Titus Thorne

Last Updated August 2, 2022

Titus Thorne

 August 2, 2022

This guide will compare and contrast MK-677 vs. sermorelin from a research standpoint and highlight the similarities and differences between these two compounds. Researchers interested in experimenting with one or both of these research chemicals will find a complete overview of what they are, the benefits they offer, and how they may be dosed in clinical or experimental settings.

To assist researchers wishing to conduct research with growth hormone releasing peptides (GHRPs) and human growth hormone-releasing hormone (GHRH) analogues, a complete guide to ordering these compounds online can be found at the end of this guide.

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

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What Is MK-677?

MK-677 is one of several code names for ibutamoren, which is a small molecule, orally active, selective agonist of the ghrelin receptor. The principal effect of MK-677 is to stimulate the production and secretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) [1].

MK-677 mimics the digestive hormone ghrelin and is chemically indistinguishable from GHRP-6. It binds to growth hormone secretion receptors (GHS-Rs) and has a pronounced effect on GH release without affecting prolactin, thyroxine, luteinizing hormone, or aldosterone to a significant extent. For this reason, there is currently strong research interest in whether MK-677 could be a safer alternative to exogenous GH therapy [2].

MK-677 has yet to pass Phase II clinical trials and its current status is a research chemical. The U.S. FDA classifies MK-677 as an Investigational New Drug and the highest known developmental phase of MK-677 is the ongoing Lumos Pharma Phase II trial for somatropin deficiency [3].

Benefits of MK-677

While MK-677 is a research chemical with no formally recognized clinical use, it has been investigated in a number of studies [4, 5, 6, 7, 8, 9, 10, 11]. Based on findings from these studies, the following benefits of MK-677 can be drawn.

Improved body composition

The main documented benefit of MK-677 is that it appears to improve body composition in research subjects [4, 5]. According to one study involving GH deficient child research subjects, MK-677 can significantly increase GH, IGF-I, and IGFBP-3 levels within just seven days, resulting in a positive effect on body composition [6].

In healthy, non-GH deficient test subjects, MK-677 has been shown to reverse diet-induced catabolism when administered at doses ranging from 5-25 mg per day. One study by Murphy et al. found that catabolism was reduced during a 14-day period of dieting when test subjects were administered MK-677, noting that the compound was beneficial for maintaining lean muscle mass [7].

MK-677 has also been investigated in obsese test subjects and shown to have a beneficial effect on body composition. A study by Svensson et al. noted that daily MK-677 administration of 25mg resulted in obsese subjects gaining 3 kg more fat-free mass compared with placebo [8].

Increased REM and Stage 4 sleep

The second documented benefit of MK-677 is that it appears to increase the duration of both REM (rapid eye movement) and Stage 4 sleep. According to one study, test subjects experienced a 20% increase in rapid-eye-movement (REM) sleep and a 50% increase in Stage 4 sleep when administered MK-677 at 25mg per day compared with placebo [9]. This finding has led to strong research interest in the beneficial effects of MK-677 with regards to sleep.

Increased bone resorption and formation

The third benefit of MK-677 is that it appears to have a positive effect on the bones of elderly test subjects, specifically on bone resorption and formation. According to a 9-week study by Murphy et al., elderly patients experienced a 29.4% in serum osteocalcin compared with a placebo with researchers noting a significant improvement in bone formation [10].

A Phase IIb study by Adunsky et al. found that MK-0677 treatment was beneficial for a group of elderly patients recovering from hip fracture [11]. These findings have helped generate strong interest in MK-677’s potentially strong impact on body composition in elderly test subjects.

MK-677 vs Sermolin

What Is Sermorelin?

Sermorelin is a human growth hormone-releasing hormone (GHRH) analogue that contains the first 29 amino acids of GHRH [12]. This makes it the shortest synthetic peptide to have the full biological activity of GHRH. The principal effect of sermorelin is to stimulate the secretion of HGH from the anterior pituitary.

