A randomized double-dummy comparison between indomethacin and nylidrin in threatened preterm labor.

We compared the tocolytic effect of indomethacin and nylidrin in a prospective double-blind trial in which the appearance of the tocolytic treatment (always intravenous infusion and rectal suppositories/oral capsules) was identical to the subjects. Sixty healthy women in imminent preterm labor between 25-34 weeks of singleton gestation were included. Thirty of these women received indomethacin (concomitantly with placebo infusion), with doses as follows: day 1, 100-mg rectal suppository followed by two oral capsules (50 mg) at 8-hour intervals; days 2 and 3, three 50-mg oral capsules each day. Thirty women received intravenous nylidrin (concomitantly with rectal/oral placebo), initiated with the dose of 50 micrograms/minute and continued at the dose of 100-150 micrograms/minute for a maximum of 3 days. Preterm labor was arrested for 24, 48, and 72 hours in 100, 96, and 90%, respectively, of subjects in the indomethacin group, compared with 100, 76, and 73% of women in the nylidrin group; the difference was significant (P less than .05) at 48 hours. Women progressed beyond 37 gestational weeks more commonly (P less than .05) with indomethacin (21 of 30, 70%) than with nylidrin (13 of 30, 43%). Indomethacin treatment was accompanied by maternal side effects 20% of the time, significantly less commonly (P less than .001) than with nylidrin (83%). The neonatal outcome was similar in the two study groups. We conclude from this double-dummy technique trial that indomethacin is more effective and better tolerated than nylidrin in arresting imminent preterm labor.