A randomized trial of superovulation with two different doses of letrozole

A comparison of letrozole regimens for ovulation induction in women with polycystic ovary syndrome

Objective

To determine the optimal letrozole regimen for ovulation induction (OI) in women with polycystic ovary syndrome (PCOS).

Design

Retrospective cohort study.

Setting

Single academic fertility clinic from 2015-2022.

Patients

A total of 189 OI cycles in 52 patients with PCOS.

Interventions

Patients were prescribed 1 of 4 letrozole regimens (group 1: 2.5 mg for 5 days, group 2: 2.5 mg for 10 days, group 3: 5 mg for 5 days, and group 4: 5 mg for 10 days).

Main outcome measures

The primary outcome was ovulation, and secondary outcomes included multifollicular development, and clinical pregnancy rate, which were analyzed with binary logistic regression. Kaplan-Meier cumulative response curves and a Cox proportional hazard regression model were used for time-dependent analyses.

Results

Mean age was 30.9 years (standard deviation [SD], 3.6) and body mass index was 32.1 kg/m2 (SD, 4.0). Group 2 (odds ratio [OR], 9.12; 95% confidence interval [CI], 1.92-43.25), group 3 (OR, 3.40; 95% CI, 1.57-7.37), and group 4 (OR, 5.94; 95% CI, 2.48-14.23) had improved ovulation rates after the starting regimen as compared with group 1. Cumulative ovulation rates exceeded 84% in all groups, yet those who received 5 mg and/or 10 days achieved ovulation significantly sooner. Multifollicular development was not increased in groups 2-4 as compared with group 1. Groups 2-4 also demonstrated improved time to pregnancy.

Conclusions

Ovulation rates are improved when starting with letrozole at 5 mg and/or a 10-day extended course as compared with the frequently-used 2.5 mg for 5 days. This may shorten time to ovulation and pregnancy.

Agents for ovarian stimulation for intrauterine insemination (IUI) in ovulatory women with infertility

BACKGROUND

Intrauterine insemination (IUI), combined with ovarian stimulation (OS), has been demonstrated to be an effective treatment for infertile couples. Several agents for ovarian stimulation, combined with IUI, have been proposed, but it is still not clear which agents for stimulation are the most effective. This is an update of the review, first published in 2007.

OBJECTIVES

To assess the effects of agents for ovarian stimulation for intrauterine insemination in infertile ovulatory women.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two trial registers from their inception to November 2020. We performed reference checking and contacted study authors and experts in the field to identify additional studies.

SELECTION CRITERIA

We included truly randomised controlled trials (RCTs) that compared different agents for ovarian stimulation combined with IUI for infertile ovulatory women concerning couples with unexplained infertility. mild male factor infertility and minimal to mild endometriosis.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane.

MAIN RESULTS

In this updated review, we have included a total of 82 studies, involving 12,614 women. Due to the multitude of comparisons between different agents for ovarian stimulation, we highlight the seven most often reported here. Gonadotropins versus anti-oestrogens (13 studies) For live birth, the results of five studies were pooled and showed a probable improvement in the cumulative live birth rate for gonadotropins compared to anti-oestrogens (odds ratio (OR) 1.37, 95% confidence interval (CI) 1.05 to 1.79; I² = 30%; 5 studies, 1924 participants; moderate-certainty evidence). This suggests that if the chance of live birth following anti-oestrogens is assumed to be 22.8%, the chance following gonadotropins would be between 23.7% and 34.6%. The pooled effect of seven studies revealed that we are uncertain whether gonadotropins lead to a higher multiple pregnancy rate compared with anti-oestrogens (OR 1.58, 95% CI 0.60 to 4.17; I² = 58%; 7 studies, 2139 participants; low-certainty evidence). Aromatase inhibitors versus anti-oestrogens (8 studies) One study reported live birth rates for this comparison. We are uncertain whether aromatase inhibitors improve live birth rate compared with anti-oestrogens (OR 0.75, CI 95% 0.51 to 1.11; 1 study, 599 participants; low-certainty evidence). This suggests that if the chance of live birth following anti-oestrogens is 23.4%, the chance following aromatase inhibitors would be between 13.5% and 25.3%. The results of pooling four studies revealed that we are uncertain whether aromatase inhibitors compared with anti-oestrogens lead to a higher multiple pregnancy rate (OR 1.28, CI 95% 0.61 to 2.68; I² = 0%; 4 studies, 1000 participants; low-certainty evidence).  Gonadotropins with GnRH (gonadotropin-releasing hormone) agonist versus gonadotropins alone (4 studies) No data were available for live birth. The pooled effect of two studies  revealed that we are uncertain whether gonadotropins with GnRH agonist lead to a higher multiple pregnancy rate compared to gonadotropins alone (OR 2.53, 95% CI 0.82 to 7.86; I² = 0; 2 studies, 264 participants; very low-certainty evidence).  Gonadotropins with GnRH antagonist versus gonadotropins alone (14 studies) Three studies reported live birth rate per couple, and we are uncertain whether gonadotropins with GnRH antagonist improve live birth rate compared to gonadotropins (OR 1.5, 95% CI 0.52 to 4.39; I² = 81%; 3 studies, 419 participants; very low-certainty evidence). This suggests that if the chance of a live birth following gonadotropins alone is 25.7%, the chance following gonadotropins combined with GnRH antagonist would be between 15.2% and 60.3%. We are also uncertain whether gonadotropins combined with GnRH antagonist lead to a higher multiple pregnancy rate compared with gonadotropins alone (OR 1.30, 95% CI 0.74 to 2.28; I² = 0%; 10 studies, 2095 participants; moderate-certainty evidence). Gonadotropins with anti-oestrogens versus gonadotropins alone (2 studies) Neither of the studies reported data for live birth rate. We are uncertain whether gonadotropins combined with anti-oestrogens lead to a higher multiple pregnancy rate compared with gonadotropins alone, based on one study (OR 3.03, 95% CI 0.12 to 75.1; 1 study, 230 participants; low-certainty evidence). Aromatase inhibitors versus gonadotropins (6 studies) Two studies  revealed that aromatase inhibitors may decrease live birth rate compared with gonadotropins (OR 0.49, 95% CI 0.34 to 0.71; I²=0%; 2 studies, 651 participants; low-certainty evidence). This suggests that if the chance of a live birth following gonadotropins alone is 31.9%,  the chance of live birth following aromatase inhibitors would be between 13.7% and 25%. We are uncertain whether aromatase inhibitors compared with gonadotropins lead to a higher multiple pregnancy rate (OR 0.69, 95% CI 0.06 to 8.17; I²=77%; 3 studies, 731 participants; very low-certainty evidence).  Aromatase inhibitors with gonadotropins versus anti-oestrogens with gonadotropins (8 studies) We are uncertain whether aromatase inhibitors combined with gonadotropins improve live birth rate compared with anti-oestrogens plus gonadotropins (OR 0.99, 95% CI 0.3 8 to 2.54;  I² = 69%; 3 studies, 708 participants; very low-certainty evidence). This suggests that if the chance of a live birth following anti-oestrogens plus gonadotropins is 13.8%, the chance following aromatase inhibitors plus gonadotropins would be between 5.7% and 28.9%. We are uncertain of the effect of aromatase inhibitors combined with gonadotropins compared to anti-oestrogens combined with gonadotropins on multiple pregnancy rate (OR 1.31, 95% CI 0.39 to 4.37;  I² = 0%; 5 studies, 901 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Based on the available results, gonadotropins probably improve cumulative live birth rate compared with anti-oestrogens (moderate-certainty evidence). Gonadotropins may also improve cumulative live birth rate when compared with aromatase inhibitors (low-certainty evidence). From the available data, there is no convincing evidence that aromatase inhibitors lead to higher live birth rates compared to anti-oestrogens. None of the agents compared lead to significantly higher multiple pregnancy rates. Based on low-certainty evidence, there does not seem to be a role for different combined therapies, nor for adding GnRH agonists or GnRH antagonists in IUI programs.

