The pharmacokinetics of the prostaglandin E1 analogue misoprostol in plasma and colostrum after postpartum oral administration

Pharmacokinetics and Bioequivalence of Misoprostol Tablets: An Open-Label, Randomized, Single-dose, Crossover Study With Healthy Chinese Volunteers

Misoprostol is a synthetic prostaglandin E1 derivative that has been used to treat duodenal and gastric ulcers, and to prevent ulcers caused by nonsteroidal anti-inflammatory drugs in many countries. Misoprostol can also be used for medical abortion. This study aimed to investigate the pharmacokinetic profiles of misoprostol tablets (test product) by comparing them with Cytotec (200 μg) (reference product). To assess the bioequivalence between test and reference products, a two-sequence, two-period crossover study was conducted with 48 healthy Chinese subjects enrolled under fasting conditions. A validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was used to determine the concentration of misoprostol acid in plasma. A mixed model analysis of variance was used to calculate the bioequivalence of pharmacokinetic (PK) parameters. The point estimate of geometric mean ratios with 90% confidence intervals for the maximum observed concentration (C_max ) and the area under the concentration-time curve (AUC_0-t ) for misoprostol acid in reference and test products were 107.8% and 106.5%, respectively (range 80%-125%). Additionally, none of the secondary PK parameters presented significant differences. No severe or more than moderate adverse events were detected in the 48 subjects. However, one subject discontinued the treatment due to drug-related gastrointestinal reactions. All adverse events were mild with rates of 19.2% and 22.9% after the administration test and reference products, respectively. Overall, the bioequivalence between the two misoprostol products was demonstrated in fasting conditions, and all subjects tolerated both treatments.

Low-dose oral misoprostol for induction of labour

BACKGROUND

Misoprostol given orally is a commonly used labour induction method. Our Cochrane Review is restricted to studies with low-dose misoprostol (initially ≤ 50 µg), as higher doses pose unacceptably high risks of uterine hyperstimulation.

OBJECTIVES

To assess the efficacy and safety of low-dose oral misoprostol for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov,  the WHO International Clinical Trials Registry Platform (14 February 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing low-dose oral misoprostol (initial dose ≤ 50 µg) versus placebo, vaginal dinoprostone, vaginal misoprostol, oxytocin, or mechanical methods; or comparing oral misoprostol protocols (one- to two-hourly versus four- to six-hourly; 20 µg to 25 µg versus 50 µg; or 20 µg hourly titrated versus 25 µg two-hourly static).

DATA COLLECTION AND ANALYSIS

Using Covidence, two review authors independently screened reports, extracted trial data, and performed quality assessments. Our primary outcomes were vaginal birth within 24 hours, caesarean section, and hyperstimulation with foetal heart changes.

