[Sulindac and indomethacin effects on lamb fetuses chronically monitored]

Sulindac and indometacin, both prostaglandins inhibitors, have a similar tocolytic effectiveness, in contrast their fetal effects seem to be different. For specify these differences we compared the effects of the infusion of sulindac with known effects of indometacin. We operated 6 fetal lambs, in which polyvinyl catheters were inserted chronically for continuous measure of heart rate, blood pressure, incidence of fetal breathing movements and arterial pH and gas tension. The fetuses were infused in a 2 hour control period with vehicle, and then with 150 mg of either sulindac or indometacin (in alternate days) for a 6 hour period. There was no change in any variable when sulindac was given, but there was a significant increase in fetal breathing movements with indometacin. The reason for this difference is not clear, and requires further studies. These results added to previous reports supports the hypothesis that sulindac could be a first choice tocolytic drug for treatment of premature labor when no fetal effect is desired.