Effects of using letrozole in combination with the GnRH antagonist protocol for patients with poor ovarian response: A meta-analysis

This meta-analysis aimed to compare the outcomes of the gonadotrophin-releasing hormone (GnRH) antagonist/letrozole protocol with those of the conventional GnRH antagonist protocol for poor responders undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). We searched for relevant articles in PubMed, EMBASE, Google Scholar, and retrieved 452 records. Eventually, we selected five eligible trials with data for 564 patients characterized as poor ovarian responders. Our meta-analysis revealed that the clinical pregnancy rate (per cycle) with administration of letrozole might be a higher than that in the control groups (risk rate [RR]: 1.57, 95% confidence interval [CI]: 1.00-2.44, p = 0.05). .Moreover,it indicated that the total dose of gonadotrophin was significantly decreased with the administration of letrozole compared to control groups(mean difference [MD]: -529.37, 95% CI: -1207.45 to -111.25, p = 0.001),.However, there was no statistical difference in the number of retrieved oocytes(MD: 0.59, 95% CI: -0.36-1.54, p = 0.22), cycle cancelation rate (RR: 0.81, 95% CI: 0.58-1.12, p = 0.20), or estradiol concentration on the day of HCG administration(MD: -28.19, 95% CI: -77.71-21.33, p = 0.26) in the presence or absence of letrozole combination in the GnRH antagonist protocol. In conclusion, letrozole administration might improve clinical pregnancy rate in conventional GnRH antagonist protocol for poor responders. Moreover, letrozole co-treatment aslo can reduce the economic burden of poor responders during the GnRH antagonist cycle. Nevertheless, large-scale and multi-center randomized controlled trials are needed to further evaluate the efficacy of adjunctive letrozole administration in the GnRH antagonist protocol.

Infertility management in women with polycystic ovary syndrome: a review

Polycystic ovary syndrome is the most common endocrine disorder in women and a major cause of anovulatory infertility. Various medical options are used, alone or in combination, to treat subfertility associated with polycystic ovary syndrome. This narrative review was conducted to provide an update and summarize the available evidence on the management of polycystic ovary syndrome related infertility. A wide literature search was performed and preferably randomized controlled trials and systematic reviews were included. Management is often centered on lifestyle changes. Pharmacological ovulation induction is the next step, with recommended use of letrozole, clomiphene citrate or gonadotropins. When it fails, assisted reproductive technologies or laparoscopic ovarian drilling are frequently advised. Combination treatment with metformin is often recommended. More recent alternative and adjunctive treatments have been suggested, like inositol, vitamin D, bariatric surgery and acupuncture, but further research is needed for recommendation.

Comparison of clomiphene and letrozole for superovulation in patients with unexplained infertility undergoing intrauterine insemination: A systematic review and meta-analysis

BACKGROUND

With the medical advancement some studies put forward that letrozole (LE), a specific aromatase inhibitor with the function of reducing oestrogen synthesis, has recently been applied as a potentially better alternative compared with clomiphene citrate (CC), owing to that it has a superior efficacy as compared with CC in patients of unexplained infertility undergoing intrauterine insemination (IUI). However, there is no one study can clear and definite whether LE can replace the CC as first line drug.