MAIN RESULTS

We included 61 trials involving 20,026 women. GRADE assessments ranged from moderate- to very low-certainty evidence, with downgrading decisions based on imprecision, inconsistency, and study limitations. Oral misoprostol versus placebo/no treatment (four trials; 594 women) Oral misoprostol may make little to no difference in the rate of caesarean section (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.59 to 1.11; 4 trials; 594 women; moderate-certainty evidence), while its effect on uterine hyperstimulation with foetal heart rate changes is uncertain (RR 5.15, 95% CI 0.25 to 105.31; 3 trials; 495 women; very low-certainty evidence). Vaginal births within 24 hours was not reported. In all trials, oxytocin could be commenced after 12 to 24 hours and all women had pre-labour ruptured membranes. Oral misoprostol versus vaginal dinoprostone (13 trials; 9676 women) Oral misoprostol probably results in fewer caesarean sections (RR 0.84, 95% CI 0.78 to 0.90; 13 trials, 9676 women; moderate-certainty evidence). Subgroup analysis indicated that 10 µg to 25 µg (RR 0.80, 95% CI 0.74 to 0.87; 9 trials; 8652 women) may differ from 50 µg (RR 1.10, 95% CI 0.91 to 1.34; 4 trials; 1024 women) for caesarean section. Oral misoprostol may decrease vaginal births within 24 hours (RR 0.93, 95% CI 0.87 to 1.00; 10 trials; 8983 women; low-certainty evidence) and hyperstimulation with foetal heart rate changes (RR 0.49, 95% CI 0.40 to 0.59; 11 trials; 9084 women; low-certainty evidence). Oral misoprostol versus vaginal misoprostol (33 trials; 6110 women) Oral use may result in fewer vaginal births within 24 hours (average RR 0.81, 95% CI 0.68 to 0.95; 16 trials, 3451 women; low-certainty evidence), and less hyperstimulation with foetal heart rate changes (RR 0.69, 95% CI 0.53 to 0.92, 25 trials, 4857 women, low-certainty evidence), with subgroup analysis suggesting that 10 µg to 25 µg orally (RR 0.28, 95% CI 0.14 to 0.57; 6 trials, 957 women) may be superior to 50 µg orally (RR 0.82, 95% CI 0.61 to 1.11; 19 trials; 3900 women). Oral misoprostol probably does not increase caesarean sections overall (average RR 1.00, 95% CI 0.86 to 1.16; 32 trials; 5914 women; low-certainty evidence) but likely results in fewer caesareans for foetal distress (RR 0.74, 95% CI 0.55 to 0.99; 24 trials, 4775 women). Oral misoprostol versus intravenous oxytocin (6 trials; 737 women, 200 with ruptured membranes) Misoprostol may make little or no difference to vaginal births within 24 hours (RR 1.12, 95% CI 0.95 to 1.33; 3 trials; 466 women; low-certainty evidence), but probably results in fewer caesarean sections (RR 0.67, 95% CI 0.50 to 0.90; 6 trials; 737 women; moderate-certainty evidence). The effect on hyperstimulation with foetal heart rate changes is uncertain (RR 0.66, 95% CI 0.19 to 2.26; 3 trials, 331 women; very low-certainty evidence). Oral misoprostol versus mechanical methods (6 trials; 2993 women) Six trials compared oral misoprostol to transcervical Foley catheter. Misoprostol may increase vaginal birth within 24 hours (RR 1.32, 95% CI 0.98 to 1.79; 4 trials; 1044 women; low-certainty evidence), and probably reduces the risk of caesarean section (RR 0.84, 95% CI 0.75 to 0.95; 6 trials; 2993 women; moderate-certainty evidence). There may be little or no difference in hyperstimulation with foetal heart rate changes (RR 1.31, 95% CI 0.78 to 2.21; 4 trials; 2828 women; low-certainty evidence). Oral misoprostol one- to two-hourly versus four- to six-hourly (1 trial; 64 women) The evidence on hourly titration was very uncertain due to the low numbers reported. Oral misoprostol 20 µg hourly titrated versus 25 µg two-hourly static (2 trials; 296 women) The difference in regimen may have little or no effect on the rate of vaginal births in 24 hours (RR 0.97, 95% CI 0.80 to 1.16; low-certainty evidence). The evidence is of very low certainty for all other reported outcomes.

AUTHORS' CONCLUSIONS

Low-dose oral misoprostol is probably associated with fewer caesarean sections (and therefore more vaginal births) than vaginal dinoprostone, and lower rates of hyperstimulation with foetal heart rate changes. However, time to birth may be increased, as seen by a reduced number of vaginal births within 24 hours. Compared to transcervical Foley catheter, low-dose oral misoprostol is associated with fewer caesarean sections, but equivalent rates of hyperstimulation. Low-dose misoprostol given orally rather than vaginally is probably associated with similar rates of vaginal birth, although rates may be lower within the first 24 hours. However, there is likely less hyperstimulation with foetal heart changes, and fewer caesarean sections performed due to foetal distress. The best available evidence suggests that low-dose oral misoprostol probably has many benefits over other methods for labour induction. This review supports the use of low-dose oral misoprostol for induction of labour, and demonstrates the lower risks of hyperstimulation than when misoprostol is given vaginally. More trials are needed to establish the optimum oral misoprostol regimen, but these findings suggest that a starting dose of 25 µg may offer a good balance of efficacy and safety.

Uterotonic Medications: Oxytocin, Methylergonovine, Carboprost, Misoprostol

Uterine atony is a common cause of primary postpartum hemorrhage, which remains a major cause of pregnancy-related mortality for women worldwide. Oxytocin, methylergonovine, carboprost, and misoprostol are commonly used to restore uterine tone. Oxytocin is the first-line agent. Methylergonovine and carboprost are both highly effective second-line agents with severe potential side effects. Recent studies have called into question the effectiveness of misoprostol as an adjunct to other uterotonic agents, but it remains a useful therapeutic in resource-limited practice environments. We review the current role these medications play in the prevention and treatment of uterine atony.

Claims of misoprostol use based on blood sampling should be viewed with skepticism

Efforts to prosecute women for induced abortion have included allegations that misoprostol was found in body fluids. These claims, however, are questionable owing to the timing of specimen collection for accurate results, the scarcity and expense of validated assays, and the onerous lab procedures required to determine the presence of the substance. Adequate scrutiny should be applied each time such a claim is made.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is an orally active prostaglandin. In most countries misoprostol is not licensed for labour induction, but its use is common because it is cheap and heat stable.

OBJECTIVES

To assess the use of oral misoprostol for labour induction in women with a viable fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 January 2014).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus placebo or other methods, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial data, using centrally-designed data sheets.

