Labetalol
Labetalol is a non-selective antagonist at alpha1, beta1, and beta2
adrenergic receptors, and is FDA approved for the treatment of
hypertension and hypertensive emergencies [19,13]. Pregnancyinduced
hypertension and preeclampsia are off-label uses [19].
Labetalol may be preferred over other beta blockers as it dilates
arterioles and decreases vascular resistance without significantly
lowering cardiac output [20]. Labetalol may be administered as an
oral or intravenous product [19]. Comparisons of the onset, duration,
and peak levels of labetalol and other anti-hypertensive therapies are
found in Table 2.
Hypotension, bradycardia, and hypoglycemia are common
adverse effects of beta blockers, and a retrospective chart review
published in 2011 in Early Human Development focused on the
prevalence of these effects in neonates who were exposed to labetalol
in utero [26]. The study included the records of women who had
severe preeclampsia per the International Society for the Study
of Hypertension in Pregnancy (ISSHP) criteria, and records were
compared between those whose blood pressure was managed using
labetalol versus those whose blood pressure was controlled without
antihypertensive medications [26]. The records of the infants
exposed to labetalol were compared to those of the control group for
gestational age at birth, birth weight, hypotension, hypoglycemia,
bradycardia, and mortality [26]. Hypotension was found to be
significantly increased in the labetalol group (29.1% versus 7.4%)
within the first 48 hours of life [26]. Mortality was also significantly
increased in the labetalol group, with 4.6% mortality rate in labetalol
exposed infants compared to no deaths in the control group [26].
The deaths were due to ongoing sepsis, progressive respiratory