BACKGROUND The differential efficacy between long GnRH agonist with antagonist can partly be due to the preexisting differences in the early antral follicles before ovarian stimulation. OBJECTIVE To compare the effect of pretreatment by estradiol with GnRH antagonist on antral follicular size coordination and basal hormone levels in GNRH antagonist protocol. MATERIALS AND METHODS On cycle d...

The mechanisms through which LH-RH antagonists suppress gonadotroph functions and LH-RH receptor (LH-RH-R) production are incompletely understood. To elucidate these mechanisms, we investigated the effects of Cetrorelix on the mRNA expression of pituitary LH-RH-R and luteinizing hormone (LH) secretion in three experimental systems with different pituitary LH-RH environments. Ovariectomy induced...

Natural cycles were abandoned in in-vitro fertilization (IVF) embryo transfer, due to premature luteinizing hormone (LH) surges--and subsequent high cancellation rates. In this study, we investigated the administration of a new gonadotrophin-releasing hormone antagonist (Cetrorelix) in the late follicular phase of natural cycles in patients undergoing IVF and intracytoplasmic sperm injection (I...

Electrospray ionization mass spectrometry (ESI-MS) was used to evaluate the structure of cetrorelix and the related impurities generated throughout the solid phase peptide synthesis (SPPS) reactions by Fmoc strategy. It was concluded that these by-products are formed as a result of incomplete removal of the protecting groups placed on side chains during synthesis. The impurity with 56 Da mass d...

UNLABELLED Conventional diagnostic procedures failed to provide a definitive diagnosis in a 15 year-old girl presenting with severe hirsutism, oligomenorrhea, and markedly elevated serum testosterone levels. To examine whether androgen overproduction was luteinizing hormone (LH) dependent and thus likely of ovarian origin we performed a new test to suppress LH secretion based on the use of Cetr...

BACKGROUND We report our experience on the efficacy of a new regimen of the GnRH antagonist, cetrorelix, and recombinant FSH, Gonal-F, for controlled ovarian stimulation in a donor oocyte programme. METHODS AND RESULTS Six oocyte donors were commenced on Gonal-F (150 IU) and two on Gonal-F 225 IU daily on day 4 together with cetrorelix 0.25 mg daily on day 8 until the day of administration of...

BACKGROUND For male hormonal contraception, combined administration of gonadotrophin-releasing hormone (GnRH) antagonists and androgens effectively suppresses spermatogenesis to azoospermia. In non-human primates this suppression can be maintained more easily by androgens alone. METHODS A clinical trial with six healthy volunteers was performed to test this approach in man. Loading doses of 1...

UNLABELLED A 75-year-old woman presenting with recent onset hirsutism and severely elevated serum androgen levels was evaluated to assess the source of excessive androgen production. Commonly recommended hormonal stimulation and suppression tests, and the usually employed imaging techniques were non-diagnostic. In this report, we describe a new suppression test based on the use of the GnRH rece...

The effects of depot formulations of the luteinizing hormone-releasing hormone (LHRH) agonist Decapeptyl (25 microg/day) for 30 days or LHRH antagonist Cetrorelix pamoate (100 microg/day) for 30 days and daily injections of 100 microg of Decapeptyl for 10 days on the expression of mRNA for pituitary LHRH receptor (LHRH-R) and the levels of LHRH-R protein were evaluated in rats. Serum sex steroi...