Gonadotropin-releasing hormone antagonist

Last updated
Gonadotropin-releasing hormone antagonist
Drug class
Cetrorelix.svg
Cetrorelix, one of the most widely used GnRH antagonists.
Class identifiers
Synonyms GnRH receptor antagonists; GnRH blockers; GnRH inhibitors; Antigonadotropins
Use Infertility; Prostate cancer; Precocious puberty; Breast cancer; Endometriosis; Uterine fibroids; Transgender people
Biological target GnRH receptor
Chemical class Peptides; Non-peptides
Legal status
In Wikidata

Gonadotropin-releasing hormone antagonists (GnRH antagonists) are a class of medications that antagonize the gonadotropin-releasing hormone receptor (GnRH receptor) and thus the action of gonadotropin-releasing hormone (GnRH). They are used in the treatment of prostate cancer, endometriosis, uterine fibroids, female infertility in assisted reproduction, and for other indications.

Contents

Some GnRH antagonists, such as cetrorelix, are similar in structure to natural GnRH (a hormone made by neurons in the hypothalamus) but that have an antagonistic effect, while other GnRH antagonists, such as elagolix and relugolix, are non-peptide and small-molecule compounds. GnRH antagonists compete with natural GnRH for binding to GnRH receptors, thus decreasing or blocking GnRH action in the body.

Medical uses

Prostate cancer

Testosterone promotes growth of many prostate tumors and therefore reducing circulating testosterone to very low (castration) levels is often the treatment goal in the management of men with advanced prostate cancer. GnRH antagonists are used to provide fast suppression of testosterone without the surge in testosterone levels that is seen when treating patients with GnRH agonists. [1] In patients with advanced disease, this surge in testosterone can lead to a flare-up of the tumour, which can precipitate a range of clinical symptoms such as bone pain, urethral obstruction, and spinal cord compression. Drug agencies have issued warnings regarding this phenomenon in the prescribing information for GnRH agonists. As testosterone surge does not occur with GnRH antagonists, there is no need for patients to receive an antiandrogen as flare protection during prostate cancer treatment. GnRH agonists also induce an increase in testosterone levels after each reinjection of the drug – a phenomenon that does not occur with GnRH antagonists.

The reduction in testosterone levels that occurs during GnRH antagonist therapy subsequently reduces the size of the prostate cancer. This in turn results in a reduction in prostate-specific antigen (PSA) levels in the patient's blood and so measuring PSA levels is a way to monitor how patients with prostate cancer are responding to treatment. GnRH antagonists have an immediate onset of action leading to a fast and profound suppression of testosterone and are therefore especially valuable in the treatment of patients with prostate cancer, where fast control of disease is needed.

The GnRH antagonist abarelix was withdrawn from the United States market in 2005 and is now only marketed in Germany for use in patients with symptomatic prostate cancer. Degarelix is a GnRH antagonist that is approved for use in patients with advanced hormone-sensitive prostate cancer throughout Europe and also in the United States. [2]

Fertility treatment

GnRH antagonists are also used for short periods in the prevention of premature LH surge and endogenous ovulation in patients undergoing ovarian hyperstimulation with FSH in preparation for in-vitro fertilization (IVF). [3] [4] [5] Typically they are administered in the mid-follicular phase in stimulated cycles after administration of gonadotropins and prior to the administration of hCG – which is given to stimulate ovulation. This protocol is likely beneficial in women expected to be hyper-responders, and probably also those expected to be poor responders to ovarian hyperstimulation. [6] There is probably little or no difference between GnRH antagonist and GnRH agonist protocols in terms of live birth or risk of miscarriage but GnRH antagonists probably reduce the risk of ovarian hyperstimulation syndrome. [7] The GnRH antagonists that are currently licensed for use in fertility treatment are cetrorelix and ganirelix.

Uterine disorders

Elagolix is indicated for the treatment of moderate to severe endometriosis pain and relugolix is indicated for the treatment of uterine fibroids.

