Last Updated August 27, 2023

 August 27, 2023

Curious about MK-677 vs. HGH?

Then you’ve come to the perfect place. Inside, we break down what researchers must know about this two potent elements.

Researchers interested in investigating alternatives to HGH therapy may be curious about the similarities and differences between MK-677 vs. HGH.

Due to increased interest in MK-677 as an HGH alternative, our team has put together this guide to examine the two side by side. Those interested in conducting MK-677 research will find advice on where to order the compound online, as well as a summary of the side effects and safety concerns to note prior to conducting a study.

Buy MK-677 from the #1 online Peptides vendor in the world...

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What is MK-677?

MK-677 (ibutamoren) is a ghrelin receptor agonist and growth hormone secretagogue, meaning it works to stimulate the secretion of endogenous human growth hormone (HGH). The compound has long been proposed as a treatment of GH deficiency, as it mimics the GH-stimulating effect of the digestive hormone ghrelin with minimal effect on sex or thyroid hormones, including prolactin, thyroxine, luteinizing hormone, and aldosterone [1].

MK-677 has been shown to be identical in function and mechanism to growth hormone-releasing peptide 6 (GHRP-6), the first GHRP ever synthesized and found to stimulate GH release to a significant extent [2].

Like GHRP-6, MK-677 acts on both the pituitary and the hypothalamus without affecting the normal negative feedback mechanisms in the GH pathway such as somatostatin and IGF-1. MK-677 was designed to have superior oral bioavailability and serum half-life compared with GHRP-6 [3].

At the time of writing, MK-677 is sold exclusively as a research chemical, and the United States Food and Drug Administration has classified the compound as an Investigational New Drug. MK-677 is currently being investigated in the Lumos Pharma Phase II trial for somatropin deficiency in GH-deficient children. This trial was put on clinical hold in July 2021 and resumed in May 2022 [4].

Benefits of MK-677

While MK-677 has no formally established therapeutic uses, it has been the subject of several studies and clinical trials and is currently being investigated as a treatment for somatropin deficiency [4]. Based on the literature to date, MK-677 is believed to offer the following benefits and advantages.

MK-677 vs. HGH | Safety and Ease of Administration

Based on current research, MK-677 appears to have a better safety profile than HGH therapy (rhGH), which has been shown to increase the risk of mortality in GH-deficient children [5] and increase the risk of harm in GH deficient adults [6]. Furthermore, the pharmacokinetic properties of MK-677 make it suitable for once-daily oral administration, negating the need for frequent dosing and injectable route of administration [7].

MK-677 and Body Composition

Several studies have investigated MK-677’s effect on body composition in both GH-deficient and healthy test subjects. The bulk of research has focused on the compound’s effect on serum GH and IGF-1 secretion in GH-deficient adults and children. Investigation into its ability to treat somatropin deficiency in children is ongoing [4, 8].

MK-677 research in non-GH-deficient research subjects has shown that it can reverse diet-induced protein catabolism in healthy individuals [9] and increase levels of fat-free mass (FFM) in obese subjects [10].

MK-677 and Bone Health

There is strong evidence that MK-677 increases markers of bone turnover in elderly subjects and has a positive effect on bone resorption and formation.

According to results from three clinical studies lasting two to nine weeks and involving 187 elderly adults (65 years or older), those treated with MK-677 experienced an increase in mean serum osteocalcin of 29.4% compared with placebo. Subjects in the MK-677 group also experienced an increase in BSAP of 10.4% and mean urinary NTX excretion of 22.6%. Based on these elevated biochemical markers, MK-677 was determined to stimulate bone turnover in elderly subjects [11].

MK-677 and Sleep Quality

One small-scale study completed in 1997 found that research subjects experienced improved quality and duration of sleep following MK-677 administration. The participants, who were administered 25mg MK-677 daily, experienced a 50% increase in Stage 4 sleep and a 20% increase in REM (rapid eye movement) sleep [12]. The positive impact of MK-677 therapy on sleep suggests that further research in this area may be warranted.

What is HGH?

Human growth hormone is a proteohormone naturally secreted by the anterior pituitary gland. It binds to the hGH receptor and stimulates the production of insulin-like growth factor I (IGF-I), which promotes longitudinal growth in children and adolescents and other crucial metabolic functions in adults [13].

When hGH entered clinical use in 1958, it was obtained from cadaveric pituitaries, but the use of recombinant hGH (rhGH) was approved in 1985. Recombinant hGH is an artificial product that has been manufactured to be nearly identical to naturally occurring HGH [13].

