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MK-677 | Reviews, Clinical Trials, and Safety

MK-677 | Reviews, Clinical Trials, and Safety MK-677 is a non-peptide ghrelin agonist and growth hormone secretagogue that has been shown to improve body composition, sleep quality, bone density, and more. Compound Overview Class of Compound: Non-peptide ghrel

By Recovery & Performance Peptides Editorial Team

MK-677 | Reviews, Clinical Trials, and Safety

MK-677 is a non-peptide ghrelin agonist and growth hormone secretagogue that has been shown to improve body composition, sleep quality, bone density, and more.

Compound Overview

Class of Compound:

Non-peptide ghrelin agonist and growth hormone secretagogue.

Mechanism of Action:

MK-677 is an orally-active, selective agonist of the ghrelin receptor, known to increase the secretion of growth hormone and insulin-like growth factor 1, without stimulating serum cortisol levels.

Notable Studies:

Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue

MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism

Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man

Also Known As:

MK-0677, oratrope, ibutamoren, L-163,191.

Research Applications:

Growth hormone deficiency

Body composition

Sleep quality

Anti-aging

Risks:

Increased appetite

Lack of human trials

Lack of FDA approval

Chemical Structure

What is MK-677?

MK-677 refers to ibutamoren mesylate, an orally active, non-peptide growth hormone secretagogue. As a selective agonist of the ghrelin receptor, MK-677 stimulates the pituitary gland to produce and release growth hormone (GH) and insulin-like growth factor 1 (IGF-1) without affecting levels of cortisol to a significant extent [1].

MK-677 has been nominated as a treatment of growth hormone deficiency (GHD, including adult-onset GHD) and catabolic conditions, and has been extensively studied in a variety of contexts, including for its roles in promoting bone formation and resorption, aiding in fat loss, and improving sleep quality​​ [2].

At the time of writing, there are no FDA-approved products containing ibutamoren mesylate, and MK-677 is classed as an Investigational New Drug in the United States, available to researchers as a reference material [2].

What Does MK-677 Do?

MK-677 is mechanistically indistinguishable from growth hormone-releasing peptide-6 (GHRP-6) and works by mimicking ghrelin, thus binding to the growth hormone secretion receptors (GHS-R) and stimulating the release of GH [3].

Preclinical animal studies have shown that MK-677 does not affect normal negative feedback mechanisms in the GH pathway such as somatostatin. MK-677 has been shown to trigger GH secretion without having a significant effect on plasma levels of aldosterone, luteinizing hormone, thyroxine, and prolactin, and only a modest effect on cortisol [1].

MK-677 is orally available, has an elimination half-life of 4-6 hours [1], and can be administered once daily [3], making it a strong candidate to treat GH deficiency as an alternative to exogenous GH therapy [4, 5].

MK-677 Benefits | Clinical Trials

Researchers at the University of Maryland have identified 16 experimental MK-677 studies and one observational study published between 1996 and 2018. These 17 studies involved a total of 1,664 test subjects, with the number of participants in each study varying between 8 and 564 [2]. Here is a summary of the main benefits of MK-677 observed:

Improves body composition: Several short-term clinical studies have found that MK-677 can positively impact body composition in test subjects. Notably:

A two-month study by Svensson et al. (1998) found that MK-677 helped increase GH levels and preserve levels of fat-free mass (FFM) when administered to twenty-four obese males while dieting. During the study, test subjects were assigned to receive either MK-677 25 mg or a placebo daily for 8 weeks.

Those who received MK-677 experienced a 40 percent increase in serum insulin-like growth factor I (IGF-I) and a significant increase in serum IGF-binding protein-3, especially during the second and eighth weeks. According to the researchers, MK-677 treatment resulted in sustained increases in lean body mass and a temporary increase in basal metabolic rate, levels suggesting that further study was needed to see if a higher dose of MK-677 or a longer treatment period would affect levels of body fat [7].

Enhances quality and duration of sleep: In 1997, Copinschi et al. found that MK-677 improved the quality and duration of sleep when administered to eight young test subjects. The study involved eight young test subjects aged 18-30 years participating in three treatment periods lasting seven days each.

The test subjects were randomly assigned to receive a bedtime dose of either MK-677 (5 and 25 mg) or placebo. Those who received MK-677 experienced a “50% increase in the duration of stage IV sleep and a more than 20% increase in REM sleep” compared to placebo. Researchers concluded that MK-677 may “simultaneously improve sleep quality and correct the relative hyposomatotropism of senescence” [8].

