Labetalol Holds Advantages Over MgSO4 In Preventing Eclampsia, Early Data Suggest


VIENNA — Labetalol may be a viable alternative to magnesium sulfate for the prevention of eclampsia, Jennifer Warren, M.D., said at the 14th World Congress of the International Society for the Study of Hypertension in Pregnancy.

Previous data from Dr. Warren's colleagues at the University of Utah, Salt Lake City, suggest that labetalol reduces cerebral perfusion pressure while maintaining cerebral blood flow.

It is potentially an ideal agent for preventing eclampsia, which is believed to be the result of cerebral overperfusion (Hypertens. Pregnancy 2002;21:185-97).

Labetalol also offers several advantages over MgSO4, including its lack of life-threatening side effects (MgSO4 is a respiratory and cardiac depressant). Labetalol has a rapid onset of action with sustained antihypertensive effects and can be administered orally with minimal need for monitoring; MgSO4 is given parenterally. In addition, labetalol is less expensive than MgSO4, according to Dr. Warren.

She presented preliminary data for the first 202 participants in the Labetalol Versus Magnesium Sulfate for the Prevention of Eclampsia Trial (LAMPET), an international, multicenter, nonblinded, randomized controlled trial in which women with preeclampsia receive either labetalol (200 mg orally every 6 hours, with additional intravenous doses every 20 minutes based on blood pressure measurements) or magnesium (6-g IV bolus followed by 2-g IV continuous infusion, with intravenous hydralazine if blood pressure remains uncontrolled after 20 minutes).

Institutions were permitted to substitute their own regimens for these. All medications were administered until 24 hours post partum.

The 115 women randomized to labetalol were similar to the 87 who received MgSO4 with regard to demographics such as maternal age, gestational age, race, height, and weight.

Admission data, including blood pressure, lab values, history, and symptoms, also did not differ.

Seizures occurred in 1.7% of the labetalol group (two women) and 2.3% of the MgSO4 group (two women), which was not a significant difference. All the seizures occurred at one institution where blood pressure control protocol violations were subsequently documented, Dr. Warren noted.

The labetalol subjects were significantly less likely to require additional blood pressure control medication (1.7% vs. 9.2%), and to experience flushing (0% vs. 12.6%). Rates of other side effects, including headache, diplopia, hypotension, nausea, vomiting, and respiratory depression, did not differ. Rates of abruption, postpartum hemorrhage, cardiac complications, and cesarean deliveries were also similar.

Intrapartum blood pressures did not differ between the two groups, but postpartum mean systolic and diastolic pressures were both significantly lower in the labetalol group, compared with the MgSO4 group (133/77 mm Hg vs. 140/80 mm Hg). Overall mean intrapartum and postpartum heart rates were also lower in the labetalol subjects, Dr. Warren reported.

Neonatal Apgar scores at 1 and 5 minutes did not differ between the groups, and there were no differences in rates of newborn intubation, respiratory depression, hypotension, hypotonia, or dysrhythmia.

The LAMPET trial, which is being conducted at three centers in two countries, will ultimately include 4,000 women. Final results are expected in about 2 years, Dr. Warren told this newspaper.

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