Sublingual misoprostol vs. oral misoprostol solution for induction of labor: A retrospective study

Introduction

Induction of labor (IOL) is one of the most common obstetrical procedures, with an increasing rate. The prostaglandin E1 analogue misoprostol is frequently used as a primary method of labor induction. The optimal dose and route of administration is yet to be ascertained.

Aim

To compare efficiacy and safety between a regimen of sublingually administered misoprostol and a regimen of orally administered misoprostol, with cesarean delivery as primary outcome.

Methods

A retrospective study was conducted including women carrying a live, singleton fetus in a cephalic position with labor induced at >37 + 0 gestational weeks at Skåne University hospital, Lund, between January 1st 2013 to December 31st 2017. Data was obtained from computerized obstetrical charts.

Results

Totally 2,404 women were included; 974 induced with sublingual misoprostol and 1,430 with oral solution. In primiparous women the cesarean delivery rate was lower in primiparous women induced with oral compared to sublingual misoprostol (20.5% vs. 28.6%, p < 0.001), whereas in parous women the rates did not differ significantly 4.9% vs. 7.5%; NS). The increased risk of caesarean remained after controlling for potential confounding factors (adjusted odds ratio 1.49 (1.14–1.95). Women induced with sublingual misoprostol had a shorter time to vaginal delivery when compared to oral solution (primiparous median 16.7 h vs. 21.7 h; p < 0.001, parous median 9.9 h vs. 13.3 h; p = 0.01), and a higher rate of vaginal delivery within 24 h (primiparas 77.7% vs. 63.3%, p < 0.001, parous 93.2% vs. 84.2%; p = 0.01).

Conclusion

IOL with oral misoprostol solution was associated with a significantly higher vaginal delivery rate when compared to sublingual misoprostol, whereas sublingual misoprostol was associated with a significantly shorter time from induction to vaginal delivery. Oral administration is considered the most safe and efficient administration of misoprostol, although more studies are needed to find the optimal route and dosage of misoprostol for IOL.

Pharmacokinetics of Vaginal vs Buccal Misoprostol for Labor Induction at Term

The IMPROVE study (NCT02408315) compared the efficacy and safety of vaginal and buccal administration of misoprostol for full‐term, uncomplicated labor induction. This report compares the pharmacokinetics of misoprostol between vaginal and buccal routes. Women greater than or equal to 14 years of age undergoing induction of labor greater than or equal to 37 weeks gestation without significant complications were randomized to vaginal or buccal misoprostol 25 μg followed by 50 μg doses every 4 h. Misoprostol acid concentrations were determined using liquid chromatography‐tandem mass spectrometry for the first 8 h in a subgroup of participants. A population pharmacokinetic model was developed using NONMEM. Plasma concentrations (n = 469) from 47 women were fit to a one‐compartment nonlinear clearance model. The absorption rate constant (k_a) was dependent on both route and dose of administration: buccal 25 μg 0.724 (95% confidence interval, 0.54–0.92) h⁻¹; 50 μg 0.531 (0.37–0.63) h⁻¹; vaginal 25 μg 0.507 (0. 2–1. 4) h⁻¹; and 50 μg 0.246 (0.103–0.453) h⁻¹. Relative bioavailability for vaginal compared to buccal route was 2.4 (1.63–4.77). There was no effect of body mass index or age on apparent clearance 705 (431–1099) L/h or apparent volume of distribution 632 (343–1008) L. The area under the concentration–time curve to 4 h following the first 25 μg dose of misoprostol was 16.5 (15.4–17.5) pg h/ml for buccal and 34.3 (32.5–36.1) pg h/ml for vaginal administration. The rate of buccal absorption was two times faster than that of vaginal, whereas bioavailability of vaginal administration was 2.4 times higher than that of buccal. Decreased time to delivery observed with vaginal dosing may be due to higher exposure to misoprostol acid compared to buccal.

A Relative Bioavailability Study of Two Misoprostol Formulations Following a Single Oral or Sublingual Administration

Introduction

Misoprostol (Cytotec) was primarily made for treating gastric ulcers. However today it is mostly used for abortion, treating postpartum hemorrhage, and for induction of labor. The tablet contains 200 µg of misoprostol, yet the dosages used for induction of labor are much smaller (25–50 µg), leading to uncertainty of dosage in daily use.

Aim

To evaluate and compare the relative bioavailability of two misoprostol products (Angusta 25 µg and Cytotec 200 µg tablets) administered orally or sublingually given in a daily clinical setting to women admitted for induction of labor at term.

Methods

Women carrying a live, singleton fetus in a cephalic position and with a gestational age between 259 and 296 days were included. Blood samples were collected at 0, 5, 10, 20, 30, 40, 50, 75, 100, 120, 180, and 240 minutes. A serum analytical assay was performed and pharmacokinetic parameters were calculated. Patients were assigned to one of three groups.

