Common Preterm Labour Drug Has More Side Effects

The findings suggest that, since the effectiveness of the two drugs appears similar, physicians should consider side effects more strongly when choosing which drug to prescribe. Newborns whose mothers had received magnesium sulfate were also more likely to be admitted to the neonatal intensive care unit than those whose mothers had received nifedipine.

Magnesium sulfate, nifedipine and other preterm labour treatments, called tocolytics, are thought to work by relaxing overactive uterine muscles and halting ongoing cervical changes that may lead to delivery. But it's not been clear if one is better than the others. The researchers randomly assigned 192 patients who were in preterm labour to receive either magnesium sulfate, which is an intravenous treatment, or nifedipine, an oral treatment.

They found that magnesium sulfate was more effective in achieving the study's primary outcome - preventing delivery for 48 hours with uterine quiescence. But there were no significant differences in the treatments' ability to delay delivery, in the gestational age of the newborn or in the birth weight of the infants.

However, two-thirds of the women who received magnesium sulfate experienced mild to severe side effects such as shortness of breath and fluid build-up in the lungs during the treatment. In contrast, one-third of the women who received nifedipine experienced side effects of the treatment, including headaches.

"The take-home message is that we saw no differences in relevant outcomes between the two groups," said Deirdre Lyell, MD, a specialist in high-risk obstetrics at the hospital's Johnson Center for Pregnancy and Newborn Service, "but there was a significant difference in the side effects experienced by the women, and some of these were very serious."

MEDICA.de; Source: Stanford University Medical Center