Labetalol (Trandate, Normodyne) is a
competitive antagonist at both a1 and
ß1-adrenergic receptors. It also has an
intrinsic sympathomimetic effect at ß2
receptors
Antihypertensive effects
of labetalol results from actions at both alpha1
and beta-adrenergic receptors.
alpha1
receptor blockade results in
vasodilatation which is further enhanced
by ß2
receptor activation.
A reduction in heart rate is
mediated by beta1
receptor antagonism.
Labetalol (Trandate,
Normodyne) does not alter serum lipids.
Adverse Effects
Orthostatic hypotension may occur due to alpha1
receptor blockade.
Liver injury has been reported with labetalol
(Trandate, Normodyne) usage.
Labetalol (Trandate, Normodyne) metabolites:
false positive for pheochromocytoma
urinary retention
Bronchospasm -- incidence similar to that
observed with metoprolol (Lopressor) or atenolol (Tenormin)
Paresthesias (scalp tingling)
Stoelting, R.K.,
"Antihypertensive Drugs", in Pharmacology and
Physiology in Anesthetic Practice, Lippincott-Raven
Publishers, 1999, 302-312.
