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Other names | MK-677; MK-0677; L-163,191; Oratrope |
Routes of administration | By mouth |
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Elimination half-life | 4–6 hours (in beagles); [1] IGF-1 levels remain elevated in humans with a single oral dose for up to 24 hours [2] |
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ECHA InfoCard | 100.236.734 |
Chemical and physical data | |
Formula | C27H36N4O5S |
Molar mass | 528.67 g·mol−1 |
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Ibutamoren (INN ) (developmental code names MK-677, MK-0677, LUM-201, L-163,191; former tentative brand name Oratrope) is a potent, long-acting, orally-active, selective, and non-peptide agonist of the ghrelin receptor and a growth hormone secretagogue, mimicking the growth hormone (GH)-stimulating action of the endogenous hormone ghrelin. [3] [4] [5] [6] [7] It has been shown to increase the secretion of several hormones including GH and insulin-like growth factor 1 (IGF-1) and produces sustained increases in the plasma levels of these hormones while also raising cortisol levels. [8]
Ibutamoren has been shown to sustain activation of the GH–IGF-1 axis, increasing growth hormone secretion by up to 97%, [9] and to increase lean body mass with no change in total fat mass or visceral fat. It is under investigation as a potential treatment for reduced levels of these hormones, such as in children or elderly adults with growth hormone deficiency, [3] [10] [11] [12] and human studies have shown it to increase both muscle mass and bone mineral density, [13] [14] making it a promising potential therapy for the treatment of frailty in the elderly. [15] [16] As of June 2017, ibutamoren is in the preclinical stage of development for growth hormone deficiency. [3]
In a small study of 14 subjects, MK-677 dosed at 25mg/day at bedtime was shown to increase rapid eye movement sleep by 20% and 50% in young and older subjects respectively. [17] Treatment with MK-677 also resulted in an approximate 50% increase in slow-wave sleep in young subjects. [17]
In a study of children with growth hormone deficiency, MK-677 performed better than other growth hormone secretagogues at improving growth hormone levels. [18] An ongoing study compares MK-677 directly to injectable hGH in terms of height velocity in this population. [19]
Since MK-677 is still an Investigational New Drug, it has not yet been approved to be marketed for consumption by humans in the United States. [3] However, it has been used experimentally by some in the bodybuilding community. The use of MK-677 is banned in most sports. [20]
Growth hormone (GH) or somatotropin, also known as human growth hormone in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. GH also stimulates production of insulin-like growth factor 1 (IGF-1) and increases the concentration of glucose and free fatty acids. It is a type of mitogen which is specific only to the receptors on certain types of cells. GH is a 191-amino acid, single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.
Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults. In the 1950s IGF-1 was called "sulfation factor" because it stimulated sulfation of cartilage in vitro, and in the 1970s due to its effects it was termed "nonsuppressible insulin-like activity" (NSILA).
Ghrelin is a hormone primarily produced by enteroendocrine cells of the gastrointestinal tract, especially the stomach, and is often called a "hunger hormone" because it increases the drive to eat. Blood levels of ghrelin are highest before meals when hungry, returning to lower levels after mealtimes. Ghrelin may help prepare for food intake by increasing gastric motility and stimulating the secretion of gastric acid.
Motilin is a 22-amino acid polypeptide hormone in the motilin family that, in humans, is encoded by the MLN gene.
Growth hormone–releasing hormone (GHRH), also known as somatocrinin among other names in its endogenous form and as somatorelin (INN) in its pharmaceutical form, is a releasing hormone of growth hormone (GH). It is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus.
Capromorelin, sold under the brand names, Entyce and Elura, is a medication used for the management of weight loss in cats and dogs. Capromorelin is a ghrelin receptor agonist known to increase appetite and weight gain.
Laron syndrome (LS), also known as growth hormone insensitivity or growth hormone receptor deficiency (GHRD), is an autosomal recessive disorder characterized by a lack of insulin-like growth factor 1 production in response to growth hormone. It is usually caused by inherited growth hormone receptor (GHR) mutations.
Growth hormone secretagogue receptor(GHS-R), also known as ghrelin receptor, is a G protein-coupled receptor that binds growth hormone secretagogues (GHSs), such as ghrelin, the "hunger hormone". The role of GHS-R is thought to be in regulating energy homeostasis and body weight. In the brain, they are most highly expressed in the hypothalamus, specifically the ventromedial nucleus and arcuate nucleus. GSH-Rs are also expressed in other areas of the brain, including the ventral tegmental area, hippocampus, and substantia nigra. Outside the central nervous system, too, GSH-Rs are also found in the liver, in skeletal muscle, and even in the heart.
Growth hormone-releasing peptide 6 (GHRP-6), also known as growth hormone-releasing hexapeptide, is one of several synthetic met-enkephalin analogues that include unnatural D-amino acids, were developed for their growth hormone-releasing activity and are called growth hormone secretagogues. They lack opioid activity but are potent stimulators of growth hormone (GH) release. These secretagogues are distinct from growth hormone releasing hormone (GHRH) in that they share no sequence relation and derive their function through activation of a completely different receptor. This receptor was originally called the growth hormone secretagogue receptor (GHSR), but due to subsequent discoveries, the hormone ghrelin is now considered the receptor's natural endogenous ligand, and it has been renamed as the ghrelin receptor. Therefore, these GHSR agonists act as synthetic ghrelin mimetics.
The growth-hormone-releasing hormone receptor (GHRHR) is a G-protein-coupled receptor that binds growth hormone-releasing hormone. The GHRHR activates a Gs protein that causes a cascade of cAMP via adenylate cyclase. GHRHR is distinct from the growth hormone secretagogue receptor, where growth hormone releasing peptides act to release growth hormone.