MAIN RESULTS

Overall there were 76 trials (14,412) women) which were of mixed quality.In nine trials comparing oral misoprostol with placebo (1109 women), women using oral misoprostol were more likely to give birth vaginally within 24 hours (risk ratio (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49; one trial; 96 women), need less oxytocin (RR 0.42, 95% CI 0.37 to 0.49; seven trials; 933 women) and have a lower caesarean section rate (RR 0.72, 95% CI 0.54 to 0.95; eight trials; 1029 women).In 12 trials comparing oral misoprostol with vaginal dinoprostone (3859 women), women given oral misoprostol were less likely to need a caesarean section (RR 0.88, 95% CI 0.78 to 0.99; 11 trials; 3592 women). There was some evidence that they had slower inductions, but there were no other statistically significant differences.Nine trials (1282 women) compared oral misoprostol with intravenous oxytocin. The caesarean section rate was significantly lower in women who received oral misoprostol (RR 0.77, 95% CI 0.60 to 0.98; nine trials; 1282 women), but they had increased rates of meconium-stained liquor (RR 1.65, 95% CI 1.04 to 2.60; seven trials; 1172 women).Thirty-seven trials (6417 women) compared oral and vaginal misoprostol and found no statistically significant difference in the primary outcomes of serious neonatal morbidity/death or serious maternal morbidity or death. The results for vaginal birth not achieved in 24 hours, uterine hyperstimulation with fetal heart rate (FHR) changes, and caesarean section were highly heterogenous - for uterine hyperstimulation with FHR changes this was related to dosage with lower rates in those with lower doses of oral misoprostol. However, there were fewer babies born with a low Apgar score in the oral group (RR 0.60, 95% CI 0.44 to 0.82; 19 trials; 4009 babies) and a decrease in postpartum haemorrhage (RR 0.57, 95% CI 0.34 to 0.95; 10 trials; 1478 women). However, the oral misoprostol group had an increase in meconium-stained liquor (RR 1.22, 95% CI 1.03 to 1.44; 24 trials; 3634 women).

AUTHORS' CONCLUSIONS

Oral misoprostol as an induction agent is effective at achieving vaginal birth. It is more effective than placebo, as effective as vaginal misoprostol and results in fewer caesarean sections than vaginal dinoprostone or oxytocin.Where misoprostol remains unlicensed for the induction of labour, many practitioners will prefer to use a licensed product like dinoprostone. If using oral misoprostol, the evidence suggests that the dose should be 20 to 25 mcg in solution. Given that safety is the primary concern, the evidence supports the use of oral regimens over vaginal regimens. This is especially important in situations where the risk of ascending infection is high and the lack of staff means that women cannot be intensely monitored.

Treatment for primary postpartum haemorrhage

BACKGROUND

Primary postpartum haemorrhage (PPH) is one of the top five causes of maternal mortality in both developed and developing countries.

OBJECTIVES

To assess the effectiveness and safety of any intervention used for the treatment of primary PPH.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2013).

SELECTION CRITERIA

Randomised controlled trials comparing any interventions for the treatment of primary PPH.

DATA COLLECTION AND ANALYSIS

We assessed studies for eligibility and quality and extracted data independently. We contacted authors of the included studies to request more information.

MAIN RESULTS

Ten randomised clinical trials (RCTs) with a total of 4052 participants fulfilled our inclusion criteria and were included in this review.Four RCTs (1881 participants) compared misoprostol with placebo given in addition to conventional uterotonics. Adjunctive use of misoprostol (in the dose of 600 to 1000 mcg) with simultaneous administration of additional uterotonics did not provide additional benefit for our primary outcomes including maternal mortality (risk ratio (RR) 6.16, 95% confidence interval (CI) 0.75 to 50.85), serious maternal morbidity (RR 0.34, 95% CI 0.01 to 8.31), admission to intensive care (RR 0.79, 95% CI 0.30 to 2.11) or hysterectomy (RR 0.93, 95% CI 0.16 to 5.41).  Two RCTs (1787 participants) compared 800 mcg sublingual misoprostol versus oxytocin infusion as primary PPH treatment; one trial included women who had received prophylactic uterotonics, and the other did not. Primary outcomes did not differ between the two groups, although women given sublingual misoprostol were more likely to have additional blood loss of at least 1000 mL (RR 2.65, 95% CI 1.04 to 6.75). Misoprostol was associated with a significant increase in vomiting and shivering.Two trials attempted to test the effectiveness of estrogen and tranexamic acid, respectively, but were too small for any meaningful comparisons of pre-specified outcomes.One study compared lower segment compression but was too small to assess impact on primary outcomes.We did not identify any trials evaluating surgical techniques or radiological interventions for women with primary PPH unresponsive to uterotonics and/or haemostatics.

AUTHORS' CONCLUSIONS

Clinical trials included in the current review were not adequately powered to assess impact on the primary outcome measures. Compared with misoprostol, oxytocin infusion is more effective and causes fewer side effects when used as first-line therapy for the treatment of primary PPH. When used after prophylactic uterotonics, misoprostol and oxytocin infusion worked similarly. The review suggests that among women who received oxytocin for the treatment of primary PPH, adjunctive use of misoprostol confers no added benefit.The role of tranexamic acid and compression methods requires further evaluation. Furthermore, future studies should focus on the best way to treat women who fail to respond to uterotonic therapy.