Results

A total of 72 patients were included. No significant differences demographic characteristics were found. The ratios for AUC, AUC (_0−t), and C_max were similar in all three groups, but CI-values were outside the required 80–125%. Sublingual administration yielded a 20–30% higher bioavailability and a 50% higher C_max than compared to the oral route.

Conclusion

The relative bioavailability between Angusta and Cytotec could not be confirmed as being equal at the 25 µg or 50 µg level because the 90% CI-values when comparing the ratios for AUC, AUC_(0−t), and C_max were wider than accepted. The reason for this could be the real-life, non-standardized circumstances in which the study was conducted. Sublingual administration seems to have higher bioavailability than oral administration. More studies are needed to ascertain an optimal dosage regime balancing both safety and efficacy for mother and child.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT02516631.

Single-dose pharmacokinetics of orally and rectally administered misoprostol in adult horses

OBJECTIVE

To characterize the pharmacokinetics of a clinically relevant dose of misoprostol administered PO or per rectum (PR) to horses.

ANIMALS

8 healthy adult horses.

PROCEDURES

In a randomized 3-way crossover design, horses received a single dose of misoprostol (5 μg/kg) administered PO (with horses fed and unfed) and PR, with a minimum 3-week washout period separating the experimental conditions. Blood samples were obtained before and at various points after drug administration (total, 24 hours), and plasma concentrations of misoprostol free acid were measured.

RESULTS

Mean maximum plasma concentration of misoprostol was significantly higher in the PR condition (mean ± SD, 967 ± 492 pg/mL) and unfed PO condition (655 ± 259 pg/mL) than in the fed PO condition (352 ± 109 pg/mL). Mean area under the concentration-versus-time curve was significantly lower in the PR condition (219 ± 131 pg•h/mL) than in the unfed (1,072 ± 360 pg•h/mL) and fed (518 ± 301 pg•h/mL) PO conditions. Mean time to maximum concentration was ≤ 30 minutes for all conditions. Mean disappearance half-life was shortest in the PR condition (21 ± 29 minutes), compared with values for the unfed (170 ± 129 minutes) and fed (119 ± 51 minutes) PO conditions. No adverse effects were noted.

CONCLUSIONS AND CLINICAL RELEVANCE

Misoprostol was rapidly absorbed and eliminated regardless of whether administered PO or PR to horses. Rectal administration may be a viable alternative for horses that cannot receive misoprostol PO, but this route may require more frequent administration to maintain therapeutic drug concentrations.

Home-Based Extended Low-Dose Oral Misoprostol in Management of First-Trimester Pregnancy Loss in Low-Resource Communities: A Randomized Trial

Objective

To investigate the efficacy, safety and tolerability of a home-based extended low-dose oral misoprostol for management of first-trimester pregnancy loss.

Materials and Methods

A randomized trial that was conducted in the Woman's Health University Hospital and El-eman Maternity Hospital, Assiut, Egypt. One hundred and sixty patients were included. They were randomly assigned to receive four tablets of 200 μg misoprostol vaginally (max. 800 μg-hospital group) or 12 tablets orally, one every 3 h, over 2 consecutive days (max. 2400 μg-extended low-dose home group). For failed first dose, another similar second dose was given. Primary outcome measure was the percentage of patients with 'medically completed miscarriages' in each group (including complete miscarriages + incomplete miscarriages with successful post-miscarriage misoprostol).

Results

The total number of patients with 'medically completed miscarriages' in home group was 65/79 (82.3%), which was comparable to the hospital group (52/71 or 73.2%) (P = 0.182). However, the majority of patients in home group had significantly successful miscarriages after a single course of low-dose oral misoprostol, experienced much less heavy bleeding attacks and had less systemic side effects.

Conclusion

In low-resource communities, the home-based extended low-dose oral misoprostol protocol proved high efficacy, safety and tolerability in management of first-trimester pregnancy loss.

Pharmacokinetics and ex vivo anti-inflammatory effects of oral misoprostol in horses

BACKGROUND

Misoprostol is an E prostanoid (EP) 2, 3 and 4 receptor agonist that is anecdotally used to treat and prevent NSAID-induced GI injury in horses. Misoprostol elicits anti-inflammatory effects in vivo in men and rodents, and inhibits TNFα production in equine leucocytes in vitro.

OBJECTIVE

Define the pharmacokinetic parameters of oral misoprostol in horses, and determine the inhibitory effect of oral misoprostol administration on equine leucocyte TNFα production in an ex vivo inflammation model.

STUDY DESIGN

Pharmacokinetic study, ex vivo experimental study.