OBJECTIVE

Our objective is to compare the LE with CC in the induction of ovulation in patients with unexplained infertility IUI.

METHOD

Searching databases consist of all kinds of searching tools, such as Medline, The Cochrane Library, Embase, PubMed, etc. All the include studies should meet our demand of this meta-analysis: RESULT:: Based on the current meta-analysis, we rigorously consider that LE has a likelihood to improve dominant follicles (MD= -0.56, I= 100%, P= .04; MD= -0.39, I= 73%, P = .0003, respectively) and reduces the miscarriage rate (RR= 0.61, I= 0%, P = .03). There is no significant differences between the 2 groups in The total rate of pregnancy, pregnancy rate per cycle, multiple pregnancy and endometrial thickness. (RR= 1.06, I= 11%, P = .38; RR= 1.09, I= 7%, P = .32; RR= 0.79, I= 0%, P = .46; respectively) CONCLUSION:: Combined with the results of current systematic review and meta-analysis through subgroup analysis and sensitivity analysis, we can be cautious: in general, compared with CC, LE is an effective treatment in the IUI cycle, has a likelihood to improve dominant follicles and reduces the miscarriage rate.

Mini review: The FDA-approved prescription drugs that induce ovulation in women with ovulatory problems

Infertility is defined as not being able to become pregnant after 12 months or more of unprotected sexual intercourse. Female infertility as a serious health issue can result from ovulation disorders, menstrual cycle problems, structural problems, and environmental factors. Ovulation occurs once a month between the time of menarche and menopause. The release of a mature egg from the ovary is controlled with the hypothalamic-pituitary-ovarian axis. Several hormones such as gonadotropin-releasing hormone (GnRH), FSH (follicle-stimulating hormone), LH (luteinizing hormone), estrogen, and progesterone play fundamental roles in the ovulation process. Both FSH and LH are the main treatment for women with ovulation disorders. Depending on the reasons for infertility, several different types of treatment are available for infertile women. Fertility drugs as an important part of treatment work like the natural hormones to treat infertility. Several fertility drugs can regulate ovulation and the release of an egg from the ovary in women with polycystic ovary syndrome (PCOS) or undergoing in vitro fertilization (IVF) treatment. This mini-review is about the FDA-approved prescription drugs that induce ovulation in women with ovulatory problems.

A Biochemical Approach to Detect Oxidative Stress in Infertile Women Undergoing Assisted Reproductive Technology Procedures

Oxidative stress plays a major role in critical biological processes in human reproduction. However, a reliable and biologically accurate indicator of this condition does not yet exist. On these bases, the aim of this study was to assess and compare the blood and follicular fluid (FF) redox status of 45 infertile subjects (and 45 age-matched controls) undergoing in vitro fertilization (IVF), and explore possible relationships between the assessed redox parameters and IVF outcomes. Reactive Oxygen Species (ROS) production, assessed by flow cytometry analysis in blood leukocytes and granulosa cells, significantly increased (p < 0.05) in infertile patients. Also, oxidative stress markers—ThioBarbituric Acid-Reactive Substances (TBARS) as an index of lipid peroxidation, and Oxygen Radical Absorbance Capacity (ORAC) to account for total antioxidant capacity, both assayed by fluorometric procedures—in blood and FF were significantly (p < 0.001) modified in infertile patients compared to the control group. Moreover, a significant correlation between blood redox markers and FF redox markers was evident. An ORAC/TBARS ratio, defined as the redox index (RI), was obtained in the plasma and FF of the patients and controls. In the patients, the plasma RI was about 3.4-fold (p < 0.0001) lower than the control, and the FF RI was about six-fold (p < 0.0001) lower than the control. Interestingly, both the plasma RI and FF RI results were significantly correlated (p < 0.05) to the considered outcome parameters (metaphase II, fertilization rate, and ongoing pregnancies). Given the reported findings, a strict monitoring of redox parameters in assisted reproductive techniques and infertility management is recommended.

Letrozole combined with low dose highly purified HMG for ovulation induction in clomiphene citrate-resistant infertile Chinese women with polycystic ovary syndrome: a prospective study

BACKGROUND AND AIM

There are still open questions about ovulation induction in clomiphene citrate-(CC)-resistant infertile women. Especially little is known about efficacy and safety of letrozole (LTZ) combined with low-dose highly purified human menopausal gonadotropin (Hp-HMG) in women with polycystic ovary syndrome (PCOS).

METHODS

Prospective, single-arm single-center trial in 200 infertile PCOS patients refractory for at least three CC-treatment cycles. Women with hyperandrogenism took Diane-35 for at least 3 months. All patients got LTZ on day 3 for 5 d in combination with Hp-HMG, starting with 75 IU from cycle day 7 and maintained for up to 3 d. The maximum dose was 150 IU. Primary end-points were ongoing and clinical pregnancy rate, secondary end-points mono-follicular development, ovulation rate, OHSS, multiple pregnancy and early pregnancy loss. Major safety end-point was the incidence of adverse events.

RESULTS

Within 395 cycles the ongoing pregnancy rate was 28.24%, for cycles 35.23%, for patients 68%. The rate of ovulation per cycle was 97.7%, percentage of mono-follicular development 70.9%. No severe OHSS, multiple pregnancy, local or systemic side effects were seen.

CONCLUSIONS

LTZ combined with low-dose Hp-HMG is an effective and safe choice for reducing hyperstimulation and increasing pregnancy rate in CC-resistant women with PCOS.

