Pilot study of labor induction with titrated oral misoprostol

Individualized misoprostol dosing for labor induction or augmentation: A review

Cesarean birth rates are greater than 20% in many developed countries. The main diagnoses contributing to the high rate of cesarean births in nulliparous women are dystocia and prolonged labor. Traditionally, a policy of vaginal dinoprostone for the treatment of unripe cervix or early amniotomy with oxytocin administration for a ripened cervix has been associated with a modest reduction in the rate of cesarean births due to arrest disorders. However, the course of vaginal dinoprostone is tedious and oxytocin should be administered through an infusion pump, which may be inconvenient in certain settings. Because misoprostol has powerful uterotropic and uterotonic effects, and has become a common agent used in the practice of obstetrics and gynecology, the United States Food and Drug Administration removed the absolute contraindication of the drug during pregnancy from its label in April 2002. However, excessive uterine contractility resulting in tachysystole or fetal distress is always a concern with the oral or vaginal use of fixed-dosage misoprostol. Therefore, misoprostol should be administered with caution to ensure that fetal hypoxia does not occur. A pilot trial examining the use of very small, frequent, titrated oral misoprostol dosages administered every 2 h was first conducted by Hofmeyr et al in 2001. Given women’s different metabolisms and responses to misoprostol, another method of titrating individualized oral misoprostol with dosing administered every hour relative to uterine response was then developed by Cheng in 2006. Based on previous studies, this titration method is potentially an ideal alternative to traditional dinoprostone, oxytocin or the previously established misoprostol dosing method for labor induction or augmentation.

Titrated oral misoprostol for augmenting labour to improve maternal and neonatal outcomes

BACKGROUND

Labour dystocia is associated with a number of adverse maternal and neonatal outcomes. Augmentation of labour is a commonly used intervention in cases of labour dystocia. Misoprostol is an inexpensive and stable prostaglandin E1 analogue that can be administered orally, vaginally, sublingually or rectally. Misoprostol has proven to be effective at stimulating uterine contractions although it can have serious, and even life-threatening side-effects. Titration refers to the process of adjusting the dose, frequency, or both, of a medication on the basis of frequent review to achieve optimal outcomes. Studies have reported on a range of misoprostol titration regimens used for labour induction and titrated misoprostol may potentially be effective and safe for augmentation of labour.

OBJECTIVES

To examine the effects and safety of titrated oral misoprostol compared with placebo, oxytocin, other interventions, or no active treatment, in women with labour dystocia.

SEARCH METHODS

The Trials Search Co-ordinator of the Cochrane Pregnancy and Childbirth Group searched the Cochrane Pregnancy and Childbirth Group's Trials Register; date of search: 29 May 2013. We also searched the reference lists of retrieved studies

SELECTION CRITERIA

Randomised trials (including quasi-randomised and cluster-randomised trials) comparing titrated oral misoprostol with placebo, other interventions (e.g. oxytocin, other prostaglandins), or no treatment in women requiring augmentation of labour were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility for inclusion, carried out data extraction and assessed risk of bias in included studies. Data were entered by one author and checked for accuracy.

