The effects of enclomiphene and zuclomiphene citrates on mouse embryos fertilized in vitro and in vivo

Letrozole as the first-line treatment of infertile women with poly cystic ovarian syndrome (PCOS) compared with clomiphene citrate: A clinical trial

Background:

The purpose of this study was to determine the efficacy and safety of letrozole on ovulation induction and pregnancy in comparison with clomiphene citrate in PCOS patients.

Materials and Methods:

The study was based on prospective randomized clinical trial comparing the efficacy of letrozole as the first-line management of the PCOS patients in comparison to clomiphene citrate during 2009 to 2011 and was performed in one private infertility clinic. The study included 100 patients divided into 2 equal groups.

Results:

Pregnancy occurred in 29 of 50 patients in letrozole group (58%) and 24 of 51 patients in clomiphene group (47%). The difference was not statistically significant (P value = 0.23). Thirty patients in clomiphene group and 36 patients in letrozole group showed regular menses after or during the treatment course. No significant difference between the 2 groups was observed (P value = 0.21).

Conclusion:

Our findings suggest letrozole and clomiphene citrate are equally effective for induction of ovulation and achieving pregnancy in patients with PCOS.

Clomiphene citrate versus tamoxifen for ovulation induction in women with PCOS: a prospective randomized trial

OBJECTIVE

To reevaluate the efficacy of induction of ovulation with CC versus TMX in a group of anovulatory subfertile women with PCOS in a randomized controlled trial.

STUDY DESIGN

A prospective randomized controlled study in which 371 PCOS patients were randomly allocated into two treatment groups: group A (187 patients) where women received CC and group B (184 patients) where they received Tamoxifen for one treatment cycle. The outcome measures were number of growing and mature follicles, serum E(2) (pg/ml), serum progesterone (ng/ml) and endometrial thickness, the occurrence of pregnancy and miscarriage.

RESULTS

The number of stimulated follicles reaching ≥ 16 mm diameter was significantly more in the CC group compared to Tamoxifen stimulated group (2.1 SD ± 0.1 vs. 1.1 SD ± 0.7, p<0.0001). The endometrium at the time of hCG administration was significantly thicker in the TMX group (10.1 ± 0.1mm vs. 9.3 ± 0.4mm, p<0.0001). Ovulation occurred in 120/187 cycles (64%) in the CC group and 95/184 cycles (51.6%) in the TMX group with a significant difference between two groups in favors of clomiphene (p=0.01). Serum E(2), on the day of hCG administration, was significantly higher in the clomiphene group (p<0.0001). Pregnancy occurred in 35/187 cycles in group A (18.7%) and 20/184 cycles (10.8%) in group B and the difference was statistically significant (p=0.04).

CONCLUSIONS

Clomiphene citrate is more successful than tamoxifen as a first line therapy for ovulation induction in women with PCOS.

Effects of metformin and clomiphene citrate on ovarian vascularity in patients with polycystic ovary syndrome

OBJECTIVE

To evaluate the effects of metformin and of clomiphene citrate (CC) on the ovarian blood perfusion and on perifollicular and peri-corpus luteum (CL) vascularity in anovulatory women with polycystic ovary syndrome (PCOS).

DESIGN

Prospective cohort study.

SETTING

University "Magna Graecia" of Catanzaro.

PATIENT(S)

Forty anovulatory nonobese patients with PCOS who ovulated under treatment with metformin (850 mg twice daily) plus placebo (metformin group) and 38 under placebo plus CC (150 mg for 5 days; CC group). Another 30 healthy normal cycled women (control group).

INTERVENTION(S)

Serial transvaginal ultrasonographic examinations.

MAIN OUTCOME MEASURE(S)

Ovary artery blood flow impedance, dimensions, and vascularization of the dominant follicle and of the CL.

RESULT(S)

No difference was observed in all parameters in metformin ovulating cycles in comparison with healthy controls. In CC ovulating cycles, ovarian artery impedance, and perifollicular and peri-CL vascularization the results were significantly different from the metformin and control groups. After grouping the stimulated cycles for reproductive outcomes, perifollicular vascularization alone ended up being significantly lower only in CC-stimulated cycles with unfavorable outcome.

