Pharmacokinetic and pharmacodynamic characteristics of ganirelix (Antagon/Orgalutran). Part I. Absolute bioavailability of 0.25 mg of ganirelix after a single subcutaneous injection in healthy female volunteers

GnRH agonists and antagonists in therapy of symptomatic uterine fibroids - current roles and future perspectives

INTRODUCTION

Uterine fibroids are the most common noncancerous tumors in women of childbearing age. This review was developed to evaluate the current role of gonadotropin-releasing hormone (GnRH) agonists and antagonists in the therapy of symptomatic uterine fibroids.

AREAS COVERED

There is a great need for alternative methods for surgical treatment of uterine fibroids. Hormonal therapy remains the first-line treatment option for most patients. GnRH analogs (agonists and antagonists) modulate the pulsatile release of GnRH. This review summarizes the available literature concerning pharmacologic principles underlying the mechanism of action of GnRH and its analogs, as well as individual therapeutic applications to which these drugs have been applied.

EXPERT OPINION

In many cases, it is possible to try to treat uterine fibroids pharmacologically. Both groups of GnRH analogs are used in therapy, agonists instead as a preparation for surgery, and antagonists as a drug for long-term use. It is essential to develop this path further and look for at least long-term-release systems or new methods of administering these drugs. It is also important from the patient's perspective to search for possible drugs that may have an additive effect of decreasing side effects when combined with GnRH analogs.

Testosterone-associated blood pressure dysregulation in women with androgen excess polycystic ovary syndrome

We tested the hypothesis that hyperandrogenemia in androgen excess polycystic ovary syndrome (AE-PCOS) is a primary driver in blood pressure (BP) dysregulation via altered sympathetic nervous system activity (SNSA), reduced integrated baroreflex gain and increased renin-angiotensin system (RAS) activation. We measured resting SNSA (microneurography), integrated baroreflex gain, and RAS with lower body negative pressure in obese insulin-resistant (IR) women with AE-PCOS [n = 8, 23 ± 4 yr; body mass index (BMI) = 36.3 ± 6.4 kg/m2] and obese IR controls (n = 7, control, 29 ± 7 yr; BMI = 34.9 ± 6.8 kg/m2), at baseline (BSL), after 4 days of gonadotropin-releasing hormone antagonist (ANT, 250 μg/day) and 4 days of ANT + testosterone (ANT + T, 5 mg/day) administration. Resting BP was similar between groups for systolic blood pressure (SBP; 137 ± 14 vs. 135 ± 14 mmHg, AE-PCOS, control) and diastolic BP (89 ± 21 vs. 76 ± 10 mmHg, AE-PCOS, control). BSL integrated baroreflex gain was similar between groups [1.4 ± 0.9 vs. 1.0 ± 1.3 forearm vascular resistance (FVR) U/mmHg], but AE-PCOS had lower SNSA (10.3 ± 2.0 vs. 14.4 ± 4.4 burst/100 heartbeats, P = 0.04). In AE-PCOS, T suppression increased integrated baroreflex gain, which was restored to BSL with ANT + T (4.3 ± 6.5 vs. 1.5 ± 0.8 FVR U/mmHg, ANT, and ANT + T, P = 0.04), with no effect in control. ANT increased SNSA in AE-PCOS (11.2 ± 2.4, P = 0.04). Serum aldosterone was greater in AE-PCOS versus control (136.5 ± 60.2 vs. 75.7 ± 41.4 pg/mL, AE-PCOS, control, P = 0.04) at BSL but was unaffected by intervention. Serum angiotensin-converting enzyme was greater in AE-PCOS versus control (101.9 ± 93.4 vs. 38.2 ± 14.7 pg/mL, P = 0.04) and reduced by ANT in AE-PCOS (77.7 ± 76.5 vs. 43.4 ± 27.3 µg/L, ANT, and ANT + T, P = 0.04) with no impact on control. Obese, IR women with AE-PCOS showed decreased integrated baroreflex gain and increased RAS activation compared with control.NEW & NOTEWORTHY Here we present evidence for an important role of testosterone in baroreflex control of blood pressure and renal responses to baroreceptor unloading in women with a common, high-risk androgen excess polycystic ovary syndrome (AE-PCOS) phenotype. These data indicate a direct effect of testosterone on the vascular system of women with AE-PCOS independent of body mass index (BMI) and insulin-resistant (IR). Our study indicates that hyperandrogenemia is a central underlining mechanism of heightened cardiovascular risk in women with PCOS.

Efficacy and safety of newly developed ganirelix acetate in infertile women for assisted reproductive technology: a prospective, randomised, controlled study

This study aimed to investigate the efficacy of Ganilever pre-filled syringe (PFS), a newly developed ganirelix acetate, for the inhibition of premature luteinising hormone (LH) surge in in vitro fertilisation (IVF). A prospective randomised controlled study was conducted (NCT03051087). A total of 236 women (Ganilever group: 114, Orgalutran group: 122) were finally analysed. The patients with LH of >10 mIU/mL on the day of human chorionic gonadotropin (hCG) injection were 0 (0.0%) and 3 (2.5%) in the Ganilever and Orgalutran groups, respectively (p= .25). The number of retrieved oocytes from two groups did not show any significant difference (12.0 ± 6.4 vs. 11.8 ± 6.3, p= .73). Furthermore, the two groups did not show significant differences in the number of good-quality oocytes and embryo, and the rate of fertilisation. Similar safety profiles were also observed. In conclusion, Ganilever PFS showed comparable IVF outcomes and safety profile in IVF, as compared to the Orgalutran. Impact StatementWhat is already known on this subject? Premature LH surge during controlled ovarian stimulation results in the induction of luteinisation of the immature follicles. Thus, gonadotrophin-releasing hormone (GnRH) antagonist protocol was suggested as an option for suppression of premature LH surge. Currently, one of GnRH antagonists being widely used is ganirelix acetate (Orgalutran^®; Organon, Oss, The Netherlands). Ganilever pre-filled syringe (PFS) is a newly developed GnRH antagonist containing ganirelix acetate as an active ingredient.What do the results of this study add? Our study demonstrated that Ganilever PFS showed comparable IVF outcomes and patient safety profile in infertile women undergoing in IVF-ET, as compared to the Orgalutran.What are the implications of these findings for clinical practice and/or further research? The results of our study will provide another available GnRH antagonist to be used in patients with IVF.

ETB receptor-mediated vasodilation is regulated by estradiol in young women

The endothelin-B (ET_B) receptor is a key regulator of vascular endothelial function in women. We have previously shown that the ET_B receptor mediates vasodilation in young women, an effect that is lost after menopause. However, the direct impact of changes in estradiol (E₂) on ET_B receptor function in women remains unclear. Therefore, the purpose of this study was to test the hypothesis that E₂ exposure modulates ET_B receptor-mediated dilation in young women. Fifteen young women (24 ± 4 yr, 24 ± 3 kg/m²) completed the study. Endogenous sex hormone production was suppressed with daily administration of a gonadotropin-releasing hormone antagonist (GnRHant; Ganirelix) for 10 days; E₂ (0.1 mg/day, Vivelle-Dot patch) was added back on days 4-10. We measured vasodilation in the cutaneous microcirculation (microvascular endothelial function) via local heating (42°C) on day 4 (GnRHant) and day 10 (GnRHant + E₂) using laser Doppler flowmetry coupled with intradermal microdialysis during perfusions of lactated Ringer's (control) and ET_B receptor antagonist (BQ-788, 300 nM). During GnRHant, vasodilatory responses to local heating were enhanced with ET_B receptor blockade (control: 83 ± 9 vs. BQ-788: 90 ± 5%CVC_max, P = 0.004). E₂ administration improved vasodilation in the control site (GnRHant: 83 ± 9 vs. GnRHant + E₂: 89 ± 8%CVC_max, P = 0.036). Furthermore, cutaneous vasodilatory responses during ET_B receptor blockade were blunted after E₂ administration (control: 89 ± 8 vs. BQ-788: 84 ± 8%CVC_max, P = 0.047). These data demonstrate that ovarian hormones, specifically E₂, modulate ET_B receptor function and contribute to the regulation of microvascular endothelial function in young women.NEW & NOTEWORTHY The endothelin-B (ETB) receptor mediates vasodilation in young women, an effect lost following menopause. It is unclear whether these alterations are due to aging or changes in estradiol (E2). During endogenous hormone suppression (GnRH antagonist), blockade of ETB receptors enhanced cutaneous microvascular vasodilation. However, during E2 administration, blockade of ETB receptors attenuated vasodilation, indicating that the ETB receptor mediates dilation in the presence of E2. In young women, ETB receptors mediate vasodilation in the presence of E2, an effect that is lost when E2 is suppressed.

