Ritodrine-induced skin rash

A 32-year-old nulligravida was hospitalized because of preterm labor and treated with intravenous ritodrine hydrochloride. After 33 days of therapy, the patient developed a fine maculopapular rash.

The great tocolytic debate: some pitfalls in the study of safety

The controversy surrounding the use of tocolytic agents has been raging for decades. Tocolytic drugs play a pivotal role in the prevention of preterm birth, which is the major cause of neonatal morbidity and mortality. Studies on the efficacy and safety of these drugs are of the utmost importance to many disciplines within the medical community. Unfortunately, many clinical decisions regarding tocolytic agents are based on incorrect information resulting from flawed studies. In this article we discuss the major design flaws common to many studies of tocolytic safety and in so doing explain some of the conflicting evidence regarding safety. Each of the two major types of study designs, preterm birth retrospective studies and prospective randomized trials, is associated with a serious flaw. Retrospective preterm birth studies give misleading and inconclusive results to the question of safety because of the use of incomplete cohorts. The inadequately sized prospective studies in the current literature lack the power to detect important clinical differences.

Toxic epidermal necrolysis associated with treatment for preterm labor

We report a 29-year-old pregnant woman who developed toxic epidermal necrolysis at 29 weeks of gestation after administration of ritodrine, indomethacin and betamethasone. Toxic epidermal necrolysis is an unreported side effect of this widely used combination of medications. Since toxic epidermal necrolysis is a potentially fatal disease, awareness of a possible association is warranted.

Perinatal factors influencing hepatic glucose-6-phosphatase enzyme activity

BACKGROUND

At discharge from neonatal units, many preterm infants are vulnerable to preprandial hypoglycemia due to insufficient liver glucose production. In most preterm infants, hepatic glucose-6-phosphatase activity (the terminal step of liver glucose production) remains abnormally low postnatally.

OBJECTIVE

To determine what perinatal factors are associated with changes in hepatic glucose-6-phosphatase enzyme activity.

STUDY DESIGN

The maximum velocity (Vmax) of the hepatic microsomal glucose-6-phosphatase enzyme, as the dependent variable, was correlated by stepwise multiple regression analysis with clinical data from a consecutive series of 45 preterm infants from a level 3 neonatal unit.

RESULTS

Significant factors (p < or = 0.0005) were the presence of pathogenic bacteria isolated from maternal high vaginal swabs (p < or = 0.0000), hyperkalemia regimen, duration of prenatal exposure to ritodrine, and delivery mode. Further analysis revealed that the highest correlation was with positive early post-delivery infant bacterial cultures.

CONCLUSION

Perinatal events and clinical interventions modulate key enzyme systems necessary for human adaptation to extrauterine life.

Double-blind, randomized, controlled trial of atosiban and ritodrine in the treatment of preterm labor: a multicenter effectiveness and safety study

OBJECTIVE

This study was undertaken to compare the efficacy and safety of intravenous administration of atosiban versus ritodrine for the treatment of preterm labor.

STUDY DESIGN

Women with preterm labor and intact membranes diagnosed at 23 to 33 gestational weeks (n = 247) were randomly assigned to treatment arms and received atosiban (6.75 mg intravenous bolus, 300 microg/min for 3 hours, then 100 microg/min intravenously) or ritodrine (0.10-0.35 mg/min intravenously) for as long as 18 hours. Tocolytic effectiveness was assessed in terms of the numbers of women who had not been delivered after 48 hours and after 7 days. Safety was assessed in terms of maternal side effects and neonatal morbidity. Secondary outcomes included mean gestational age at delivery and mean birth weight. An intent-to-treat analysis was performed with the Cochran-Mantel-Haenszel test.

RESULTS

The proportion of women who had not been delivered at 48 hours was 84.9% (n = 107) in the atosiban group and 86.8% (n = 105) in the ritodrine group. At 7 days 92 women had still not been delivered in both the atosiban (73.0%) and ritodrine (76.0%) groups. Neither of these differences was statistically significant. The incidence of maternal cardiovascular side effects was substantially lower in the atosiban group (4.0% vs 84.3%, P <.001). In addition, intravenous therapy was terminated more frequently as a result of maternal adverse events in the ritodrine group (29.8%) than in the atosiban group (0.8%). The overall occurrences of fetal adverse events in the two treatment groups were comparable. Neonatal morbidity was similar between the treatment groups after adjustment for unbalanced enrollment of women with multiple pregnancies and for gestational ages within treatment groups.

