A pilot study on the combined use of letrozole, mifepristone and misoprostol in termination of first trimester pregnancy up to 9 weeks’ gestation

Comparing letrozole and mifepristone pre-treatment in medical management of first trimester missed miscarriage: a prospective open-label non-inferiority randomised controlled trial

OBJECTIVE

To investigate whether letrozole pre-treatment is non-inferior to mifepristone pre-treatment, followed by misoprostol, for complete evacuation in the medical treatment of first-trimester missed miscarriage.

DESIGN

Prospective open-label non-inferiority randomised controlled trial.

SETTING

A university-affiliated hospital.

POPULATION

We recruited 294 women diagnosed with first-trimester missed miscarriage who opted for medical treatment.

METHODS

Participants were randomly assigned to: (i) the mifepristone group, who received 200 mg mifepristone orally followed 24-48 h later by 800 μg misoprostol vaginally; or (ii) the letrozole group, who received 10 mg letrozole orally once-a-day for 3 days, followed by 800 μg misoprostol vaginally on the third (i.e. last) day of letrozole administration.

MAIN OUTCOME MEASURES

The primary outcome was the rate of complete evacuation without surgical intervention at 42 days post-treatment. Secondary outcomes included induction-to-expulsion interval, adverse effects, women's satisfaction, number of doses of misoprostol required, duration of vaginal bleeding, pain score on the day of misoprostol administration and other adverse events.

RESULTS

The complete evacuation rates were 97.8% (95% CI 95.1%-100%) and 97.2% (95% CI 94.4%-99.9%) in the letrozole and mifepristone groups, respectively (p ≤ 0.001 for non-inferiority). The mean induction-to-tissue expulsion interval in the letrozole group was longer compared with the mifepristone group (15.4 vs 9.0 h) (p = 0.03). The letrozole group had less heavy post-treatment bleeding and an earlier return of menses. There were no statistically significant differences in the number of doses of misoprostol required, the duration of vaginal bleeding, the pain score on the day of misoprostol administration and the rate of other adverse events between the two groups. The majority of the women (91.2% and 93.9% in the letrozole and mifepristone groups, respectively) were satisfied with their treatment option.

CONCLUSIONS

Letrozole is non-inferior to mifepristone as a pre-treatment, followed by misoprostol, for the medical treatment of first-trimester missed miscarriage.

Prospective open-label non-inferiority randomised controlled trial comparing letrozole and mifepristone pretreatment in medical management of first trimester missed miscarriage: study protocol

INTRODUCTION

Medical treatment is a less invasive alternative to surgical management of missed miscarriage. Studies have shown that pretreatment with mifepristone can increase the complete abortion rate in management of first-trimester missed miscarriage compared with misoprostol alone. Two studies have also shown that pretreatment with letrozole could increase the efficacy compared with misoprostol alone. So far, there is no trial comparing letrozole and mifepristone pretreatment for missed miscarriage. We designed this randomised controlled trial to test the hypothesis that for first-trimester missed miscarriage, letrozole pretreatment is non-inferior to mifepristone pretreatment followed by misoprostol in terms of complete abortion rate.

METHODS AND ANALYSIS

This is a prospective open-label non-inferiority randomised controlled trial conducted in a single centre. In total, 294 women diagnosed with first-trimester missed miscarriage opting for medical treatment is recruited with informed consent. They are randomly assigned to receive mifepristone or letrozole pretreatment. In the mifepristone group, each woman takes 200 mg mifepristone orally followed 24-48 hours later by 800 µg misoprostol vaginally. In the letrozole group, each woman takes 10 mg letrozole orally per day for 3 days, followed by 800 µg misoprostol vaginally on the third day of letrozole administration. Follow-up is conducted on days 15 and 42 after misoprostol administration. The primary outcome is the overall complete abortion rate. Secondary outcomes include side effects and complications during the study period. Data will be analysed with both intention-to-treat and per protocol approaches. A p<0.05 will be considered as indicating statistical significance.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Institutional Review Board of the University of Hong Kong-Shenzhen Hospital with approval number: (2020)166. Findings will be disseminated in a peer-reviewed journal and in national and/or international meetings to guide future practice.

TRIAL REGISTRATION NUMBER

ChiCTR2000041480.

The efficacy of letrozole supplementation for medical abortion: a meta-analysis of randomized controlled trials

INTRODUCTION

The efficacy of letrozole supplementation for medical abortion remains controversial. We conduct a systematic review and meta-analysis to explore the influence of letrozole supplementation for medical abortion.

METHODS

We searched PubMed, Embase, Web of Science, EBSCO, and Cochrane Library databases through October 2018 for randomized controlled trials (RCTs) assessing the effect of letrozole supplementation for medical abortion. This meta-analysis is performed using the random-effect model.