Other uses

GnRH antagonists are being investigated in the treatment of women with hormone-sensitive breast cancer. [8] [9] In men, they are being investigated in the treatment of benign prostatic hyperplasia [10] and also as potential contraceptive agents. [11] GnRH antagonists could be used as puberty blockers in transgender youth and to suppress sex hormone levels in transgender adolescents and adults, but have not been studied in this context. [12] [13] [14] [15]

Available forms

GnRH antagonists marketed for clinical or veterinary use
NameBrand/code name(s)Approved/intended usesTypeRoute(s)Launch/status*Hits
Abarelix PlenaxisProstate cancerPeptideIM2003116,000
Cetrorelix CetrotideFemale infertility (assisted reproduction)PeptideSC2000134,000
Degarelix FirmagonProstate cancerPeptideSC2008291,000
Elagolix OrilissaEndometriosis; Uterine fibroidsNon-peptideOral2018126,000
Ganirelix OrgalutranFemale infertility (assisted reproduction)PeptideSC2000134,000
Linzagolix KLH-2109; OBE-2109Endometriosis; Uterine fibroidsNon-peptideOralPhase III [16] 9,730
Relugolix ReluminaUterine fibroids, prostate cancerNon-peptideOral201944,900
Notes: Launch/status = Launch year or developmental status (as of February 2018). Hits = Google Search hits (as of February 2018).

Currently approved GnRH antagonists include the peptide molecules abarelix, cetrorelix, degarelix, and ganirelix and the small-molecule compounds elagolix and relugolix. GnRH antagonists are administered by subcutaneous injection (cetrorelix, degarelix, ganirelix), by intramuscular injection (abarelix), or by oral administration (elagolix, relugolix).

Another non-peptide and orally-active GnRH antagonist that is in development is linzagolix. [17]

Side effects

As with all hormonal therapies, GnRH antagonists are commonly associated with hormonal side effects such as hot flushes, headache, nausea and weight gain. [18] [19] [20] When used in fertility treatment they can also be associated with abdominal pain and ovarian hyperstimulation. [18] [20] Subcutaneously administered agents are also associated with injection-site reactions [19] [21] and abarelix (neither of these being GnRH agonists, but instead being antagonists) has been linked with immediate-onset systemic allergic reactions. [22]

Pharmacology

GnRH antagonists competitively and reversibly bind to GnRH receptors in the pituitary gland, blocking the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary. [23] [24] In men, the reduction in LH subsequently leads to rapid suppression of testosterone production in the testes; in women it leads to suppression of estradiol and progesterone production from the ovaries. GnRH antagonists are able to abolish gonadal sex hormone production and to suppress sex hormone levels into the castrate range, or by approximately 95%.

Unlike the GnRH agonists, which cause an initial stimulation of the hypothalamic–pituitary–gonadal axis (HPG axis) that leads to a surge in testosterone or estrogen levels, GnRH antagonists have an immediate onset of action and rapidly reduce sex hormone levels without an initial surge. [1] [25]

Chemistry

GnRH antagonists include peptides such as cetrorelix and non-peptide and small-molecule compounds such as elagolix. Peptide GnRH antagonists are GnRH analogues.

Chemical structures of peptide GnRH antagonists
CompoundAmino acid sequenceMarketed
Cetrorelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-NH2Yes
Abarelix Ac-D-Nal-D-Cpa-D-Pal-Ser-N-MeTyr-D-Asn-Leu-Lys(iPr)-Pro-D-Ala-NH2Yes
Ganirelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Tyr-D-hArg(Et)2-Leu-hArg(Et)2-Pro-D-Ala-NH2Yes
Degarelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Aph(Hor)-D-Aph(Cba)-Leu-Lys(iPr)-Pro-D-Ala-NH2Yes
Teverelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Tyr-D-hCit-Leu-Lys(iPr)-Pro-D-Ala-NH2No
Ozarelix Ac-D-Nal-D-Cpa-D-Pal-Ser-N-MeTyr-D-hCit-Nle-Arg-Pro-D-Ala-NH2No
Ornirelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Lys(Pic)-D-Orn(6Anic)-Leu-Lys(iPr)-Pro-D-Ala-NH2No
Iturelix Ac-D-Nal-D-Cpa-D-Pal-Ser-Lys(Nic)-D-Lys(Nic)-Leu-Lys(iPr)-Pro-D-Ala-NH2No
Acyline Ac-D-Nal-D-Cpa-D-Pal-Ser-Aph(Ac)-D-Aph(Ac)-Leu-Lys(iPr)-Pro-D-Ala-NH2No
Azaline B Ac-D-Nal-D-Cpa-D-Pal-Ser-Aph(Atz)-D-Aph(Atz)-Leu-Lys(iPr)-Pro-D-Ala-NH2No
Sources: [28]

