

  •  Antihypertensive effects of labetalol results from actions at both alpha1 and beta-adrenergic receptors.

    •  α1 receptor blockade results in vasodilatation which is further enhanced by β2 receptor activation.

    • A reduction in heart rate is mediated by β1 receptor antagonism

  •  Labetalol does not alter serum lipids.

Adverse Effects

 Orthostatic hypotension may occur due to α1 receptor blockade.

 Liver injury has been reported with labetalol usage.

 Labetalol metabolites: false positive for pheochromocytoma

 urinary retention

 Bronchospasm -- incidence similar to that observed with metoprolol or atenolol

 Paresthesias (scalp tingling)

Stoelting, R.K., "Antihypertensive Drugs", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, 302-312.