Comparison of oral ritodrine and magnesium gluconate for ambulatory tocolysis.

Magnesium sulfate has been administered intravenously to arrest preterm labor but the oral form of this drug cannot be used for continual tocolysis. This trial involved the administration of oral magnesium gluconate to determine its effectiveness compared with that of ritodrine hydrochloride in 50 patients whose labor had been arrested by parenteral therapy. Group A (n = 25) received 1 gm of oral magnesium gluconate every 2 to 4 hours for tocolysis and group B (n = 25) received 10 mg of ritodrine every 2 to 4 hours. The number of patients who progressed to 37 weeks' gestation was similar (group A, 21 versus group B, 19) and the time gained in utero was not different (group A, 6.4 weeks versus group B, 5.9 weeks). There was a trend toward more side effects with the use of ritodrine (40%) compared with magnesium gluconate (16%), but the numbers were too small to reveal a significant difference. These data suggest that magnesium gluconate used as an oral tocolytic is as effective as a beta-agonist in patients whose labor is arrested initially with intravenous therapy.