CONCLUSION

Atosiban was comparable in clinical effectiveness to conventional ritodrine therapy but was better tolerated than ritodrine, with no evidence of significant maternal or fetal adverse events. Neonatal morbidity, which was similar between the two treatment arms, was apparently related to the gestational age of the infant rather than to the exposure to either tocolytic agent.

Nifedipine versus ritodrine for suppression of preterm labor; a meta-analysis

BACKGROUND

Since large randomized clinical trials comparing the effectiveness of nifedipine and ritodrine in the suppression of preterm labor are lacking, we performed a meta-analysis on the subject.

METHODS

We searched the databases Medline and EMBASE using the keywords 'nifedipine', 'ritodrine' and 'randomized' or 'randomised'. The studies were scored for blinding, method of randomization and type of analysis ('intention-to-treat' versus 'par protocol'). Subsequently, two by two tables were constructed using 'delay of labor by 48 hours or more', 'delay of labor beyond 36 weeks gestation', perinatal mortality, respiratory distress syndrome and admission to a neonatal intensive care unit as end points. Homogeneity between the studies was tested with a Breslow-Day test. Pooled odds ratios were calculated in case homogeneity could not be rejected.

RESULTS

We could detect ten studies that were published between 1986 and 1998, incorporating data of 681 patients. Nifedipine reduced the risk of delivery within 48 hours compared to ritodrine, but this difference was not statistically significant (odds ratio 0.85, 95% confidence interval 0.54 to 1.1). Nifedipine also reduced the risk of delivery before 36 weeks compared to ritodrine, and this difference was statistically significant (odds ratio 0.59, 95% confidence interval 0.39 to 0.90). We are not aware of studies reporting on long-term outcome.

CONCLUSION

Since studies reporting on long-term outcome are lacking, the choice between nifedipine and ritodrine can only be based on obstetrical and short-term neonatal outcomes. From that perspective, nifedipine should be the drug of first choice for the suppression of preterm labor.

Influence of maternal magnesium sulphate and ritodrine treatment on the neonate: a study with six-month follow-up

Magnesium sulphate and ritodrine are commonly used drugs in the prevention of preterm delivery. However, the effects of these treatments on the newborn are controversial. It has previously been suggested that antenatal tocolytic magnesium sulphate decreases the incidence of cerebral palsy, but increases paediatric mortality. On the other hand, antenatal ritodrine treatment has been reported to increase the incidence of neonatal peri-intra-ventricular haemorrhage (PIVH). We investigated the cerebral ultrasonographic findings, neurological outcome and apparent life-threatening events (ALTE) among 63 infants, born before 33 wk of gestation, whose mothers were antenatally treated for premature birth with ritodrine or magnesium sulphate, and for pre-eclampsia with magnesium sulphate. Cerebral ultrasonography was performed during the first week of life and repeated before hospital discharge. The pathological findings were confirmed by a paediatric radiologist. A paediatrician and a physiotherapist performed the neurological follow-up examination of the survivors at 6 mo of age. We found Grade 3-4 PIVH in 15% of the infants exposed to maternal ritodrine treatment, in 9% of the infants whose mothers received tocolytic magnesium treatment, and in none of those exposed to maternal magnesium treatment for pre-eclampsia (p = 0.19). However, no differences were observed in 6-mo development or in the rate of paediatric mortality and ALTE among these three study groups. Because of the retrospective design and the limited number of subjects, the results of this study must be interpreted with caution.

Obstetric risk factors for periventricular leukomalacia among preterm infants

OBJECTIVE

To evaluate the obstetric antecedents of cystic periventricular leukomalacia and transient echodense periventricular lesions among preterm infants.

DESIGN

A cohort study of preterm singleton infants born between 25 and 33 weeks gestation.

SETTING

Pavia, Italy.

POPULATION

Three hundred and forty-nine infants admitted to a Division of Neonatal Intensive Care who were screened for periventricular leukomalacia.

METHOD

The obstetric factors in infants with either cystic periventricular leukomalacia or transient echodense periventricular lesions were compared to those in infants with negative cranial ultrasonographic findings. Stepwise multiple logistic regression analysis was used to evaluate the association between risk factors and outcomes adjusting for confounders.