METHODS

Six healthy adult horses of mixed breeds were used. In phase one, horses were given 5 μg/kg misoprostol orally, and blood was collected at predetermined times for determination of misoprostol free acid (MFA) by UHPLC-MS/MS. Pharmacokinetic parameters were calculated. In phase two, horses were dosed as in phase one, and blood was collected at T0, 0.5, 1 and 4 h following misoprostol administration for leucocyte isolation. Leucocytes were stimulated with 100 ng/mL LPS, and TNFα mRNA concentrations were determined via quantitative real-time PCR.

RESULTS

About 5 μg/kg oral misoprostol produced a rapid time to maximum concentration (Tmax ) of 23.4 ± 2.4 min, with a maximum concentration (Cmax ) of 0.29 ± 0.07 ng/mL and area under the curve (AUC0-∞ ) of 0.4 ± 0.12 h ng/mL. LPS stimulation of equine leucocytes ex vivo significantly increased TNFα mRNA concentrations, and there was no significant effect of misoprostol even at the Tmax .

MAIN LIMITATIONS

Only a single dose was used, and sample size was small.

CONCLUSIONS

Misoprostol is rapidly absorbed following oral administration in horses, and a single 5 μg/kg dose had no significant inhibitory effect on ex vivo LPS-stimulated TNFα mRNA production in leucocytes. Further studies analysing different dosing strategies, including repeat administration or combination with other anti-inflammatory drugs, are warranted.

Early medical abortion with self-administered low-dose mifepristone in combination with misoprostol

AIM

The aim of the present study was to investigate the safety and efficacy of low-dose mifepristone combined with self-administered misoprostol for termination of early pregnancy.

METHODS

A total of 533 women seeking medical abortion in early pregnancy (≤49 days since the last menstrual period) were divided randomly into hospital- (H-Mis, 250) and self- (S-Mis, 283) administered misoprostol groups. Women in two groups took 100 mg of oral mifepristone in hospital followed by 200 μg of sublingual misoprostol 24 h later in hospital or home. The primary outcome parameter was complete abortion without surgical intervention. Secondary outcomes were uterine bleeding, return of regular menses, side effects and patient acceptability.

RESULTS

High rates of complete abortion were observed for both the H-Mis group (243/250; 94.8%) and the S-Mis group (266/283; 94.0%). No significant differences in outcomes (complete abortion/failure rates) or side effects were observed between the two groups. General satisfaction rates were similar for the two groups (H-Mis, 231/250, 92.4%; S-Mis, 263/283, 92.9%; P > 0.05). Higher convenience of administration (H-Mis, 211/250, 84.4%; S-Mis, 270/283, 95.4%; P < 0.05) and privacy protection (H-Mis, 214/250, 85.6%; S-Mis, 267/283, 94.3%; P < 0.05) satisfaction rates were obtained for the S-Mis group than for the H-Mis group.

CONCLUSION

Self-administered sublingual misoprostol is as safe and effective as hospital-administered misoprostol following low-dose mifepristone to terminate early pregnancy (≤49 days of amenorrhoea) with fewer side effects.

The combination route versus sublingual and vaginal misoprostol for the termination of 13 to 24 week pregnancies: A randomized clinical trial

OBJECTIVE

The goal of this study was to compare the effectiveness of misoprostol via sublingual and vaginal administration versus the combination route in the termination of 13 to 24 week pregnancies.

MATERIALS AND METHODS

One hundred and ninety-five patients, divided into three groups, were enrolled in this study. In the vaginal group, two 200-μg misoprostol tablets were inserted into the posterior fornix every 4 hours for 48 hours. In the sublingual group, patients took two 200-μg misoprostol tablets every 4 hours for up to 48 hours. In the combination group, two 200-μg misoprostol tablets were inserted within the posterior fornix followed by the administration of 400 μg misoprostol sublingually every 4 hours for a period of 48 hours. Efficacy was defined as a successful termination without the need for any interventions.

RESULTS

The success rate, after 24-48 hours, was not significantly different among the three groups. It was significantly higher within the first 12 hours of misoprostol administration within the sublingual group (p = 0.031). Nonetheless, the overall failure rate was not significantly different between three groups. The mean duration of abortion was shortest among the sublingual group (655 ± 46 minutes), p = 0.005, and the number of misoprostol tablets administered was lower when compared to the other groups (5.9 ± 0.3), p = 0.001. The duration of abortion and the number of misoprostol tablets used significantly varied in the cases in which the patient had a history of a previous normal vaginal delivery (NVD; p = 0.007). The average number of tablets administered was the lowest in the sublingual group. The prevalence of fever among the NVD cases were significantly higher in the combination group (p = 0.008). Overall, of all the methods, patients preferred the sublingual route (p = 0.001).

