A comparison of letrozole to gonadotropins for ovulation induction, in subjects who failed to conceive with clomiphene citrate

A comparison of oral versus injectable ovarian stimulation in IUI in women ≥38 years of age with decreased ovarian reserve

PURPOSE

To compare pregnancy rates of oral ovarian hyperstimulation agents (clomiphene citrate (CC) and letrozole) versus injectable agents (gonadotropins) in intrauterine insemination (IUI) in the older reproductive age group with diminished ovarian reserve.

METHODS

A retrospective cohort study was performed among 210 women 38-43 years of age undergoing IUI with controlled ovarian hyperstimulation (COH) at a single academic institution between 2009 and 2018.

RESULTS

A total of 335 IUI cycles met inclusion criteria. Gonadotropins were the most frequently used ovarian hyperstimulation agent (n = 264), followed by CC (n = 38) and letrozole (n = 33). Mean age of the cohort was 40.5 (±1.6) years (range 38-43) did not differ significantly among groups (p = 0.41). Mean AFC and number of mature follicles on day of ovulation trigger also did not differ among groups (p = 0.98, p = 0.10). Overall clinical pregnancy rate was 7.5% per cycle, and rates for CC, letrozole, and gonadotropins respectively were 5.3%, 9.1%, 7.5% per cycle (p = 0.347). There was one multiple gestation pregnancy (twins), which was in a patient stimulated with gonadotropins.

CONCLUSION

This is the first study to compare CC, letrozole, and gonadotropins in older reproductive age women with decreased ovarian reserve. The findings reveal that COH/IUI in older women with decreased ovarian reserve is a viable option (clinical pregnancy rate of 7.5% per cycle), and suggest that oral stimulation agents may be the first-line option, with letrozole having conferred the highest clinical pregnancy rate, 9.1%, which is notable given the typical poor fecundability of this population. However, larger population studies are needed to support this.

Committee Opinion No. 663: Aromatase Inhibitors in Gynecologic Practice

Aromatase inhibitors have been used for the treatment of breast cancer, ovulation induction, endometriosis, and other estrogen-modulated conditions. For women with breast cancer, bone mineral density screening is recommended with long-term aromatase inhibitor use because of risk of osteoporosis due to estrogen deficiency. Based on long-term adverse effects and complication safety data, when compared with tamoxifen, aromatase inhibitors are associated with a reduced incidence of thrombosis, endometrial cancer, and vaginal bleeding. For women with polycystic ovary syndrome and a body mass index greater than 30, letrozole should be considered as first-line therapy for ovulation induction because of the increased live birth rate compared with clomiphene citrate. Lifestyle changes that result in weight loss should be strongly encouraged. Aromatase inhibitors are a promising therapeutic option that may be helpful for the management of endometriosis-associated pain in combination therapy with progestins.

Cost effectiveness of letrozole and purified urinary FSH in treating women with clomiphene citrate-resistant polycystic ovarian syndrome: a randomized controlled trial

We aimed to compare the cost effectiveness of letrozole versus purified urinary follicle stimulating hormone (FSH) in treating patients with clomiphene citrate (CC)-resistant polycystic ovary syndrome (PCOS). This was a randomized trial conducted in Cairo University and Beni-Suef University Hospitals, Egypt. A cohort of 140 eligible women was randomized to receive either letrozole 2.5 mg twice daily for five days, or FSH using a graduated regimen starting with a dose of 75 IU. Treatment was repeated for three months if pregnancy did not occur. There were no significant differences between the two treatments in the cumulative clinical pregnancy rate (30% vs. 34%; p = 0.578), cumulative ovulation rate (47% vs. 57%; p = 0.236), miscarriage rate (9% vs. 4%, p > 0.999) or multiple pregnancy rate (0% and 8%, p = 0.491) but the FSH cycles were 4.8 times more expensive. Letrozole and FSH were both effective in treating women with CC-resistant PCOS but letrozole was more cost effective.Study registration number: NCT02304107.

