Histrelin
Encyclopedia
Histrelin acetate is a nonapeptide analog of gonadotropin-releasing hormone
Gonadotropin-releasing hormone
Gonadotropin-releasing hormone , also known as Luteinizing-hormone-releasing hormone and luliberin, is a tropic peptide hormone responsible for the release of follicle-stimulating hormone and luteinizing hormone from the anterior pituitary. GnRH is synthesized and released from neurons within...

 (GnRH) with added potency. When present in the bloodstream, it acts on particular cells of the pituitary gland
Pituitary gland
In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...

 called gonadotrope
Gonadotrope
Gonadotropes are endocrine cells in the anterior pituitary that produce the gonadotropins, follicle-stimulating hormone and luteinizing hormone...

s. Histrelin stimulates these cells to release luteinizing hormone
Luteinizing hormone
Luteinizing hormone is a hormone produced by the anterior pituitary gland. In females, an acute rise of LH called the LH surge triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell-stimulating hormone , it stimulates Leydig cell...

 and follicle-stimulating hormone
Follicle-stimulating hormone
Follicle-stimulating hormone is a hormone found in humans and other animals. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and Luteinizing hormone act...

. Thus it is considered a gonadotropin-releasing hormone agonist
Gonadotropin-releasing hormone agonist
A gonadotropin-releasing hormone agonist is a synthetic peptide modeled after the hypothalamic neurohormone GnRH that interacts with the gonadotropin-releasing hormone receptor to elicit its biologic response, the release of the pituitary hormones FSH and LH.GnRH agonists are pregnancy category...

 or GnRH agonist
Agonist
An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...

.

Histrelin is marketed by Endo Pharmaceuticals under the brand names Vantas and Supprelin LA.

Pharmacology

In a process known as downregulation, daily stimulation of pituitary gonadotropes causes them to become desensitized
Desensitization (medicine)
For medical purposes, desensitization is a method to reduce or eliminate an organism's negative reaction to a substance or stimulus.For example, if a person with diabetes mellitus has a bad allergic reaction to taking a full dose of beef insulin, the doctor gives the person a very small amount of...

 to the effects of histrelin. As a consequence, levels of LH
Luteinizing hormone
Luteinizing hormone is a hormone produced by the anterior pituitary gland. In females, an acute rise of LH called the LH surge triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell-stimulating hormone , it stimulates Leydig cell...

 and FSH
Follicle-stimulating hormone
Follicle-stimulating hormone is a hormone found in humans and other animals. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and Luteinizing hormone act...

 fall after a short period of time. From that point forward, as long as histrelin is administered, the levels of LH and FSH in the blood remain low.

This prolonged lowering of LH and FSH levels is the rationale for therapy using GnRH agonists. Since LH and FSH stimulate the gonad
Gonad
The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...

s to produce estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...

s and androgen
Androgen
Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors...

s in females and males respectively, histrelin can effectively be used to decrease the sex steroid
Sex steroid
Sex steroids, also known as gonadal steroids, are steroid hormones that interact with vertebrate androgen or estrogen receptors. Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and...

s in the blood of patients.

Indications

Histrelin is used to treat hormone-sensitive cancers of the prostate
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

 in men and uterine fibroids
Uterine fibroids
A uterine fibroid is a benign tumor that originates from the smooth muscle layer and the accompanying connective tissue of the uterus.Fibroids are the most common benign tumors in...

 in women. In addition, histrelin has been proven to be highly effective in treating central precocious puberty
Precocious puberty
As a medical term, precocious puberty describes puberty occurring at an unusually early age. In most of these children, the process is normal in every respect except the unusually early age, and simply represents a variation of normal development. In a minority of children, the early development is...

 in children.

It is available as a daily intramuscular injection.

Histrelin is also available in a 12-month subcutaneous implant (Vantas) for the palliative treatment of advanced prostate cancer (since 2005 in the US, and since Jan 2010 in the UK).

A 12-month subcutaneous implant (Supprelin LA) for central precocious puberty (CPP) was approved on May 3, 2007 by the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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