Labetalol (Trandate, Normodyne) (α-1
and β Adrenoceptor Antagonist)
Labetalol is a competitive antagonist
at both alpha1 and beta1-adrenergic receptors. It
also has an intrinsic sympathomimetic effect at
beta2 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 beta2
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.