No reduction of manual removal after misoprostol for retained placenta: a double-blind, randomized trial

OBJECTIVE

To test the effect of 800 μg of misoprostol orally on the prevention of manual removal of retained placenta.

DESIGN

Multicenter, double-blinded, placebo-controlled, randomized trial.

SETTING

One university and one non-university teaching hospital in the Netherlands.

SAMPLE

99 women with retained placenta (longer than 60 min after childbirth) in the absence of postpartum hemorrhage.

METHODS

Eligible women were administered either 800 μg of misoprostol or placebo orally.

MAIN OUTCOME MEASURES

Number of manual removals of retained placenta and amount of blood loss.

RESULTS

Manual removal of retained placenta was performed in 50% of the women who received misoprostol and in 55% who received placebo (relative risk 0.91, 95% confidence interval 0.62-1.34). No difference in the amount of blood loss (970 vs. 1120 mL; p = 0.34) was observed between the two groups.

CONCLUSIONS

Administration of 800 μg of oral misoprostol, one hour after childbirth, does not seem to reduce the number of manual removals of retained placentas. The time elapsing results in the delivery of 50% of the retained placentas at the expense of an increased risk of postpartum hemorrhage.

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.

Frequent low-dose misoprostol for termination of second-trimester pregnancy

OBJECTIVES

To determine the efficacy of an application regimen of low-dose frequent misoprostol for second-trimester pregnancy termination.

METHODS

A total of 250 women between 12 and 20 weeks of gestation who were scheduled for second-trimester pregnancy termination received 200 microg vaginal misoprostol followed by 100 microg oral misoprostol every 2 h until expulsion of the fetus. Mechanical cervical dilatation with a 16-French Foley balloon catheter was performed if no cervical dilatation was observed after 24 h. The main outcome measures were the delivery rate within 24 h and the factors influencing the interval between the onset of induction and abortion. Secondary outcome measures were the side-effects of the regimen and the total misoprostol dose required.

RESULTS

With application of this protocol, 245 women (98%) delivered within 24 h of induction. The mean (+/-standard deviation) misoprostol dose used was 728+/-297 microg (200-2100 microg). Cox regression analysis revealed that vaginal spotting or nulliparity do not effect the induction-abortion time. On the other hand, using this regimen induction to abortion time tends to be longer in the presence of live fetuses (odds ratio (OR) = 0.45; confidence interval (CI) =0.2-0.8; p=0.008) and pregnancies with gestational age > 16 weeks (OR= 0.59; CI = 0.4-0.8; p= 0.003) when compared with cases of in utero death and pregnancies with a gestational age of 12-13 weeks, respectively. Twenty-seven women (10.8%) experienced one or more side-effects attributable to misoprostol.

CONCLUSION

The 100-microg oral misoprostol every 2 h following 200 microg vaginal misoprostol is a highly effective protocol for inducing abortion at 12-20 weeks of pregnancy. Cases with live fetuses or pregnancies with older gestational age (> 16 weeks) deliver in a longer time period.

Side effects of oral misoprostol for the prevention of postpartum hemorrhage: results of a community-based randomised controlled trial in rural India

OBJECTIVE

To investigate the side effects of 600 microg oral misoprostol given for the mother and the newborn to prevent postpartum hemorrhage (PPH).

METHODS

One thousand six hundred twenty women delivering at home or subcentres in rural India were randomised to receive misoprostol or placebo in the third stage of labour. Women were evaluated for shivering, fever, nausea, vomiting and diarrhea at 2 and 24 h postpartum. Newborns were evaluated within 24 h for diarrhea, vomiting and fever. Symptoms were graded as absent, mild-to-moderate or severe.

RESULTS

Women who received misoprostol had a significantly greater incidence of shivering (52%vs. 17%, p < 0.001) and fever (4.2%vs. 1.1%, p < 0.001) at 2 h postpartum compared with women who received placebo. At 24 h, women in the misoprostol group experienced significantly more shivering (4.6%vs. 1.4%, p < 0.001) and fever (1.4%vs. 0.4%, p < 0.03). There were no differences in nausea, vomiting or diarrhea between the two groups. There were no differences in the incidence of vomiting, diarrhea or fever for newborns.

CONCLUSIONS

Misoprostol is associated with a significant increase in postpartum maternal shivering and fever with no side effects for the newborn. Given its proven efficacy for the prevention of PPH, the benefits of misoprostol are greater than the associated risks.

