A pilot study on the use of a 7-day course of letrozole followed by misoprostol for the termination of early pregnancy up to 63 days

The Effectiveness of Letrozole Alone or in Combination with Methotrexate in the Management of Ectopic Pregnancy, A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to investigate the effect of letrozole alone or in combination with Methotrexate on the management of ectopic pregnancy. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were applied for reporting. The EMBASE, PubMed, Scopus, and Web of Science databases were searched for relevant studies focused on women diagnosed with ectopic pregnancy and managed non-surgically with letrozole alone or in combination with methotrexate (MTX) until April 2024. The success rate, laboratory findings, and complications were analyzed and reported. Meta-analysis was done using RevMan 5.4.1 software. Out of 129 unique studies obtained, 7 of them were found eligible for final review; of which, 3 were nonrandomized prospective cohort studies, 2 were randomized clinical trials, and 2 study were case studies. In 5 studies letrozole was used as monotherapy. While in another study letrozole was used with MTX. The meta-analysis showed a significantly lower level of β-HCG in the letrozole group compared to MTX, 7 days after initiation of treatment (Fixed effect model, MD = -92.22, 95%CI: [-159.39, -25.04], P = 0.007, I2 = 0%). There was no significant difference in the level of anti-mullerian hormone (AMH) between groups (Fixed effect model, MD = 0.18, 95%CI: [-0.09, 0.45], P = 0.20, I2 = 0%). Success rate, platelet count, and level of liver enzymes seemed to be better or similar among patients receiving Letrozole compared to patients receiving Methotrexate. Letrozole exhibits potential as a therapeutic option for ectopic pregnancies; however, further randomized clinical trials are necessary to establish strong evidence.

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.

Single dose letrozole and misoprostol for termination of pregnancy through 63 days' gestation: A pilot study

OBJECTIVES

We conducted a pilot study to evaluate a single dose of letrozole 30 mg prior to misoprostol 800 mcg buccally for medication abortion STUDY DESIGN: We enrolled 40 participants seeking medication abortion up to 63 days' gestation at a site in Salt Lake City, UT. Participants received a single dose of letrozole 30 mg in-clinic followed 2 days later by misoprostol 800 mcg buccally at home. They took a second dose of misoprostol if they had no bleeding within 24 hours of the first. Participants returned 7 to 10 days later for assessment of abortion outcome and side effects RESULTS: Thirty-seven participants (93%) returned for follow-up and 2 (5%) went to another facility from which research staff obtained outcome data. Three-fourths (29/39, 74%, 95% CI: 60%-89%) had a complete abortion; 4 (10%, 95% CI: 0.3%-20%) had an incomplete abortion and opted for aspiration, and 6 (15%, 95% CI: 4%-27%) had an ongoing pregnancy. All subjects with follow-up reported taking the first dose of misoprostol. Ten (27%) took the second dose as well; only three did so due to no bleeding. Nineteen participants (51%) reported side effects after letrozole prior to misoprostol and two people (5%) rated these effects as severe. Side effects following misoprostol occurred in 33 participants (89%) and were as expected based on previous literature. No serious adverse events were reported CONCLUSION: A single dose of letrozole 30 mg followed by misoprostol had lower than desirable efficacy and does not warrant further study.

IMPLICATIONS

A single dose of letrozole does not appear to be an effective adjunct to misoprostol for medication abortion.

Medical methods for first trimester abortion

BACKGROUND

Medical abortion became an alternative method of pregnancy termination following the development of prostaglandins and antiprogesterone in the 1970s and 1980s. Recently, synthesis inhibitors of oestrogen (such as letrozole) have also been used to enhance efficacy. The most widely researched drugs are prostaglandins (such as misoprostol, which has a strong uterotonic effect), mifepristone, mifepristone with prostaglandins, and letrozole with prostaglandins. More evidence is needed to identify the best dosage, regimen, and route of administration to optimise patient outcomes. This is an update of a review last published in 2011.