CONCLUSION(S)

In patients with PCOS who ovulate under treatment with metformin, the ovarian blood flows are similar to those observed in healthy women, whereas CC administration reduces the ovarian and, specifically, the perifollicular vascularization.

The role of aromatase inhibitors in ameliorating deleterious effects of ovarian stimulation on outcome of infertility treatment

Clinical utilization of ovulation stimulation to facilitate the ability of a couple to conceive has not only provided a valuable therapeutic approach, but has also yielded extensive information on the physiology of ovarian follicular recruitment, endometrial receptivity and early embryo competency. One of the consequences of the use of fertility enhancing agents for ovarian stimulation has been the creation of a hyperestrogenic state, which may influence each of these parameters. Use of aromatase inhibitors reduces hyperestrogenism inevitably attained during ovarian stimulation. In addition, the adjunct use of aromatase inhibitors during ovarian stimulation reduces amount of gonadotropins required for optimum stimulation. The unique approach of reducing hyperestrogenism, as well as lowering amount of gonadotropins without affecting the number of mature ovarian follicles is an exciting strategy that could result in improvement in the treatment outcome by ameliorating the deleterious effects of the ovarian stimulation on follicular development, endometrial receptivity, as well as oocyte and embryo quality.

Clinical use of aromatase inhibitors (AI) in premenopausal women

Aromatase inhibitors (AI) block the last enzymatic step of estrogen production, the aromatization of the A-cycle of aromatizable androgens and particularly, androstenedione (delta4) and testosterone (T). Molecules designed for interfering with aromatase activity have existed for many years. Yet the activity of products of the aminogluthetimide era was unspecific and these substances carried too many side effects for being used clinically. Newer third generation AIs, however, are highly specific and essentially devoid of side effects. These molecules have recently been approved for treating breast cancer in postmenopausal women either, in advanced forms or, as part of adjuvant therapy. In women whose ovaries are active, a temporary inhibition of E2 production will raise gonadotropins and in turn, stimulate follicular growth. In cancer patients, this property precludes the use of AIs in women whose ovaries are still active, unless gonadotropins are blocked. But in infertility patients, this property of AIs has been put to play for inducing ovulation. AIs have been used both in women who do not ovulate but whose hypothalamo-pituitary-gonadal (HPG) axis is active (oligo-anovulators of PCOD type) and those who ovulate regularly but in whom multiple ovulation is sought for treating unexplained infertility or as part of IVF. Like clomiphene citrate (CC), AIs are not usable in women whose gonadotropins are suppressed, as in the case of hypothalamic amenorrhea. The sum of data available on the use of AI for inducing ovulation remains however meager to this date and is mainly constituted of pilot and non-randomized trials. Yet mounting evidence tends to support AIs' advantages over CC for induction of ovulation. Hence, we think that the likelihood that these drugs will play a key role in induction of ovulation in the future is high. AIs appear particularly interesting for treating unexplained infertility because AI-FSH/hMG regimens are lighter than FSH-only regimens while retaining the high pregnancy rates of these latter treatments.

[Use of aromatase inhibitors in infertile women]

Aromatase inhibitors (AI) block the last enzymatic step of estrogen production, the aromatization of the A-cycle of aromatizable androgens and particularly, androstenedione (D4) and testosterone (T). Molecules designed for interfering with aromatase activity have existed for many years. Yet the activity of products of the aminogluthetimide era was too unspecific and these substances carried too many side effects for being used clinically. Today, however, 3rd generation AIs have become available that are highly specific and essentially devoid of side effects. These molecules have recently been approved for treating breast cancer in post-menopausal women, either in advanced forms, or as part of adjuvant therapy. In women whose ovaries are active, a temporary inhibition of E2 production will activate gonadotropins and in turn, stimulate follicular growth. In cancer patients, this property precludes the use of AIs in women whose ovaries are still active, unless gonadotropins are blocked. In infertile patients, this property of AIs has been put to play for inducing ovulation. AIs have been used both in women who do not ovulate but whose hypothalamo-pituitary-gonadal (HPG) axis is active (oligo-anovulators of PCOD type) and in those who ovulate regularly but in whom multiple ovulation is sought for treating infertility or as part of IVF. Like CC, AIs are not usable in women whose gonadotropins are suppressed, as in the case of hypothalamic amenorrhea. The sum of data available on the use of AI for inducing ovulation remains however meager to this date and is mainly constituted of pilot and non-randomized trials. Yet mounting evidence tends to support AIs' advantages over CC for induction of ovulation. Hence, we think that these drugs will play a key role for the induction of ovulation in the future.