A randomized controlled trial of clomifene citrate, metformin, and pioglitazone versus letrozole, metformin, and pioglitazone for clomifene-citrate-resistant polycystic ovary syndrome

OBJECTIVE

To examine the efficacy of clomifene citrate, metformin, and pioglitazone versus letrozole, metformin, and pioglitazone among women with polycystic ovary syndrome (PCOS) resistant to clomifene citrate.

METHODS

A prospective double-blind randomized controlled trial of women younger than 40 years who had primary/secondary infertility associated with PCOS and had not ovulated in response to clomifene citrate regimens previously was conducted at a center in Cairo, Egypt, between August 1, 2013, and December 31, 2014. Computer-generated random number tables and opaque envelopes were used to assign participants to group A or group B. Participants allocated to group A received 100mg clomifene citrate daily for 5 days from the third day of the menstrual cycle, whereas those in group B received 5mg letrozole daily in the same regimen. All patients received 850 mg metformin and 15 mg pioglitazone for 10 days from the first day of the menstrual cycle. The primary outcome was cumulative ovulation rate. Analyses were by intention to treat.

RESULTS

Fifty women were assigned to each group. Ovulation occurred in 108 (92.3%) of 117 cycles in group A and 93 (86.9%) of 107 cycles in Group B (P=0.184).

CONCLUSION

Combined treatment with letrozole, metformin, and pioglitazone was efficacious among women with PCOS resistant to clomifene citrate. ClinicalTrials.gov: NCT01909141.

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.).

Assessment of multiple intrauterine gestations from ovarian stimulation (AMIGOS) trial: baseline characteristics

OBJECTIVE

To identify baseline characteristics of women with unexplained infertility to determine whether treatment with an aromatase inhibitor will result in a lower rate of multiple gestations than current standard ovulation induction medications.

DESIGN

Randomized, prospective clinical trial.

SETTING

Multicenter university-based clinical practices.

PATIENT(S)

A total of 900 couples with unexplained infertility.

INTERVENTION(S)

Collection of baseline demographics, blood samples, and ultrasonographic assessments.

MAIN OUTCOME MEASURE(S)

Demographic, laboratory, imaging, and survey characteristics.

RESULT(S)

Demographic characteristics of women receiving clomiphene citrate (CC), letrozole, or gonadotropins for ovarian stimulation were very consistent. Their mean age was 32.2 ± 4.4 years and infertility duration was 34.7 ± 25.7 months, with 59% primary infertility. More than one-third of the women were current or past smokers. The mean body mass index (BMI) was 27 and mean antimüllerian hormone level was 2.6; only 11 women (1.3%) had antral follicle counts of <5. Similar observations were identified for hormonal profiles, ultrasound characterization of the ovaries, semen parameters, and quality of life assessments in both male and female partners.

CONCLUSION(S)

The cause of infertility in the couples recruited to this treatment trial is elusive, as the women were regularly ovulating and had evidence of good ovarian reserve both by basal FSH, antimüllerian hormone levels, and antral follicle counts; the male partners had normal semen parameters. The three treatment groups have common baseline characteristics, thereby providing comparable patient populations for testing the hypothesis that use of letrozole for ovarian stimulation can reduce the rates of multiples from that observed with gonadotropin and CC treatment.

CLINICAL TRIAL REGISTRATION NUMBER

NCT 01044862.

First reported case of sextuplets conceived via letrozole for ovulation induction

OBJECTIVE

To report the first case of sextuplets conceived via letrozole during ovulation induction.

DESIGN

Case report.

SETTING

Private fertility clinic.

PATIENT(S)

A 32-year-old female with a history of secondary infertility and polycystic ovary syndrome.

INTERVENTION(S)

Letrozole, 7.5 mg, on cycle days 3-7 after a progesterone-induced menses.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy.

RESULT(S)

Sexchorionic-sexamniotic pregnancy.

CONCLUSION(S)

High-order multiple gestations are possible with letrozole ovulation induction, so patients should be counseled appropriately and follicle monitoring considered.

A comparison of the efficacy of two doses of letrozole alone or with continuous recombinant follicle-stimulating hormone for ovulation induction in anovulatory women

AIMS

To determine the efficacy of letrozole alone or with recombinant follicle-stimulating hormone (rFSH) for ovarian induction in anovulatory women.

METHODS

A total of 322 patients undergoing intrauterine insemination (IUI) were included in this retrospective study. Letrozole (2.5 or 5.0 mg) was administered from days 5 to 9 of menses, alone or followed with rFSH started on day 9 until the day of human chorionic gonadotropin administration. A single IUI was performed 24 h after ovulation.

RESULTS

The number of follicles, endometrial thickness and serum estradiol levels were significantly higher in the letrozole + rFSH groups than in the letrozole-alone groups (p < 0.05), but no significant difference was found between the two doses of letrozole, whether alone or with rFSH. Women treated with 5.0 mg/day of letrozole + rFSH required a total dose of rFSH similar to women treated with 2.5 mg/day of letrozole + rFSH (230.77 ± 118.29 vs. 258.55 ± 130.13 IU, respectively; p = 0.205). There was no significant difference in pregnancy rates between the two doses of letrozole, whether alone or with rFSH.

CONCLUSION

Treatment with letrozole + rFSH was more efficacious than letrozole alone for pregnancy in the IUI program; however, the effect of 5.0 mg/day of letrozole versus 2.5 mg/day of letrozole on ovulation was equivalent, regardless of whether rFSH was used.

Minimal stimulation protocol using letrozole versus microdose flare up GnRH agonist protocol in women with poor ovarian response undergoing ICSI

BACKGROUND

To compare the IVF outcomes of letrozole/antagonist and microdose GnRH agonist flare up protocols in poor ovarian responders undergoing intracytoplasmic sperm injection.