OBJECTIVES

To compare the effectiveness and side effects of different medical methods for first trimester abortion.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Global Health, and LILACs on 28 February 2021. We also searched Clinicaltrials.gov and the World Health Organization's (WHO) International Clinical Trials Registry Platform, and reference lists of retrieved papers.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) that compared different medical methods for abortion before the 12th week of gestation. The primary outcome is failure to achieve complete abortion. Secondary outcomes are mortality, surgical evacuation, ongoing pregnancy at follow-up, time until passing of conceptus, blood transfusion, side effects and women's dissatisfaction with the method.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected and evaluated studies for inclusion, and assessed the risk of bias. We processed data using Review Manager 5 software. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 99 studies in the review (58 from the original review and 41 new studies). 1. Combined regimen mifepristone/prostaglandin Mifepristone dose: high-dose (600 mg) compared to low-dose (200 mg) mifepristone probably has similar effectiveness in achieving complete abortion (RR 1.07, 95% CI 0.87 to 1.33; I2 = 0%; 4 RCTs, 3494 women; moderate-certainty evidence). Prostaglandin dose: 800 µg misoprostol probably reduces abortion failure compared to 400 µg (RR 0.63, 95% CI 0.51 to 0.78; I2= 0%; 3 RCTs, 4424 women; moderate-certainty evidence). Prostaglandin timing: misoprostol administered on day one probably achieves more success on complete abortion than on day three (RR 1.94, 95% CI 1.05 to 3.58; 1489 women; 1 RCT; moderate-certainty evidence). Administration strategy: there may be no difference in failure of complete abortion with self-administration at home compared with hospital administration (RR 1.63, 95% CI 0.68 to 3.94; I2 = 84%; 2263 women; 4 RCTs; low-certainty evidence), but failure may be higher when administered by nurses in hospital compared to by doctors in hospital (RR 2.69, 95% CI 1.39 to 5.22; I2 = 66%; 3 RCTs, 3056 women; low-certainty evidence). Administration route: oral misoprostol probably leads to more failures than the vaginal route (RR 2.38, 95% CI 1.46 to 3.87; I2 = 39%; 3 RCTs, 1704 women; moderate-certainty evidence) and may be associated with more frequent side effects such as nausea (RR 1.14, 95% CI 1.03 to 1.26; I2 = 0%; 2 RCTs, 1380 women; low-certainty evidence) and diarrhoea (RR 1.80 95% CI 1.49 to 2.17; I2 = 0%; 2 RCTs, 1379 women). Compared with the vaginal route, complete abortion failure is probably lower with sublingual (RR 0.68, 95% CI 0.22 to 2.11; I2 = 59%; 2 RCTs, 3229 women; moderate-certainty evidence) and may be lower with buccal administration (RR 0.71, 95% CI 0.34 to 1.46; I2 = 0%; 2 RCTs, 479 women; low-certainty evidence), but sublingual or buccal routes may lead to more side effects. Women may experience more vomiting with sublingual compared to buccal administration (RR 1.33, 95% CI 1.01 to 1.77; low-certainty evidence). 2. Mifepristone alone versus combined regimen The efficacy of mifepristone alone in achieving complete abortion compared to combined mifepristone/prostaglandin up to 12 weeks is unclear (RR of failure 3.25, 95% CI 0.81 to 13.09; I2 = 83%; 3 RCTs, 273 women; very low-certainty evidence). 3. Prostaglandin alone versus combined regimen Nineteen studies compared prostaglandin alone to a combined regimen (prostaglandin combined with mifepristone, letrozole, estradiol valerate, tamoxifen, or methotrexate). Compared to any of the combination regimens, misoprostol alone may increase the risk for failure to achieve complete abortion (RR of failure 2.39, 95% CI 1.89 to 3.02; I2 = 64%; 18 RCTs, 3471 women; low-certainty evidence), and with more diarrhoea. 4. Prostaglandin alone (route of administration) Oral misoprostol alone may lead to more failures in complete abortion than the vaginal route (RR 3.68, 95% CI 1.56 to 8.71, 2 RCTs, 216 women; low-certainty evidence). Failure to achieve complete abortion may be slightly reduced with sublingual compared with vaginal (RR 0.69, 95% CI 0.37 to 1.28; I2 = 87%; 5 RCTs, 2705 women; low-certainty evidence) and oral administration (RR 0.58, 95% CI 0.11 to 2.99; I2 = 66%; 2 RCTs, 173 women). Failure to achieve complete abortion may be similar or slightly higher with sublingual administration compared to buccal administration (RR 1.11, 95% CI 0.71 to 1.74; 1 study, 401 women).