See also

Related Research Articles

<span class="mw-page-title-main">Luteinizing hormone</span> Gonadotropin secreted by the adenohypophysis

Luteinizing hormone is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. In females, an acute rise of LH known as an LH surge, triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell–stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone. It acts synergistically with follicle-stimulating hormone (FSH).

<span class="mw-page-title-main">Gonadotropin-releasing hormone</span> Mammalian protein found in Homo sapiens

Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and released from GnRH neurons within the hypothalamus. The peptide belongs to gonadotropin-releasing hormone family. It constitutes the initial step in the hypothalamic–pituitary–gonadal axis.

<span class="mw-page-title-main">Goserelin</span> Chemical compound

Goserelin, sold under the brand name Zoladex among others, is a medication which is used to suppress production of the sex hormones, particularly in the treatment of breast and prostate cancer. It is an injectable gonadotropin releasing hormone agonist.

Ovarian hyperstimulation syndrome (OHSS) is a medical condition that can occur in some women who take fertility medication to stimulate egg growth, and in other women in very rare cases. Most cases are mild, but rarely the condition is severe and can lead to serious illness or death.

<span class="mw-page-title-main">Nafarelin</span> Pharmaceutical drug

Nafarelin, sold under the brand name Synarel among others, is a gonadotropin-releasing hormone agonist medication which is used in the treatment of endometriosis and early puberty. It is also used to treat uterine fibroids, to control ovarian stimulation in in vitro fertilization (IVF), and as part of transgender hormone therapy. The medication is used as a nasal spray two to three times per day.

<span class="mw-page-title-main">Buserelin</span> Chemical compound

Buserelin, sold under the brand name Suprefact among others, is a medication which is used primarily in the treatment of prostate cancer and endometriosis. It is also used for other indications such as the treatment of premenopausal breast cancer, uterine fibroids, and early puberty, in assisted reproduction for female infertility, and as a part of transgender hormone therapy. In addition, buserelin is used in veterinary medicine. The medication is typically used as a nasal spray three times per day, but is also available for use as a solution or implant for injection into fat.

<span class="mw-page-title-main">Triptorelin</span> GnRH-agonist

Triptorelin, sold under the brand name Decapeptyl among others, is a medication that acts as an agonist analog of gonadotropin-releasing hormone, repressing expression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

<span class="mw-page-title-main">Gonadotropin-releasing hormone agonist</span> Drug class affecting sex hormones

A gonadotropin-releasing hormone agonist is a type of medication which affects gonadotropins and sex hormones. They are used for a variety of indications including in fertility medicine and to lower sex hormone levels in the treatment of hormone-sensitive cancers such as prostate cancer and breast cancer, certain gynecological disorders like heavy periods and endometriosis, high testosterone levels in women, early puberty in children, as a part of transgender hormone therapy, and to delay puberty in transgender youth among other uses. It is also used in the suppression of spontaneous ovulation as part of controlled ovarian hyperstimulation, an essential component in IVF. GnRH agonists are given by injections into fat, as implants placed into fat, and as nasal sprays.

The gonadotropin-releasing hormone receptor (GnRHR), also known as the luteinizing hormone releasing hormone receptor (LHRHR), is a member of the seven-transmembrane, G-protein coupled receptor (GPCR) family. It is the receptor of gonadotropin-releasing hormone (GnRH). The GnRHR is expressed on the surface of pituitary gonadotrope cells as well as lymphocytes, breast, ovary, and prostate.