RESULTS

The prevalence of cystic periventricular leukomalacia and transient echodense lesions was 5.7% (20/349) and 14% (49/349), respectively. The main risk factors for cystic leukomalacia were first trimester haemorrhage (OR 4.49; 95% CI 1.63-12.39), maternal urinary tract infection on admission (OR 5.71; 95% CI 1.91-17.07), and neonatal acidosis (pH < 7.2) at birth (OR 5.97; 95% CI 1.93-18.52). Meconium-stained amniotic fluid (OR 3.95; 95% CI 1.42-10.98) and long term (> 72 hours) ritodrine tocolysis (OR 2.54; 95% CI 1.28-5.05) were associated with an increased risk of echodense lesions. The likelihood of overall leukomalacia (cystic plus echodense periventricular lesions) was increased among cases with meconium-stained amniotic fluid (OR 4.06; 95% CI 1.65-10.0), long-term ritodrine tocolysis (OR 2.56; 95% CI 1.38-4.72), maternal infection (OR 1.73; 95% CI 1.0-3.0), and acidosis at birth (OR 1.98; 95% CI 1.0-3.98).

CONCLUSIONS

This study confirms that maternal infection, acidosis at birth, and meconium-stained amniotic fluid increase the risk of periventricular leukomalacia in preterm infants. Long-term ritodrine use seems to increase the risk for transient echodense lesions.

Ritodrine-related liver injury. Case reports and review of the literature

beta-sympathicomimetic ritodrine chloridrate is a commonly used tocolytic agent for the treatment of preterm labour. Previous reports have described the occurrence of liver test abnormalities during ritodrine administration but the clinical significance and incidence of this side effect are still unclear. We report on two cases including one with a positive rechallenge of liver injury during oral ritodrine administration and a review of the literature.

A prospective, randomized trial of nifedipine vs. ritodrine in threatened preterm labor

OBJECTIVES

To compare the tocolytic efficacy and maternal tolerance of nifedipine with ritodrine in the management of threatened preterm labor.

METHODS

Prospective randomized study of 52 singleton pregnancies with preterm labor between 26 and 34 week's gestation. The capacity to delay delivery 48 h, 7 days, until week 36 or until fetal weight reached 2500 g were the outcome variables assessed. Doppler ultrasound studies were performed on the fetal umbilical artery as control.

RESULTS

No significant differences were found in the delay of delivery, but significantly fewer maternal side-effects were found in the nifedipine group. Doppler ultrasound results were similar in both groups.

CONCLUSIONS

Nifedipine is a valid and well-tolerated alternative among the tocolytic drugs, and apparently does not significantly alter fetal vascular blood flow.

Optimising maternal-fetal outcomes in preterm labour: a decision analysis

OBJECTIVE

To compare, using decision analytic techniques, maternal and fetal risk and benefits of three strategies for the management of preterm labour after 32 weeks. These strategies are empiric tocolysis, no tocolysis, or amniocentesis for fetal maturity testing.

DATA SOURCES

Published medical literature provided the probabilities, including those for tocolysis efficacy, maternal and neonatal outcomes, and steroid efficacy.

DATA

Synthesis Separate decision trees were created for hypothetical cohorts of patients presenting with preterm labour at 32, 34, and 36 weeks of gestation to compare strategies. The primary outcome was the total number of expected adverse maternal and neonatal events for each strategy at each gestational age.

RESULTS

At 32 weeks tocolysis yielded the lowest total number of adverse maternal and neonatal events. At 34 weeks, both tocolysis and no tocolysis yielded similar overall outcomes. At 36 weeks most clinical outcomes were good regardless of strategy.

CONCLUSIONS

This analysis supports the empiric use of tocolytics at 32 weeks. At 34 weeks, either tocolysis or no tocolysis appear to be reasonable alternatives. At 36 weeks no tocolysis is probably preferred. This analysis also suggests that amniocentesis should not be employed in the management of preterm labour at these gestational ages.

A randomized comparison of nifedipine and ritodrine for suppression of preterm labor

OBJECTIVES

To compare the efficacy and safety of nifedipine and ritodrine in preventing preterm labor, and to evaluate maternal side effects and neonatal outcome.

STUDY DESIGN

Non-blind, randomized controlled trial

RESULTS

A randomized trial of 102 pregnant women with gestational ages under 34 weeks, including 24 with twin pregnancies and 45 on betasympathicomimetic drugs, who had regular uterine contractions with either observed cervical changes or preterm rupture of membranes. After stratification women were randomly assigned to receive either ritodrine intravenously or nifedipine orally. Fifty-five women were randomized to the nifedipine group and 47 to the ritodrine group. As expected, both groups were comparable in terms of several entry variables, including mean gestational age, ruptured membranes, treatment with tocolytic drugs, cervical examination, contraction frequency, age, and twin gestation. Delivery of women in the nifedipine group was delayed for 48 h, 7 days, and until 34 weeks gestation in 33 (60%), 26 (47%) and 21(38%) cases, respectively, compared with 31 (66%), 21(45%) and 11(23%) women in the ritodrine group (no significant difference). Maternal side effects were significantly less common in the nifedipine group than in the ritodrine group, however after 7 days of therapy there was no difference between the two groups. Neonatal outcome was similar in the two groups, with four neonatal deaths in the nifedipine and five in the ritodrine group.