In most countries including the United States, HGH is available as a prescription drug with the generic name somatropin. Its use is largely restricted to patients with a GH deficiency in childhood, patients with documented hypopituitarism, and those with AIDS wasting syndrome or short bowel syndrome [3].

Benefits of HGH

HGH therapy in individuals with GH deficiency has demonstrated numerous benefits, including [13]:

  • Improved longitudinal growth
  • Enhanced metabolic functions
  • Increased lipolysis and lean body mass
  • Decreased fat mass
  • Improvements in VO(2max) and maximal power output.

While these findings cannot be extrapolated to healthy test subjects, there is strong evidence that many athletes use GH in sports and that it has a strong effect on athletic performance [14].

For example, an 8-week randomized trial conducted in 2010 found that recreationally trained athletes who received 2mg/day of GH experienced a temporary increase in sprint capacity accompanied by a reduction in fat mass and an increase in lean body mass [15]. However, researchers cautioned that the sample size of the study was too small to draw meaningful conclusions about safety and that the purported benefits of GH, such as increased sprint capacity, were not maintained six weeks after GH was discontinued.

Best Healing Peptides? | MK-677 vs. HGH

Researchers curious about MK-677 vs. HGH will note that these compounds are strikingly dissimilar. MK-677 derives from the GHRP-6 molecule, while synthetic somatropin is a human growth hormone analog. This section will highlight the similarities and differences between MK-677 and HGH.

Similarities Between MK-677 vs. HGH

Both MK-677 and rhGH have been studied in GH deficient adults and children and shown to have a pronounced effect on [3]:

  • Serum GH and IGF-1 concentrations
  • Bone mineral density
  • Body composition
  • Quality of life

The main similarity between MK-677 and HGH is that they can both be used to ultimately raise GH and IGF-1 levels in test subjects, leading to the benefits we noted above, which include improved body composition, improved bone health, and enhanced sleep quality.

Differences Between MK-677 vs. HGH

There are numerous differences between MK-677 vs. HGH that we highlight below.

Route of Administration

rhGH is typically administered via subcutaneous injection while MK-677 is most often administered orally, thanks to its high oral bioavailability [3].


While a dose of rhGH has a shorter duration of action, typically <5 hours, MK-677 has a much longer half-life and elevates IGF-1 levels for up to 24 hours following a single dose [3, 13].

Mechanism of Action

While exogenous HGH therapy directly raises serum GH concentrations, MK-677 works to induce the endogenous secretion of growth hormone. Injectable rhGH binds directly to GH receptors and stimulates the release of IGF-1, causing many peripheral effects such as stimulation of cell proliferation, survival and differentiation, and inhibition of apoptosis. By contrast, MK-677 works via the pituitary and hypothalamus and its action is specific to the GHS-R [3].

Volume of Research

Recombinant GH has been far more extensively studied than MK-677 and significantly more is known about its benefits and side effects, especially over the long term. For instance, studies lasting up to six months have linked GH to increased lean body mass and reduced fat mass [16], increased exercise tolerance [17], and increased maximum oxygen uptake [18].

By comparison, far less is known about the effects of long-term MK-677 administration, especially its side effects and safety profile. One of the lengthiest MK-677 trials was a 24-week study involving elderly hip fracture patients [19], suggesting that additional long-term research involving MK-677 is required.

Peptides For Healing | Recommended Dosage and Cycle

HGH (somatropin) in the United States is regulated as a prescription medication, available from pharmacies only by prescription from a licensed healthcare provider. Any individual with a condition that might require hGH therapy should consult their primary healthcare provider, who if appropriate, will establish an hGH dosing schedule and provide guidelines for self-administration.

By contrast, MK-677 is sold as a research chemical and it falls upon researchers to establish an appropriate MK-677 dosing protocol. Researchers may draw on data from the above-cited studies and trials to aid in designing future studies [8, 9, 10, 11, 12, 19].

Based on our review of the available literature, here is a sample MK-677 protocol with the objective of wound healing and regeneration:

  • Daily Dosage: 12.5-25mg of MK-677.
  • Frequency/Timing: Cause subject to ingest one to two 12.5mg MK-577 capsules daily.
  • Study Duration: Three to six months, until desired outcome is achieved.
  • Cycle: MK-677 is not typically cycled.
  • Notes: Subjects should be monitored for insulin resistance. MK-677 is commonly sold in the form of 12.5mg MK-677 capsules.

How to Order Peptides Online

Researchers interested in exploring the benefits of MK-677 will be pleased to know that it is available online from our preferred vendor, Peptide Sciences.

Peptide Sciences lists MK-677 capsules for sale on its main website. Each bottle contains 60 capsules and each capsule contains 12.5mg MK-677. The bottles cost $125 each if purchased individually, but researchers can save 8% if buying three units ($115 each).