Established and In-trial GPCR Families in Clinical Trials: A Review for Target Selection

The largest family of drug targets in clinical trials constitute of GPCRs (G-protein coupled receptors) which accounts for about 34% of FDA (Food and Drug Administration) approved drugs acting on 108 unique GPCRs. Factors such as readily identifiable conserved motif in structures, 127 orphan GPCRs despite various de-orphaning techniques, directed functional antibodies for validation as drug targets, etc. has widened their therapeutic windows. The availability of 44 crystal structures of unique receptors, unexplored non-olfactory GPCRs (encoded by 50% of the human genome) and 205 ligand receptor complexes now present a strong foundation for structure-based drug discovery and design. The growing impact of polypharmacology for complex diseases like schizophrenia, cancer etc. warrants the need for novel targets and considering the undiscriminating and selectivity of GPCRs, they can fulfill this purpose. Again, natural genetic variations within the human genome sometimes delude the therapeutic expectations of some drugs, resulting in medication response differences and ADRs (adverse drug reactions). Around ~30 billion US dollars are dumped annually for poor accounting of ADRs in the US alone. To curb such undesirable reactions, the knowledge of established and currently in clinical trials GPCRs families can offer huge understanding towards the drug designing prospects including "off-target" effects reducing economical resource and time. The druggability of GPCR protein families and critical roles played by them in complex diseases are explained. Class A, class B1, class C and class F are generally established family and GPCRs in phase I (19%), phase II(29%), phase III(52%) studies are also reviewed. From the phase I studies, frizzled receptors accounted for the highest in trial targets, neuropeptides in phase II and melanocortin in phase III studies. Also, the bioapplications for nanoparticles along with future prospects for both nanomedicine and GPCR drug industry are discussed. Further, the use of computational techniques and methods employed for different target validations are also reviewed along with their future potential for the GPCR based drug discovery.

[Effects of cetrorelix versus ganirelix in gonadotropin-releasing hormone antagonist cycles for preventing premature luteinizing hormone surges and on clinical outcomes of IVF-ET cycles]

OBJECTIVE

To compare the effects of cetrorelix and ganirelix in gonadotropin-releasing hormone antagonist (GnRH-ant) cycles for preventing premature luteinizing hormone (LH) surges and on clinical outcomes of IVF-ET cycles.

METHODS

We retrospectively analyzed 2572 GnRH-ant cycles of in vitro fertilization and embryo transfer from January, 2013 to December, 2016, including 1368 cycles with cetrorelix treatment and 1204 cycles with ganirelix treatment. The baseline characteristics of the patients and the clinical outcomes of the two groups were compared.

RESULTS

Compared with those receiving ganirelix treatment, the patients with cetrorelix treatment had a significantly younger age (33.10 vs 33.89 years, P < 0.001) and a lower body mass index (21.57 vs 21.84 kg/m², P=0.024). After adjustment for age and body mass index of the patients, no significant differences were found between the two groups in the levels of follicle-stimulating hormone (FSH), LH, estradiol (E₂), progesterone (P) levels either at the baseline or on the day of hCG triggering, or in the number of oocytes retrieved (P > 0.05). The two groups also had comparable percentages of patients with LH > 10 U/L on the day of hCG triggering (3.7% vs 3.2%) and similar spontaneous ovulation rate (0.6% vs 0.5%), clinical pregnancy rate (47.7% vs 45.9%) and live birth rate (37.5% vs 33.6%) following fresh embryo transfer (P > 0.05). The incidence of moderate to severe ovarian hyperstimulation syndrome, however, was significantly higher in ganirelix group than in cetrorelix group (0.7% vs 0.1%, P=0.006).

CONCLUSIONS

Cetrorelix and ganirelix can achieve comparable effects for preventing premature LH surges and can achieve similar clinical outcomes of GnRH-ant cycles, but ganirelix is associated with a significantly higher incidence of moderate to severe ovarian hyperstimulation syndrome.

Progestin vs. Gonadotropin-Releasing Hormone Antagonist for the Prevention of Premature Luteinizing Hormone Surges in Poor Responders Undergoing in vitro Fertilization Treatment: A Randomized Controlled Trial

Objective: Progestin was recently used as an alternative of gonadotropin-releasing hormone (GnRH) analog for preventing premature luteinizing hormone (LH) surge with the aid of vitrification techniques, however, limited data were available about the potential of progestin in poor responders undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment. We performed a randomized parallel controlled trial to investigate the difference of progestin and GnRH antagonist in poor responders. Methods: A total of 340 poor responders who met with Bologna criteria were randomly allocated into the progestin-primed ovarian stimulation (PPOS) group and GnRH antagonist group. Fresh embryo transfer was preferred in the GnRH antagonist group and freeze-all was performed in the PPOS group. The primary outcome was the incidence of premature LH surge, secondary outcomes were the number of retrieved oocytes, the number of viable embryos and the pregnancy outcomes. Results: The results showed that the incidence of premature LH surge in PPOS group was lower than that in antagonist group (0 vs. 5.88%, P < 0.05). In PPOS group, the average numbers of oocytes and viable embryos were comparable to those in GnRH antagonist group (3.7 ± 2.6 vs. 3.4 ± 2.4; 1.6 ± 1.7 vs. 1.4 ± 1.3, P > 0.05), the live birth rate was similar between the two groups (21.8 vs. 18.2%, RR 1.25 (95% confidence interval 0.73, 2.13), P > 0.05). Conclusions: The study demonstrated that PPOS had a more robust control for preventing premature LH rise than GnRH antagonist in poor responders, but PPOS in combination with freeze-all did not significantly increase the probability of pregnancy than GnRH antagonist protocol for poor responders.

The effect of rLH supplementation to the GnRH-antagonist protocol on endocrine dynamics in the advanced reproductive age

PURPOSE

To explore serum endocrine dynamics, specifically LH levels, following rLH supplementation to rFSH following GnRH-antagonist treatment in the advance reproductive age.

METHODS

Women were prospectively and similarly treated employing rFSH and the flexible GnRH-antagonist protocol, while rLH was supplemented only to the study group. Serum FSH, LH, E_2, and P were evaluated throughout the follicular phase. Three strategies were a priori planned to examine endocrine dynamics among women enrolled.

RESULTS

While serum LH drop were similar before GnRH-antagonist stimulation, it dropped more times in the control group compared to the study group. Among women receiving rFSH only, serum LH levels dropped ≤2, ≤1 and ≤0.5 mIU/mL in 71.4, 46.4, and 28.6% of cases, while this occurred only in 38.7% (P = 0.01), 6.5% (P = 0.0004) and 3.2% (P = 0.007) of women receiving combined rFSH and rLH treatment, respectively. The same trend was found when serum LH dropped in at least two occasions following the GnRH-antagonist administration. Conversely, serum LH diagrams throughout the follicular phase did not differ between the two groups. Furthermore, individual area under the curve values of LH, E_2, and P was similar between the two groups following GnRH-antagonist initiation.

CONCLUSIONS

Different strategies to explore LH dynamics following the GnRH-antagonist administration have resulted in diverse results, implying the need for a consensus definition of LH threshold for adequate folliculogenesis and steroidogenesis. Such action would pave the way for understanding which groups of patients may benefit from rLH supplementation.

Reproductive hormone influences on thermoregulation in women

The present discussion reviews current knowledge regarding influences of the primary reproductive hormones on mechanisms of thermoregulatory control in women. The human body is remarkably capable of maintaining body temperature within a few tenths of a degree of normal (37°C) over a wide range of activity and environmental exposures; this regulation is accomplished via integration of central and peripheral thermal information at the preoptic area of the anterior hypothalamus (PO/AH). We describe both central and peripheral mechanisms involved in controlling thermoregulation in humans, and how these mechanisms are affected by sex and hormone exposure. Estrogens generally promote vasodilation, heat dissipation, and lower body temperature and progesterone or progestins generally have the opposite effect. Estrogens and progesterone/progestins can also interact with androgens; this is an important point because androgens in the body can increase in both older and younger women. The study of reproductive hormone (estrogens, progesterone, luteinizing, and follicle stimulating hormones) effects on body systems is challenging because of the complex and multifaceted influences of these hormones, both individually and in combination. Thus, a number of methods to alter hormone exposure are explained in this article. We conclude that men and women do not exhibit major quantitative differences in physiological thermoregulatory responses to exercise and/or body heating when factors such as fitness and body size are taken into account. However, female and male reproductive hormones have important influences that can significantly alter individual thermoregulatory responses at various points throughout the lifespan.

