Letrozole Treatment in Normal and GnRH Deficient Women
| Status: | Archived |
|---|---|
| Conditions: | Healthy Studies, Endocrine |
| Therapuetic Areas: | Endocrinology, Other |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 7/1/2011 |
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.
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.
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