The clinical efficacy of oral tocolytic therapy. Oral tocolysis with magnesium chloride: a randomized controlled prospective clinical trial. A prospective randomized comparison of oral terbutaline and magnesium oxide for the maintenance of tocolysis.
Our purpose was to determine whether maintenance oral tocolytic therapy after preterm labor stabilization decreases uterine activity, reduces the rate of recurrent preterm labor and subsequent preterm birth, or improves neonatal outcome.
                Women with documented idiopathic preterm labor stabilized with acute tocolytic therapy were randomized to three groups: placebo, terbutaline 5 mg, or magnesium chloride 128 mg, all given orally every 4 hours. Patients and providers were blinded to group assignment. All subjects were enrolled in a comprehensive system of preterm birth prevention that included preterm labor education, weekly clinic visits, home uterine contraction assessment, daily phone contact, and 24-hour perinatal nurse access.
                Of the 248 patients who were randomized, 39 were delivered before discharge and 4 were lost to follow-up, leaving 205 for final analysis: 68 placebo, 72 terbutaline, and 65 magnesium. The terbutaline group had significantly more side effects than the placebo group did. All groups had otherwise similar perinatal outcomes when confounding variables were controlled for. Overall, the three groups had a preterm birth rate < 37 weeks of 55.6% delivery, < 34 weeks of 15.6%, a 20.4% rate of newborn intensive care unit admission, and a mean neonatal length of stay of 6.3 days.
                Maintenance oral tocolytic therapy did not decrease uterine activity, reduce the rate of recurrent preterm labor or preterm birth, or improve perinatal outcome. Overall improvement in perinatal outcome may be achieved with a comprehensive program of preterm birth prevention without the use of maintenance oral tocolytic therapy. A prospective randomized clinical trial was conducted to assess the efficacy and safety of enteric-coated magnesium chloride (SLOW MAG) as an oral tocolytic agent. Seventy-five patients between 24 and 34 weeks' gestation who were treated with intravenous magnesium sulfate for a first episode of preterm labor were enrolled. After a 12-hour contraction-free period on intravenous therapy, patients were randomized by sealed envelope to one of three groups: group 1, SLOW MAG (535 mg every 4 hours); group 2, oral ritodrine (20 mg every 4 hours); or group 3, no therapy (control). Patients receiving oral therapy were treated until delivery or completion of 36 weeks' gestation. No difference was found between groups with respect to time gained with the use of oral therapy or number completing 36 weeks' gestation. Therapy with enteric-coated magnesium chloride was associated with significantly fewer side effects (20%) as compared with ritodrine (48%) (p less than 0.01). Our results suggest that compared with ritodrine, enteric-coated magnesium chloride is as effective in prolonging pregnancy and preventing recurrent preterm labor. However, neither enteric-coated magnesium chloride nor ritodrine appeared to be any more effective in the prevention of preterm delivery than observation alone. We compared oral magnesium oxide with oral terbutaline sulfate in a prospective, randomized manner to determine efficacy and side effects. Preterm labor patients whose labor was arrested with parenteral tocolysis were randomized to oral tocolysis with either magnesium oxide, 200 mg every 3 to 4 hours (n = 23), or terbutaline, 2.5 to 5 mg every 3 to 4 hours (n = 27). The number of patients who were delivered of infants before 36 weeks' gestation was similar between groups (18.5% receiving terbutaline versus 17.4% receiving magnesium). At least one side effect occurred in 81.5% of patients in the terbutaline group and 47.8% in the magnesium group (p less than 0.01). Finally, the cost for 1 day of magnesium (20 cents) is approximately one third the cost of terbutaline (56 cents). These data suggest that oral magnesium oxide is as effective as terbutaline for the maintenance of tocolysis, with fewer side effects and at a lower cost.
There is not enough evidence to show any difference between magnesium maintenance therapy compared with either placebo or no treatment, or alternative therapies (ritodrine or terbutaline) in preventing preterm birth after an episode of threatened preterm labour.