CONCLUSIONS

Nifedipine seems to be as effective as ritodrine in the treatment of preterm labor and is associated with less frequent side effects.

Nifedipine and ritodrine in the management of preterm labor: a randomized multicenter trial

OBJECTIVE

To compare the efficacy of nifedipine with ritodrine in the management of preterm labor.

METHODS

One hundred eighty-five singleton pregnancies with preterm labor were assigned randomly to either ritodrine intravenously (n = 90) or nifedipine orally (n = 95). The principal outcome assessed was delay of delivery.

RESULTS

Ritodrine was discontinued in 12 patients because of severe maternal side effects, and their results were excluded from further analysis. More women in the ritodrine group delivered within 24 hours (22 versus 11, P = .006), within 48 hours (29 versus 21, P = .03), within 1 week (45 versus 36, P = .009), and within 2 weeks (52 versus 43, P = .005) compared with those receiving nifedipine. There were significantly fewer maternal side effects in the nifedipine group. Apgar scores and umbilical artery and vein pHs were similar in both groups. The number of admissions to the neonatal intensive care unit (NICU) in the nifedipine group was significantly lower than in the ritodrine group (68.4 versus 82.1%, P = .04).

CONCLUSION

Nifedipine in comparison with ritodrine in the management of preterm labor is significantly associated with a longer postponement of deliver, fewer maternal side effects, and fewer admissions to the NICU.

Ritodrine- and terbutaline-induced hypokalemia in preterm labor: mechanisms and consequences

The effects of ritodrine and terbutaline on potassium homeostasis, renal function, and cardiac rhythm were assessed in women treated with these drugs for preterm labor. Timed blood and urine samples were obtained for two hours before and during six hours of intravenous ritodrine (N = 5) and terbutaline (N = 5) administered in pharmacologically equivalent doses. No differences were found in any parameters affecting potassium homeostasis or renal function between these drugs. A decrease in mean plasma potassium of 0.9 mEq/liter occurred after 30 minutes of drug infusion (4.2 +/- 0.1 to 3.3 +/- 0.1 mEq/liter, P < 0.005) before any significant changes in plasma glucose (75.0 +/- 4.7 to 93.7 +/- 6.1 mg/dl, P = NS) or plasma insulin (12.4 +/- 6.0 to 28.4 +/- 5.1 mU/ml, P = NS). The mean plasma potassium after four hours of drug infusion was 2.5 +/- 0.1 mEq/liter. Plasma insulin rose to a level known to induce cellular potassium uptake (39.2 +/- 7.7 mU/ml) after 60 minutes of drug therapy and remained at this level for four hours. Hyperlactatemia occurred at four hours (4.7 +/- 0.8 mmol/liter) and the plasma lactate/pyruvate ratio increased in a 10:1 ratio. Both drugs significantly reduced glomerular filtration rate, sodium, potassium, and chloride excretion and urinary flow rate. Changes in acid-base homeostasis, plasma aldosterone, or renal potassium excretion did not contribute to ritodrine-or terbutaline-induced hypokalemia. In 83 women with preterm labor randomly assigned to ritodrine (N = 42) or terbutaline (N = 41), the maximum decrease in plasma potassium occurred after six hours of drug infusion. During Holter monitoring, 3 of 14 women treated with ritodrine or terbutaline developed symptomatic cardiac arrhythmias at the lowest plasma potassium while no women treated with saline and morphine (N = 12) developed cardiac arrhythmias (P = 0.14). We conclude that ritodrine and terbutaline induce profound hypokalemia by stimulating cellular potassium uptake and both drugs cause significant renal sodium and fluid retention and cardiac arrhythmias. Careful monitoring of electrolytes, fluid balance, and cardiac rhythm should occur during tocolytic therapy with ritodrine or terbutaline.

Hyperamylasemia in response to ritodrine or ephedrine administered to pregnant women

BACKGROUND

Ritodrine and ephedrine can induce hyperamylasemia in pregnant women. The incidence of these beta-agonist-induced hyperamylasemias and their interaction on serum amylase activity are not known.

STUDY DESIGN

Serum amylase activity was determined 12 to 24 hours after the administration of ritodrine alone (n = 140), ephedrine alone (n = 160), ephedrine and ritodrine simultaneously (n = 34), and ephedrine after prolonged (> or = 7 days) use of ritodrine (n = 101).