Challenges and methodology for testing young healthy women in physiological studies

Physiological responses and control of body systems differ between women and men. Moreover, within women, female gonadal hormones have important influences on organs and systems outside of reproduction. Until the NIH Revitalization Act of 1993, laboratories focused physiological research primarily on men, and this focus placed limitations on women's health care. Thus, the NIH directive to include women required scientists and physicians studying humans to consider female reproductive physiology. Even though this directive was enacted over 20 years ago, there is still a great deal of misunderstanding as to the best methods to control hormones or account for changes in internal hormone exposure in women. This discussion describes common methods investigators use to include women in physiological studies and to examine the impact of female reproductive hormone exposure for research purposes. In some cases, the goal is to control for phase of the cycle, so women are studied when the endogenous hormones should be similar to each other. When the goal of the research is to examine the effects of hormones on a physiological response, it is important to use methods that will change hormone exposure in a controlled fashion. We recommend a method that employs gonadotropin-releasing hormone (GnRH) agonist or antagonist to suppress estrogens, gonadotropins, progesterone, and androgens followed by administration of these hormones. While this method is more invasive, it is safe and is the strongest research design to examine both hormone effects within women and between women and men.

Androgens influence microvascular dilation in PCOS through ET-A and ET-B receptors

Hyperandrogenism and vascular dysfunction often coexist in women with polycystic ovary syndrome (PCOS). We hypothesized that testosterone compromises cutaneous microvascular dilation in women with PCOS via the endothelin-1 ET-B subtype receptor. To control and isolate testosterone's effects on microvascular dilation, we administered a gonadotropin-releasing hormone antagonist (GnRHant) for 11 days in obese, otherwise healthy women [controls, 22.0 (4) yr, 36.0 (3.2) kg/m(2)] or women with PCOS [23 (4) yr, 35.4 (1.3) kg/m(2)], adding testosterone (T; 2.5 mg/day) on days 8-11. Using laser Doppler flowmetry and cutaneous microdialysis, we measured changes in skin microcirculatory responsiveness (ΔCVC) to local heating while perfusing ET-A (BQ-123) and ET-B (BQ-788) receptor antagonists under three experimental conditions: baseline (BL; prehormone intervention), GnRHant (day 4 of administration), and T administration. At BL, ET-A receptor inhibition enhanced heat-induced vasodilation in both groups [ΔCVC control 2.03 (0.65), PCOS 2.10 (0.25), AU/mmHg, P < 0.05]; ET-B receptor inhibition reduced vasodilation in controls only [ΔCVC 0.98 (0.39), 1.41 (0.45) AU/mmHg for controls, PCOS] compared with saline [ΔCVC controls 1.27 (0.48), PCOS 1.31 (0.13) AU/mmHg]. GnRHant enhanced vasodilation in PCOS [saline ΔCVC 1.69 (0.23) AU/mmHg vs. BL, P < 0.05] and abolished the ET-A effect in both groups, a response reasserted with T in controls. ET-B receptor inhibition reduced heat-induced vasodilation in both groups during GnRHant and T [ΔCVC, controls: 0.95 (0.21) vs. 0.51 (13); PCOS: 1.27 (0.23) vs. 0.84 (0.27); for GnRHant vs. T, P < 0.05]. These data demonstrate that androgen suppression improves microvascular dilation in PCOS via ET-A and ET-B receptors.

The role of GnRH antagonists in assisted reproduction

The different schemes of application of gonadotrophin-releasing hormone (GnRH) antagonists in ovarian stimulation protocols for assisted reproduction are reviewed. Starting from the initial schemes of single and/or multiple doses, the efficacy of GnRH antagonists in 'soft' protocols of ovarian stimulation has been evaluated in natural cycles, and the possibility of inducing the final oocyte maturation under antagonists either with native luteinizing hormone-releasing hormone or with GnRH agonists. The largest clinical studies carried out with cetrorelix or with ganirelix and published to date were analysed. Apart from the benefits of reducing the duration of the treatment, gonadotrophin requirements and ovarian hyperstimulation syndrome incidence, there is still a serious debate on the potential deleterious effect of GnRH antagonists on implantation and pregnancy rates. More specific aspects such as cycle programming, application of GnRH antagonists in protocols for poor responders etc., were also reviewed in this survey.

Mechanisms contributing to low orthostatic tolerance in women: the influence of oestradiol

The impact of 17β-oestradiol (E2) exposure on autonomic control of orthostasis in young women is unclear. We tested the hypothesis that autonomic cardiovascular regulation is more sensitive to E2 exposure in women with low orthostatic tolerance. Women underwent an initial maximal lower body negative pressure (LBNP) test to place them into a low (LT, n = 7, 22 ± 1 years old, body mass index 22 ± 1 kg m(-2)) or a high orthostatic tolerance group (HT, n = 7, 22 ± 1 years old, body mass index 24 ± 1 kg m(-2)). We then suppressed endogenous reproductive hormone production using a gonadotrophin-releasing hormone antagonist (GnRHant) for 10 days, with E2 administration during the last 7 days of GnRHant. We measured R-R interval and beat-by-beat blood pressure during the modified Oxford protocol, and changes in heart rate, blood pressure and forearm vascular resistance (FVR) during submaximal LBNP. During submaximal LBNP, FVR increased in HT (ANOVA P < 0.05) but not in LT (ANOVA P > 0.05), and stroke volume was lower in LT relative to HT at all levels of LBNP (P < 0.05). Compared with GnRHant, E2 administration shifted FVR lower in LT (ANOVA P < 0.05), with no effect in HT. Administration of E2 increased baroreflex control of heart rate (derived from the modified Oxford protocol) in LT (GnRHant 10.7 ± 2.5 ms mmHg(-1) vs. E2 16.1 ± 2.4 ms mmHg(-1), P < 0.05) but not in HT (GnRHant 13.4 ± 1.9 ms mmHg(-1) vs. E2 15.3 ± 2.4 ms mmHg(-1), n.s.). In conclusion, blunted peripheral vasoconstriction and lower stroke volume contribute to compromised orthostatic tolerance in women; this inability to vasoconstrict is further exacerbated by exposure to E2. Furthermore, E2 administration increases baroreflex-mediated heart rate responses to orthostasis in low orthostatic tolerant women, which is likely to be a compensatory mechanism for the blunted peripheral vascular resistance and lower central volume.

Blood pressure and water regulation: understanding sex hormone effects within and between men and women

Cardiovascular disease remains the leading cause of death for both men and women. Hypertension is less prevalent in young women compared with young men, but menopausal women are at greater risk for hypertension compared with men of similar age. Despite these risks, women do not consistently receive first line treatment for the early stages of hypertension, and the greater morbidity in menopause reflects this neglect. This review focuses on ovarian hormone effects on the cardiovascular and water regulatory systems that are associated with blood pressure control in women. The study of ovarian hormones within young women is complex because these hormones fluctuate across the menstrual cycle, and these fluctuations can complicate conclusions regarding sex differences. To better isolate the effects of oestrogen and progesterone on the cardiovascular and water regulation systems, we developed a model to transiently suppress reproductive function followed by controlled hormone administration. Sex differences in autonomic regulation of blood pressure appear related to ovarian hormone exposure, and these hormonal differences contribute to sex differences in hypertension and orthostatic tolerance. Oestrogen and progesterone exposure are also associated with plasma volume expansion, and a leftward shift in the osmotic operating point for body fluid regulation. In young, healthy women, the shift in osmoregulation appears to have only a minor effect on overall body water balance. Our overarching conclusion is that ovarian hormone exposure is the important underlying factor contributing to differences in blood pressure and water regulation between women and men, and within women throughout the lifespan.

Progesterone enhances adrenergic control of skin blood flow in women with high but not low orthostatic tolerance

Women are more susceptible to orthostatic intolerance. Peripheral α-adrenergic responsiveness is important in orthostasis and is lower in women compared to men, and is modulated by female sex hormones. We tested the hypothesis that oestradiol attenuates peripheral cutaneous adrenergic responses in women with low orthostatic tolerance (LT), whereas progesterone enhances adrenergic responses in women with high orthostatic tolerance (HT). After completing a maximal lower body negative pressure test to determine level of orthostatic tolerance (cumulative stress index, CSI), women self administered a gonadotropin releasing hormone (GnRH) antagonist for 16 days to suppress endogenous sex hormone production. Oestradiol (E2, 0.2 mg day−1, patch; days 4–16), and progesterone (P4, 200 mg day−1, oral; days 12–16) were administered. Skin blood flow responses to graded intradermal microdialysis infusions of noradrenaline (NA) were measured during GnRH antagonist, E2, and E2+P4, in eight HT (s.e.m. = 22 ± 1 years, CSI −871 ± 86 mmHg min) and eight LT (21 ± 1 years, CSI −397 ± 65 mmHg min) women. In separate probes, NA was infused alone, and co-infused with the nitric oxide synthase inhibitor NG-monomethyl-l-arginine (l-NMMA, 10 mm), the non-selective cyclooxygenase inhibitor ketorolac tromethamine (Keto, 10 mm), and combined l-NMMA + Keto (10 mm each). Progesterone administration enhanced adrenergic responses in HT women (logEC50 GnRH −4.02 ± 0.39, E2+P4 −5.18 ± 0.31, P < 0.05); this response was reversed with Keto (E2+P4 logEC50 NA+Keto −3.82 ± 0.35, P < 0.05). In contrast, no change in adrenergic responsiveness occurred in LT women during any hormone condition. These data indicate differential regulation of cutaneous adrenergic responses by progesterone via the cyclooxygenase pathway in women with high and low orthostatic tolerance.