Misoprostol: pharmacokinetic profiles, effects on the uterus and side-effects

Misoprostol, a synthetic prostaglandin E1 analogue, is commonly used for medical abortion, cervical priming, the management of miscarriage, induction of labor and the management of postpartum hemorrhage. It can be given orally, vaginally, sublingually, buccally or rectally. Studies of misoprostol's pharmacokinetics and effects on uterine activity have demonstrated the properties of the drug after various routes of administration. These studies can help to discover the optimal dose and route of administration of misoprostol for individual clinical applications. Misoprostol is a safe drug but serious complications and teratogenicity can occur with unsupervised use.

Determination of misoprostol acid in human plasma by liquid chromatography coupled to tandem mass spectrometry

A rapid and sensitive liquid chromatographic/tandem mass spectrometric method for determination of misoprostol acid, the active metabolite of misoprostol, was developed and validated. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a C(18) column. An API 4000 tandem mass spectrometer equipped with Turbo IonSpray ionization source was used as detector and was operated in the negative ion mode. Multiple reaction monitoring using the precursor to product ion combinations of m/z 367-249 and 296-269 was performed to quantify misoprostol acid and the internal standard hydrochlorothiazide, respectively. The method was linear in the concentration range of 10.0-3000 pg mL(-1) using 200 microL plasma. The lower limit of quantification was 10.0 pg mL(-1). The intra- and inter-day relative standard deviation over the entire concentration range was less than 8.3%. Accuracy determined at three concentrations (25.0, 200 and 2700 pg mL(-1) for misoprostol acid) ranged from -0.5 to 1.2% in terms of relative error. Each plasma sample was chromatographed within 3.5 min. The method was successfully used in a pharmacokinetic study of misoprostol in human plasma after an oral administration of 0.6 mg misoprostol.

Misoprostol versus oxytocin for the reduction of postpartum blood loss

OBJECTIVE

To compare the effect of 400 mug of oral misoprostol with 5 U of intravenous oxytocin in the reduction of postpartum blood loss and prevention of postpartum hemorrhage.

METHODS

In a prospective, double-blind, randomized controlled trial conducted in a tertiary maternity hospital 622 women received either 400 mug of oral misoprostol or 5 U of intravenous oxytocin after delivery of the anterior shoulder or within 1 min of delivery. The primary outcome was a hematocrit drop of 10% or greater 24 h postpartum. The secondary outcomes were a hemoglobin drop of 30 mg/L or greater, the use of additional oxytocin, an estimated blood loss greater than 1000 mL, manual removal of the placenta, a blood transfusion, and shivering and fever (>or=38 degrees C) as adverse effects of misoprostol.

RESULTS

There was no difference between the 2 groups regarding the primary outcome (a >or=10% hematocrit drop occurred in 3.4% and 3.7% of the participants in the oxytocin and misoprostol groups, P=0.98). The rate of use of additional oxytocin was higher in the misoprostol group (51% versus 40.5%, P=0.01). Shivering was confined to the misoprostol group (6.8%), and fever occurred in 12.5% of the women in the misoprostol group and 0.3% of the women in the oxytocin group.

CONCLUSION

The routine use of 400 microg of oral misoprostol was no less effective than 5 U of intravenous oxytocin in reducing blood loss after delivery, as assessed by change in postpartum hematocrit. The adverse effects of misoprostol were mild and self-limiting.

Treatment for primary postpartum haemorrhage

BACKGROUND

Primary postpartum haemorrhage (PPH) is one of the top five causes of maternal mortality in both developed and developing countries.

OBJECTIVES

To assess the effectiveness and safety of pharmacological, surgical and radiological interventions used for the treatment of primary PPH.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2006).

SELECTION CRITERIA

Randomised controlled trials comparing pharmacological, surgical techniques and radiological interventions for the treatment of PPH.

DATA COLLECTION AND ANALYSIS

We assessed studies for eligibility and quality, and extracted data, independently. We contacted authors of the included studies for more information.

MAIN RESULTS

Three studies (462 participants) were included. Two placebo-controlled randomised trials compared misoprostol (dose 600 to 1000 mcg) with placebo and showed that misoprostol use was not associated with any significant reduction of maternal mortality (two trials, 398 women; relative risk (RR) 7.24, 95% confidence interval (CI) 0.38 to 138.6), hysterectomy (two trials, 398 women; RR 1.24, 95% CI 0.04 to 40.78), the additional use of uterotonics (two trials, 398 women; RR 0.98, 95% CI 0.78 to 1.24), blood transfusion (two trials, 394 women; RR 1.33, 95% CI 0.81 to 2.18), or evacuation of retained products (one trial, 238 women; RR 5.17, 95% CI 0.25 to 107). Misoprostol use was associated with a significant increase of maternal pyrexia (two trials, 392 women; RR 6.40, 95% CI 1.71 to 23.96) and shivering (two trials, 394 women; RR 2.31, 95% CI 1.68 to 3.18). One unblinded trial showed better clinical response to rectal misoprostol compared with a combination of syntometrine and oxytocin. We did not identify any trial dealing with surgical techniques, radiological interventions or haemostatic drugs for women with primary PPH unresponsive to uterotonics.