In contrast to MK-677 which can be administered orally, sermorelin is administered intravenously or subcutaneously. It was previously available as a U.S. FDA-approved medicine under the brand names “Geref” and “Gerel” but was discontinued in 2008 due to manufacturing difficulties. Sermorelin is currently classified as a research chemical and is commonly available as sermorelin acetate, which is simply the acetate salt form of regular sermorelin.

Benefits of Sermorelin

Although sermorelin is currently classified as a research chemical with no formally recognized clinical use, it was FDA-approved (until 2008) to diagnose and treat GH deficiency in children. Researchers are currently studying sermorelin for the following potential benefits.

Fat loss

Sermorelin is currently being studied for its potential fat loss benefits. One study found that it may be helpful for the management of body composition in men with metabolic syndrome or subclinical hypogonadism (SH) [13]. Further research into sermorelin’s effect in healthy test subjects appears warranted and research is ongoing.

Improved sleep

There is currently strong research interest in the effect of sermorelin on sleep. A study involving rainbow trout showed that sermorelin could stimulate the production and secretion of HGH and orexin, a neurochemical that helps regulate the sleep cycle [14]. Research has revealed that sermorelin supports porper orexin secretion and function, helping growth and healing take place during sleep.


There is strong interest in sermorelin as an anti-aging peptide following a study involving swine that showed sermorelin had a significant impact on the rate of tissue growth and repair [15]. Sermorelin is currently being investigated for its potential benefit on skin quality and appearance, as well as the healing that may take place as a result of improved sleep.

Best Healing Peptides? | MK-677 vs. Sermorelin

Researchers curious about MK-677 vs. Sermorelin should know that there are several distinct similarities and differences between these two research chemicals. In this section, the main clinical findings will be explored and outlined.

The Similarities Between MK-677 vs. Sermorelin

Here are the main similarities between MK-677 vs. Sermorelin.

Legal status

The main similarity between MK-677 vs. Sermorelin is that both substances are currently classified as research chemicals. This means that neither one is in clinical use and that both are available to researchers who wish to conduct experiments.

Treatment for somatotropin deficiency

The second similarity between MK-677 vs. Sermorelin is that both of these research chemicals have, at various points, been investigated as potential treatments for somatotropin deficiency. MK-677 is currently being investigated in an ongoing Lumos Pharma Phase II trial as a potential treatment for somatotropin deficiency [3], while sermorelin was, prior to 2008, an FDA-approved medicine used to diagnose and treat children with idiopathic growth hormone deficiency [12].

Favorable safety profile compared with recombinant GH

The third similarity between MK-677 vs. Sermorelin is that both substances appear to have a favorable safety profile to recombinant GH (i.e. somatropin) [4]. Although MK-677 and sermorelin work along different pathways (MK-677 is a GHRP while sermorelin is a GHRH analogue), they both stimulate the natural production and secretion of HGH and have not been linked to the same side effects as recombinant GH. There is no research data to show that either compound causes side effects seen with exogenous GH therapy such as increased all-cause mortality in GH deficient children [16] and increased risk of harm in GH deficient adults [17].

In summary, both MK-677 and sermorelin have a pronounced effect on endogenous GH secretion and can be used (by researchers) to raise GH and IGF-1 levels in test subjects without encountering risks associated with recombinant GH therapy [4].

The Differences Between MK-677 vs. Sermorelin

Despite a number of similarities between MK-677 vs. Sermorelin, there are several areas where these research chemicals differ significantly. These areas will be highlighted in this section.

Route of administration

A key difference between MK-677 vs. Sermorelin is that the former may be administered orally [4], while the latter is administered intravenously or subcutaneously [12].


The second key difference between MK-677 vs. Sermorelin is that MK-677 is designed to be taken orally, once every 24 hours [4]. It has a much longer half-life than sermorelin [12].

Mechanism of action

The third key difference between MK-677 vs. Sermorelin is that they work along different pathways. MK-677 is a GHRP that works via the pituitary and the hypothalamus, which means that its action is specific to the GHS-R [4]. In contrast, sermorelin is a GHRH analogue [12].

