A comparison of ritodrine, terbutaline, and magnesium sulfate for the suppression of preterm labor. Comparison of magnesium sulfate, terbutaline and a placebo for inhibition of preterm labor. A randomized study. Terbutaline pump maintenance therapy for prevention of preterm delivery: a double-blind trial. Efficacy and safety of nifedipine versus magnesium sulfate in the management of preterm labor: a randomized study. Oral tocolysis with magnesium chloride: a randomized controlled prospective clinical trial. The use of ritodrine and magnesium sulfate in the arrest of premature labor. [Treatment of preterm labor with ritodrine]. [Tocolytic therapy with magnesium sulfate and terbutaline for inhibition of premature labor]. The clinical efficacy of oral tocolytic therapy.
Ritodrine, terbutaline, and magnesium sulfate have all been used in the United States as tocolytic drugs. Studies have shown each of these drugs to be effective in suppressing preterm labor. The current study was undertaken in order to compare their relative safety and efficacy and to evaluate the effectiveness of a second drug when the first-used drug failed to stop contractions. No differences in efficacy could be demonstrated between the drugs; however, there was a marked difference in the incidence of maternal side effects. Because of an unacceptable level of side effects, we have stopped the use of terbutaline at our institution. Magnesium sulfate has been recommended as a safe and effective agent for inhibiting preterm labor. Its reported adequacy as a tocolytic agent, however, has not been substantiated by randomized, controlled trials. To assess the efficacy of magnesium sulfate, we initiated a prospective, randomized study comparing the capabilities of magnesium sulfate, terbutaline and a placebo (5% dextrose in lactated Ringer's solution) for labor inhibition. The study population consisted of 54 patients between 26 and 34 weeks of gestation and in preterm labor. The diagnosis of labor was made if, following hydration, persistent uterine contractions occurred at a frequency of at least three in a ten-minute period and cervical examination suggested active labor. Success was defined as postponement of delivery for at least 48 hours after initiation of therapy. Despite a trend toward increased efficacy in the terbutaline group there were no significant differences between the three treatment groups with regard to capability of delaying delivery at least 48 hours. Also, there were no significant differences between the groups with regard to gestational age at delivery, birth weight and neonatal survival. The fact that delivery occurred in less than 48 hours of approximately one-half the patients under the best of circumstances emphasizes the need for more effective techniques for the inhibition of preterm labor and the need for a better understanding of the mechanisms involved in the initiation of preterm labor. This study's aim was to determine whether maintenance therapy with terbutaline administered by pump prolongs gestation in women after treatment with intravenous magnesium sulfate tocolysis for suspected preterm labor.
                Consenting women with a singleton gestation and intact membranes who had uterine contractions and >1 cm cervical dilation, 80% effacement, or progressive cervical change and whose contractions were successfully arrested with intravenous magnesium were randomly assigned to receive either terbutaline or normal saline solution placebo by subcutaneous infusion pump. Pump therapy was administered with a standardized protocol. Pump therapy was discontinued and parenteral magnesium was resumed if recurrent preterm labor developed while women were on the therapeutic regimen at <34 weeks' gestation and no contraindication for tocolysis existed. If recurrent labor was arrested, pump therapy was restarted according to the original treatment group. A sample size of 48 women was required to detect a 2-week intergroup difference in mean time to delivery. Analyses were based on intent to treat.
                Fifty-two women received terbutaline (n = 24) or placebo (n = 28). At random assignment the groups were similar with respect to age, race, parity, previous preterm delivery, gestational age, and cervical examination. Overall there was a 1-day difference in mean time to delivery between the groups (terbutaline 29 +/- 22 days and placebo 28 +/- 23 days, P = .78). There were no differences in the rates of preterm delivery at <34 and <37 weeks' gestation. Neonatal outcomes were similar.
                Maintenance terbutaline therapy administered by pump does not prolong gestation in women successfully treated for suspected preterm labor. Our purpose was to establish the efficacy and safety of nifedipine versus magnesium sulfate in arresting preterm labor and the efficacy of nifedipine versus terbutaline in preventing recurrent labor.
                Singleton pregnancies at < 34 weeks in preterm labor were randomized to either oral nifedipine or intravenous magnesium sulfate. In case of tocolysis failure ritodrine was added. After labor was arrested, the patients in the nifedipine group were maintained on oral nifedipine, and those in the magnesium sulfate group were treated with oral terbutaline until completing 34 weeks.
                Of 100 patients 80 were considered eligible, of whom 39 were randomized to the nifedipine group. Both groups were comparable in terms of a number of entry variables, including cervical examination, contraction frequency, and gestational age. Both drugs were equally effective in arresting labor and delaying delivery > 48 hours, 92% versus 93%. Both study groups had a similar incidence of side effects, although four (10%) of magnesium sulfate-treated patients required drug discontinuation because of severe symptoms. Nifedipine was as effective as terbutaline in preventing recurrent labor, 26% versus 24%, and in achieving a gestation > 34 weeks, 62% versus 68%.
                Oral nifedipine is as effective as magnesium sulfate and terbutaline in arresting and preventing idiopathic preterm labor. 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. Sixty-seven cases of premature labor (48 with unruptured and 19 with ruptured membranes) were treated with ritodrine or magnesium sulfate infusion supplemented with oral ritodrine in case of initial success. Both treatment regimens were found effective irrespective of maternal age, parity, ethnic background and number of previous abortions. The study supports the clinical experience indicating that early administration of tocolytic agents is highly successful in arresting premature labor and preventing its dire consequences. To investigate the treatment of preterm labor with the beta-adrenergic agonist ritodrine.
                126 women with preterm labor were randomly assigned to intravenous infusion of ritodrine or magnesium sulfate treatment. Using minimal effective dosage for inhibition of uterine activity, terminating therapy on time, and repeating the i.v. infusion if contraction restarted were the strategy for treatment.
                Ritodrine was significantly more effective both in the treating period for suppression of contraction (2.33 +/- 0.63 hr for initiation of inhibiting uterine activity, 9.38 +/- 3.88 days of accumulative treating period) and prolongation of gestation (4.81 +/- 2.83 wks) than that of the magnesium sulfate (P < 0.001, 0.005 and 0.01 respectively), and had a term labor of 73.44%. There was no serious cardiac and pulmonary complications in the ritodrine group.
                The present study has shown that ritodrine as a tocolytic agent is highly effective for the management of preterm labor and relative safe for mother and fetus. Magnesium sulfate has been recommended as a safe and effective tocolytic agent. However has not been substantiated by randomized, controlled trials. To assess the efficacy of magnesium sulfate, we initiated prospective randomized study competing the capabilities of magnesium sulfate and terbutaline for labor inhibition. The study population consisted of 30 patients (15 patients with terbutaline and 15 patients with magnesium sulfate) between 28 and 36 weeks of gestation and in preterm labor. One patient in terbutaline group was excluded of the study because we found a severe fetal distress. The diagnosis of labor was made if, persistent uterine contractions occurred at a frequency of at last three in a team-minute period and cervical examination suggested active labor. Success was defined as postponement of delivery for at least 48 hours after initiation of therapy. Despite a trend toward increased efficacy in the terbutaline group (tocolytic Bishop grade and its success) there were no significant differences between the two treatment groups with regard to capability of delaying delivery at least 48 hours. Although there were significant differences for terbutaline regard the tocolysis time. For all these reasons, the efficacy between both groups of treatment is similar, and in a future cases, will be necessary to choose the better agent for every case to study. 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.
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.