Peptide Sciences gets every batch of MK-677 capsules tested by an independent lab and posts the lab results on its website. This lets researchers verify the purity of each batch before deciding whether to place an order.

Here is how to order MK-677 from this excellent vendor:

  • Select the desired number of MK-677 bottles and click the “Add to Cart” tab. After doing so, you will see a summary of your shopping cart. Shipping charges are waived on orders over $200 to U.S. addresses.
  • After checking your order, click on the “Proceed to Checkout” tab and fill in your billing information, shipping information, preferred shipping method, and payment method on the next page.
  • Peptide Sciences currently recommended choosing FedEx as the shipping method to avoid delays and accepts a range of convenient payment methods like Apple Cash, Cash App, Zelle, credit cards (via Mesh Payments), Flex payment, and electronic checks.
  • The final step is to click on the “Place Order” tab and wait for confirmation. Peptide Sciences usually confirms the order within 24 hours.
  • For any order-related questions, email the Peptide Sciences team and expect a personalized response in 24-48 hours.

Buy MK-677 from the #1 online Peptides vendor in the world...

Side Effects and Safety | HGH vs. MK-677

HGH therapy has been administered clinically since the late 1950s while MK-677 is still undergoing clinical trials, so far less is known about the latter compound’s side effects and safety. This limitation notwithstanding, we summarize the documented side effects of each below.

HGH Side Effects and Safety

Side effects of doctor-supervised rhGH replacement therapy in children and adolescents include [20]:

  • Rash and pain at injection site
  • Transient fever
  • Prepubertal gynecomastia
  • Arthralgia
  • Edema
  • Benign intracranial hypertension
  • Insulin resistance
  • Progression of scoliosis
  • Slipped capital femoral epiphysis
  • Development of neoplasms (GH stimulates cell multiplication)

MK-677 Side Effects and Safety

MK-677 appears to be well-tolerated by test subjects, within the limits of the available research [3].

The following side effects were reported in a year-long MK-677 study involving 65 healthy yet elderly subjects [21]:

  • Lowered insulin sensitivity
  • Lowered low-density lipoprotein cholesterol
  • Mild, transient muscular pain
  • Mild, transient edema
  • Higher cortisol levels
  • Higher fasting blood glucose levels (0.3 mmol/L, 5 mg/dL on average)
  • Higher appetite

In a 24-week study involving elderly patients admitted for hip fracture, researchers concluded that MK-677 may increase the rate of congestive heart failure in that narrowly defined patient population [19]. Notwithstanding the study’s limitations, the findings underscore the need to investigate the safety of long-term MK-677 administration.


MK-677 vs. HGH | Verdict

Researchers curious about MK-677 vs. HGH will note that both compounds raise serum GH and IGF-1 concentrations in subjects. However, the two differ markedly in terms of their route of administration, duration of action, mechanism of action, and pharmacokinetics.

In summary, MK-677 is an oral GHS that has few known side effects, while recombinant hGH is an injectable prescription medication that has been linked to numerous short- and long-term side effects.

Researchers wishing to explore the benefits of MK-677 are highly advised to order from Peptide Sciences. This reputable vendor has a proven track record of supplying research-grade peptides to researchers worldwide.


