Ibutamoren () (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 An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

of the

ghrelin receptor 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 en ...

and a

growth hormone secretagogue Growth hormone secretagogues or GH secretagogues (GHSs) are a class of drugs which act as secretagogues (i.e., induce the secretion) of growth hormone (GH). They include agonists of the ghrelin/growth hormone secretagogue receptor (GHSR), such ...

, mimicking the

growth hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) 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 h ...

(GH)-stimulating action of the

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

ghrelin Ghrelin (; or lenomorelin, INN) is a hormone 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 highe ...

. It has been shown to increase the

secretion 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...

of several hormones including GH and

insulin-like growth factor 1 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. IGF-1 is a protein that in humans is ...

(IGF-1) and produces sustained increases in the plasma levels of these hormones without affecting

cortisol Cortisol is a steroid hormone, in the glucocorticoid class of hormones. When used as a medication, it is known as hydrocortisone. It is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in the adrenal gland ...

levels.

Effect on lean mass

Ibutamoren has been shown to sustain activation of the GH–IGF-1 axis 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 Growth hormone deficiency (GHD), or human growth hormone deficiency, is a medical condition resulting from not enough growth hormone (GH). Generally the most noticeable symptom is that an individual attains a short height. Newborns may also presen ...

, and human studies have shown it to increase both

muscle mass Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...

and

bone mineral density Bone density, or bone mineral density, is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optica ...

, making it a promising potential therapy for the treatment of frailty in the elderly. As of June 2017, ibutamoren is in the

preclinical In drug development, preclinical development, also termed preclinical studies or nonclinical studies, is a stage of research that begins before clinical trials (testing in humans) and during which important feasibility, iterative testing and drug ...

stage of development for growth hormone deficiency.

Effect on sleep architecture

In a small study of 14 subjects, MK-677 dosed at 25mg/day at bedtime was shown to increase REM sleep by 20% and 50% in young and older subjects respectively. Treatment with MK-677 also resulted in an approximate 50% increase in stage IV sleep in young subjects.

Non-research use

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. However, it has been used experimentally by some in the bodybuilding community. Since it chemically mimics the hormone

, it functions as a

neuropeptide Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the ...

in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

and crosses the blood-brain-barrier. According to some recent research and discussion, there is a concern that its particularly longer half-life might over-stimulate the ghrelin receptors in the brain.

References

External links

Ibutamoren - AdisInsight

MK-677 and A Potential Dementia Link - Loungecity.orgGhrelin Over-Stimulation, ''Molecular Psychiatry'' Study - Nature.org
{{GH/IGF-1 axis signaling modulators 4-Phenylpiperidines Anti-aging substances Experimental drugs Ghrelin receptor agonists Growth hormone secretagogues Indolines Spiro compounds Orphan drugs

Effect on lean mass

Effect on sleep architecture

Non-research use

See also

References

External links