Aromatase inhibitors for the treatment of infertility

Ovarian stimulation during infertility treatment is used either alone or in conjunction with intrauterine insemination and assisted reproductive technologies. At the present time, the two main medications used for ovarian stimulation include an oral antioestrogen, clomiphene citrate and injectable gonadotrophins. In spite of the high ovulation rate, the use of clomiphene citrate is associated with adverse side effects and low pregnancy rates. In clomiphene citrate failures, gonadotrophin injections are generally the next treatment option but, especially in polycystic ovarian syndrome, are associated with increased risk of severe ovarian hyperstimulation syndrome and high multiple pregnancies. Therefore, an effective oral treatment that could be used without risk of ovarian hyperstimulation syndrome and with minimal monitoring is preferred. It was hypothesised that aromatase inhibitors can be administered early in the follicular phase to induce ovulation by releasing the hypothalamus and/or pituitary from oestrogen negative feedback. The success of aromatase inhibitors in induction and augmentation of ovulation has been reported. In addition, increased intraovarian androgen levels may synergise with central effects of decreased oestrogen to enhance ovarian response to gonadotrophin stimulation. This increased sensitivity to follicle-stimulating hormone may be especially useful in poor responders. The potential future applications for aromatase inhibitors in infertility management are also discussed.

Aromatase inhibition for ovarian stimulation: future avenues for infertility management

Ovarian stimulation is applied during infertility management either alone or in conjunction with intrauterine insemination and assisted reproductive technologies. At the present time, the two main medications used for ovarian stimulation include an oral antiestrogen, clomiphene citrate, and injectable gonadotropins. In spite of the high ovulation rate with the use of clomiphene citrate, the pregnancy rate is much lower. In clomiphene citrate failures, gonadotropin injections have generally been used as the next treatment option. Treatment with gonadotropins is difficult to control and characteristically associated with increased risk of severe ovarian hyperstimulation syndrome and high multiple pregnancies. Therefore, an effective oral treatment that could be used without risk of hyperstimulation and with minimal monitoring is the preferred therapy. We hypothesize that aromatase inhibitors can be administered early in the follicular phase to induce ovulation by releasing the hypothalamus or pituitary from estrogen negative feedback. Based on this hypothesis, we have reported the success of aromatase inhibitors in induction and augmentation of ovulation in addition to improving ovarian response to gonadotropin stimulation. Moreover, there are other potential applications for aromatase inhibitors in infertility management, including improving implantation in assisted reproduction and in-vitro maturation.

Clomiphene citrate-induced perturbations during meiotic maturation and cytogenetic abnormalities in mouse oocytes in vivo and in vitro

OBJECTIVE

To determine if clomiphene citrate induces temporal perturbations during meiotic maturation and aneuploidy in mouse oocytes.

DESIGN

A controlled dose study involving mouse oocytes in vivo and in vitro.

SETTING

Clinical and academic research setting in a university medical center.

INTERVENTION(S)

Oocytes were obtained after superovulation and from mature follicles.

MAIN OUTCOME MEASURE(S)

Cytogenetic analysis of oocytes for aneuploidy, premature centromere separation, premature anaphase, and single chromatids, and the frequencies of metaphase I and diploid oocytes.

RESULT(S)

Clomiphene citrate resulted in a decrease in the number of ovulated oocytes and a significant (P<.05) increase in hyperploidy at 100 mg/kg in vivo. In vitro, 5.0 microg/mL of clomiphene citrate significantly (P<.05) increased hyperploidy and reduced the proportion of metaphase I oocytes.

CONCLUSION(S)

These findings suggest that clomiphene citrate has the potential for inducing aneuploidy in mouse oocytes both in vivo and in vitro and that the rate of oocyte maturation is altered after clomiphene exposure in vitro. Additional data are needed to support the results of this study.