SM-130686 is a small-molecule drug which acts as a potent, orally-active agonist of the ghrelin/growth hormone secretagogue receptor (GHSR) and growth hormone secretagogue, with around half the potency of the endogenous agonist ghrelin as a stimulator of growth hormone release. It produces dose-dependent increases in muscle mass and decrease in body fat, and is under investigation for the treatment of growth hormone deficiency and other medical conditions. Concerns about its potential use as a performance-enhancing drug for athletes have led to the development of urine tests for SM-130686 and other GHSR agonists, even though no drugs from this class have yet progressed to clinical use.
Tabimorelin (INN) is a drug which acts as a potent, orally-active agonist of the ghrelin/growth hormone secretagogue receptor (GHSR) and growth hormone secretagogue, mimicking the effects of the endogenous peptide agonist ghrelin as a stimulator of growth hormone (GH) release. It was one of the first GH secretagogues developed and is largely a modified polypeptide, but it is nevertheless orally-active in vivo. Tabimorelin produced sustained increases in levels of GH and insulin-like growth factor 1 (IGF-1), along with smaller transient increases in levels of other hormones such as adrenocorticotropic hormone (ACTH), cortisol, and prolactin. However actual clinical effects in adults with growth hormone deficiency were limited, with only the most severely GH-deficient patients showing significant benefit, and tabimorelin was also found to act as a CYP3A4 inhibitor which could cause it to have undesirable interactions with other drugs.
Cyril Y. Bowers, M.D., emeritus professor of medicine at Tulane University School of Medicine, attended medical school at the University of Oregon and did an internship at the University of Washington. He then studied biochemistry at Cornell University and attended the postgraduate school of medicine at the University of Pennsylvania. From 1961-2004 he was the director of the Section of Endocrinology & Metabolism in the department of medicine at Tulane University School of Medicine. Bowers has served on the editorial board of several endocrine journals, was a member of the National Institute of Diabetes and Digestive and Kidney Diseases Study Section for eight years and has written over 400 articles in peer-reviewed journals, including chapters in books and over 200 abstracts.
Growth hormone secretagogues or GH secretagogues (GHSs) are a class of drugs which act as secretagogues of growth hormone (GH). They include agonists of the ghrelin/growth hormone secretagogue receptor (GHSR), such as ghrelin (lenomorelin), pralmorelin (GHRP-2), GHRP-6, examorelin (hexarelin), ipamorelin, and ibutamoren (MK-677), and agonists of the growth hormone-releasing hormone receptor (GHRHR), such as growth hormone-releasing hormone, CJC-1295, sermorelin, and tesamorelin.
Macimorelin (INN) – or Macrilen – is a drug that was developed by Aeterna Zentaris for use in the diagnosis of adult growth hormone deficiency. Macimorelin acetate, the salt formulation, is a synthetic growth hormone secretagogue receptor agonist. It is a growth hormone secretagogue receptor agonist, causing release of growth hormone from the pituitary gland. Macimorelin acetate is described chemically as D-Tryptophanamide, 2-methylalanyl-N-[(1R)-1-(formylamino)-2-(1H-indol-3-yl)ethyl]-acetate.
Pralmorelin (INN), also known as pralmorelin hydrochloride (JAN) and pralmorelin dihydrochloride (USAN), as well as, notably, growth hormone-releasing peptide 2 (GHRP-2), is a growth hormone secretagogue (GHS) used as a diagnostic agent that is marketed by Kaken Pharmaceutical in Japan in a single-dose formulation for the assessment of growth hormone deficiency (GHD).
Anamorelin (INN), also known as anamorelin hydrochloride, is a non-peptide, orally-active, centrally-penetrant, selective agonist of the ghrelin/growth hormone secretagogue receptor (GHSR) with appetite-enhancing and anabolic effects which is under development by Helsinn Healthcare SA for the treatment of cancer cachexia and anorexia.
Examorelin (INN) (developmental code names EP-23905, MF-6003), also known as hexarelin, is a potent, synthetic, peptidic, orally-active, centrally-penetrant, and highly selective agonist of the ghrelin/growth hormone secretagogue receptor (GHSR) and a growth hormone secretagogue which was developed by Mediolanum Farmaceutici. It is a hexapeptide with the amino acid sequence His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2 which was derived from GHRP-6. These GH-releasing peptides have no sequence similarity to ghrelin, but mimic ghrelin by acting as agonists at the ghrelin receptor.
Hormonal breast enhancement or augmentation is a highly experimental potential medical treatment for the breasts in which hormones or hormonal agents such as estrogen, progesterone, growth hormone (GH), and insulin-like growth factor 1 (IGF-1) are utilized or manipulated to produce breast enlargement in women. It is a possible alternative or supplement to surgical breast augmentation with breast implants or fat transfer and other means of medical breast enlargement.
Ulimorelin is a drug with a modified cyclic peptide structure which acts as a selective agonist of the ghrelin/growth hormone secretagogue receptor (GHSR-1a). Unlike many related drugs, ulimorelin has little or no effect on growth hormone (GH) release in rats. However, like ghrelin and other ghrelin agonists, ulimorelin does stimulate GH release with concomitant increases in insulin-like growth factor 1 (IGF-1) in humans. It has been researched for enhancing gastrointestinal motility, especially in gastroparesis and in aiding recovery of bowel function following gastrointestinal surgery, where opioid analgesic drugs used for post-operative pain relief may worsen existing constipation. While ulimorelin has been shown to increase both upper and lower gastrointestinal motility in rats, and showed promising results initially in humans, it failed in pivotal clinical trials in post operative ileus.