AUTHORS' CONCLUSIONS

Safe and effective medical abortion methods are available. Combined regimens (prostaglandin combined with mifepristone, letrozole, estradiol valerate, tamoxifen, or methotrexate) may be more effective than single agents (prostaglandin alone or mifepristone alone). In the combined regimen, the dose of mifepristone can probably be lowered to 200 mg without significantly decreasing effectiveness. Vaginal misoprostol is probably more effective than oral administration, and may have fewer side effects than sublingual or buccal. Some results are limited by the small numbers of participants on which they are based. Almost all studies were conducted in settings with good access to emergency services, which may limit the generalisability of these results.

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.

Misclassification in Assessment of First Trimester In-utero Exposure to Drugs Used Proximally to Conception: the Example of Letrozole Utilization for Infertility Treatment

Letrozole is an aromatase inhibitor that has an unapproved use for ovulation induction with infertility. Because of the proximity of this use to conception, we selected letrozole to study the effect of 3 different methods for identifying the pregnancy start date and their impact on exposure misclassification. Using electronic health data from the US Sentinel database (2001-2015), we identified live-birth pregnancies conceived through in-vitro fertilization or intrauterine insemination. The pregnancy start was calculated using 1) a validated algorithm to estimate the last menstrual period (LMP), 2) LMP + 14 days (i.e., conception estimate), and 3) the fertility-procedure date. We identified 47,628 live-births after intrauterine insemination (n = 24,962) and in-vitro fertilization (n = 22,666), in which 2,458 (5.3%) mothers received letrozole. The algorithm-based conception estimate occurred within 14 days of the fertility procedure for 78.3% of pregnancies. Defining pregnancy start as LMP (45.7/1,000 pregnancies) or LMP + 14 days (12.7/1,000 pregnancies) overestimated letrozole exposure during pregnancy by 8.4-fold and 2.3-fold, respectively, compared with defining it at the date of the fertility procedure (5.5/1,000 pregnancies). While most studies of drug utilization in pregnancy use LMP as the conventional pregnancy start, this introduced substantial exposure misclassification in the example of letrozole. LMP + 14 days was less biased. Researchers should carefully consider the impact of the method for identifying the pregnancy start date on the potential for exposure misclassification.

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.

The effect of 7 days of letrozole pretreatment combined with misoprostol on the expression of progesterone receptor and apoptotic factors of placental and decidual tissues from first-trimester abortion: a randomized controlled trial

OBJECTIVE

To evaluate if letrozole-induced suppression of estradiol reduces progesterone receptor expression and apoptosis in the first-trimester placenta.

STUDY DESIGN

We performed a double-blinded, randomized, placebo-controlled trial. We randomized 20 women requesting first-trimester abortion with gestation up to 63 days to receive either letrozole 10 mg daily or placebo pretreatment for 7 days before administrating 400 mcg of vaginal misoprostol followed by suction abortion. We collected the placental and decidual tissues on which we performed immunohistochemical staining for progesterone receptor and apoptotic markers (active caspase 3, caspase 3, Bcl2, CD95, fas ligand) and determined H-scores of each based on the intensities of staining. We performed terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay for apoptosis in the samples of four women to confirm the findings from apoptotic markers.

RESULTS

We excluded one woman in the letrozole group from the analysis because she had passage of abortus after taking letrozole, leaving 19 women (9 in the letrozole group, 10 in the placebo group) for analysis. There was no significant difference in the H-scorings of progesterone receptor and apoptotic markers, as well as proportion of apoptotic cells on TUNEL assay between the two groups. The H-scores for the progesterone receptor were 8.17 ± 2.67 (mean ± SD) in the letrozole group and 9.01 ± 2.82 in the placebo group (p=0.36).

CONCLUSION

We did not detect a difference in the expression of progesterone receptor and apoptotic markers in placental and decidual tissues after letrozole pretreatment for 7 days in first-trimester abortion.

IMPLICATIONS

We did not confirm the hypothesis that letrozole reduces progesterone receptor expression and induces apoptosis in the first-trimester placenta. Further studies are required to allow better understanding of the mechanism by which estrogen suppression following the use of letrozole can lead to improved abortion rate in the first trimester.

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.