MAIN RESULTS

We included two randomised trials with a total of 581 women each comparing different regimens of titrated oral misoprostol with intravenous oxytocin. One study compared 20 mcg doses of misoprostol dissolved in water (repeated every hour up to four hours, after which the dose was increased to 40 mcg per hour up to a maximum total dose of 1600 mcg), while the second study gave women 75 mcg doses (repeated after four hours provided there were no adverse effects observed).Neither trial reported maternal death, severe maternal morbidity, or fetal/neonatal mortality outcomes, and only a few fetal/neonatal morbidity outcomes were considered, none of which were significantly different between groups. For several outcomes (such as maternal side-effects, instrumental birth, maternal blood transfusion for hypovolaemia and epidural analgesia), the number of events was generally too low for sufficient statistical power to be achieved. Maternal satisfaction was not reported in either trial. One trial reported a slight reduction in the median duration of labour from the start of augmentation to vaginal delivery in the oxytocin group.Neither trial reported significantly higher rates of caesarean section (CS) in the oral misoprostol group. Rates of vaginal delivery within 12 and 24 hours of commencing augmentation were not significantly different in the trial using a 20 mcg misoprostol dose. Neither trial had significantly higher rates of uterine hyperstimulation with fetal heart rate changes in the titrated oral misoprostol group. However, the rates of this outcome varied so greatly between the two studies as to suggest that other factors were at play. The only significant differences between groups related to uterine hyperstimulation (without fetal heart rate changes), and results were not consistent in the two trials. In the trial examining the higher dose of misoprostol, more women in the misoprostol group experienced hyperstimulation of labour measured over a 10-minute period compared with those receiving oxytocin (risk ratio (RR) 1.17, 95% confidence interval (CI) 1.02 to 1.35, 350 women). In the study examining the lower titrated dose of misoprostol, there was a lower incidence of tachysystole when labour was augmented with titrated oral misoprostol than with oxytocin (RR 0.39, 95% CI 0.17 to 0.91, 231 women) with no occurrences of hypertonus in either group of women.

AUTHORS' CONCLUSIONS

Important uncertainties still exist on the safety and acceptability of titrated oral misoprostol compared with intravenous oxytocin regimens in women with dystocia following spontaneous onset of labour. Although in facilities where electronic oxytocin infusion is not available, low-dose titrated misoprostol may offer a better alternative to an uncontrolled oxytocin infusion to avoid hyperstimulation. Further research is needed in both high- and low-resource settings More trials should be conducted to evaluate the effect of a standard titration oral misoprostol regimen, both following spontaneous labour and labour induction. Comparisons with other augmentation methods are also warranted, as are any effects on women's birth experiences.

The use of misoprostol in termination of second-trimester pregnancy

Misoprostol, a synthetic prostaglandin E1 analog, is initially used to prevent peptic ulcer. The initial US Food and Drug Administration-approved indication in the product labeling is the treatment and prevention of intestinal ulcer disease resulting from nonsteroidal anti-inflammatory drugs use. In recent two decades, misoprostol has approved to be an effective agent for termination of pregnancy in various gestation, cervical ripening, labor induction in term pregnancy, and possible management of postpartum hemorrhage. For the termination of second-trimester pregnancy using the combination of mifepristone and misoprostol seems to have the highest efficacy and the shortest time interval of abortion. When mifepristone is not available, misoprostol alone is a good alternative. Misoprostol, 400 μg given vaginally every 3-6 hours, is probably the optimal regimen for second-trimester abortion. More than 800 μg of misoprostol is likely to have more side effects, especially diarrhea. Although misoprostol can be used in women with scarred uterus for termination of second-trimester pregnancy, it is recommended that women with a scarred uterus should receive lower doses and do not double the dose if there is no initial response. It is also important for us to recognize the associated teratogenic effects of misoprostol and thorough consultation before prescribing this medication to patients regarding these risks, especially when failure of abortion occurs, is needed.

Titrated oral misoprostol solution compared with intravenous oxytocin for labor augmentation: a randomized controlled trial

OBJECTIVE

To compare titrated oral misoprostol to intravenous oxytocin for labor augmentation among women at 36 to 42 weeks of gestation with spontaneous onset of active labor.

METHODS

Women meeting the general selection criteria with regular contractions and an effaced cervix dilated between 3 and 9 cm, and who had inadequate uterine contractions (two or fewer contractions every 10 minutes) during the first stage of labor, were randomly assigned to titrated oral misoprostol or intravenous oxytocin. Augmentation-to-vaginal delivery interval and vaginal delivery within 12 or 24 hours were the primary outcomes. The data were analyzed by intention to treat.

RESULTS

Of the 231 women, 118 (51.1%) were randomized to titrated oral misoprostol and 113 (48.9%) to titrated intravenous oxytocin. The median interval from the start of augmentation to vaginal delivery was 5.22 hours (3.77-8.58 hours, 25th-75th percentile) in the misoprostol group, and 5.20 hours (3.23-6.50 hours, 25th-75th percentile) in the intravenous oxytocin group (P=.019). Complete vaginal delivery occurred within 12 hours for 92 women (78.0%) in the misoprostol group and for 97 women (85.8%) in the oxytocin group (P=.121; relative risk 0.91, 95% confidence interval 0.80-1.03). There were no significant differences between the two groups who delivered vaginally within 24 hours. Side effects and neonatal outcomes also did not differ between the two groups.