Greater exercise sweating in obese women with polycystic ovary syndrome compared with obese controls

PURPOSE

We examined estradiol and testosterone effects on thermoregulation in women with and without Polycystic Ovary syndrome (PCOS). We hypothesized that core temperature (Tc) threshold for sweating during exercise is delayed in women with PCOS and that testosterone delays the Tc set point for sweating during exercise.

METHODS

For 16 d, we suppressed estrogens, progesterone, and testosterone with a gonadotropin-releasing hormone antagonist (GnRHant) in seven women with and seven women without PCOS (control); we added 17[beta]-estradiol (0.2 mg.d-1, two patches) on days 4-16 (E2) and testosterone (2.5 mg.d-1, orally) on days 13-16 (E2 + T). Under each hormone condition, subjects cycled in a temperature of 35 degrees C at 60% of age-predicted HRmax for 40 min.

RESULTS

Tc sweating threshold was lower in women in the PCOS group compared with those in the control during GnRHant (37.21 degrees C +/- 0.51 degrees C vs 37.70 degrees C +/- 0.12 degrees C, P < 0.05); neither E2 nor E2 + T influenced the thermoregulatory responses in PCOS. E2 decreased Tc sweating threshold in control (37.06 degrees C +/- 0.69 degrees C, P < 0.05), but E2 + T attenuated this response (37.53 degrees C +/- 0.19 degrees C). Peak sweating rate was greater in women in the PCOS group compared with those in the control group during GnRHant (1.06 +/- 0.47 vs 0.47 +/- 0.11 mg.cm-2.min-1) and E2 + T (0.85 +/- 0.41 vs 0.44 +/- 0.10 mg.cm-2.min-1, P < 0.05). Compared with the control group, total sweat losses were greater in the PCOS group during GnRHant (0.614 +/- 0.189 vs 0.419 +/- 0.098 L) and during E2 + T (0.696 +/- 0.281 vs 0.434 +/- 0.164 L, P < 0.05) but not during E2 (0.639 +/- 0.231 and 0.505 +/- 0.214 L for PCOS and control groups, respectively, P = 0.09).

CONCLUSIONS

Thermoregulation was adequate in women with PCOS; however, the women with PCOS achieved thermoregulation at the expense of producing higher sweat volumes.

Sex hormone effects on body fluid and sodium regulation in women with and without exercise-associated hyponatremia

We hypothesized that exercise-associated hyponatremia (EAH) is a function of excess sodium loss combined with high water intake in women at risk for dysnatremias during endurance exercise. We further hypothesized that estradiol and progesterone exposure increases fluid retention and sodium loss during exercise in women at risk for EAH. For 16 days we suppressed estrogens and progesterone with a gonadotropin-releasing hormone antagonist (GnRH ant) in seven women with (Hypo) and nine women without (no Hypo) a history of hyponatremia; we added 17β-estradiol (0.2 mg/day patches) for days 4–16 (E2) and progesterone (200 mg/day) for days 13–16 (E2-P4). Under each hormone condition, subjects cycled in 35°C at 65% peak oxygen consumption (V̇o2peak) for 60 min, then at 55–60% V̇o2peak for 120 min. Subjects drank 8 ml/kg of water (and replenished urine volume) every 30 min over the final 120 min of exercise. S[Na+] fell by 4.3, 3.9, and 3.1 meq/l ( P < 0.05) with drinking during GnRH ant, E2, and E2-P4 in Hypo, with little fall in no Hypo. Under all conditions, combined urine and sweat sodium loss were similar between Hypo [−85.6 (SD 36.2), −86.4 (SD 39.2), and −112.0 (SD 30.0) meq] and no Hypo [−98.0 (SD 54.8), −80.9 (SD 57.6), and −105.1 (SD 46.4) meq, for GnRH, E2, and E2-P4], as was mass balance of electrolytes (EMB) for Hypo [−104.8 (SD 32.8), −103.6 (SD 42.1), and −132.8 (SD 34.9) meq] compared with no Hypo [−128.8 (SD 57.2), −113.5 (SD 61.1), and −143.4 (SD 49.6) meq for GnRH, E2, and E2-P4]. Mass balance of water [VMB, for Hypo, 0.42 (SD 0.10), 0.62 (SD 0.25), and −0.11 (SD 0.11) liter] compared with no Hypo [0.01 (SD 0.15), 0.03 (SD 17), and −0.16 (SD 0.13) liter for GnRH, E2, and E2-P4, P < 0.05] indicates water retention was the primary contributor to the lower S[Na+] in Hypo women.

Exogenous oestradiol and progesterone administration does not cause oedema in healthy young women

OBJECTIVE

Oedema is an increase in the extravascular component of extracellular fluid volume (ECFV). Fluid movement across the ECF is controlled by hydrostatic and oncotic pressures, which are influenced by oestradiol and progesterone. Thus we hypothesized that oestradiol decreases, while combined oestradiol + progesterone increases, protein and fluid movement out of the vasculature.

SUBJECTS

Subjects were eight healthy women (22 +/- 2 years).

DESIGN

Oestrogens and progesterone were suppressed with a gonadotropin-releasing hormone antagonist for 16 days; oestradiol (2 x 0.1 mg/day patches) was added for days 5-16 (E(2)) and progesterone (200 mg/day) was added for days 13-16 (E(2)-P(4)).

MEASUREMENTS

We estimated intravascular (plasma) volume (PV), transcapillary albumin escape rate (TER(alb)), and Starling forces (hydrostatic pressures of plasma and interstitium, plasma colloid pressure, capillary filtration coefficient) in the forearm on days 2 (GnRH antagonist), 9 (E(2)) and 16 (E(2)-P(4)).

RESULTS

In E(2), P([E2]) increased from 85 +/- 26 to 984 +/- 136 pmol/ml (P < 0.05), with no change in P([P4]). In E(2)-P(4), P([E2]) increased to 775 +/- 195 pmol/ml and P([P4]) increased from 6.4 +/- 3.2 to 43.8 +/- 16.2 nmol/l, P < 0.05). TER(alb) was lower during E(2) (5.1 +/- 0.9) and E(2)-P(4) (5.0 +/- 1.1) compared to GnRH antagonist (5.8 +/- 0.9%/h, P < 0.05). Plasma volume was unchanged by E(2), and showed a trend (P = 0.07) for an increase during E(2)-P(4) (48.2 +/- 2.9, 49.0 +/- 3.0 and 53.9 +/- 3.5 ml/kg for GnRH antagonist, E(2), E(2)-P(4), respectively). Starling forces were unaffected by hormone treatments. Plasma renin activity and serum aldosterone concentration increased during E(2)-P(4).

CONCLUSIONS

Neither E(2) nor E(2)-P(4) altered TER(alb) sufficiently to impact Starling forces indicating neither E(2) nor P(4) administration at these levels would likely cause oedema.

Aging attenuates both the regularity and joint synchrony of LH and testosterone secretion in normal men: analyses via a model of graded GnRH receptor blockade

Testosterone (T) secretion declines in the aging male, albeit for unknown reasons. From an ensemble perspective, repeated incremental signaling among gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and T is required to maintain physiological androgen availability. Pattern-regularity statistics, such as univariate approximate entropy (ApEn) and bivariate cross-ApEn, provide specific and sensitive model-free measurement of altered multi-pathway control. The present study exploits partial muting of one pathway (GnRH drive) to appraise adaptive regulation of LH and T secretion in young and aging individuals. Analyses comprised 100 paired 18-h LH and T concentration time series obtained in 25 healthy men ages 20-72 yr each administered placebo and three graded doses of a specific GnRH-receptor antagonist. Graded blockade of GnRH drive increased the individual regularity of LH and T secretion and the synchrony of LH-T feedforward and T-LH feedback in the cohort as a whole (P<0.001 for each). However, age markedly attenuated ganirelix-induced enhancement of univariate T orderliness and bivariate LH-T feedback and T-LH feedback synchrony (P <or= 0.0025). In summary, the present analyses support the thesis that aging disrupts coordinate control of T secretion, LH-T feedforward, and T-LH feedback in healthy men. Thus the experimental strategy of stepwise silencing of an agonistic pathway may have utility in dissecting the bases of altered neurohormonal linkages in other systems.