Aids bone formation and resorption: Other studies have investigated the effects of MK-677 on bone formation and resorption:

A 1999 paper published by Murphy et al. as “MK-677 Study Group” reported the findings from three separate studies into the effects of MK-677 on bone turnover in healthy and functionally impaired elderly adults.

The first study involved 32 healthy seniors who were assigned to receive either MK-677 at 10 mg or 25 mg, or placebo.

The second study involved 50 healthy adults aged 65-85 who received either MK-677 at 25 or 50 mg/day or placebo, while the third study involved 105 elderly patients with functional impairment aged 65-94 who received MK-677 (5, 10, or 25 mg) or placebo. According to the authors, “once-daily dosing of MK-677 stimulates bone turnover in elderly adults” [9].

A randomized, double-blind, parallel, and placebo-controlled trial by Svensson et al. (1999) assigned 24 obese patients to receive either MK-677 25 mg or placebo. Researchers found that short-term MK-677 treatment led to increases in markers of bone resorption and formation but suggested that further long-term studies were needed to gauge MK-677’s effect on bone mass [10].

Experimental treatment of Alzheimer’s Disease: A 2008 study by Sevigny et al. examined whether MK-677 could slow the rate of progression of symptoms in patients with Alzheimer’s Disease (AD). The researchers were operating on the belief that MK-677's ability to raise IGF-1 levels would clear amyloid beta plaques from the nervous systems of AD subjects, thus slowing the disease’s progression.

The study involved a total of 563 patients with mild to moderate AD who were randomly assigned to receive MK-677 25 mg or placebo daily for 12 months. 416 patients completed the study, and those in the MK-677 group experienced a 60 percent increase in serum IGF-1 levels at six months and a 72.9 percent increase after one year. Unfortunately, scores from the diagnostic tests used to assess the volunteers found that MK-677 was “ineffective at slowing the rate of progression of AD” [11].

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MK-677 Side Effects

The results of a study into the effects of MK-677 on healthy, older adults showed that it causes the following side effects [13]:

Increased fasting blood glucose levels (0.3 mmol/L, 5 mg/dL on average)

Decreased insulin sensitivity

Increased appetite (typically subsides within a few months)

Transient, mild lower extremity edema and muscle pain

Decreased low density lipoprotein cholesterol

Increased cortisol levels

This is consistent with the results of other MK-677 human clinical trials to date, which have not linked the compound to any severe side effects.

Is MK-677 Safe?

Little is known about the long-term safety of MK-677 as the drug has yet to pass a phase 2 trial and further research is needed to confirm its safety.

The most recent phase 2 trial involving MK-677 aimed to investigate the safety and efficacy of MK-677 for treating somatropin deficiency in children. However, this trial was suspended in July of 2021, before reaching a conclusion [4].

Notably, one 24-week study involving 123 elderly hip fracture patients was discontinued due to MK-677’s potential to increase the rate of congestive heart failure (CHF) in a few of the patients, with researchers concluding that the compound had an unfavorable safety profile in that specific population [14].

These findings indicate that a long-term safety study with independent validation is required before drawing any conclusions about the safety of MK-677.

MK-677 Dosage Calculator

Because MK-677 is an experimental compound with no officially recommended dosage, researchers may consult the above-cited literature to see how it has been administered in past studies.

Researchers typically start with an MK-677 dose of 12.5-25 mg/day across a variety of objectives.

Since it takes some time to achieve GH increase in the subject, the compound should be administered for an extended duration. Commonly, the material is given in cycles of 16-20 weeks, followed by a break of about one month.

Where to Buy MK-677 Online? | 2024 Edition

Qualified researchers may purchase MK-677 as a reference material from a number of online vendors. In our team’s experience, very few suppliers actually supply research-grade MK-677 or reliably deliver it worldwide.

Fortunately, we have found two vendors that do supply high-quality MK-677.

Chemyo

Chemyo is one of our top recommended vendors of MK-677, and here’s why:

Independently-Tested Compounds: Each batch of MK-677 sold by Chemyo is tested in a third-party lab and the reports are published online for full transparency. This lets researchers verify the purity of what they’re buying before they place an order.

Reasonable Prices: Chemyo sells research-grade MK-677 50mL (25mg/mL) for just $80, and researchers can save 10% when subscribing to the vendor’s newsletter.

Convenient Payments: Researchers will be pleased to know that Chemyo accepts major credit cards, eChecks, and BTC.

Buy MK-677 from our top-rated vendor...

Limitless Life

Limitless Life is another extremely competent research chemicals vendor, and one that we trust based on their quality analysis, express shipping, and wonderful customer care team.