RESULTS

A significantly higher incidence of hyperamylasemia (amylase > 215 IU/L) was seen in a group treated with ritodrine alone (60/140, 43 percent), ephedrine alone (54/160, 34 percent), or ephedrine plus ritodrine (24/34, 71 percent) compared with untreated pregnant women (21/426, 4.9 percent). There was no difference in the incidence of hyperamylasemia among the untreated pregnant women and women who received ephedrine after long-term ritodrine (8/101, 7.9 percent). Isozyme patterns, examined in 72 out of the 146 women with hyperamylasemia after such medications, indicated that salivary-type amylase exclusively was hypersecreted.

CONCLUSIONS

Clinical doses of beta-agonists such as ephedrine or ritodrine induce hypersecretion of salivary-type amylase in approximately one-third of women who are pregnant. Desensitization to beta-agonists may occur after prolonged use of ritodrine.

Ritodrine-induced leukopenia: a case report and literature review

Ritodrine hydrochloride, a beta 2-adrenergic receptor agonist, has been widely applied in the treatment of premature labor for many years and generally considered as a safe medication. It can however induce some serious side effects, such as pulmonary edema, myocardial ischemia, ketoacidosis, miscellaneous metabolic alterations, and leukopenia. This report presents a rare case of leukopenia in a Chinese woman as a result of low dose continuous intravenous infusion of ritodrine, in which the white blood cell count dropped rapidly and recovered quickly following the cessation of administration. The rapid and spontaneous reversal of leukopenia was most probably due to early recognition and intervention of this drug-induced side effect.

Does the use of a tocolytic agent affect the success rate of external cephalic version?

OBJECTIVE

Our purpose was to study the effect of ritodrine tocolysis on the success rate of external cephalic version at > or = 36 weeks' gestation.

STUDY DESIGN

This was a prospective, double-blinded, randomized study. All patients were > or = 36 weeks' gestation, confirmed by early ultrasonography. External cephalic version assessment included nonstress testing before and after external cephalic version and ultrasonographic evaluation of type of breech, estimated fetal weight, position of placenta and fetal spine, and amniotic fluid index. Patients were excluded if the breech was not mobile or if they had any contraindications to tocolysis or external cephalic version. After randomization 283 patients received either ritodrine (111 micrograms/min) or identical placebo by intravenous infusion for > or = 20 minutes. Up to three attempts at external cephalic version under ultrasonographic surveillance were performed. With an alpha error of 0.05 and a beta of 0.2, 264 patients were required to complete this study.

RESULTS

There were no differences between study groups in maternal age, body mass index, gestational age, amniotic fluid index, position of fetal spine, and placental location. Statistical analysis controlled for parity because parity had a major influence on success rates. There was a higher success rate in the group receiving ritodrine tocolysis (52% vs 42%, p = 0.028). Ritodrine improved success rates in nulliparous patients (43% vs 25%, p = 0.026) but not in parous subjects (66% vs 58%, p = 0.385).

CONCLUSION

Ritodrine tocolysis improves the success rate of external cephalic version performed at > or = 36 weeks in nulliparous patients.

[Effect of prolonged intravenous ritodrine tocolysis on diurnal glucose profiles in pregnant women with normal carbohydrate tolerance]

Our purpose was to investigate an effect of prolonged intravenous ritodrine tocolysis on maternal carbohydrate metabolism in women with normal glucose tolerance. In patients with preterm labor, diurnal plasma glucose levels were measured both during the 24 hours after beginning the therapy (phase 1) and each day during over five days of continuous ritodrine tocolysis (phase 2). We also measured diurnal plasma glucose levels in normal pregnant women without any therapy (control group). In phase 1, in comparison with before therapy, a significant increase in the plasma glucose levels was observed with the highest level at 9 hours after starting ritodrine (146.4 +/- 31.6mg/dl). The higher plasma glucose levels persisted during phase 1. Although infusion rates were similar in both phases, maternal plasma glucose levels in phase 1 were significantly higher than in phase 2 (mean plasma glucose level, 128.1 +/- 21.3mg/dl vs. 92.7 +/- 11.6 mg/dl, p < 0.05; maximum plasma glucose level, 159.5 +/- 25.2mg/dl vs. 106.6 +/- 14.5mg/dl, p < 0.05). Diurnal glucose levels in phase 2 were similar to those in the control group. In phase 1, there seemed to be a dose-dependent relation between the ritodrine infusion rates and plasma glucose levels, but we did not find any relationship between them in phase 2. In conclusion, although hyperglycemia occurs during the initial phase of continuous ritodrine therapy (at least 24 hours), prolonged ritodrine infusion leads to normalization of the maternal plasma glucose levels.