<span class="mw-page-title-main">Histrelin</span> Chemical compound

Histrelin acetate, sold under the brand names Vantas and Supprelin LA among others, is a nonapeptide analogue of gonadotropin-releasing hormone (GnRH) with added potency. When present in the bloodstream, it acts on particular cells of the pituitary gland called gonadotropes. Histrelin stimulates these cells to release luteinizing hormone and follicle-stimulating hormone. Thus it is considered a gonadotropin-releasing hormone agonist or GnRH agonist.

<span class="mw-page-title-main">Ganirelix</span> Pharmaceutical drug

Ganirelix acetate, sold under the brand names Orgalutran and Antagon among others, is an injectable competitive gonadotropin-releasing hormone antagonist. It is primarily used in assisted reproduction to control ovulation. The drug works by blocking the action of gonadotropin-releasing hormone (GnRH) upon the pituitary, thus rapidly suppressing the production and action of LH and FSH. Ganirelix is used in fertility treatment to prevent premature ovulation that could result in the harvesting of eggs that are too immature to be used in procedures such as in vitro fertilization.

<span class="mw-page-title-main">Cetrorelix</span> Drug used in IVF procedures

Cetrorelix, or cetrorelix acetate, sold under the brand name Cetrotide, is an injectable gonadotropin-releasing hormone (GnRH) antagonist. A synthetic decapeptide, it is used in assisted reproduction to inhibit premature luteinizing hormone surges The drug works by blocking the action of GnRH upon the pituitary, thus rapidly suppressing the production and action of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In addition, cetrorelix can be used to treat hormone-sensitive cancers of the prostate and breast and some benign gynaecological disorders. It is administered as either multiple 0.25 mg daily subcutaneous injections or as a single-dose 3 mg subcutaneous injection. The duration of the 3 mg single dose is four days; if human chorionic gonadotropin (hCG) is not administered within four days, a daily 0.25 mg dose is started and continued until hCG is administered.

Controlled ovarian hyperstimulation is a technique used in assisted reproduction involving the use of fertility medications to induce ovulation by multiple ovarian follicles. These multiple follicles can be taken out by oocyte retrieval for use in in vitro fertilisation (IVF), or be given time to ovulate, resulting in superovulation which is the ovulation of a larger-than-normal number of eggs, generally in the sense of at least two. When ovulated follicles are fertilised in vivo, whether by natural or artificial insemination, there is a very high risk of a multiple pregnancy.

<span class="mw-page-title-main">Degarelix</span> Chemical compound

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<span class="mw-page-title-main">Elagolix</span> Chemical compound

Elagolix, sold under the brand name Orilissa, is a gonadotropin-releasing hormone antagonist medication which is used in the treatment of pain associated with endometriosis in women. It is also under development for the treatment of uterine fibroids and heavy menstrual bleeding in women. The medication was under investigation for the treatment of prostate cancer and enlarged prostate in men as well, but development for these conditions was discontinued. Elagolix is taken by mouth once or twice per day. It can be taken for up to 6 to 24 months, depending on the dosage.

<span class="mw-page-title-main">Relugolix</span> Chemical compound

Relugolix, sold under the brand names Orgovyx and Relumina among others, is a gonadotropin-releasing hormone antagonist medication which is used in the treatment of prostate cancer in men and uterine fibroids in women. It is taken by mouth.

<span class="mw-page-title-main">Gonadotropin-releasing hormone modulator</span> Type of medication which modulates the GnRH receptor

A GnRH modulator, or GnRH receptor modulator, also known as an LHRH modulator or LHRH receptor modulator, is a type of medication which modulates the GnRH receptor, the biological target of the hypothalamic hormone gonadotropin-releasing hormone. They include GnRH agonists and GnRH antagonists. These medications may be GnRH analogues like leuprorelin and cetrorelix – peptides that are structurally related to GnRH – or small-molecules like elagolix and relugolix, which are structurally distinct from and unrelated to GnRH analogues.

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