Serum concentrations of enclomiphene and zuclomiphene across consecutive cycles of clomiphene citrate therapy in anovulatory infertile women

OBJECTIVE

To determine the serum concentrations of enclomiphene and zuclomiphene across consecutive cycles of clomiphene citrate treatment in anovulatory infertile women.

DESIGN

Prospective cohort.

SETTING

Tertiary institutional infertility clinic.

PATIENT(S)

Fourteen consenting anovulatory infertile women receiving standardized, cyclic, incremental treatment with clomiphene citrate for ovulation induction.

INTERVENTION(S)

Clomiphene citrate treatment (50-150 mg/d, cycle days 5-9), titrated to the minimum effective ovulation-inducing dose, was administered for three to six total cycles. Blood samples were obtained on cycle days 3 and 10 in each treatment cycle.

MAIN OUTCOME MEASURE(S)

Serum concentrations of enclomiphene and zuclomiphene.

RESULT(S)

Cycle day 3 zuclomiphene levels were below assay limits in all initial cycles, increased progressively across three consecutive cycles, and thereafter plateaued. Cycle day 3 enclomiphene concentrations were uniformly undetectable. Cycle day 10 enclomiphene levels increased with dose administered, but these observations were not statistically significant.

CONCLUSION(S)

Clomiphene citrate induction of ovulation results in an isomer-specific systemic accumulation of zuclomiphene across consecutive cycles of treatment. The combined maximum concentration of enclomiphene and zuclomiphene attained in practice approximates 100 nmol/L and is generally well below levels previously demonstrated to have adverse effects in vitro.

Identification of estrogen receptor protein and messenger ribonucleic acid in human spermatozoa

OBJECTIVE

The processes leading to fertilization involve a series of sequential events including the deposition and transport of sperm in the female genital tract. It is becoming evident that spermatozoa in which a hyperactive state has been induced are more effective in both reaching and penetrating the oocyte. Many of the changes that spermatozoa undergo are the result of their ability to respond to the milieu of the female genital tract. In the presence of estrogen sperm have been shown to have increased their metabolic activity and flagellar activity and to have an increased ability to penetrate oocytes. Most important, these observed changes in sperm physiology occur quickly, suggesting a novel second-messenger system coupled to the estrogen receptor. Established effects of steroid hormones involve mediation of the signal through genomic expression. However, because it has not been definitively demonstrated whether the human sperm express the estrogen receptor, the mechanism by which estrogen exert its effect remains to be elucidated.

STUDY DESIGN

The presence of estrogen receptors on human spermatozoa was investigated. Immunohistochemistry performed on human spermatozoa indicates that the estrogen receptors are located on the tailpiece. In addition, protein from human spermatozoa was isolated and subjected to Western blot analysis.

RESULTS

Results indicate a single band of approximately 65 kd, similar to that of the native human estrogen receptor. Ribonucleic acid obtained from the human spermatozoa was reverse transcribed into deoxyribonucleic acid. With use of selected primers, this deoxyribonucleic acid was amplified by polymerase chain reaction. Resolution and examination of the expansion products demonstrated a single band of deoxyribonucleic acid of 450 bp, identical to that expected from the selected primers. The specificity of this reverse transcriptase-polymerase chain reaction amplified deoxyribonucleic acid sequence was verified by Southern blotting.

CONCLUSION

For the first time we provide evidence as to the expression of estrogen receptor by human spermatozoa.

A rapid evolution mechanism may contribute to changes in sex ratio, multiple birth incidence, frequency of auto-immune disease and frequency of birth defects in Clomid conceptions

Under conditions favourable to the horizontal transmission of genetic material, a clomiphene isomer is hypothesized to encourage an alternate ovulatory route, with consequence for the sex ratio, multiple birth incidence, incidence of auto-immune disease, and frequency of malformations.

Future directions: anti-hormones in reproductive medicine

Anti-hormones are important in reproductive medicine because they are useful tools that teach us about the normal physiological actions of hormones. They also provide effective therapies to control or treat a variety of pathogenic processes. We expect that the future repertoire of anti-hormones will include the paracrine and autocrine regulators of specific cell functions, in addition to the endocrine systems described here. The availability of recombinant DNA expression systems for an ever larger portion of the human genome will surely accelerate the development of novel anti-hormones.