MATERIALS AND METHODS

A randomized controlled trial was performed in patients with one or more previous failed IVF cycles in which four or less oocytes were retrieved when the gonadotrophin starting dose was at least 300 IU/day. Sixty patients were randomized by computer-generated list to receive either letrozole/antagonist (mild stimulation) n = 30 or GnRH-a protocol (microdose flare) n = 30.

RESULTS

Both groups were similar with respect to background and hormonal characteristics (age, duration of infertility, BMI, FSH, LH and E2). The clinical pregnancy rate per cycle was similar in both groups (13.3 vs. 16.6%; OR = 0.769; 95% CI = 0.185, 3.198). The doses of used gonadotropins and the number of stimulation days were significantly lower in the letrozole/antagonist protocol. The peak E2 level on the day of hCG, the endometrial thickness, the retrieved oocytes, the number of fertilized oocytes, the number of transferred embryos and the cancellation rate were statistically similar in both groups.

CONCLUSIONS

The letrozole/antagonist protocol is a cost-effective and patient-friendly protocol that may be used in poor ovarian responders for IVF/ICSI.

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.

Ovarian stimulation and intrauterine insemination at the quarter centennial: implications for the multiple births epidemic

Ovarian stimulation and intrauterine insemination (OS/IUI), a mainstay of current infertility therapy and a common antecedent to IVF, is a significant driver of the multiple births epidemic. Redress of this challenge, now marking its quarter centennial, will require a rethinking of current practice patterns. Herein we explore prospects for prevention, mitigation, and eventual resolution. We conclude that the multiple births attributable to OS/IUI may not be entirely preventable but that the outlook for their mitigation is promising, if in need of solidification. Specifically, we observe that low-dose (≤ 75 IU) gondotropin, clomiphene, and especially off-label letrozole regimens outperform high-dose (≥ 150 IU) gonadotropin counterparts in the gestational plurality category while maintaining comparable per-cycle pregnancy rates. Accordingly we recommend that, subject to appropriate exceptions, high-dose gonadotropin regimens be used sparingly and that whenever possible they be replaced with emerging alternatives. Finally, we posit that OS/IUI is not likely to be superseded by IVF absent further commoditization and thus greater affordability.

Effects of a non-steroidal aromatase inhibitor on ovarian function in cattle

Effects of the non-steroidal aromatase inhibitor letrozole on ovarian function in cattle were determined. The hypothesis that letrozole would arrest growth of the dominant follicle, resulting in emergence of a new follicular wave at a predictable post-treatment interval, was tested. Heifers were assigned randomly to four groups 4 days after follicular ablation (~2½ days after wave emergence) and given intravenous doses of 500 (n = 9), 250 (n = 10), or 125 µg kg–1 (n = 10) letrozole or phosphate-buffered saline (controls; n = 10). Blood was collected and ovarian structures were monitored daily by transrectal ultrasonography. Plasma concentrations of LH and FSH were measured by radioimmunoassay; plasma concentrations of letrozole were determined by high-performance liquid chromatography tandem mass spectrometry. A single intravenous dose of letrozole did not induce regression of the dominant follicle present at the time of treatment, nor did it directly affect FSH release. Conversely, treatment with letrozole increased endogenous concentrations of LH and extended the lifespan of the dominant follicle, which delayed the next FSH surge and subsequent follicular wave emergence. Letrozole continues to have potential as a non-steroidal treatment for controlling ovarian function in cattle.

Extended high dose letrozole regimen versus short low dose letrozole regimen as an adjuvant to gonadotropin releasing hormone antagonist protocol in poor responders undergoing IVF-ET

OBJECTIVE

To compare the efficacy and cost-effectiveness of extended high dose letrozole regimen/HPuFSH-gonadotropin releasing hormone antagonist (GnRHant) protocol with short low dose letrozole regimen/HPuFSH-GnRHant protocol in poor responders undergoing IVF-ET.

METHODS

In this randomized controlled trial, 136 women who responded poorly to GnRH agonist long protocol in their first IVF cycle were randomized into two equal groups using computer generated list and were treated in the second IVF cycle by either extended letrozole regimen (5 mg/day during the first 5 days of cycle and 2.5 mg/day during the subsequent 3 days) combined with HPuFSH-GnRHant protocol or short letrozole regimen (2.5 mg/day from cycle day 3-7) combined with HPuFSH-GnRHant protocol.

RESULTS

There were no significant differences between both groups with regard to number of oocytes retrieved and clinical pregnancy rate (5.39 ± 2.08 vs. 5.20 ± 1.88 and 22.06% vs. 16.18%, respectively).The total gonadotropins dose and medications cost per cycle were significantly lower in extended letrozole group (44.87 ± 9.16 vs. 59.97 ± 14.91 ampoules and 616.52 ± 94.97 vs. 746.84 ± 149.21 US Dollars ($), respectively).The cost-effectiveness ratio was 2794 $ in extended letrozole group and 4616 $ in short letrozole group.

CONCLUSION

Extended letrozole regimen/HPuFSH-GnRHant protocol was more cost-effective than short letrozole regimen/HPuFSH-GnRHant protocol in poor responders undergoing IVF-ET.