Letrozole, Gonadotropin, or Clomiphene for Unexplained Infertility

BACKGROUND

The standard therapy for women with unexplained infertility is gonadotropin or clomiphene citrate. Ovarian stimulation with letrozole has been proposed to reduce multiple gestations while maintaining live birth rates.

METHODS

We enrolled couples with unexplained infertility in a multicenter, randomized trial. Ovulatory women 18 to 40 years of age with at least one patent fallopian tube were randomly assigned to ovarian stimulation (up to four cycles) with gonadotropin (301 women), clomiphene (300), or letrozole (299). The primary outcome was the rate of multiple gestations among women with clinical pregnancies.

RESULTS

After treatment with gonadotropin, clomiphene, or letrozole, clinical pregnancies occurred in 35.5%, 28.3%, and 22.4% of cycles, and live birth in 32.2%, 23.3%, and 18.7%, respectively; pregnancy rates with letrozole were significantly lower than the rates with standard therapy (gonadotropin or clomiphene) (P=0.003) or gonadotropin alone (P<0.001) but not with clomiphene alone (P=0.10). Among ongoing pregnancies with fetal heart activity, the multiple gestation rate with letrozole (9 of 67 pregnancies, 13%) did not differ significantly from the rate with gonadotropin or clomiphene (42 of 192, 22%; P=0.15) or clomiphene alone (8 of 85, 9%; P=0.44) but was lower than the rate with gonadotropin alone (34 of 107, 32%; P=0.006). All multiple gestations in the clomiphene and letrozole groups were twins, whereas gonadotropin treatment resulted in 24 twin and 10 triplet gestations. There were no significant differences among groups in the frequencies of congenital anomalies or major fetal and neonatal complications.

CONCLUSIONS

In women with unexplained infertility, ovarian stimulation with letrozole resulted in a significantly lower frequency of multiple gestation but also a lower frequency of live birth, as compared with gonadotropin but not as compared with clomiphene. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01044862.).

Factors associated with nonresponse to ovulation induction using letrozole among women with World Health Organization group II anovulation

CONTEXT:

Letrozole, a third generation aromatase inhibitor is gaining importance in ovulation induction. Some prefer to use it as a second line agent in women who fail to respond to clomifene citrate. However, our knowledge about the predictors of response to letrozole is limited.

AIMS:

The study was aimed at identifying the factors associated with letrozole resistance among women with World Health Organization (WHO) group II anovulation.

SUBJECTS AND METHODS:

Study was conducted at the infertility clinic at a tertiary care hospital in Sri Lanka. A case–control study design was used and included 50 subjects with WHO group II anovulation (25 clomifene responsive and 25 clomifene resistant). After a treatment cycle of letrozole, the factors were compared between the subjects who responded and those who failed to respond to treatment.

RESULTS:

Ovulation was achieved in 76% (n = 19) of subjects who had responded to clomifene previously and in 24% (n = 6) with clomifene resistance. The factors associated with letrozole resistance included the presence of hirsutism (odds ratio [OR]: 3.89; 95% confidence interval [CI]: 1.2–12.3) and clomifene resistance (OR: 10.03; 95% CI: 2.81–35.7). The early follicular phase mean (standard deviation) luteinizing hormone level was significantly higher among the nonresponders (9.75 [4.78] – 7.28 [2.3]; P = 0.02). Nonresponders showed significantly lower levels of oestradiol on the 5^th and 9^th days (28.50 [3.39] pg/mL vs. 7.49 [3.62] pg/mL; P = 0.0007 and 142.04 [76.22] pg/mL vs. 28.10 [12.8] pg/mL; P = 0.0001) of the menstrual cycle, respectively.