Gonadotropin-releasing hormone I analog acts as an antiapoptotic factor in mouse blastocysts

Both GnRH-I and its receptor (GnRHR)-I have been shown to be expressed in the mammalian preimplantation embryo. In this study, we investigated the molecular mechanisms of GnRH-I in the regulation of early embryonic development in mouse. We found that GnRH-I and GnRHR-I mRNAs were detectable throughout early embryonic stages and that expression levels of both increased significantly after the early blastocyst stage. In blastocysts, GnRH-I and GnRHR-I expression was detected in both inner cell mass and trophectoderm cells. The pregnant uterus also expressed both genes, suggesting that preimplantation embryos could be affected by GnRH through both paracrine and autocrine signaling. Treatment with GnRH-I agonist, buserelin, promoted development of two-cell-stage embryos to the expanded and hatched blastocyst stages and inhibited apoptosis in a dose-dependent manner. In contrast, treatment with GnRH-I antagonist, ganirelix acetate, inhibited development of preimplantation embryos beyond the expanded blastocyst stage and induced apoptosis; both effects could be reversed by cotreatment with GnRH-I agonist. GnRH-I antagonist-induced cell death was mediated by disruption of mitochondrial function, release of cytochrome c, and activation of caspase-3. Furthermore, treatment with GnRH-I antagonist decreased expression of two antiapoptotic growth factors, epidermal growth factor and IGF-II, in blastocysts. These results indicate that GnRH-I, acting as an antiapoptotic factor, is an important growth factor in development of mouse blastocysts.

GnRH-antagonists in reproductive medicine

Suppression of sex steroid production based on desensitisation and down-regulation of pituitary gonadotropin-releasing hormone (GnRH)-receptors by agonistic GnRH-analogues resulting in the blockage of gonadotropin release from the anterior pituitary gland is a well-established approach in a variety of clinical conditions. Antagonistic analogues of GnRH exert their effect by competing with endogenous GnRH for pituitary binding sites. Because of the lack of any intrinsic activity of these compounds, the characteristic initial 'flare-up' effect of GnRH-agonist administration is absent. A more rapid suppression of gonadotropin release from the pituitary gland can be achieved, enabling shorter treatment regimes in ovarian hyperstimulation for assisted reproduction. As yet, GnRH-antagonists have attained market approval only for the indication of premature luteinizing hormone (LH) surge prevention in controlled ovarian hyperstimulation and palliative treatment of advanced prostatic cancer. However, GnRH-antagonists may be useful in a variety of other malignant and non-malignant indications where rapid sex steroid suppression is desired, such as uterine leiomyomas, endometriosis, gynaecological cancers or benign prostatic hyperplasia. In the context of infertility treatment, available data on the application of GnRH-antagonists in the treatment of endometriosis and uterine leiomyomas are reviewed.

Clinical efficacy of the gonadotropin-releasing hormone antagonist, ganirelix, in Korean women undergoing controlled ovarian hyperstimulation for in vitro fertilization and embryo transfer with recombinant follicle-stimulating hormone

AIM

To assess the clinical efficacy and safety of the gonadotropin-releasing hormone (GnRH) antagonist, ganirelix (Orgalutran), treatment in women undergoing controlled ovarian hyperstimulation (COH) for in vitro fertilization and embryo transfer (IVF-ET) in Korean women.

METHODS

This was a non-comparative, open-label, single-center trial carried out on 31 infertile Korean women. A daily dose of 0.25 mg of the GnRH antagonist, ganirelix, was given, beginning on the sixth day of recombinant follicle-stimulating hormone (FSH) treatment. If the ovarian response was low, ganirelix treatment was delayed until the leading follicle reached a mean diameter of 14 mm. The ganirelix treatment was continued until the day of human chorionic gonadotropin (hCG) injection. Descriptive statistics were recorded for all parameters.

RESULTS

The median duration of ganirelix treatment was 4 days (range: 2-6 days) and the median total recombinant FSH dose was 1350 IU (900-2350 IU). During ganirelix treatment, the incidence of luteinizing hormone (LH) rises (LH = 10 IU/L) was 3.2% (one of 31 cases). On the day ovulation was triggered by hCG, the mean number of follicles >/=11 mm in diameter was 12.4 +/- 4.5, and the median of serum estradiol concentration was 4289.9 (1893.7-8268.5) pmol/L. The mean number of oocytes per retrieval was 10.9 +/- 6.1. The fertilization rate was 61.5%, and the mean number of replaced embryos was 2.8 +/- 0.6. The mean implantation rate was 10.0%, and the clinical pregnancy rate per transfer was 23.3% (seven of 30 cases) and the ongoing pregnancy rate per transfer was 20.0% (six of 30 cases).

CONCLUSION

The results of the present study support ganirelix as a safe, short, convenient and effective treatment for patients undergoing COH for IVF in Korean women.

Progesterone increases plasma volume independent of estradiol

Adequate plasma volume (PV) and extracellular fluid (ECF) volume are essential for blood pressure and fluid regulation. We tested the hypotheses that combined progesterone (P4)-estrogen (E2) administration would increase ECF volume with proportional increases in PV, but that P4would have little independent effect on either PV or ECF volume. We further hypothesized that this P4-E2-induced fluid expansion would be a function of renin-angiotensin-aldosterone system stimulation. We suppressed P4and E2with a gonadotropin-releasing hormone (GnRH) antagonist in eight women (25 ± 2 yr) for 16 days; P4(200 mg/day) was added for days 5–16 (P4) and 17β-estradiol (2 × 0.1 mg/day patches) for days 13–16 (P4-E2). On days 2 (GnRH antagonist), 9 (P4), and 16 (P4-E2), we estimated ECF and PV. To determine the rate of protein and thus water movement across the ECF, we also measured transcapillary escape rate of albumin. In P4, [Formula: see text] increased from 2.5 ± 1.3 to 12.0 ± 2.8 ng/ml ( P < 0.05) with no change in [Formula: see text] (21.5 ± 9.4 to 8.6 ± 2.0 pg/ml). In P4-E2, plasma concentration of P4remained elevated (11.3 ± 2.7 ng/ml) and plasma concentration of E2increased to 254.1 ± 52.7 pg/ml ( P < 0.05). PV increased during P4(46.6 ± 2.5 ml/kg) and P4-E2(48.4 ± 3.9 ml/kg) compared with GnRH antagonist (43.3 ± 3.2 ml/kg; P < 0.05), as did ECF (206 ± 19, 244 ± 25, and 239 ± 27 ml/kg for GnRH antagonist, P4, and P4-E2, respectively; P < 0.05). Transcapillary escape rate of albumin was lowest during P4-E2(5.8 ± 1.3, 3.5 ± 1.7, and 2.2 ± 0.4%/h for GnRH antagonist, P4, and P4-E2, respectively; P < 0.05). Serum aldosterone increased during P4and P4-E2compared with GnRH antagonist (79 ± 17, 127 ± 13, and 171 ± 25 pg/ml for GnRH antagonist, P4, and P4-E2, respectively; P < 0.05), but plasma renin activity and plasma concentration of ANG II were only increased by P4-E2. This study is the first to isolate P4effects on ECF; however, the mechanisms for the ECF and PV expansion have not been clearly defined.

Influence of hormonal stimulation on in vitro fertilization/embryo transfer outcome

OBJECTIVE

To compare efficacy and efficiency of ovarian stimulation therapy.

STUDY DESIGN

Retrospective study compares ovarian response as number of retrieved oocytes, fertilization rates, endometrial patterns, number of pregnancies and pregnancy rates to different stimulation protocols.

RESULTS

The least number of cancelled cycles was in long protocols with buserelin. There was no difference in overall number of retrieved oocytes between the rFSH and HMG protocols, but 75% of the patients undergoing both protocols had higher number of oocytes after rFSH. The highest pregnancy rate (35.13%) was with rFSH. There was no statistical correlation between endometrial pattern and type of protocol used. Data showed the 9 mm cut-off value for endometrial thickness, and RI = 0.58 for subendometrial blood flow between the pregnant and non-pregnant group of patients. Nitriderm patches significantly decreased (P < 0.05) subendometrial RI of the patients with impaired uterine perfusion, increased endometrial thickness and achieved better morphology.

CONCLUSIONS

These findings demonstrate that rFSH alone and in long protocol gives better results in wide patient population. Nitriderm patches seem to have good impact on pregnancy rate, but further studies are necessary before making any statements.

A randomized prospective trial comparing gonadotropin-releasing hormone (GnRH) antagonist/recombinant follicle-stimulating hormone (rFSH) versus GnRH-agonist/rFSH in women pretreated with oral contraceptives before in vitro fertilization

OBJECTIVE

To compare the effects of oral contraceptive (OC) pill pretreatment in recombinant FSH/GnRH-antagonist versus recombinant FSH/GnRH-agonist stimulation in in vitro fertilization (IVF) patients, and to evaluate optimization of retrieval day.

DESIGN

Prospective, randomized, multicenter study.