Toxic hepatitis: a rare complication associated with the use of ritodrine during pregnancy

OBJECTIVES

To evaluate the incidence of toxic hepatitis associated with the use of ritodrine in pregnancy.

DESIGN

A prospective study.

SETTING

A large teaching hospital in Barcelona, Spain.

PATIENTS

One hundred and twenty-three consecutive pregnant women, 101 singleton and 22 multiple pregnancies, receiving intravenous ritodrine with normal transaminase levels prior to the initiation of therapy.

MEASUREMENTS

Serum glutamic pyruvic transaminase (SGPT) and glutamic oxaloacetic transaminase (SGOT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (PA), direct and total bilirubin.

RESULTS

In two (l.9%) of 101 singleton and two (9.1%) of 22 multiple pregnancies, elevation of SGOT and SGPT levels was detected. PA, GGT, and bilirubin were normal in all women studied. Other causes of hepatitis were ruled out, and no other signs of liver impairment were found in these women. Transaminase levels recovered rapidly in all cases after discontinuation of therapy.

CONCLUSION

Elevation of liver enzymes is a rare complication of ritodrine. Discontinuation of therapy does not appear to be indicated as long as other signs of liver dysfunction are not present and tocolytic treatment is required.

Placental transfer of lidocaine hydrochloride after prolonged continuous maternal intravenous administration

We treated a patient with arrhythmia during pregnancy with prolonged intravenous administration of lidocaine hydrochloride. This was a case of twin-to-twin transfusion syndrome and the arrhythmia was caused by ritodrine therapy. In total, 14.1 g lidocaine (50 mg.hr-1 for 282 hr) were used. Since there are no descriptions of human placental transfer of lidocaine after such a prolonged continuous intravenous administration, we measured lidocaine concentrations in maternal and fetal serum, and in the amniotic fluid (AF) at delivery. Fetal serum lidocaine concentrations (donor: 0.83 microgram.ml-1; recipient: 0.82 microgram.ml-1) were lower than in the maternal serum (1.6 micrograms.ml-1), while the AF lidocaine concentrations (donor: 1.05 micrograms.ml-1; recipient: 1.04 micrograms.ml-1) were higher than those of the fetal sera. The fetal/maternal concentration ratios of lidocaine were 0.52 for the donor and 0.51 for the recipient, which were similar to those described previously after administration of lidocaine in labour.

Ritodrine and nifedipine as tocolytic agents: a preliminary comparison

The effectiveness of the tocolytic agent and other betamimetic drugs in the treatment of preterm labor remains controversial. Effectiveness or efficancy of ritodrine has not yet convincingly been proven. A major concern are the marked side effects of beta-mimetics. The calcium channel blocker nifedipine has been used for tocolysis shortly after its introduction in clinical practice and is considered to be a probable good alternative for ritodrine. The efficacy of nifedipine versus ritodrine in the treatment of preterm labor was assessed in a retrospective study. 32 patients received intravenous ritodrine and 29 oral nifedipine. As endpoints were used: postponement of delivery, maternal side effects and perinatal outcome. The results of this retrospective study suggest that nifedipine is more successful in postponing delivery than ritodrine. Maternal side effects seemed to occur more frequently and be more serious in patients treated with ritodrine as compared to nifedipine. Perinatal outcome seemed better in the nifedipine group than in the ritodrine group. The promising data from small prospective studies and the results of this retrospective study warrant further large prospective studies on the definitive place of nifedipine in the treatment of premature labor. Until the results of such a trial are available we advocate the use of nifedipine in case of preterm labor, especially in a patient with diabetes mellitus, ruptured membranes, cardiac disease or multiple pregnancy, in order to avoid the characteristic side effects of beta-mimetics.

Effective treatment of drug-induced agranulocytosis using recombinant human granulocyte colony stimulating factor in pregnancy

Drug-induced immune system mediated agranulocytosis is a rare but potentially life-threatening condition. There have been only a few reports on the drug-induced agranulocytosis during pregnancy. We present a case of agranulocytosis after prolonged intravenous infusion of ritodrine hydrochloride and additional administration of indomethacin suppositories, effectively treated using recombinant human granulocyte colony stimulating factor without any infection in a mother with twin-to-twin transfusion syndrome. Recombinant human granulocyte colony stimulating factor may have a potential use for drug-induced agranulocytosis during pregnancy.