The use of high dose letrozole in ovulation induction and controlled ovarian hyperstimulation

Letrozole, an aromatase inhibitor, has been demonstrated to be effective as an ovulation induction and controlled ovarian hyperstimulation agent. However, dose administration has generally been limited to 5 days at 2.5 to 7.5 mg daily. We undertook a retrospective review of over 900 treatment cycles using letrozole in doses as high as 12.5 mg per day. Results indicate that such doses do indeed offer benefit to patients; in that there is increased follicular growth and a higher number of predicted ovulations with higher doses of the drug. However, increasing doses does not produce a detrimental effect upon endometrial thickness. High-dose letrozole may be of value in women who fail to respond adequately to lower doses. Furthermore, randomized trials are needed to determine whether high-dose letrozole might actually be optimal as a starting dose for certain treatment groups.

Estimating rates of multiple gestation pregnancies: sample size calculation from the assessment of multiple intrauterine gestations from ovarian stimulation (AMIGOS) trial

Infertility afflicts 15% of couples who wish to conceive. Despite intensive evaluation of both male and female partners, the etiology may remain unknown leading to a diagnosis of unexplained infertility. For such couples, treatment often entails ovulation induction (OI) with fertility medications coupled with intrauterine insemination. Complications of this therapy include ovarian hyperstimulation syndrome and creation of multiple gestation pregnancies, which can be complicated by preterm labor and delivery, and the associated neonatal morbidity and expense of care for preterm infants. The Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation (AMIGOS) study is designed to assess whether OI in couples with unexplained infertility with an aromatase inhibitor produces mono-follicular development in most cycles, thereby reducing multiple gestations while maintaining a comparable pregnancy success rate to that achieved by OI with either gonadotropins or clomiphene citrate. These results will provide future guidance of therapy for couples with unexplained infertility, and if comparable pregnancy rates are achieved with a substantial reduction in multiple gestations, the public health benefit will be considerable.

A bovine model for examining the effects of an aromatase inhibitor on ovarian function in women

OBJECTIVE

To test the hypothesis that treatment with an aromatase inhibitor (letrozole) will terminate dominant ovarian follicle growth and result in the emergence of a new follicular wave, regardless of the stage of follicular development at the time of treatment.

DESIGN

Prospective study.

SETTING

Academic research center.

ANIMAL(S)

Postpubertal beef heifers.

INTERVENTION(S)

Randomized trial involving treatment with letrozole on days 1-3, 3-5, 5-7 (day 0 = pretreatment ovulation) or no treatment.

MAIN OUTCOME MEASURE(S)

Follicular development, corpus luteum (CL) development, hormone profiles, and plasma aromatase inhibitor concentration.

RESULT(S)

Multiple doses of letrozole lengthened the period of follicular dominance, delayed emergence of the next follicular wave, and resulted in a larger CL regardless of the stage of the follicular wave in which treatments were initiated. No effects on circulating FSH concentrations were detected, but the stimulatory effects on the dominant follicle and CL were associated with increased plasma concentrations of LH in letrozole-treated animals. Plasma P concentrations were numerically higher throughout the luteal phase in letrozole-treated versus control heifers, but differences were not significant.

CONCLUSION(S)

The results provide rationale for the hypothesis that the mechanism of action responsible for the stimulatory effect of aromatase inhibitors on ovarian function involves an elevation in circulating concentrations of LH rather than FSH.

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.

Extended letrozole regimen versus clomiphene citrate for superovulation in patients with unexplained infertility undergoing intrauterine insemination: a randomized controlled trial

BACKGROUND

The aim of this randomized controlled trial was to compare the efficacy of extended letrozole regimen with clomiphene citrate in women with unexplained infertility undergoing superovulation and intrauterine insemination (IUI).

METHODS

Two hundred and fourteen patients with unexplained infertility were randomized into two equal groups using computer generated list and were treated by either letrozole 2.5 mg/day from cycle day 1 to 9 (extended letrozole group, 211 cycles) or clomiphene citrate 100 mg/day from cycle day 3 to 7 (clomiphene citrate group,210 cycles). Intrauterine insemination was performed 36 to 40 hours after HCG administration.

RESULTS

Both groups were comparable with regard to number of mature follicles (2.24 +/- 0.80 Vs 2.13 +/- 0.76) and the day of HCG administration. Serum estradiol was significantly greater in clomiphene citrate group (356 +/- 151 Vs 822 +/- 302 pg/ml, P = < 0.001) and the endometrial thickness was significantly greater in extended letrozole group (9.10 +/- 1.84 Vs 8.18 +/- 1.93 mm, P = < 0.001).The pregnancy rate per cycle and cumulative pregnancy rate were significantly greater in extended letrozole group (18.96% Vs 11.43% and 37.73% Vs 22.86%, respectively).

CONCLUSION

The extended letrozole regimen had a superior efficacy as compared with clomiphene citrate in patients of unexplained infertility undergoing superovulation and IUI.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01232075.

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.

Effect of letrozole at 2.5 mg or 5.0 mg/day on ovarian stimulation with gonadotropins in women undergoing intrauterine insemination

OBJECTIVE

To determine the effect of combined therapy of letrozole (2.5 mg or 5.0 mg) with recombinant follicle-stimulating hormone (FSH) in comparison with the administration of recombinant FSH alone in an intrauterine insemination (IUI) program.

DESIGN

Retrospective study.

SETTING

Assisted fertilization program in a specialized infertility center.

PATIENT(S)

110 women undergoing IUI and gonadotropin therapy.

INTERVENTION(S)

Recombinant FSH alone administered from day 3 or combined with letrozole, 2.5 or 5.0 mg/day, on days 3 to 7, and gonadotropins starting on day 7 of the menstrual cycle. Transvaginal ultrasound examinations were done until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of human chorionic gonadotropin (hCG), and IUI performed 30 to 40 hours later.