SETTING

Private practice and university centers.

PATIENT(S)

Eighty patients undergoing IVF who met the appropriate inclusion criteria.

INTERVENTION(S)

Four study centers recruited 80 patients. The OC regimen began on cycle days 2 to 4 and was discontinued on a Sunday after 14 to 28 days. The recombinant FSH regimen was begun on the following Friday. The GnRH-agonist group was treated with a long protocol; the GnRH-antagonist was initiated when the lead follicle reached 12 to 14 mm. When two follicles had reached 16 to 18 mm, hCG was administered.

MAIN OUTCOME MEASURE(S)

The primary outcome measures were the number of cumulus-oocyte complexes, day of the week for oocyte retrieval, and total dose and days of stimulation of recombinant FSH. Secondary efficacy variables included pregnancy and implantation rate; serum E(2) levels on stimulation day 1; serum E(2), P, and LH levels on the day of hCG administration; follicle size on day 6 and day of hCG administration; the total days of GnRH-analogue treatment; total days on OC; total days from end of OC to oocyte retrieval; and the cycle cancellation rate.

RESULT(S)

Patient outcomes were similar for the days of stimulation, total dose of gonadotropin used, two-pronuclei embryos, pregnancy (44.4% GnRH-antagonist vs. 45.0% GnRH-agonist, P=.86) and implantation rates (22.2% GnRH-antagonist vs. 26.4% GnRH-agonist, P=.71). Oral contraceptive cycle scheduling resulted in 78% and 90% of retrievals performed Monday through Friday for GnRH-antagonist and GnRH-agonist. A one day delay in OC discontinuation and recombinant FSH start would result in over 90% of oocyte retrievals occurring Monday through Friday in both groups.

CONCLUSION(S)

The OC pretreatment in recombinant FSH/GnRH-antagonist protocols provides a patient-friendly regimen and can be optimized for weekday retrievals. No difference was seen in number of 2PN embryos, cryopreserved embryos, embryos transferred, implantation and pregnancy rates between the two stimulation protocols.

Use of antagonists in ovarian stimulation protocols

Gonadotrophin-releasing hormone (GnRH) antagonists have been introduced in IVF to prevent premature LH surge. They bind competitively to pituitary receptors and prevent endogenous GnRH from exerting any stimulus on pituitary cells, avoiding the initial 'flare-up' effect and decreasing gonadotrophin secretion within a few hours. Pituitary reserve and gonadotrophin synthesis are not affected; therefore, the recovery of pituitary function is rapid. Two different regimes have been described. The multiple-dose protocol involves the administration of 0.25 mg cetrorelix (or ganirelix) daily from day 6-7 of stimulation, or when the leading follicle is 14-15 mm, until human chorionic gonadotrophin (HCG) administration. The single-dose protocol involves the single administration of 3 mg cetrorelix on day 7-8 of stimulation. Both antagonists with either regimen seem to be equally effective in the prevention of the LH surge. Compared with a long luteal agonist protocol, the treatment is shorter and requires a smaller amount of gonadotrophins. Pregnancy rate seems to be lower, but a decrease in the incidence of severe ovarian hyperstimulation syndrome (OHSS) is reported by several studies. A promising aspect of antagonists may be the possibility of making treatment less aggressive. Finally, in antagonist cycles, ovulation triggering is possible by GnRH agonists, avoiding the deleterious effect of HCG and thus preventing OHSS.

GnRH antagonists

Ovarian stimulation is an important step in the success rate of in vitro fertilization (IVF) allowing multiple follicular growth, several oocytes and consequently more embryos. The combination of GnRH-antagonists (GnRH-ant) and gonadotrophins is now available for clinical use and represent a valid alternative to classical protocol with GnRH agonist. GnRH-antagonists induce a direct block of GnRH receptor with a rapid decrease in LH and FSH, preventing LH surge. Two protocols has been designed for assisted reproduction technology (ART) treatment: multiple-dose protocol and a single-dose. Both protocols are simply, efficacious, started in the late follicular phase and do not have side effects. A review of GnRH-antagonist applications in ART cycles are presented. Smaller doses of gonadotrophins, shorter stimulation period and lower ovarian hyperstimulation syndrome (OHSS) incidence are reported in literature using GnRH-antagonist compared to agonist. Triggering of ovulation, the use in polycystic ovarian syndrome (PCOS) and poor reponders patients are other interesting indication. Regarding to pregnancy rate and potentially adverse effects of drugs on endometrium or implantation needed more data.

Effects of estrogen and progesterone administration on extracellular fluid

To determine the effect of estrogen and progesterone on plasma volume (PV) and extracellur fluid volume (ECFV), we suppressed endogenous estrogen and progesterone by using the gonadotropin-releasing hormone (GnRH) antagonist ganirelix acetate in seven healthy women (22 ± 1 yr). Subjects were administered GnRH antagonist for 16 days. Beginning on day 5 of GnRH antagonist administration, subjects were administered estrogen (E2) for 11 days, and beginning on day 12 of GnRH antagonist administration, subjects added progesterone (E2-P4) for 4 days. On days 2, 9, and 16 of GnRH antagonist administration, we estimated ECFV (inulin washout), transcapillary escape rate of albumin (TERalb), and PV (Evans blue dye). Plasma E2concentration increased from 17.9 ± 4.5 (GnRH antagonist) to 195.9 ± 60.1 (E2, P < 0.05) to 245.6 ± 62.9 pg/ml (E2-P4, P < 0.05). Compared with GnRH antagonist (1.3 ± 0.5 ng/ml), plasma P4concentration was unchanged during E2(0.9 ± 0.3 ng/ml) and increased to 9.4 ± 3.1 ng/ml during E2-P4( P < 0.05). Both E2(44.1 ± 3.1 ml/kg) and E2-P4(47.7 ± 2.8 ml/kg) increased PV compared with GnRH antagonist (42.8 ± 1.3 ml/kg, P < 0.05). Within-subjects TERalbwas a strong negative predictor of PV (mean r = 0.92 ± 0.03, P < 0.05), and TERalbwas lowest during E2-P4(5.7 ± 0.5, 4.1.0 ± 1.1, and 2.8 ± 0.9%/h, P < 0.05, for GnRH antagonist, E2, and E2-P4, respectively). ECFV was reduced during E2(227 ± 31 ml/kg, P < 0.05) compared with both GnRH antagonist (291 ± 37 ml/kg) and E2-P4(283 ± 19 ml/kg). Thus the percentage of extracellular fluid in the plasma compartment increased to 21.0% ( P < 0.05) during E2compared with GnRH antagonist (16.1%) and E2-P4(17.2%) admistration. Thus E2increased PV via actions on the capillary endothelium to lower TERalband favor intravascular water retention, whereas during E2-P4PV increased via the combined responses of ECFV expansion and lower TERalb.

Gonadotropin-Releasing Hormone Antagonists for Assisted Reproductive Techniques

Gonadotropin-releasing hormone (GnRH) antagonists have been tested extensively in ovarian stimulation protocols for assisted reproductive techniques (ART). GnRH antagonists immediately and rapidly inhibit gonadotropin release by the anterior pituitary gland by competitive blockage of the GnRH receptor, preventing and interrupting luteinising hormone surges in controlled ovarian hyperstimulation for infertility treatment. A review of the available literature on GnRH antagonists for ART is presented, focusing on the pharmacological and clinical properties of the two compounds available on the market, cetrorelix and ganirelix. Both cetrorelix and ganirelix are well tolerated and effective drugs for controlled ovarian hyperstimulation and are of comparable value for infertility treatment. Cetrorelix is available as a 0.25mg preparation for daily injections and as a 3mg intermediate depot preparation. Ganirelix is available as a 0.25mg preparation for daily injections.Currently, two treatment protocols are used in clinical practice: the GnRH antagonist multiple-dose protocol and the GnRH antagonist single-dose protocol. Both protocols are effective and well tolerated. Cetrorelix and ganirelix have not yet been directly compared in a clinical trial; nor have the single-dose and the multiple-dose approaches been compared in a randomised, controlled trial. Data to compare these compounds in clinical terms can be extrapolated only from results of phase II dose-finding studies and phase III studies comparing GnRH agonist cycles with GnRH antagonists in single- and multiple-dose protocols. Therefore, all conclusions on clinical differences between cetrorelix and ganirelix should remain tentative, as they are based on a limited amount of available data.Randomised, controlled trials comparing cetrorelix and ganirelix are warranted to further evaluate benefits and drawbacks of individual GnRH antagonists. Furthermore, more data are needed to determine the efficacy and safety of cetrorelix and ganirelix in established treatment protocols in patients other than those included in clinical trials investigating new drugs, such as "poor responders", patients with polycystic ovaries, patients with a history of allergy or overweight patients.