AUTHORS' CONCLUSIONS

There is insufficient evidence to show that the addition of misoprostol is superior to the combination of oxytocin and ergometrine alone for the treatment of primary PPH. Large multi-centre, double-blind, randomised controlled trials are required to identify the best drug combinations, route, and dose of uterotonics for the treatment of primary PPH. Further work is required to assess the best way of managing women who fail to respond to uterotonics therapy.

Oral misoprostol vs. intravenous oxytocin in reducing blood loss after emergency cesarean delivery

OBJECTIVE

To compare the effectiveness of oral misoprostol and intravenous oxytocin in reducing blood loss in women undergoing indicated or elective cesarean delivery (CD) under spinal anesthesia.

METHODS

In this prospective, double-blind pilot study, 56 parturients who received 5 IU of intravenous oxytocin after cord clamping were randomized to further receive either misoprostol orally and a placebo infusion intravenously or placebo orally and an oxytocin infusion intravenously.

RESULTS

After adjustment was made for the sonographically estimated amniotic fluid volume, there was no statistical difference in blood loss between the 2 groups (mean+/-S.D., 1083+/-920 mL in the oxytocin group vs. 970+/-560 mL in the misoprostol group; P=.59).

CONCLUSION

Oxytocin followed by oral misoprostol is as effective as an oxytocin injection followed by an oxytocin infusion in reducing postoperative blood loss after CD, and the protocol may be a safe, valuable, and cost-effective alternative to oxytocin alone. Visual estimation of intraoperative blood loss undervalues the effective value of misoprostol use by 30%.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is a synthetic prostaglandin that can be given orally or vaginally. In most countries misoprostol has not been licensed for use in pregnancy, but its unlicensed use is common because misoprostol is cheap, stable at room temperature and effective in causing uterine contractions. Oral use of misoprostol may be convenient, but high doses could cause uterine hyperstimulation and uterine rupture which may be life-threatening for both mother and fetus.

OBJECTIVES

To assess the effectiveness and safety of oral misoprostol used for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2005).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus other methods, placebo or no treatment, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed trial quality and extracted data, using centrally-designed data sheets.

MAIN RESULTS

Forty-one trials (8606 participants) were included. In four trials comparing oral misoprostol with placebo (474 participants), women using oral misoprostol were less likely to have long labours (relative risk (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49), needed less oxytocin (RR 0.32, 95% CI 0.24 to 0.43) and had a lower caesarean section rate (RR 0.62, 95% CI 0.40 to 0.96). In nine trials comparing oral misoprostol with vaginal dinoprostone (2627 participants), women given oral misoprostol were less likely to need a caesarean section, but this reduction reached statistical significance only in the subgroup with intact membranes (RR 0.78, 95% CI 0.66 to 0.94). Uterine hyperstimulation was more common after oral misoprostol (RR 1.63, 95% CI 1.09 to 2.44) although this was not associated with any adverse fetal events. Seven trials (1017 participants) compared oral misoprostol with intravenous oxytocin. The only difference between the groups was an increase in meconium-stained liquor in women with ruptured membranes following administration of oral misoprostol (RR 1.72, 95% 1.08 to 2.74). Sixteen trials (3645 participants) compared oral and vaginal misoprostol and found no difference in the primary outcomes. There was less uterine hyperstimulation without fetal heart rate changes in those given oral misoprostol (RR 0.37, 95% 0.23 to 0.59). Oral misoprsotol was associated with increased need for oxytocin augmentation (RR 1.28, 95% 1.11 to 1.48) and more meconium-stained liquor (RR 1.27, 1.01 to 1.60).

AUTHORS' CONCLUSIONS

Oral misoprostol appears to be more effective than placebo and at least as effective as vaginal dinoprostone. However, there remain questions about its safety because of a relatively high rate of uterine hyperstimulation and the lack of appropriate dose ranging studies. In countries where misoprostol remains unlicenced for the induction of labour, many practitioners will prefer the legal protection of using a licenced product like dinoprostone. There is no evidence that misoprostol given orally is inferior to the vaginal route and has lower rates of hyperstimulation. If misoprostol is used orally, the dose should not exceed 50 mcg.

Misoprostol 50 μg Sublingually versus Vaginally for Labor Induction at Term: A Randomized Study

OBJECTIVE

To compare the efficacy of misoprostol 50 mug vaginally and 50 mug sublingually for labor induction at term.

MATERIALS AND METHODS

One hundred and sixty women were randomized to receive misoprostol 50 microg vaginally (n = 80) or 50 microg sublingually misoprostol (n = 80). The doses were given every 4 h (maximum 6 doses). Primary outcome measure was number of cesarean deliveries. Induction to delivery time, delivery within 24 h, the number of misoprostol doses given; the need for oxytocin augmentation, tachysystole and uterine hyperstimulation rates and neonatal outcomes were secondary outcome measures.