CONCLUSIONS:

The features associated with resistance to Letrozole at a dose of 2.5 mg show some overlap with those associated with clomifene resistance. However, some features do not show similar association. The effectiveness of letrozole at a dose of 2.5 mg in induction of ovulation among women with clomifene resistance is low and it does not seem to be a suitable treatment at a dose of 2.5 mg for this indication.

Congenital malformations among babies born following letrozole or clomiphene for infertility treatment

CONTEXT

Clomiphene citrate (CC) is the first line drug for ovulation induction but because of its peripheral antiestrogenic effect, letrozole was introduced as the 2nd line drug. It lacks the peripheral antiestrogenic effect and is associated with similar or even higher pregnancy rates. Since letrozole is a drug for breast cancer, its use for the purpose of ovulation induction became controversial in the light of studies indicating an increased incidence of congenital malformations.

AIMS

To evaluate and compare the incidence of congenital malformations among offsprings of infertile couples who conceived naturally or with clomiphene citrate or letrozole treatment.

SETTINGS AND DESIGN

A retrospective cohort study done at a tertiary infertility centre.

METHODS AND MATERIAL

A total of 623 children born to infertile women who conceived naturally or following clomiphene citrate or letrozole treatment were included in this study. Subjects were sorted out from medical files of both mother and newborn and follow up study was done based on the information provided by parents through telephonic conversations. Babies with suspected anomaly were called and examined by specialists for the presence of major and minor congenital malformations. Other outcomes like multiple pregnancy rate and birth weight were also studied.

RESULTS

Overall, congenital malformations, chromosomal abnormalities were found in 5 out of 171 (2.9%) babies in natural conception group and 5 out of 201 babies in the letrozole group (2.5%) and in 10 of 251 babies in the CC group (3.9%).

CONCLUSIONS

There was no significant difference in the overall rate of congenital malformations among children born to mothers who conceived naturally or after letrozole or CC treatment.

KEY MESSAGES

Congenital malformations have been found to be comparable following natural conception, letrozole and clomiphene citrate. Thus, the undue fear against letrozole may be uncalled for.

Effect of gonadotropin-releasing hormone antagonists on intrauterine insemination cycles in women with polycystic ovary syndrome: a meta-analysis

Polycystic ovary syndrome (PCOS) patients undergoing controlled ovarian stimulation and intrauterine insemination (COS/IUI) often face the risk of premature luteinization, which may result in lower pregnancy rate and higher miscarriage rate. This review was performed to identify if adjuvant treatment with GnRH antagonist (GnRH-ant) could effectively improve the clinical outcome of patients with PCOS undergoing COS/IUI. A literature search was conducted on the PubMed, EMBASE and Cochrane library databases. Two randomized controlled trials were included in this review, enrolling a total of 333 cycles. The patients who received GnRH-ant treatment had lower progesterone levels on the hCG day and a reduced premature luteinization rate. However, the rates of live birth, clinical pregnancy and miscarriage did not significantly differ between the GnRH-ant supplementation group and control group. In conclusion, although the existing randomized controlled trials indicate that GnRH-ant can effectively decrease the premature luteinizaton rate, evidence to support its use to improve clinical pregnancy outcomes in PCOS patients undergoing COS/IUI treatment is insufficient.

Endometrial receptivity markers in infertile women stimulated with letrozole compared with clomiphene citrate and natural cycles