Research and regulatory history

The fourth key difference is that sermorelin has gained FDA approval as a treatment for children with idiopathic growth hormone deficiency [12], while MK-677 has yet to pass a phase II clinical trial. Researchers should know that sermorelin was discontinued for reasons related to its manufacture and not due to safety or efficacy issues. There is a clear disparity between the volume of research conducted into MK-677 vs. Sermorelin. The majority of studies involving MK-677 have involved small sample sizes and low numbers of test subjects, whereas studies involving sermorelin have been robust enough to warrant FDA approval.

MK-677 vs Sermolin

Peptides For Healing | Recommended Dosing/Cycle

As both MK-677 and sermorelin are currently classified as research chemicals, neither peptide has a “recommended” dosing regime or “cycle”. We can however summarize how these substances have been dosed and cycled in past studies and clinical trials.

MK-677 Dosing/Cycles

Most studies involving MK-677 have dosed this research chemical in the range of 5-25 mg per day for short durations of 7-14 days, with the exception of one long-term study that lasted 24 weeks.

A sample MK-677 dosing schedule would be as follows:

  • Daily Dosage: 5-25mg depending on research goals.
  • Frequency: Once daily.
  • Study Duration: 2-9 weeks.
  • Cycle: MK-677 is not typically ‘cycled’.
  • Notes: Subjects should be monitored for insulin resistance.

Sermorelin Dosing/Cycles

As sermorelin was previously an FDA-approved drug, it has a more clearly defined set of parameters when it comes to dosing and cycling.

  • As a test for the diagnosis of growth hormone deficiency sermorelin can be dosed at 1 microg/kg bodyweight [12].
  • As a treatment for prepubertal children with idiopathic growth hormone deficiency sermorelin can be administered once daily via subcutaneous injections at 30 microg/kg bodyweight [12].

A difference between MK-677 vs. Sermorelin dosing/cycles is that the longest known MK-677 to date lasted just 24 weeks [11], while sermorelin has been tested for over 36 months of continuous treatment [12]. This clearly illustrates how further long-term research involving MK-677 is warranted before drawing any conclusions about dosing/cycles.

How to Order Peptides Online

Researchers interested in exploring MK-677 vs. Sermorelin can readily find both of these research chemicals for sale online.

Our preferred MK-677 vendor is Peptide Sciences. Here are some of the reasons why our team selected Peptide Sciences as our top MK-677 vendor:

  • Low prices: Peptide Sciences sells bottles of 60 12.5mg MK-677 capsules for $125. The cost-per-bottle drops to just $115 when researchers purchase three or more bottles.
  • Third-Party Testing: Every batch of MK-677 capsules is tested in a third-party lab and the reports are posted online for full transparency. This lets researchers verify the purity of the capsules prior to purchase.
  • Fast Shipping: All orders to the United States over $200 ship free and typically arrive within 2-3 business days. Due to Covid-related shipping delays, researchers can pay for expedited shipping from other providers.
  • Convenient payment options: Peptide Sciences accepts a wide variety of payment options including Apple Cash, Cash App, Zelle, credit cards (via Mesh Payments), Flex payment, and electronic checks.
  • 30-Day Money-Back Guarantee: Researchers can get a full refund if they aren’t entirely satisfied with their order from Peptide Sciences.

Researchers can also buy sermorelin legally from Research Peptides. Here are some of the reasons why Peptide Sciences is our leading choice for sermorelin:

  • Reasonable prices: Peptide Sciences also sells sermorelin 2mg and sermorelin 5mg. Prices start at just US$33 for sermorelin 2mg and US$49.5 for sermorelin 5mg. Researchers who purchase ten or more vials can save ten percent on their order.
  • High-quality peptides: Peptide Sciences post lab results for every batch of peptides on their website. Researchers can see the certificate of analysis and data from mass spectrometry tests before placing an order.
  • Great customer service: Research Peptides have a strong customer service team who are always helpful and accommodating.
    Secure payment methods: Peptide Sciences accepts a range of payment options including all major credit cards and cryptocurrencies.
  • Fast shipping: Researchers ordering from within the U.S. and enjoy delivery times of 2-3 days while researchers based internationally can expect delivery within 7-10 days.