Ritodrine tocolysis and neonatal intraventricular-periventricular hemorrhage

Betamimetic drugs are commonly used for tocolytic therapy. To determine their potential role in periventricular-intraventricular neonatal hemorrhage (IVH), 103 preterm births with cranial ultrasonography results were evaluated for the history of betamimetic therapy. The study group was divided into three subgroups according to the cause of the preterm delivery: 44 patients were accepted as tocolysis failure (group A); 53 patients were too late for tocolysis (group B), and these latter cases were taken as controls for group A; for the remaining 6 patients, tocolysis was contraindicated due to fetomaternal reasons (group C), and these cases were not included in the analysis. In group A, 32 patients got ritodrine, 6 patients got combined therapy including ritodrine plus magnesium sulfate or nifedipine. When cases in group A who got ritodrine only or combined therapy are compared with the no-treatment group, no significant difference in neonatal IVH incidences could be found (p > 0.005). Ritodrine does not appear to affect the incidence of neonatal IVH.

[Pulmonary edema after cesarean section in a parturient with long term use of ritodrine]

A 31-year-old multigravida with a gestation of 31 weeks was admitted in premature labor with placenta previa. The premature labor had been inhibited for two and half months with a tocolytic agent (ritodrine). However, at 32-week gestation an infection was found, the labor broke through the therapy and cesarean section was carried out under spinal anesthesia. Acute pulmonary edema developed post-operatively. An endotracheal intubation was performed followed by respiratory management for four days. Ritodrine is the beta-minetic used most extensively in the therapy of premature labor. However, with overdosage, maternal cardiac and pulmonary complications may occur. In this case, it is possible to have been caused by the long term use of ritodrine. Additionally, the excessive fluid administration, hypoprotenemia, decreased colloid osmotic pressure and infection also might have been the contributing factors for the disorder.

Prolonged intravenous ritodrine therapy: a comparison between multiple and singleton pregnancies

To compare multiple and singleton pregnancies in the treatment of threatened preterm delivery with prolonged intravenous ritodrine, 32 women with multiple pregnancy (26 twins, 6 triplets, 70 fetuses, 30.3 +/- 3.5 weeks) and 51 women with singleton pregnancy (31.3 +/- 2.6 weeks) admitted for threatened preterm delivery without rupture of the membranes were the subjects of a retrospective study of obstetric data, perinatal outcome and maternal adverse effects. Significance was assessed by chi 2 test and Student's t test. Multiple pregnancies were associated with a marked increase in the duration of tocolysis (17.2 +/- 17.3 vs. 7.6 +/- 8.1 days, P < 0.01), incidence of delivery before 37 weeks (87.5 vs. 35.3%, P < 0.01) and incidence of maternal cardiovascular complications (34.4 vs. 4.0%, P < 0.01), including three cases of pulmonary edema. The incidences of delivery before 32 weeks (12.5 vs. 7.8%) and of neonatal death (2.9 vs. 0%) were not significantly different in the two groups. Multiple pregnancies dramatically increased the incidence of maternal adverse effects of prolonged intravenous ritodrine therapy. Neonatal benefit is questionable and was difficult to establish since it was not a randomized study.

[Ritodrine induced pulmonary edema after caesarean section for a triplet pregnancy]

Selective beta-sympathomimetic drugs are frequently used for tocolysis. But, since these drugs exhibit some beta-1 activity as well, they may bring about pulmonary edema, myocardial ischemia, cardiac arrhythmia and others as side effects. A 29 year-old female with a triplet pregnancy had premature contraction at 26 weeks of gestation. High doses of IV ritodrine were given for tocolysis for 8 weeks until caesarean section. One hour after caesarean section at 35 weeks of gestation, she complained of dyspnea. Urinary output decreased and chest X-ray showed pulmonary edema. She was intubated and artificial ventilation with PEEP was performed in ICU. Echocardiogram showed left ventricular dilatation. ECG showed inverted T waves on all leads. We diagnosed her as suffering from acute heart failure, pulmonary edema and acute renal failure. Hemodialysis was performed for 6 hrs but PCWP was still 18 mmHg. So CVVH was added to hemodialysis. Five hrs after the start of CVVH, her symptoms gradually started to subside. Total fluid removal was 5.8 l over 16 hrs. Three days after admission she was extubated and five days later returned to her ward. We concluded that pulmonary edema, heart failure and renal failure were induced by the long-term high dose medication of ritodrine, resulting in volume overload and myocardial dysfunction.

Ephedrine remains the vasopressor of choice for treatment of hypotension during ritodrine infusion and epidural anesthesia

BACKGROUND

Historically, ephedrine has been the vasopressor of choice for treatment of most cases of hypotension in obstetric patients. However, the choice of vasopressor in the parturient receiving a beta-adrenergic agent for tocolysis has not been evaluated extensively. The current study evaluated whether ephedrine or phenylephrine better restores uterine blood flow and fetal oxygenation during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes.