Though various advantages associated with the use of letrozole as an ovulation inducing drug are documented, there is inadequate information regarding its effect on endometrial receptivity. Expression of endometrial receptivity markers including αvβ3 integrin, L-selectin, LIF, and pinopods during the implantation window in infertile women stimulated with letrozole or clomiphene citrate (CC), and spontaneous cycles is investigated. A total of 36 women were included in the study out of which 16 women were diagnosed with primary unexplained infertility and the other 20 women with severe oligoasthenozoospermic/azoospermic male partners. Both groups were sub-divided into three groups; women stimulated with letrozole, or with CC, and the third group was allowed to ovulate spontaneously (natural cycles). Women having natural cycles and not given any drug were considered as controls. Once ovulation was confirmed by ultrasonography, endometrial samples were collected on the seventh day post-ovulation and analyzed. In women with unexplained infertility treated with letrozole and CC, epithelial and stromal expression of αvβ3 integrin, L-selectin, leukemia inhibitory factor (LIF), and pinopod formation was found to be significantly higher as compared to controls. Expression of these receptivity markers was found to be comparable amongst the letrozole, CC, and control groups in women with severe oligoasthenozoospermic/azoospermic male partners. Cell cycle analysis showed similar cell cycle phase fractions on comparing the CC and the letrozole groups. Stimulation with letrozole and CC appears to enhance endometrial receptivity in women with unexplained infertility. However, letrozole and CC did not have any significant effect on the endometrial receptivity markers of women with severe oligoasthenozoospermic/azoospermic male partners.

Sequential clomiphene citrate/hMG versus hMG for ovulation induction in clomiphene citrate-resistant women

OBJECTIVE

This study was designed to compare sequential clomiphene citrate/hMG regimen to hMG regimen for ovulation induction in clomiphene citrate-resistant women.

STUDY DESIGN

A comparative prospective study.

PATIENTS AND METHODS

Ninety infertile women were randomized to receive either sequential CC/hMG regimen (45 women) or low-dose step-up protocol of hMG (45 women). All participants had received at least six consecutive cycles of clomiphene citrate for ovulation induction within the last year before inclusion in this study, but they did not conceive. The CC/hMG regimen group received clomiphene citrate 100 mg/day for 5 days, followed by hMG 75 IU for 4 days. The hMG group received low-dose step-up protocol for 10-14 days. To detect the number and size of the follicles, TVS was done on cycle day 8 and repeated daily or every other day according to follicular development. When one to three follicles reached a diameter ≥18 mm, hCG injection was scheduled. Before hCG injection, the E2 level and endometrial thickness were evaluated. β-hCG levels were measured on cycle day 22.

RESULTS

There was no significant difference between the two studied groups regarding the demographic data, sperm parameters, and day 3 FSH, LH and estradiol. Also, there was no significant difference between the two studied groups regarding endometrial thickness, number of mature follicles, peak of E2 before hCG injection and number of cases that developed ovarian cyst or OHSS. The dose of gonadotropins used was significantly low in the CC/hMG group compared to the hMG group (295.2 ± 75.5 vs. 625.3 ± 65.0, respectively), and the pregnancy rate was significantly high in the CC/hMG group compared to the hMG group [12 (26.7 %) vs. 3 (6.7 %), respectively, p < 0.05].

CONCLUSION

The sequential CC/hMG regimen is as effective as hMG regimen for ovulation induction, produces satisfactory pregnancy results and reduces the treatment cost.

Infertility: evaluation and initial management

Treating the infertile client with competence and compassion is within the scope of practice for advanced practice clinicians. However, due to both a lack of emphasis on infertility treatment in many advanced practice education programs and confusion regarding diagnosis and treatment by many practitioners, infertility is often undertreated by these providers. A basic infertility evaluation, patient counseling, and prescriptive therapy with oral ovulation-inducing agents by a knowledgeable practitioner is cost-effective and may result in successful pregnancy in women who otherwise may not be adequately and quickly treated prior to referral to a reproductive endocrinologist. A diagnosis of infertility is often stressful and frustrating for a couple. Midwives and advanced practice nurses are uniquely qualified to provide both compassionate care and competent treatment during this time. This article provides the clinician with an overview of infertility diagnosis, evaluation, and initial management with lifestyle modifications and oral ovulation-inducing agents.