MAIN OUTCOME MEASURE(S)

Recombinant FSH dose required, number of follicles greater than 14 mm and 18 mm, endometrial thickness, pregnancy rates, miscarriages, and characteristics of newborns.

RESULT(S)

Women treated with FSH and 5.0 mg/day of letrozole required a lower dose of FSH than the group cotreated with 2.5 mg/day of letrozole or with FSH alone. Throughout most of the follicular phase, the endometrial thickness was statistically significantly less in both letrozole cotreatment groups compared with the FSH control group. By the day of hCG administration, the endometrial thickness was comparable among all the groups. The pregnancy rates were the same with recombinant FSH alone or combined with letrozole.

CONCLUSION(S)

In terms of cost-effectiveness, 5.0 mg/day of letrozole is more effective than the 2.5 mg/day in cotreatment with no adverse effect on pregnancy rate or outcome.

Letrozole: present and future role in the treatment of breast cancer

State of the art hormonal therapy for women with breast cancer has evolved over the last few years. Tamoxifen used to be the gold standard for adjuvant treatment of postmenopausal women with hormone-sensitive early breast cancer and also for patients with metastatic disease in whom hormonal manipulation was considered, but the introduction of third generation aromatase inhibitors has changed this concept. This article discusses the clinical implications of recent trials with one of the aromatase inhibitors letrozole, including pharmacokinetic and pharmacodynamic data as well as recent data on relative benefits and side effects compared with other available hormonal agents. Relevant ongoing clinical-translational trials evaluating this agent are also discussed.

Adjuvant endocrine treatment of early breast cancer

Endocrine therapy plays a pivotal role in the early treatment of estrogen receptor (ER)-positive breast cancer. Although evidence suggests that chemotherapy may work partly through ovarian ablation in young women who have ER-positive tumors, combined chemotherapy and endocrine therapy are generally advocated. In postmenopausal women, aromatase inhibition has become the new "gold standard" of treatment. More research is needed to define optimal regimens (aromatase inhibitor monotherapy versus tamoxifen sequential application), optimal duration of therapy and potential advantages of particular compounds. The optimal use of estrogen suppression (ovarian ablation with or without aromatase inhibition) and tamoxifen (administered sequentially or in concert with ovarian ablation) in premenopausal women has yet to be defined.

Letrozole treatment of precocious puberty in girls with the McCune-Albright syndrome: a pilot study

CONTEXT

Girls with McCune-Albright syndrome (MAS) and related disorders have gonadotropin-independent precocious puberty due to estrogen secretion from ovarian cysts. Their puberty does not respond to GnRH agonist therapy, and short-acting aromatase inhibitors have had limited effectiveness.

OBJECTIVE

Our objective was to assess the effectiveness of the potent, third-generation aromatase inhibitor letrozole in decreasing pubertal progression in girls with MAS and to assess the response of indices of bone turnover associated with the patients' polyostotic fibrous dysplasia.

DESIGN

Subjects were evaluated at baseline and every 6 months for 12-36 months while on treatment with letrozole 1.5-2.0 mg/m(2).d.

SETTING

This was an open-label therapeutic trial at a single clinical center.

PATIENTS

Patients included nine girls aged 3-8 yr with MAS and/or gonadotropin-independent puberty.

MAIN OUTCOME MEASURES

Measures included rates of linear growth, bone age advance, mean ovarian volume, estradiol, episodes of vaginal bleeding, and levels of the indices of bone metabolism: serum osteocalcin, alkaline phosphatase, urinary hydroxyproline, pyridinoline, deoxypyridinoline, and N-telopeptides.

RESULTS

Girls had decreased rates of growth (P < or = 0.01) and bone age advance (P < or = 0.004) and cessation or slowing in their rates of bleeding over 12-36 months of therapy. Mean ovarian volume, estradiol, and indices of bone metabolism fell after 6 months (P < or = 0.05) but tended to rise by 24-36 months. Uterine volumes did not change. One girl had a ruptured ovarian cyst after 2 yr of treatment.

CONCLUSIONS

This preliminary study suggests that letrozole may be effective therapy in some girls with MAS and/or gonadotropin-independent precocious puberty. Possible adverse effects include ovarian enlargement and cyst formation.

New advances in ovulation induction

PURPOSE OF REVIEW

To review recent advances in ovulation induction.

RECENT FINDINGS

Aromatase inhibitors can replace clomiphene citrate as ovulation-inducing substances. The most widely used aromatase inhibitor for this purpose is letrozole and the optimal dose is 5 mg daily for 5 days. Compared to clomiphene citrate, it is associated with a thicker endometrium and a better pregnancy rate. It is as effective as gonadotropin but yet less expensive. The overall rates of congenital malformation among newborns conceived after infertility treatment with letrozole or clomiphene citrate are similar. When letrozole is combined with gonadotropin, it leads to lower gonadotropin requirements with pregnancy rates comparable to gonadotropin treatment alone. Another promising aromatase inhibitor is anastrazole. Recent evidence suggests that luteinizing hormone activity in human menopausal gonadotropin modifies follicular development so that fewer intermediate-sized follicles develop. Compared to the use of follicular stimulating hormone only, human menopausal gonadotropin is associated with less ovarian hyperstimulation.

SUMMARY

Aromatase inhibitors are alternative drugs to clomiphene or gonadotropin for ovulation induction or superovulation.