CONCLUSION

Labor augmentation with titrated oral misoprostol or intravenous oxytocin resulted in similar rates of vaginal delivery within 12 and 24 hours.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00695331.

LEVEL OF EVIDENCE

I.

Comparison of labor induction with titrated oral misoprostol solution between nulliparous and multiparous women

AIM

To compare the outcomes of labor induction with oral misoprostol solution between nulliparous and multiparous women.

METHODS

We retrospectively reviewed the medical records of all patients between 37 and 42 weeks of gestation with a Bishop score <or=6 who underwent labor induction with titrated oral misoprostol solution. The women were allocated into two groups: nulliparous and multiparous. The women received one basal unit of misoprostol solution (20 mL, 1 microg/mL) every hour for four doses; additional doses were titrated against individual uterine response. The interval of latent and active phase and vaginal delivery within 12 h were the primary outcomes.

RESULTS

Of the 112 women included in the study, 49 (43.8%) mulliparae and 63 (56.2%) multiparae underwent labor induction with titrated oral misoprostol solution. Complete vaginal delivery occurred within 12 h in 21 (42.9%) nulliparae and 54 (85.7%) multiparae (RR, 0.54; 95% CI, 0.39-0.76). All induction intervals, including the latent and active phases, were significantly shorter in the multiparous group (P < 0.01). Induction failure did not occur in any patient in either of the groups. There were no instances of hyperstimulation, which was defined as tachysystole or hypertonus with nonreassuring fetal heart rate pattern, although tachysystole, defined as the presence of at least six contractions in 10 min over at least two 10-min windows, occurred in four (8.2%) nulliparous women and in four (6.3%) multiparous women. Hypertonus, defined as a single contraction lasting more than 2 min, did not occur in either group. None of the neonates in either group had an Apgar score of <7 at 1 min.

CONCLUSION

Titrated oral misoprostol solution is a promising method of labor induction for both nulliparous and multiparous women.

Titrated oral compared with vaginal misoprostol for labor induction: a randomized controlled trial

OBJECTIVE

To compare the efficacy and safety of titrated oral misoprostol and vaginal misoprostol for labor induction.

METHODS

Women between 34 and 42 weeks of gestation with an unfavorable cervix (Bishop score less than or equal to 6) and an indication for labor induction were randomLy assigned to receive titrated oral or vaginal misoprostol. The titrated oral misoprostol group received a basal unit of 20 mL misoprostol solution (1 mcg/mL) every 1 hour for four doses and then were titrated against individual uterine response. The vaginal group received 25 mcg every 4 hours until attaining a more favorable cervix. Vaginal delivery within 12 hours was the primary outcome. The data were analyzed by intention-to-treat.

RESULTS

Titrated oral misoprostol was given to 101 (48.8%) women and vaginal misoprostol to 106 (51.2%) women. Completed vaginal delivery occurred within 12 hours in 75 (74.3%) women in the titrated oral group and 27 (25.5%) women in the vaginal group (relative risk [RR] 8.44, 95% confidence interval [CI] 4.52-15.76). The incidence of hyperstimulation was 0.0% in the titrated oral group compared with 11.3% in the vaginal group (RR 0.08, 95% CI 0.01-0.61). Although more women experienced nausea (10.9%) in the titrated oral group (RR 27.07, 95% CI 1.57-465.70), fewer infants had Apgar scores of less than 7 at 1 minute in the titrated oral group than in the vaginal group (RR 0.10, 95% CI 0.01-0.76).

CONCLUSION

Titrated oral misoprostol is associated with a lower incidence of uterine hyperstimulation and a lower cesarean delivery rate than vaginal misoprostol for labor induction in patients with unfavorable cervix.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00529295

LEVEL OF EVIDENCE

I.