No influence of body weight on pregnancy rate in patients treated with cetrorelix according to the single- and multiple-dose protocols

The question of whether adjustment to body weight is necessary in in-vitro fertilization (IVF) cycles using GnRH antagonists is currently under discussion. Therefore, a data analysis of five prospective studies using either the single- or the multiple-dose antagonist protocol with cetrorelix (Cetrotide) was performed. The influence of stimulation procedure, gonadotrophins and body weight on pregnancy rate was evaluated in a linear logit model. The effect of the stimulation procedure and body weight on the cumulus-oocyte complex (COC) and follicle number was explored in an ANOVA model. Cetrorelix plasma concentrations were tested for any correlation with body weight. Baseline and outcome parameters in different body weight groups (<50 kg, 50-59 kg, 60-69 kg, 70-79 kg, > or =80 kg) were assessed for human menopausal gonadotrophin and recombinant human FSH stimulation separately. Cetrorelix plasma concentrations were correlated with body weight, but no influence of the type of stimulation or body weight on pregnancy rate was found. Body weight did not influence cetrorelix plasma concentrations. In contrast, body weight significantly influenced the number of retrieved COC as well as the number of follicles on the day of human chorionic gonadotrophin administration. Body weight does not influence the outcome of treatment in cetrorelix cycles.

Use of gonadotrophin-releasing hormone agonists to trigger ovulation

The introduction of gonadotrophin-releasing hormone (GnRH) agonists combined with gonadotrophins is considered to be one of the most significant advances in the development of in vitro fertilization (IVF) treatment. However, ovarian hyperstimulation syndrome (OHSS) remains a significant complication of controlled ovarian hyperstimulation. One possible strategy to reduce the risk of this complication would be the use of GnRH agonists instead of human chorionic gonadotrophin (hCG) to trigger the final stages of oocyte maturation. GnRH agonists are able to induce an endogenous surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and the effect may be more physiological than that of exogenous hCG. Several uncontrolled and controlled clinical studies have confirmed the efficacy of GnRH agonists for triggering ovulation, and pregnancy rates are comparable to those achieved with hCG. The incidence of OHSS appears to be decreased, but larger controlled studies are required to confirm this observation. The recent introduction of GnRH antagonists has led to renewed interest in the use of GnRH agonists to induce final oocyte maturation. An international multicentre randomized controlled trial has been completed recently comparing the efficacy of GnRH agonist with hCG for triggering ovulation in women undergoing controlled ovarian hyperstimulation using the GnRH antagonist ganirelix for pituitary suppression. The aim of the study was to determine the efficacy of the novel protocol for ovarian stimulation before IVF, in terms of pregnancy outcomes and the prevention of OHSS.

The gonadotrophin-releasing hormone antagonist ganirelix--history and introductory data

The gonadotrophin-releasing hormone antagonist ganirelix has recently become available to clinicians. Its indication, prevention of premature luteinizing hormone surges in assisted reproduction programmes, has been investigated extensively in numerous studies. This article summarizes the major results from pharmacokinetics studies, a double-blind dose-finding trial and three large-scale phase III randomized clinical trials, comparing ganirelix and the most commonly used gonadotrophin-releasing hormone agonists, buserelin,leuprolide and triptorelin, in a long protocol. It is concluded that controlled ovarian hyperstimulation with ganirelix offers significant advantages in terms of convenience of treatment as reflected in a considerably reduced treatment period.Safety and tolerance as well as overall clinical outcome are good.

Monitoring during gonadotrophin-releasing hormone antagonist protocols

The results of the four large industry sponsored multicentre clinical trials comparing gonadotrophin-releasing hormone (GnRH) antagonists and agonists in controlled cycles of assisted reproduction are reviewed from the perspective of implications for monitoring ovarian responses. The simplicity and consistency of antagonist-controlled cycles in normal women indicate that patients in assisted reproduction programmes should undergo fewer assessments and will receive shorter treatment cycles. However, the two-stage pattern of follicular recruitment in antagonist-controlled cycles leads to follicles of different size profiles at the end of the follicular phase compared with those obtained in agonist-controlled cycles (one recruitment process only). Increasing the dose of follicle-stimulating hormone (FSH) may increase oocyte yield, but does not obviate the difference between the two types of cycle. This difference has implications for the criteria used to determine timing of administration of the luteinization signal before oocyte retrieval.

Gonadotropin-Releasing Hormone Antagonists

Gonadotropin-releasing hormone (GnRH) antagonists are now widely used in protocols of patients with controlled ovarian hyperstimulation to treat infertility. By competitively binding to the pituitary GnRH receptor, they lead to a rapid suppression of gonadotropins and consecutively sex hormones. In the past, GnRH agonists have been exclusively used for these patients, with the disadvantage of an initial rise of gonadotropins--the flare-up effect. Several trials comparing the agonistic and antagonistic analogs of GnRH found no significant differences in oocyte quality, fertilization and pregnancy rates. Slightly lower implantation and pregnancy rates, and estradiol levels, in patients treated with GnRH antagonists has raised concern about eventual extrapituitary adverse effects. However, no convincing evidence has yet been found for any detrimental ovarian effects of GnRH antagonists. The lower rate of ovarian hyperstimulation syndrome, a potentially severe disadvantage of infertility treatment, is a positive feature of GnRH antagonists. The key point is that GnRH antagonists have been proven to be as effective and safe as GnRH agonists. This broadens the spectrum of indications for GnRH antagonists to sex hormone-dependent disorders like endometriosis, uterine fibroids, and gynecological cancers such as breast and ovarian cancer.

Use of third generation gonadotropin-releasing hormone antagonists in in vitro fertilization-embryo transfer: a review

Before gonadotropin-releasing hormone agonists (GnRHa) became available, approximately 20% of stimulated cycles within an in vitro fertilization (IVF) program were cancelled due to premature LH surges. By using the GnRHa to prevent LH surges via gonadotrope GnRH receptor down-regulation and desensitization, this percentage decreased to about 2%, and concomitantly, the IVF and pregnancy rates per cycle initiated were increased. Several treatment schedules currently are in use, including the so-called "long protocol," in which the GnRHa is begun in the luteal phase and down-regulation occurs before the start of the gonadotropin-stimulation treatment phase. This is generally the most effective regimen and is presently the most frequently used protocol. However, it has some disadvantages, such as hypoestrogenic side effects and an increase in the number of ampules of FSH or hMG required for adequate stimulation. There is a new generation of GnRH antagonists now clinically available, that has been able to minimize the potential side effects and provide reliable antagonism at the GnRH receptor. These agents seem better suited than GnRHa for assisted reproductive technology (ART) cycles inasmuch as they can prevent LH surges without requiring complete gonadotropin suppression. We have reviewed the current literature concerning their use in IVF cycles.

Comparable clinical outcome using the GnRH antagonist ganirelix or a long protocol of the GnRH agonist triptorelin for the prevention of premature LH surges in women undergoing ovarian stimulation

This multicentre, randomized study was performed to assess the efficacy and safety of 0.25 mg ganirelix (Orgalutran, Antagon) treatment, using triptorelin (Decapeptyl) in a long protocol as a reference treatment. In total, 236 subjects were randomized to treatment with ganirelix (0.25 mg, s.c.) and 119 to triptorelin (0.1 mg, s.c.) treatment (treatment ratio 2:1). Treatment with ganirelix started on day 6 of stimulation, whereas treatment with triptorelin started on menstrual cycle day 21 to 24 of the previous cycle (i.e. the midluteal phase). The ganirelix regimen was on average 17 days shorter (9 versus 26 days) compared to the triptorelin regimen. The median total dose of recombinant FSH (Puregon) used was 450 IU less (1350 versus 1800 IU) in the ganirelix protocol. The initial follicular growth was faster and, consequently, oestradiol concentrations were higher in the ganirelix group. On the day of human chorionic gonadotrophin (HCG), the mean number of follicles > or = 11 mm was 10.1 and 10.7 and the median serum oestradiol concentration was 1090 and 1370 pg/ml in the ganirelix and triptorelin groups respectively. Per attempt, 7.9 and 9.6 oocytes (mean) were retrieved in the ganirelix and triptorelin groups respectively. The fertilization rates (64.0% ganirelix and 64.9% triptorelin) and the mean number of good quality embryos (2.7 and 2.9) were comparable in both treatment groups. The implantation rate was identical (22.9%). The ongoing pregnancy rate per attempt was 31.0 and 33.9% in the ganirelix and triptorelin groups respectively. The ganirelix regimen showed an improved local tolerance in that the percentage of subjects with at least one local skin reaction was 2-fold lower than in the triptorelin group (11.9 versus 24.1%). Taking all data together, it may be concluded that ganirelix offers a new treatment regimen in ovarian stimulation that is short, safe and well-tolerated, optimizing convenience for the patient.