Below is why they are so trusted:

Quality MK-677: Limitless Life’s third-party lab tests include HPLC-MS analysis to make certain that each lot of MK-677 is suitably pure and potent.

Very Fast Shipping: Limitless Life guarantees delivery within 24-48 hours when using their express shipping method, with other, less efficient, options also available.

CONNECTED / MODULES

Post-session references

Selected from shared article topics. Source links are retained where available.

01

Handling & safety lane

Source-derived education, not individual medical guidance or an instruction to dose.

DOSAGE SOURCE

MK-677 Sleep Protocol — Dosing Timing That Works

Research from the University of Virginia School of Medicine found that MK-677 (ibutamoren) increased REM sleep duration by 50% and enhanced sleep quality scores significantly when administered 90 minutes before bedtime. But only when dosing timing aligned with the body's natural growth hormone secretion pattern. Take it at the wrong time of day and you're dosing against your circadian rhythm, which undermines the very mechanism that makes MK-677 effective for sleep improvement. Our team has worked with researchers who've tested dozens of MK-677 sleep improvement protocols across varying doses and administration windows. The gap between protocols that work and those that produce only side effects comes down to three timing principles most online guides completely ignore. What's the optimal MK-677 sleep improvement protocol dosage timing? The optimal MK-677 sleep improvement protocol uses 12.5–25mg administered 90 minutes before target sleep onset, typically between 8:30–9:30 PM for a 10 PM bedtime. This timing leverages MK-677's 24-hour half-life to peak growth hormone release during the body's natural nocturnal GH pulse window (11 PM–2 AM), enhancing deep sleep architecture without causing morning grogginess or daytime appetite disruption. Here's what most protocols miss: MK-677 doesn't create sleep. It amplifies the body's existing GH-mediated sleep deepening mechanism. The compound works as a ghrelin receptor agonist and growth hormone secretagogue, meaning it triggers pul…
SIDE EFFECTS

Long-Term Side Effects

There have not been many long-term studies of the use of MK-677. So whether there are long-term side effects remains an open question. The few longer-term MK-677 studies that do exist did not note any long-term side effects. These have studied the use of MK-677 over two years [18] and 18 months [16] respectively. Still, even though the available evidence suggests that it appears safe over a couple of years, we need to remember that the research isn’t clear yet and so caution is warranted.
02

Question drills

Open a question for its connected answer.

01What If I Experience Increased Hunger at Night — Does That Mean It's Working?+

Yes, ghrelin receptor activation inherently stimulates appetite, particularly in the first 2–4 weeks before receptor adaptation occurs. This confirms the compound is binding correctly, though appetite stimulation doesn't correlate with muscle recovery efficacy. Some individuals experience minimal hunger increase yet show full IGF-1 elevation. If nighttime hunger disrupts sleep quality, consider moving your dose 90 minutes earlier (2 hours pre-sleep instead of 30–60 minutes), which slightly reduces peak ghrelin signaling intensity while maintaining GH pulse timing. Alternatively, a small serving of casein protein (20–25g) taken with the dose blunts hunger without significantly raising insulin if timed correctly.

SOURCE / realpeptides.co ↗
02What If Dosing Continues Beyond 12 Months?+

No controlled sarcopenia trial has extended beyond 24 months. Lean mass gains in the first 12 months appear to plateau rather than continue accruing. The 2008 University of Virginia study showed most gains occurred in months 3–9, with minimal further change between months 9–12. Chronic GH pathway activation raises theoretical concerns about insulin resistance and glucose dysregulation, which were observed as dose-limiting factors in several trials. Long-term safety data in elderly populations is sparse.

SOURCE / realpeptides.co ↗
03What If I Experience Increased Appetite or Water Retention on MK-677?+

Both are expected peripheral effects of GHSR activation and don't negate sleep benefits. Increased appetite occurs because ibutamoren mimics ghrelin, the hunger hormone. This is the same receptor that regulates GH release. Water retention results from aldosterone modulation and mild sodium retention, presenting as 1–3 kg weight gain in the first 7–10 days. Neither effect interferes with sleep architecture improvements. If water retention becomes uncomfortable, reduce sodium intake to below 2,300mg daily and ensure adequate potassium (3,500–4,700mg). The retention typically stabilises within three weeks as the renin-angiotensin system adapts.

