Prostacyclin and Thromboxane Levels in Women with Severe Preeclampsia Undergoing Magnesium Sulfate Therapy During Antepartum and Postpartum Periods

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Abstract
Objective: To study effects of magnesium sulfate (MgSO4) on prostacyclin (PGI2) and thromboxane A2 (TXA2) levels in women with severe preeclampsia during antepartum and postpartum periods. Methods: Women with severe preeclampsia were randomized into two groups. Patients in Group A were continuously infused with MgSO4 for 24 hours postpartum. In Group B, MgSO4 administration was discontinued when urinary output was of ≥100 ml/hr for 2 consecutive hours. Patient demographic data were collected. Venous blood was drawn at time of MgSO4 administration and 24 hours after delivery. Plasma levels of 6-keto-PGF1α and TXB2, stable metabolites of PGI2 and TXA2, were measured by enzyme-linked immunosorbent assay (ELISA). Data are presented as mean ± SE, and analyzed by paired t-test. Results: A total of 50 patients were recruited, with 27 in Group A and 23 in Group B. There were no statistical differences for demographic data between the two groups with regards to maternal age; gestational age; systolic and diastolic blood pressures at admission, 12 hours postpartum, and 24 hours postpartum; and mode of delivery. Platelet counts were all within the normal range at the time of enrollment. MgSO4 was administered for an average of 10 hours postpartum in Group B. Maternal blood pressures returned to normal or close to normal levels in both groups at 24 hours postpartum. 6-keto PGF1α levels were significantly decreased 24 hours after delivery compared with the levels at enrollment in both groups, (Group A: 98 ± 13 vs. 180 ± 28 pg/mL; Group B: 142 + 17 vs. 194 ± 31 pg/mL, p < 0.05, respectively). However, there was no difference detected between the two groups. TXB2 levels were not different between group A and Group B at the time of enrollment, 38 ± 9 vs. 33 ± 8 pg/mL, and 24 hours postpartum, 26 ± 5 vs. 25 ± 3 pg/mL, respectively. Conclusions: Administration of MgSO4 does not affect prostacyclin and thromboxane levels in the maternal circulation in women with preeclampsia during antepartum and postpartum periods. We speculate that a higher level of prostacyclin before delivery may reflect compensatory effects of this vasodilator to offset increased maternal blood pressure during pregnancy.