CONCLUSION

Sublingual misoprostol has a higher efficacy when compared to the vaginal and combination methods.

Orally administered misoprostol for induction of labor with prelabor rupture of membranes at term

Prelabor rupture of membranes (PROM) occurs in approximately 8% to 10% of women with term pregnancies. The management of PROM continues to be controversial. Approaches include expectant management and immediate induction of labor. The use of orally administered misoprostol for the management of women with PROM may provide significant advantages when they choose immediate induction of labor. This literature review presents current evidence that supports the use of oral misoprostol for women with PROM, including the benefits of a decreased interval time from PROM to vaginal birth, good safety profile, and reductions in the use of oxytocin augmentation and epidural anesthesia. In addition to clinically proven benefits to women of oral misoprostol for PROM, it also has the potential to reduce chorioamnionitis by reducing the number of sterile vaginal examinations performed thereby reducing the risk of ascending bacteria. Women have also reported acceptability and satisfaction when using oral misoprostol for immediate induction of labor. This review of literature discusses what is known about the use of orally administered misoprostol for the management of term PROM and makes recommendations for clinical use.

[Pharmacology of misoprostol (pharmacokinetic data, adverse effects and teratogenic effects)]

Misoprostol is a synthetic analogue of prostaglandin E1. It is used in gynaecology because of its properties of myometrium smooth muscle cells contraction and its effects on the cervix. Misoprostol oral bioavailability is low and several authors have assessed whether the administration by other routes increased its pharmacodynamic effects. This paper summarizes the pharmacokinetic studies after other routes of administration: vaginal, sublingual, buccal or rectal. It also provides an update on its adverse effects and teratogenic effects.

The pharmacology of prostaglandins for induction of labor

Prostaglandin medications are frequently used in the process of induction of labor. Understanding the history and research that supports prostaglandin use for induction of labor is crucial for safe practice. Dinoprostone has been the standard of care for cervical ripening in term pregnancies. Misoprostol administration via various routes has been shown to be efficacious. Oral misoprostol in particular is effective and associated with reassuring maternal and fetal outcomes. In addition, cost has become a variable in decision making regarding best practice. More research is necessary to determine the safest medication, route, dose, and interval of administration. This article reviews cervical physiology and endogenous prostaglandin activity in relation to labor, and the pharmacologic profiles of synthetic prostaglandins currently used for induction of labor.

Comparison of induction of labor with vaginal misoprostol plus oxytocin versus oxytocin alone in term primigravidae

OBJECTIVE

To compare the efficacy and complications of intravaginal misoprostol application before starting oxytocin infusion with oxytocin infusion alone for labor induction in term primigravidae pregnancies with low-Bishop score.

METHODS

This randomized study included 101 primigravidae women with singleton pregnancies >38 weeks and a Bishop score of <6. Group 1 (50 patients) received a 50-μg dose of intravaginal misoprostol, with an oxytocin infusion started 3 h later. Group 2 (51 patients) received only an oxytocin infusion for labor induction. The time from induction to delivery, the route of delivery and complications were analyzed.

RESULTS

The mean time from induction to delivery was 10.4 ± 2.1 h in Group 1 and 13.7 ± 3.4 in Group 2 (p < 0.001). The rates of vaginal delivery, Apgar scores at 1st and 5th min, placental abruption, and postpartum hemorrhage were similar between the two groups.

CONCLUSION

Intravaginal application of 50-μg misoprostol before starting oxytocin infusion is a more effective method of labor induction than oxytocin infusion alone in term primigravidae pregnant women with low-Bishop scores.

Induction of labor with vaginal misoprostol plus oxytocin versus oxytocin alone

OBJECTIVE

To compare the effect of an oxytocin infusion alone or preceded by an intravaginal application of misoprostol for labor induction in women with term pregnancies and a low Bishop score.

METHODS

This study randomized 100 multiparous women with singleton pregnancies over 38 weeks and a Bishop score less than 6 to receive either a single 50-microg dose of misoprostol intravaginally 3 hours before initiation of the oxytocin infusion or only an oxytocin infusion. The time from induction to delivery, the route of delivery, and maternal and fetal outcomes were analyzed.

RESULTS

The mean time from induction to delivery was 9.36+/-1.97 hours in the misoprostol plus oxytocin group and 11.08+/-3.23 in the oxytocin alone group (P=0.002). The rates of vaginal delivery, 1- and 5-minute Agpar scores, placental abruption, and postpartum hemorrhage were similar between the 2 groups, as were the rates of admission to the neonatal intensive care unit. There were no cases of perinatal asphyxia.

CONCLUSION

A 50-microg intravaginal application of misoprostol before starting the oxytocin infusion is a more effective method of labor induction than an oxytocin infusion alone for our study population.