SOURCE / realpeptides.co ↗
04What If I Experience Overwhelming Hunger That Disrupts Dietary Adherence?+

Switch to split dosing (10mg morning, 10mg evening) or reduce total daily dose to 10–12.5mg to lower peak ghrelin receptor occupancy. The hunger response is dose-dependent and predictable. It's not a failure of willpower but a direct pharmacological effect of ghrelin pathway activation. Prioritize high-protein, high-fiber meals that delay gastric emptying and extend satiety signaling. Avoid fasted training or prolonged gaps between meals during the initial 2–3 weeks when hunger adaptation is still occurring.

SOURCE / realpeptides.co ↗
05What If I'm Highly Caffeine-Tolerant — Does That Change the Interaction?+

Partial tolerance develops to caffeine's stimulant effects, but cortisol response remains largely intact even in habitual users consuming 400mg+ daily. A study in Psychopharmacology found that chronic caffeine users (>6 months at high intake) still exhibited a 20–30% cortisol increase following a 200mg dose, compared to 40–50% in naive users. The magnitude is attenuated, but the timing of the cortisol peak (60–90 minutes post-intake) and its duration (2–3 hours) remain consistent. For researchers with high baseline tolerance, extending the separation window to two hours instead of 90 minutes compensates for the sustained cortisol elevation. Caffeine tolerance does not eliminate the pharmacodynamic blunting. It just reduces it slightly.

SOURCE / realpeptides.co ↗
03

Evidence cooldown

Research context and source excerpts for a slower second read.

RESEARCH

So, Does MK-677 Heal Tendons? Examining the Evidence

This is the million-dollar question, and the honest answer is nuanced. We can't point to a massive, double-blind, placebo-controlled human trial titled "The Effects of Ibutamoren on Acute Achilles Tendon Ruptures." That study doesn't exist yet. Scientific research, especially with non-patented compounds, moves slowly. However, we can build a very strong, evidence-based case by connecting the dots. Here's what we know: It Unequivocally Raises GH and IGF-1: Numerous human studies have confirmed that MK-677 is incredibly effective at what it's designed to do. Studies on various populations, from young men to elderly subjects, have shown that daily administration of MK-677 can increase serum IGF-1 levels by anywhere from 40% to 90%. This isn't theoretical; it's a documented physiological effect. GH Therapy is Proven to Bolster Connective Tissue: We have decades of research on Growth Hormone therapy. Studies have repeatedly shown that GH administration increases collagen synthesis rates, thickens tendons, and can accelerate recovery from injuries. This is the foundational proof-of-concept. MK-677 achieves the same end goal (elevated GH/IGF-1) through a different, more natural mechanism. Ancillary Benefits Create a Pro-Recovery Environment: Healing isn't just about collagen. MK-677's effects go further. The elevation in GH and IGF-1 also leads to improved nitrogen retention, which is crucial for building any kind of tissue. Furthermore, a significant portion of the body's GH release occurs during deep sleep. Many users report a dramatic improvement in sleep quality and duration while using MK-677. Better sleep equals a better hormonal environment for healing. This isn't a side effect; it's a core component of the recovery equation. Our team has found that researchers investigating complex recovery scenarios are rarely looking for a single-pathway solution. They seek compounds that create a systemic shift. That’s the appeal here. You're not just targeting one small mechanism; you're fundamentally altering the body's hormonal environment to one that prioritizes growth and repair. While anecdotal reports from athletes should always be taken with a grain of salt, the sheer volume of positive feedback regarding nagging injuries finally healing while on MK-677 is hard to completely dismiss. It aligns perfectly with what the science would predict.

RESEARCH

Navigating the Research Landscape Responsibly

Understanding the science of detection is crucial for responsible conduct in both research and athletics. Ibutamoren is on the WADA Prohibited List under Section S2: Peptide Hormones, Growth Factors, Related Substances, and Mimetics. It is banned at all times, both in-competition and out-of-competition, for all athletes in sports governed by the WADA code. There is no ambiguity here. Its use in this context is prohibited. For the scientific community, the focus remains on understanding its potential. But this research must be conducted within ethical and legal frameworks. The data gathered from responsible studies helps shape our understanding of human physiology. For more insights into the world of peptides and research compounds, you can always check out our YouTube channel, where we break down complex topics into understandable segments. The conversation around MK-677 and its detection isn't just a technical one; it's about integrity. It’s about understanding the rules of the game, whether that game is professional sports or professional science. So, when we circle back to the original question—is MK-677 detectable in urine?—the answer is a clear and resounding yes. The science is solid, the tests are sensitive, and the detection window is significant. Acknowledging this reality is the first step for anyone, whether they're an athlete weighing the risks or a researcher planning a protocol. It's about making informed decisions based on facts, not fiction.

05

Product & matchup locker

Linked catalog and comparison files.

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