Letrozole or clomiphene citrate as first line for anovulatory infertility: a debate

Clomiphene citrate has been traditionally used as the drug of choice in treating women with anovulatory infertility. In the last decade letrozole, an aromatase inhibitor has emerged as alternative ovulation induction agent. Literature confirms that letrozole has a definitive role in anovulatory women who have not responded to the clomiphene therapy. However its role as an alternative to clomiphene as first line therapy continues to be debated. Although it is probable that the overall benefits of letrozole surpass clomiphene citrate, currently available data does not confirm this view. There is need for large well-designed trials.

Letrozole for ovulation induction and controlled ovarian hyperstimulation

PURPOSE OF REVIEW

Letrozole, an aromatase inhibitor, is the newest addition to our armamentarium in the treatment of infertility. It is utilized in much the same way as clomiphene citrate, but with some additional benefits. In this review, the latest studies will be summarized with emphasis on dose, duration of use, safety, number of mature follicles, and pregnancy outcomes.

RECENT FINDINGS

Letrozole has fewer side effects, and a shorter half-life than clomiphene citrate, and no demonstrable effect upon the receptivity of the endometrium. It is efficacious in treating women with chronic anovulation, unexplained infertility and diminished ovarian reserve. Its safety is superior to clomiphene citrate. Utilizing bio-equivalent doses, letrozole pregnancy rates are equal or superior to clomiphene citrate. Several studies suggest situations where it is more efficacious than gonadotropin treatment.

SUMMARY

With further study, this drug could replace clomiphene citrate as the primary medication for chronic anovulation and/or unexplained infertility. It could augment or even obviate the use of gonadotropins in the treatment of women who have been unsuccessful in achieving pregnancy with clomiphene citrate. It may also be an adjunct for women with diminished ovarian reserve. Further studies are needed to determine optimal dosing and long term safety for women treated with the drug.

Aromatase inhibitors for female infertility: a systematic review of the literature

Ovulation induction remains a milestone in the treatment of women with anovulatory infertility. Clomiphene citrate (CC) is considered the first line treatment for induction of ovulation in women with polycystic ovary syndrome (PCOS), while it may be used for ovulation induction in unexplained infertility. Aromatase inhibitors (AI) have been introduced as a new treatment option that could challenge CC for ovulation induction. A systematic review of the literature was conducted in order to highlight the efficacy and safety of AI in female infertility. Current data from randomized and non-randomized trials suggest that AI may have a role in ovulation induction regimens in PCOS patients, as well as for ovarian stimulation, since they achieve comparable clinical pregnancy rates to CC. Furthermore, when combined with gonadotrophins, AI improve the ovarian response of poor responders and reduce the gonadotrophin dose required. However, the current review is based on small trials with a limited number of patients. If solid data from future large adequately powered randomized trials support current evidence regarding efficacy and safety, AI might offer a new treatment choice for infertile women.

Comparison of letrozole with continuous gonadotropins and clomiphene-gonadotropin combination for ovulation induction in 1387 PCOS women after clomiphene citrate failure: a randomized prospective clinical trial

PURPOSE

Letrozole, though reported to be an effective ovulation inducing agent, warrants larger randomized trials. The purpose of this study is to compare the efficacy of letrozole with that of rFSH and clomiphene citrate(CC)/rFSH for ovarian stimulation in IUI cycles.

METHODS

Randomized, prospective, single-blinded clinical trial. 1387 PCOS women after CC failure were randomized into three groups: Group A received letrozole, Group B received CC with two doses rFSH and Group C received continuous rFSH day 2 onwards until hCG injection.

RESULTS

Group A, B and C had an ovulation rate of 79.30%, 56.95% and 89.89% and cycle cancellation rate of 20.70%, 43.05% and 10.11%, respectively. Pregnancy rates in Group A, B and C were 23.39%, 14.35% and 17.92%, while the miscarriage rates were 13.80%, 16.67% and 14.52%, respectively.

CONCLUSION

Letrozole appears to be a suitable ovulation inducing agent in PCOS women with CC failure and is found to be most effective when baseline estradiol level >60 pg/ml.