Randomized controlled trial of three doses of letrozole for ovulation induction in patients with unexplained infertility

The aromatase inhibitor letrozole is a novel agent that can be used as an alternative to clomiphene citrate for ovulation induction in patients with unexplained infertility. The dose of letrozole used has varied between studies, and this study aimed to compare the three most commonly used doses: 2.5, 5 and 7.5 mg. A total of 179 patients were randomly recruited in this prospective study with 58, 61 and 60 patients in each dosage group respectively. This study reports a significantly higher (P < 0.05) number of follicles (total, > 14 mm and > or = 18 mm) on the day of administration of human chorionic gonadotrophin in the 7.5 mg group, associated with significantly fewer (P < 0.05) days of stimulation. However the pregnancy and miscarriage rates were similar in the three groups. In conclusion, it seems that the use of higher doses of letrozole offers no advantage in terms of pregnancy rates over the lower (2.5 mg) dose.

Potential of aromatase inhibitors for ovulation and superovulation induction in infertile women

For almost half a century, the first-line treatment for ovulation induction in cases of anovulation, unexplained infertility, or mild male factor has been clomifene (clomiphene citrate). Clomifene is an effective and safely used oral agent, but is known to have relatively common antiestrogenic endometrial and cervical mucous adverse effects that could prevent pregnancy in the face of successful ovulation. In addition, there is a significant risk of multiple pregnancies with clomifene compared with natural cycles. These drawbacks are mainly a result of the extended antiestrogenic effect of clomifene as a result of its accumulation in the body (clomifene isomers have a half-life of several days up to few weeks). Because of these problems, we proposed the concept of aromatase inhibition as a new method of ovulation induction that could avoid many of the adverse effects of clomifene. Over the last few years several published studies, both controlled and noncontrolled, compared clomifene and treatment with aromatase inhibitors (AIs), either alone or in combination with gonadotropins, for ovulation induction or augmentation. These studies found AIs as effective as clomifene in inducing ovulation, with the major advantage of absence of any antiestrogenic adverse effects. Several other major advantages of AIs include the lower serum estrogen production per developing follicle resulting in more physiological estrogen levels around the time of ovulation and good pregnancy rates with a lower incidence of multiple pregnancy than with clomifene. When combined with gonadotropins for assisted reproductive technologies, AIs reduce the dose of gonadotropins required for optimal follicle recruitment and improve the response to gonadotropin stimulation in poor responders. Such preliminary evidence suggests that AIs may replace clomifene in the future because of similar efficacy with a reduced adverse-effect profile. However, we believe that definitive studies in the form of randomised controlled trials comparing clomifene with AIs are needed.

Follicular phase dynamics with combined aromatase inhibitor and follicle stimulating hormone treatment

OBJECTIVE

The objective of this study was to evaluate follicular phase parameters during ovarian stimulation with FSH alone or with the aromatase inhibitor letrozole.

METHODS

Two groups of women undergoing intrauterine insemination (IUI): group I (389 patients; mean age 35 +/- 4.3 yr) underwent 630 IUI cycles stimulated with letrozole and FSH; and group II (134 patients; mean age 36.0 +/- 4.6 yr) underwent 166 IUI cycles stimulated with FSH only. Each group was stratified into ovulatory and anovulatory cycles. Patients were monitored by ultrasound for folliculometry and blood sampling for hormonal assay on d 3, 7, 9, or 10 of the cycle, and on the day of human chorionic gonadotropin administration.

RESULTS

Group I had a significantly lower follicular count greater than 10 mm on d 7, greater than 12 mm on d 9 or 10, and greater than 15 mm on the day of human chorionic gonadotropin administration compared to group II (P = 0.006, <0.001, and <0.001, respectively). After stratifying patients by diagnosis, this relationship was maintained only for patients with ovulatory infertility (P = 0.003, <0.001, and <0.001, respectively). Serum estradiol (E2) was significantly lower in the group I ovulatory and anovulatory at the last three monitoring visits (P < 0.001). However, the difference in E2 levels decreased in the preovulatory period with similar E2 levels per mature follicle. No premature preovulatory progesterone rise was observed in either group. However, significantly lower progesterone levels were observed in the second half of the follicular phase in group I (P = 0.02 and <0.001). Endometrial thickness was significantly lower in group I at the second and third visits (P < 0.001, 0.01) but was comparable to group II at the last monitoring visit. Although, the pregnancy rates were similar between the two groups, the multiple pregnancy rate was significantly higher in the FSH-only group (P = 0.039).

CONCLUSION

The addition of letrozole modifies the follicular, hormonal, and endometrial dynamics of FSH-stimulated cycles with possible positive effects on the overall cycle outcome.

Aromatase inhibitors in ovarian stimulation for IVF/ICSI: a pilot study

This prospective randomized pilot study was aimed at investigating the effect of the novel addition of aromatase inhibitors to an ovarian stimulation protocol for IVF or intracytoplasmic sperm injection, on endocrine parameters including serum androgen, oestrogen, progesterone, LH and FSH concentrations. The patients were randomized to receiving letrozole (group A; n = 10), versus no letrozole (group B; n = 10) in an ovarian stimulation protocol with recombinant FSH 150 IU/day starting on day 2 of the cycle, and gonadotrophin-releasing hormone antagonist 0.25 mg/day starting on day 6 of the cycle. Median LH concentrations were significantly higher (P < 0.01) in group A versus group B during letrozole administration. Median serum oestradiol concentrations were lower in group A versus group B, and median serum FSH, testosterone and androstenedione concentrations were higher in group A versus group B, throughout the follicular phase, without reaching significance. Median endometrial thickness was significantly higher (P < 0.05) in group A versus group B on the day of human chorionic gonadotrophin administration. Pregnancies were achieved. This pilot study supports the idea that aromatase inhibitors can contribute to normal potential of implantation and follicular response, without having negative anti-oestrogenic effects.