RESULTS

The mean induction to delivery time was 748 +/- 379 min in the vaginal group and 711 +/- 425 in the sublingual group (p = 0.56). The number of women delivering within 24 h was 73 (91.3%) in the vaginal group and 74 (92.5%) in the sublingual group (p = 0.78). The mean number of misoprostol doses required was significantly higher in the sublingual group (1.9 +/- 1.2) compared with the vaginal group (1.1 +/- 0.4; p < 0.001). More women in the sublingual group experienced tachysystole (n = 14, 17.5%) compared with the vaginal group (n = 3, 3.8%; p = 0.005). Seven cases (8.8%) in the vaginal group and 12 cases in the sublingual group (15%) required emergent cesarean delivery for fetal heart rate abnormalities (p = 0.22). Other neonatal outcomes including umbilical artery pH, Apgar scores and intensive care unit admission were similar in the two groups.

CONCLUSION

Sublingual misoprostol is as efficacious as vaginal misoprostol for induction of labor. More frequent tachysystole is observed with misoprostol 50 microg sublingually, but neonatal outcomes are similar.

Misoprostol versus methylergometrine: pharmacokinetics in human milk

OBJECTIVE

The purpose of this study to compare breast milk pharmacokinetics between misoprostol 200 mug and methylergometrine 250 mug after single oral dosing in women who require postpartum uterotonic therapy.

STUDY DESIGN

Open prospective randomized phase I study measuring misoprostol and methylergometrine on postpartum days 3 to 6 in milk 0.5, 1, 2, 3, 4, and 5 hours postdose, and in maternal serum at 0.5 and 1 hours (misoprostol) and 1 and 2 hours (methylergometrine) in 10 lactating women per group.

RESULTS

Milk misoprostol levels rose and declined rapidly, which gave a milk elimination half-life of less than one half that of methylergometrine (mean +/- SE, 1.1 +/- 0.3 hours [median, 0.6 hours] vs 2.33 +/- 0.3 hours [median, 1.9 hours]; P = .003). Milk/plasma ratios for misoprostol were one third of those for methylergometrine at 1 hour ( P < .0001) and 2 hours ( P < .0015).

CONCLUSION

Misoprostol warrants further investigation as an alternative to postpartum methylergometrine because it enters and leaves breast milk at twice the rate, with one third of the milk/plasma ratio, which significantly lowers infant exposure and facilitates a timed dosing regimen.

Does the route of administration of misoprostol make a difference? The uterotonic effect and side effects of misoprostol given by different routes after vaginal delivery

OBJECTIVE

To compare the postpartum uterotonic effect and side effects of misoprostol administered by different routes.

STUDY DESIGN

Fifty women were given misoprostol 400 microg either by the oral solution, oral tablet, rectal or vaginal route, or intramuscular syntometrine 1 ml after spontaneous vaginal delivery. Pre- and post-treatment uterine activity were measured with intrauterine pressure catheters.

RESULTS

Uterine activity produced by oral solution misoprostol 400 microg was significantly higher than that of oral tablet, rectal and vaginal misoprostol (P = 0.004, 0.002, respectively). Onset of action after oral solution misoprostol was faster than by the oral tablet (P = 0.01), rectal (P < 0.001) and vaginal (P< 0.001) routes. Shivering and pyrexia were most common with oral solution misoprostol. Maximum body temperature recorded was significantly higher with oral solution misoprostol than with oral tablet, rectal and vaginal misoprostol (P = 0.009, 0.001, respectively).

CONCLUSION

Different routes of administering misoprostol greatly influence the effects achieved. Oral solution misoprostol produces the fastest and strongest uterotonic effect, with the most side effects.

Misoprostol and pregnancy: ever-increasing indications of effective usage

PURPOSE OF REVIEW

The subject of misoprostol in the field of reproductive health care has courted much controversy. The aim of this review is to survey the literature published in this field over the past year, and to evaluate developments in this area. This article will cover termination of pregnancy, induction of labor and the issue of postpartum hemorrhage.

RECENT FINDINGS

The use of misoprostol as a single agent remains of clinical value when mifepristone is unavailable. The sublingual and rectal routes are alternative modes of administration. For induction of labor, the optimum dose and route of misoprostol is still undetermined. Lower doses of between 20 microg to 40 microg may increase the safety profile for labor induction. Misoprostol may be a useful adjunct to the therapeutic options available for the prevention and treatment of postpartum hemorrhage.

SUMMARY

There are many potential uses for misoprostol in pregnancy. However clinicians must judge the evidence and the emotive debate surrounding this field and decide how it will influence their clinical practice depending on the priorities of their own clinical circumstances.

