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Clinical Trial Summary

This research study involves the use of the drugs Letrozole, GnRH, and NAL-GLU GnRH antagonist. Letrozole is a drug that is approved by the U.S. Food and Drug Administration (FDA) for use in breast cancer treatment that has been found to block the formation of estrogen. The NAL-GLU GnRH antagonist is a drug that temporarily blocks the action of GnRH. GnRH is a hormone that the body makes that stimulates other hormones that then control the function of the ovary.

The purpose is to study the effects of the administration of letrozole in women with GnRH deficiency at the same time that they receive gonadotropin-releasing hormone (GnRH). In addition, administration of letrozole and NAL-GLU GnRH antagonist in healthy women with normal menstrual cycles will be done to evaluate the role of estrogen in the control of the hormone FSH, or Follicle Stimulating Hormone, in the female reproductive cycle. A better understanding of FSH control may help in the development of new treatments for women with difficulty conceiving.


Clinical Trial Description

The negative feedback control of FSH is crucial for the precise regulation of follicular development in the female. An important component of this feedback is exerted by estrogen. Letrozole will be used to block aromatase and therefore estradiol production in normal and GnRH deficient females. These studies will dissect the relative roles of estradiol and inhibin on FSH secretion at the pituitary and hypothalamus.

The aromatase inhibitors block aromatization of androgens to estrogens, allowing us to examine the relative contribution of estradiol and inhibin to FSH regulation. Using normal subjects and GnRH-deficient subjects receiving replacement GnRH allows us to compare the effect of relative estradiol blockade at the pituitary (GnRH deficient subjects) vs the pituitary and hypothalamus (normal subjects), thus determining the direct site of estradiol action.

A more thorough understanding of estrogen and inhibin feedback on FSH will improve our understanding of the failure of follicle development in subsets of patients with infertility, such as polycystic ovary syndrome, in which FSH levels are normal but follicles fail to develop. Study of FSH control will also help us understand the failure of negative feedback on FSH, which can result in multiple follicular development and multiple gestation and its associated costs and risks. Thus, these studies may afford new therapeutic options for conception in infertile patients while simultaneously providing new methods to avoid the risks of multiple gestations. ;


Study Design

Allocation: Non-Randomized, Intervention Model: Parallel Assignment, Masking: Open Label


Related Conditions & MeSH terms


NCT number NCT00351416
Study type Interventional
Source Massachusetts General Hospital
Contact
Status Active, not recruiting
Phase Phase 2/Phase 3
Start date July 2004
Completion date December 2018

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