METHODS

Fourteen chronically instrumented gravid ewes between 0.8 and 0.9 timed gestational age were used. On separate days, each animal underwent the experimental protocol with one of three agents: ephedrine, phenylephrine, and normal saline-control. The experimental protocol was as follows: (1) at time zero, intravenous infusion of ritodrine was begun; (2) at 120 min, 2% lidocaine was given epidurally to achieve a sensory level of at least T6; and (3) at 135 min, an intravenous bolus of either ephedrine, phenylephrine, or normal saline-control was given, followed by a continuous intravenous infusion of the same agent for 30 min. In the ephedrine and phenylephrine experiments, the rate of infusion was adjusted to maintain maternal mean arterial pressure close to baseline.

RESULTS

Ritodrine infusion alone significantly increased maternal heart rate and cardiac output in all three groups. Epidural anesthesia during ritodrine infusion significantly decreased maternal mean arterial pressure, heart rate, cardiac output, uterine blood flow, and fetal arterial oxygen tension for each of the three groups. Both ephedrine and phenylephrine restored maternal mean arterial pressure to baseline, as designed. Ephedrine significantly increased uterine blood flow and fetal arterial oxygen tension when compared with normal saline--control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with normal saline--control, but ephedrine did not.

CONCLUSIONS

Although ephedrine and phenylephrine provided similar restoration of maternal mean arterial pressure, ephedrine was superior to phenylephrine in restoring uterine blood flow during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. Also, ephedrine, but not phenylephrine, significantly improved fetal oxygenation, when compared to normal saline--control.

Beta adrenergic agonists and pulmonary oedema in preterm labour

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Measurement of pulmonary capillary pressure during ritodrine tocolysis in twin pregnancies: a new noninvasive technique

Five twin pregnant women were studied during treatment of preterm labor with ritodrine. Maternal pulmonary capillary pressure (PCP) and cardiac function were measured by noninvasive simultaneous recordings of the indirect carotid pulse, electrocardiography, phonocardiography, and M-mode echocardiography. Pulmonary capillary pressure significantly increased from the control value of 9 +/- 3.0 to 18 +/- 2.2 mmHg during the infusion period of therapy. Cardiac index and preejection period to left ventricular ejection time ratio were also increased during treatment with ritodrine. Our findings suggest that noninvasive measurement of PCP and cardiac function may be useful in monitoring twin pregnancies that develop cardiovascular side effects during tocolytic therapy.

Randomized, double blind, placebo controlled comparison of ritodrine and hexoprenaline for tocolysis prior to external cephalic version at term

External cephalic versions in the study period were performed in a double blind design by 2 experienced practitioners. Sixty-three patients were allocated to treatment with either placebo, ritodrine or hexoprenaline. The main outcome measure studied was successful completion of external cephalic version. Hexoprenaline, but not ritodrine, was statistically more likely to be associated with successful version than placebo (p = 0.04 versus p = 0.22).

Premature rupture of the membranes--aggressive versus conservative approach: effect of tocolytic and antibiotic therapy

The purpose of this randomized, prospective study was to evaluate the efficacy of tocolytic and antibiotic therapy in the prolongation of pregnancy and neonatal outcome in the treatment of premature rupture of the membranes without clinical labor. Delivery was delayed for 48 h, 7 days and beyond 35 weeks of gestation in 87, 39 and 18%, respectively, of patients in the treated group (n = 39) compared with 50, 12 and 17% of patients in the nontreated group (n = 42). The incidence of a low Apgar score (< 7 at 5 min), requiring artificial ventilation, and infectious morbidity was more common in the treated group than in the nontreated group (18 vs. 0, 41 vs. 17 and 39 vs. 17%, respectively). There was no significant cost difference in survivors between the treated and nontreated groups, although the mothers in the treated group were significantly more expensive. From these observations, it appears that tocolysis and antibiotics are not effective in PROM cases.

Beta-adrenoceptor tocolysis and effects on the heart of fetus and neonate. A review

A literature of 92 scientific papers addressing the effects of beta-adrenoceptor stimulation on the heart have been collected with the support of a computer-based MEDLINE system and critically examined. Neither in animal experiments nor in a wide clinical use of tocolytics for more than two decades has a risk for the hearts of fetus and neonate been confirmed, because there is no or only very little stimulating action on the beta-adrenoceptors of fetal and newborn's hearts as their sympathetic innervation is still immature.