  1. Patchett AA, Nargund RP, Tata JR, Chen MH, Barakat KJ, Johnston DB, Cheng K, Chan WW, Butler B, Hickey G, et al. Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue. Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):7001-5. doi: 10.1073/pnas.92.15.7001. PMID: 7624358; PMCID: PMC41459.
  2. Bowers CY. Growth hormone-releasing peptide (GHRP). Cell Mol Life Sci. 1998 Dec;54(12):1316-29. doi: 10.1007/s000180050257. PMID: 9893708.
  3. Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018 Jan;6(1):45-53. doi: 10.1016/j.sxmr.2017.02.004. Epub 2017 Apr 8. PMID: 28400207; PMCID: PMC5632578.
  4. Ibutamoren – Lumos Pharma/Merck – AdisInsight. (2022). Retrieved 28 July 2022, from
  5. Carel JC, Ecosse E, Landier F, Meguellati-Hakkas D, Kaguelidou F, Rey G, Coste J. Long-term mortality after recombinant growth hormone treatment for isolated growth hormone deficiency or childhood short stature: preliminary report of the French SAGhE study. J Clin Endocrinol Metab. 2012 Feb;97(2):416-25. doi: 10.1210/jc.2011-1995. Epub 2012 Jan 11. PMID: 22238382.
  6. Cummings DE, Merriam GR. Growth hormone therapy in adults. Annu Rev Med. 2003;54:513-33. doi: 10.1146/ Epub 2001 Dec 3. PMID: 12471175.
  7. Smith RG. Development of growth hormone secretagogues. Endocr Rev. 2005 May;26(3):346-60. doi: 10.1210/er.2004-0019. Epub 2005 Apr 6. PMID: 15814848.
  8. Codner E, Cassorla F, Tiulpakov AN, Mericq MV, Avila A, Pescovitz OH, Svensson J, Cerchio K, Krupa D, Gertz BJ, Murphy G. Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children. Clin Pharmacol Ther. 2001 Jul;70(1):91-8. doi: 10.1067/mcp.2001.116514. PMID: 11452249.
  9. Murphy MG, Plunkett LM, Gertz BJ, He W, Wittreich J, Polvino WM, Clemmons DR. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998 Feb;83(2):320-5. doi: 10.1210/jcem.83.2.4551. PMID: 9467534.
  10. Svensson J, Lönn L, Jansson JO, Murphy G, Wyss D, Krupa D, Cerchio K, Polvino W, Gertz B, Boseaus I, Sjöström L, Bengtsson BA. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. J Clin Endocrinol Metab. 1998 Feb;83(2):362-9. doi: 10.1210/jcem.83.2.4539. PMID: 9467542.
  11. Murphy MG, Bach MA, Plotkin D, Bolognese J, Ng J, Krupa D, Cerchio K, Gertz BJ. Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group. J Bone Miner Res. 1999 Jul;14(7):1182-8. doi: 10.1359/jbmr.1999.14.7.1182. PMID: 10404019.
  12. Copinschi G, Leproult R, Van Onderbergen A, Caufriez A, Cole KY, Schilling LM, Mendel CM, De Lepeleire I, Bolognese JA, Van Cauter E. Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man. Neuroendocrinology. 1997 Oct;66(4):278-86. doi: 10.1159/000127249. PMID: 9349662.
  13. Bidlingmaier M, Strasburger CJ. Growth hormone. Handb Exp Pharmacol. 2010;(195):187-200. doi: 10.1007/978-3-540-79088-4_8. PMID: 20020365.
  14. Siebert DM, Rao AL. The Use and Abuse of Human Growth Hormone in Sports. Sports Health. 2018 Sep/Oct;10(5):419-426. doi: 10.1177/1941738118782688. Epub 2018 Jun 22. PMID: 29932857; PMCID: PMC6116101.
  15. Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung KC, Graham K, Ho KK. The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial. Ann Intern Med. 2010 May 4;152(9):568-77. doi: 10.7326/0003-4819-152-9-201005040-00007. PMID: 20439575.
  16. Binnerts A, Swart GR, Wilson JH, Hoogerbrugge N, Pols HA, Birkenhager JC, Lamberts SW. The effect of growth hormone administration in growth hormone deficient adults on bone, protein, carbohydrate and lipid homeostasis, as well as on body composition. Clin Endocrinol (Oxf). 1992 Jul;37(1):79-87. doi: 10.1111/j.1365-2265.1992.tb02287.x. PMID: 1424196.
  17. Jørgensen JO, Pedersen SA, Thuesen L, Jørgensen J, Møller J, Müller J, Skakkebaek NE, Christiansen JS. Long-term growth hormone treatment in growth hormone deficient adults. Acta Endocrinol (Copenh). 1991 Nov;125(5):449-53. doi: 10.1530/acta.0.1250449. PMID: 1759534.
  18. Cuneo RC, Salomon F, Wiles CM, Hesp R, Sönksen PH. Growth hormone treatment in growth hormone-deficient adults. I. Effects on muscle mass and strength. J Appl Physiol (1985). 1991 Feb;70(2):688-94. doi: 10.1152/jappl.1991.70.2.688. PMID: 2022560.
  19. Adunsky A, Chandler J, Heyden N, Lutkiewicz J, Scott BB, Berd Y, Liu N, Papanicolaou DA. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011 Sep-Oct;53(2):183-9. doi: 10.1016/j.archger.2010.10.004. Epub 2010 Nov 9. PMID: 21067829.
  20. Souza FM, Collett-Solberg PF. Adverse effects of growth hormone replacement therapy in children. Arq Bras Endocrinol Metabol. 2011 Nov;55(8):559-65. doi: 10.1590/s0004-27302011000800009. PMID: 22218437.
  21. Nass, Ralf et al. “Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.” Annals of internal medicine vol. 149,9 (2008): 601-11. doi:10.7326/0003-4819-149-9-200811040-00003

Scientifically Fact Checked by:

Dimitar Marinov, Ph.D.

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