RESULTS

Six RCTs involving 555 patients are included in the meta-analysis. Overall, compared with control group for pregnant women, letrozole supplementation shows significantly increased complete abortion (RR = 1.38; 95% CI = 1.07-1.78; p = .01), and decreased estradiol (std. MD = -2.86; 95% CI = -4.45 to -1.27; p = .0004), but has no remarkable effect on induction-abortion time (std. MD = -1.03; 95% CI = -2.99-0.93; p = .30), progesterone (std. MD = 0.02; 95% CI = -0.30-0.34; p = .89), vaginal hemorrhage (std. MD = 1.84; 95% CI = 0.05-70.90; p = .74), nausea and vomiting (std. MD = 073; 95% CI = 0.44-1.21; p = .22).

CONCLUSIONS

Letrozole supplementation provides benefits to medical abortion in pregnant women.

Letrozole vs. Placebo Pretreatment in the Medical Management of First Trimester Missed Miscarriage: a Randomized Controlled Trial

Introduction

Misoprostol is used for the medical management of miscarriage as it is more effective in the early stages of pregnancy. Letrozole has an anti-estrogen effect and is used for the pretreatment of miscarriage with misoprostol.

Aim

The aim of this study was compare the efficacy and safety of letrozole with placebo pretreatment in the medical management of first trimester missed miscarriage.

Design

This was a prospective randomized case-control study.

Patients and Methods

Four hundred and thirty-eight women were randomly divided into two groups of 219; the placebo group received placebo tablets twice daily for 3 days, followed by 800 micrograms of misoprostol vaginally on the fourth day of enrolment, while the letrozole group received letrozole 10 mg twice daily for three days followed by 800 micrograms misoprostol administered vaginally. Symptoms and side effects were recorded, and the women advised to return to hospital if they experienced severe pain or bleeding or intolerable side effects and to report to hospital for a check-up one week after misoprostol administration. Ultrasound was done seven days after misoprostol administration to monitor outcomes. Surgical evacuation was carried out if medical management failed.

Results

There were significant differences between the two groups, with better outcomes found for the letrozole group in terms of rates of complete miscarriage, onset of vaginal bleeding, and interval between induction and onset of expulsion (p < 0.001). A higher rate of nausea and vomiting was reported for the letrozole group (p = 0.002). Differences between groups with regard to pre- and post-termination hemoglobin levels, fever, severe pain and severe bleeding needing evacuation were not statistically significant.

Conclusion

Adding letrozole to misoprostol improves the success rate and decreases the interval between induction and expulsion in cases of first trimester miscarriage; however, nausea and vomiting is higher with letrozole.

Fetal safety profile of aromatase inhibitors: Animal data

Aromatase inhibitors (AIs) are a class of drugs that act by blocking the production of estrogens from androgens. The current review concentrates on the prenatal developmental toxicity of AIs in experimental models. Available data indicate that AIs may affect pregnancy at human therapeutic or lower doses. The window of vulnerability to AIs is not limited to organogenesis, but also includes the preimplantation stage and fetal periods. Decreased embryo/fetal survival was the prominent treatment-related effect. Morphological anomalies noted in fetuses exposed to AIs included skeletal anomalies, abnormal head morphology, increased ano-genital distance in female fetuses, and minor urinary tract system anomalies. Placental enlargement was consistently reported in rats and non-human primates after maternal treatment with several AIs. In conclusion, data from basic scientific research suggest that low intensity exposure to AIs applied during a wide gestational window can profoundly affect prenatal development.

The effectiveness of using misoprostol with and without letrozole for successful medical abortion: A randomized placebo-controlled clinical trial

Background:

In developing countries it is important to the exploration of available and safe regimens for medical abortion. The present study was designed to assess the effect of letrozole compared to placebo pretreatment followed by sublingual misoprostol for therapeutic abortion in eligible women with gestational age less than 17 weeks.

Materials and Methods:

In this randomized control trail, 130 women eligible for legal abortions were randomly divided into two groups of case and controls. Cases received daily oral dose of 10 mg letrozole 10 mg letrozole for three days followed by sublingual misoprostol. Controls received daily oral dose of placebo followed by sublingual misoprostol. The dose of misoprostol was administrated according to ACOG guidelines based on patients’ gestational age. The rate of complete abortion, induction-of-abortion time, and side-effects were assessed as main outcomes.

Results:

Complete abortion was observed in 46 (76.7%) letrozole group and 26 (42.6%) controls (P < 0.0001). Also, in 14 subjects of letrozole group and 35 subjects in placebo group, the placenta was not delivered during follow-up and curettage was performed. The mean interval induction-to-abortion was 5.1 h in letrozole group and 8.9 h in control (P < 0.0001). The cumulative rates of the induction-of-abortion time were a significant difference between the two groups (P < 0.0001). The incidence and severity of side-effects was comparable for the two groups (P = 0.9).

Conclusion:

Letrozole could be a quite beneficial adjuvant to misoprostol for induction of complete abortion in those who are candidates for legal medical abortion.