Misoprostol for treating postpartum haemorrhage: a randomized controlled trial [ISRCTN72263357]

BACKGROUND: Postpartum haemorrhage remains an important cause of maternal death despite treatment with conventional therapy. Uncontrolled studies and one randomised comparison with conventional oxytocics have reported dramatic effects with high-dose misoprostol, usually given rectally, for treatment of postpartum haemorrhage, but this has not been evaluated in a placebo-controlled trial. METHODS: The study was conducted at East London Hospital Complex, Tembisa and Chris Hani Baragwanath Hospitals, South Africa. Routine active management of the third stage of labour was practised. Women with more than usual postpartum bleeding thought to be related to inadequate uterine contraction were invited to participate, and to sign informed consent. All routine treatment was given from a special 'Postpartum Haemorrhage Trolley'. In addition, participants who consented were enrolled by drawing the next in a series of randomised treatment packs containing either misoprostol 5 x 200 microg or similar placebo, which were given 1 orally, 2 sublingually and 2 rectally. RESULTS: With misoprostol there was a trend to reduced blood loss >/=500 ml in 1 hour after enrolment measured in a flat plastic 'fracture bedpan', the primary outcome (6/117 vs 11/120, relative risk 0.56; 95% confidence interval 0.21 to 1.46). There was no difference in mean blood loss or haemoglobin level on day 1 after birth < 6 g/dl or blood transfusion. Side-effects were increased, namely shivering (63/116 vs 30/118; 2.14, 1.50 to 3.04) and pyrexia > 38.5 degrees C (11/114 vs 2/118; 5.69, 1.29 to 25). In the misoprostol group 3 women underwent hysterectomy of whom 1 died, and there were 2 further maternal deaths. CONCLUSIONS: Because of a lower than expected incidence of the primary outcome in the placebo group, the study was underpowered. We could not confirm the dramatic effect of misoprostol reported in several unblinded studies, but the results do not exclude a clinically important effect. Larger studies are needed to assess substantive outcomes and risks before misoprostol enters routine use.

Misoprostol overdose during the first trimester of pregnancy

Misoprostol is a synthetic prostaglandin E1 used during the first trimester of pregnancy as an adjacent to RU486 for medical termination of pregnancy. We present a case of a healthy 23-year-old woman who was admitted due to misoprostol overdose, used to induce an illegal abortion. Manifestations of toxicity included abdominal pain, vomiting, diarrhea and confusion. Treatment was supportive and included gastric lavage and administration of activated charcoal. Recovery was completed within a few hours, and the patient was scheduled for a dilatation and curettage the following day.

Current strategies for the prevention of postpartum haemorrhage in the third stage of labour

PURPOSE OF REVIEW

Despite evidence that active management of the third stage of labour reduces the incidence of postpartum haemorrhage, expectant management is still widely practised. Factors accounting for this situation include the desire for a more natural experience of childbirth, the philosophy that active management is unnecessary in low-risk women, and avoidance of the adverse effects of conventional uterotonic agents. This review will evaluate the various strategies currently used for the prevention of primary postpartum haemorrhage.

RECENT FINDINGS

Since publication of the first systematic review comparing active with expectant management in 1988, active management of the third stage using oxytocics has become increasingly adopted. Recent surveys, however, show that there are still wide variations in practice around the world. Recent interest has focused on the use of misoprostol for the prevention of postpartum haemorrhage. Carbetocin, an oxytocin receptor agonist, shows promise but has not been evaluated for use after vaginal births.

SUMMARY

Active management of the third stage of labour is superior to expectant management in terms of blood loss, postpartum haemorrhage and other serious complications, but is associated with unpleasant side effects and hypertension when ergometrine is included. Intramuscular oxytocin results in fewer side effects. Oral and rectal misoprostol has been extensively assessed and found to be less effective than conventional oxytocics with more side effects. Until alternative regimes of misoprostol are studied in large controlled trials, misoprostol is not recommended for routine use in the third stage of labour. Of the remaining uterotonic agents evaluated, intramuscular carbetocin appears the most promising.

Misoprostol: A Quarter Century of Use, Abuse, and Creative Misuse

Misoprostol is a prostaglandin E1 analog originally intended for use to prevent NSAID-induced gastric ulcers. However, because of its cervical ripening and uterotonic property, misoprostol has become one of the most useful drugs in obstetrics and gynecology. Misoprostol has proven to be a very convenient and flexible drug because of its formulation as a tablet that is stable and that can be administered orally, rectally, vaginally and by the sublingual route. Beginning with its abuse for illegal abortion in the late 1980s, misoprostol has quickly become established as one of the most effective drugs for terminating pregnancies in the first and second trimesters, as well as for inducing labor in the third trimester. Its use for routine prevention of postpartum hemorrhage has not been so successful, partly as the high doses required for this indication often result in troublesome side effects. Despite the large body of medical evidence about its efficacy and relative safety, the use of misoprostol in pregnant women remained off-label until the spring of 2002.