Pharmacodynamic effects and plasma pharmacokinetics of single doses of cetrorelix acetate in healthy premenopausal women

OBJECTIVE

To investigate the pharmacodynamic effects and plasma pharmacokinetics of single subcutaneous doses of cetrorelix acetate in healthy premenopausal women.

SETTING

Phase I clinical research unit.

PATIENT(S)

Healthy, premenopausal women aged 19 to 35 years.

INTERVENTION(S)

Single subcutaneous morning doses of cetrorelix acetate (1, 3, or 5 mg peptide base) were investigated in a randomized, single-blind, placebo-controlled, parallel-group design. After a control cycle, 36 women received cetrorelix acetate (12 per dose) and 12 received placebo on the eighth individual cycle day. Transvaginal ultrasound was performed, and blood samples for LH, FSH, E2 were collected during both cycles and for pharmacokinetics up to 168 hours after dosing. The serum hormone levels were determined by electrochemicoluminescence immunoassay and plasma cetrorelix concentrations by radioimmuno assay.

RESULTS

Cetrorelix acetate administration led to a rapid, marked, and reversible suppression of serum LH, E2, and to a lesser extent FSH concentrations. The median intra-individual shifts between treatment and control cycle were -1.0, 4.0, 8.0, and 9.5 days for serum LH maximum and -1.0, 4.5, 7.0, and 10.0 days for ovulation following placebo or 1, 3, and 5 mg cetrorelix acetate, peptide base, respectively. The area under the concentration-time curve (AUC) and peak cetrorelix concentrations in plasma (Cmax) increased proportionally with dose.

CONCLUSIONS

Cetrorelix acetate showed pronounced and reversible LH and E2 suppression and a dose-dependent postponement of LH surge and ovulation after single subcutaneous administrations to healthy premenopausal women. Dose proportionality over the range of 1 mg to 5 mg cetrorelix acetate, peptide base was demonstrated.

Efficacy and safety of ganirelix acetate versus leuprolide acetate in women undergoing controlled ovarian hyperstimulation

OBJECTIVE

To assess the efficacy, safety, and local tolerance of ganirelix acetate for the inhibition of premature luteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation (COH).

DESIGN

Phase III, multicenter, open-label randomized trial.

SETTING

In vitro fertilization (IVF) centers in North America.

PATIENT(S)

Healthy female partners (n = 313) in subfertile couples for whom COH and IVF or intracytoplasmic sperm injection were indicated.

INTERVENTION(S)

Patients were randomized to receive one COH cycle with ganirelix or the reference treatment, a long protocol of leuprolide acetate in conjunction with follitropin-beta for injection.

OUTCOME MEASURE(S)

Number of oocytes retrieved, pregnancy rates, endocrine variables, and safety variables.

RESULT(S)

The mean number of oocytes retrieved per attempt was 11.6 in the ganirelix group and 14.1 in the leuprolide group. Fertilization rates were 62.4% and 61.9% in the ganirelix and leuprolide groups, respectively, and implantation rates were 21.1% and 26.1%. Clinical and ongoing pregnancy rates per attempt were 35.4% and 30.8% in the ganirelix group and 38.4% and 36.4% in the leuprolide acetate group. Fewer moderate and severe injection site reactions were reported with ganirelix (11.9% and 0.6%) than with leuprolide (24.4% and 1.1%).

CONCLUSION(S)

Ganirelix is effective, safe, and well tolerated. Compared with leuprolide acetate, ganirelix therapy has a shorter duration and fewer injections but produces a similar pregnancy rate.

Embryo implantation and GnRH antagonists: GnRH antagonists in ART: lower embryo implantation?

Recently, concerns have been raised regarding possible adverse effects of gonadotrophin-releasing hormone (GnRH) antagonists on extra-pituitary reproductive cells and organs, i.e. ovarian cells, oocyte, embryo, endometrium. These concerns are based on numerous in-vitro studies suggesting decreased biosynthesis of growth factors caused by local action of GnRH antagonists. Clinically, it has been shown that the use of high doses (< or =1 mg daily) of GnRH antagonists is associated with low implantation rates in IVF. Although such direct adverse effect of GnRH antagonists cannot be ruled out at this time, so far clinical experience points to profound LH suppression as the major caveat associated with the use of high doses of GnRH antagonists. Very low LH concentrations are associated with aberrant concentrations of oestradiol during ovarian stimulation, which may in turn adversely effect implantation potential. The clinical data available thus far on the use of GnRH antagonists originate from protocols designed for clinical studies. It is predicted that as more clinical experience is gained, and with protocol modifications to suit individual patient response, GnRH antagonists will be comparable with the agonists in terms of cycle outcome.

Treatment with the gonadotrophin-releasing hormone antagonist ganirelix in women undergoing ovarian stimulation with recombinant follicle stimulating hormone is effective, safe and convenient: results of a controlled, randomized, multicentre trial. The European Orgalutran Study Group

A multicentre, open-label, randomized study of the gonadotrophin-releasing hormone (GnRH) antagonist ganirelix (Orgalutran((R))/Antagon((TM))) was performed in women undergoing ovarian stimulation with recombinant FSH (rFSH: Puregon((R))). The study was designed as a non-inferiority study using a long protocol of buserelin (intranasal) and rFSH as a reference treatment. A total of 730 subjects was randomized in a treatment ratio of 2:1 (ganirelix:buserelin) using an interactive voice response system which stratified for age, type of infertility and planned fertilization procedure [IVF or intracytoplasmic sperm injection (ICSI)]. The median duration of GnRH analogue treatment was 5 days in the ganirelix group and 26 days in the buserelin group, whereas the median total rFSH dose was 1500 IU and 1800 IU respectively. In addition, in the ganirelix group the mean duration of stimulation was 1 day shorter. During ganirelix treatment the incidence of LH rises (LH >/=10 IU/l) was 2.8% versus 1.3% during rFSH stimulation in the buserelin group. On the day of triggering ovulation by human chorionic gonadotrophin (HCG), the mean number of follicles >/=11 mm diameter was 10.7 and 11.8, and the median serum oestradiol concentrations were 1190 pg/ml and 1700 pg/ml in the ganirelix and buserelin groups respectively. The mean number of oocytes per retrieval was 9.1 and 10.4 respectively, whereas the mean number of good quality embryos was 3.3 and 3.5 respectively. The fertilization rate was equal in both groups (62.1%), and the same mean number of embryos (2.2) was replaced. The mean implantation rates were 15.7% and 21.8%, and the ongoing pregnancy rates per attempt were 20.3% and 25.7% in the ganirelix and buserelin groups respectively. Evaluation of all safety data indicated that the ganirelix regimen was safe and well tolerated. The overall incidence of ovarian hyperstimulation syndrome was 2.4% in the ganirelix group and 5.9% in the reference group. The results of this study support a safe, short and convenient treatment regimen of ganirelix, resulting in a good clinical outcome for patients undergoing ovarian stimulation for IVF or ICSI.

Pharmacokinetic and pharmacodynamic characteristics of ganirelix (Antagon/Orgalutran). Part II. Dose-proportionality and gonadotropin suppression after multiple doses of ganirelix in healthy female volunteers

OBJECTIVE

To assess the dose-proportionality and pharmacodynamic properties of multiple doses of ganirelix (Antagon/Orgalutran; NV Organon, Oss, the Netherlands).

DESIGN

Randomized, parallel, pharmacokinetic, and pharmacodynamic study.

SETTING

Phase I clinical research unit.

PATIENT(S)

Three groups of 15 healthy female volunteers of reproductive age.

INTERVENTION(S)

Subcutaneous injections of 0.125 mg, 0.25 mg, or 0.50 mg of ganirelix were given once daily for 7 days. Blood samples were taken to assess serum ganirelix, LH, FSH, and E2 concentrations.

MAIN OUTCOME MEASURE(S)

Pharmacokinetic parameters and hormone suppression.

RESULT(S)

Steady-state levels were reached between days 2 and 3. Peak concentrations, which occurred approximately 1 hour after dosing, increased in a dose-proportional manner and averaged 5.2 ng/mL, 11.2 ng/mL, and 22.2 ng/mL for the 0.125-mg, 0.25-mg, and 0.50-mg doses, respectively. Corresponding mean values for the area under the curve over one dosing interval (24 hours) were 33 ng x h/mL, 77.1 ng x h/mL, and 137.8 ng x h/mL, respectively. After the last 0.25-mg dose of ganirelix, serum LH, FSH, and E2 concentrations were maximally decreased (by 74%, 32%, and 25% at 4 hours, 16 hours, and 16 hours after injection, respectively). Serum hormone levels returned to pretreatment values within 2 days after the last injection.

CONCLUSION(S)

The pharmacokinetics of ganirelix were dose-proportional within the dose range studied. Multiple injections resulted in immediate suppression of gonadotropins, which was rapidly reversed after treatment discontinuation.