Side Effects and Safety

There are significant differences in terms of side effects and safety between MK-677 and Sermorelin. Due to the limited data available about MK-677, it is difficult to draw any conclusions about the long-term safety of this research chemical [4]. The longest known trial involving MK-677 (Adunsky et al.) was discontinued after 24 weeks due to its potential to “increase the rate of congestive heart failure (CHF)” [11]. As MK-677 has yet to pass any Phase II clinical trial, further research into its side effects and safety is warranted.

By contrast, sermorelin has been far more extensively studied and sermorelin side effects are much better known. The most common side effects are [18, 19]:

  • Flushing or redness in the face [12]
  • Swelling, achiness, redness, or discomfort at the injection site [12]
  • Nausea [18]
  • Vomiting [18]
  • Loss of color in the face or paleness [19]
  • Headaches [19]

Some of the rarer side effects associated with sermorelin include [18]:

  • Rashes
  • Itching
  • Difficulty breathing/shortness of breath
  • Hives
  • Tightness in chest
  • Inflammation/swelling

Buy MK-677 from our #1 recommended vendor...

MK-677 vs. Sermorelin | Verdict

In summary, researchers who are curious about MK-677 vs. Sermorelin should know that these research chemicals have significant differences in terms of their benefits, side effects, and safety profiles. MK-677 has yet to pass Phase II clinical trials, while sermorelin is a GHRH analogue that previously held FDA approval as a medicine used to treat children with idiopathic growth hormone deficiency.

Crucially, researchers should know that sermorelin was discontinued in 2008 for reasons other than safety and efficacy, and the literature on sermorelin is much more extensive than that on MK-677 which has been the subject of limited, short-term trials.

Hopefully, this guide has highlighted clear areas where further research is warranted, especially in terms of MK-677’s utility and long-term side effects and safety. Researchers interested in pursuing these lines of inquiry are advised to contact our preferred vendor, Research Peptides, for more information.

MK-677 vs Sermolin


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  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. Ibutamoren – Lumos Pharma/Merck – AdisInsight. (2022). Retrieved 6 January 2022, from https://adisinsight.springer.com/drugs/800007434
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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. Neuroendocrinology. 1997 Oct;66(4):278-86. doi: 10.1159/000127249. PMID: 9349662.
  11. 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.
  12. Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999 Aug;12(2):139-57. doi: 10.2165/00063030-199912020-00007. PMID: 18031173.
  13. Sinha DK, Balasubramanian A, Tatem AJ, Rivera-Mirabal J, Yu J, Kovac J, Pastuszak AW, Lipshultz LI. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol. 2020 Mar;9(Suppl 2):S149-S159. doi: 10.21037/tau.2019.11.30. PMID: 32257855; PMCID: PMC7108996.
  14. Shepherd, B. S., Johnson, J. K., Silverstein, J. T., Parhar, I. S., Vijayan, M. M., McGuire, A., & Weber, G. M. (2007). Endocrine and orexigenic actions of growth hormone secretagogues in rainbow trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 146(3), 390-399.
  15. Bagno, L. L., Kanashiro‐Takeuchi, R. M., Suncion, V. Y., Golpanian, S., Karantalis, V., Wolf, A., … & Valdes, D. (2015). Growth hormone–releasing hormone agonists reduce myocardial infarct scar in swine with subacute ischemic cardiomyopathy. Journal of the American Heart Association, 4(4), e001464.
  16. 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.
  17. Cummings DE, Merriam GR. Growth hormone therapy in adults. Annu Rev Med. 2003;54:513-33. doi: 10.1146/annurev.med.54.101601.152147. Epub 2001 Dec 3. PMID: 12471175. Drugs.com. (2015). Sermorelin acetate. https://www.drugs.com/cdi/Sermorelin-acetate.html
  18. Mayo Clinic (n.d.). Sermorelin (Injection Route). https://www.mayoclinic.org/drugs-supplements/sermorelin-injection-route/side-effects/drg-20065923?p=1

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