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MK-677, aka ibutamoren, is the only orally bioavailable growth hormone secretagogue (GHS) that effectively boosts growth hormone (GH) levels. 
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Increase muscle growth

Improve sleep

Lower cholesterol (LDL) levels

  • What is MK-677?

    MK-677 (ibutamoren, LUM-201, or L-163,191) is a non-peptide compound developed in the 1960s by the American pharmaceutical company Merck & Co. with the aim to treat GHD.

    The non-peptide structure of this compound makes it orally active, with oral bioavailability of over 60%. Thus, MK-677 can be taken as a capsule rather than an injection.

    Its non-peptide structure can be classified as either a spiroindoline and spiropiperidine. Yet, it functions similarly to peptide-based GHSs, such as the growth hormone-releasing peptide-6 (GHRP-6).

    MK-677 appears to be relatively selective towards the GHS receptors and elevates GH levels while causing only mild and transient increases in other pituitary hormones like prolactin.

    MK-677 has gathered significant interest as a potential alternative to injectable peptides. Upon oral administration, MK-677 can cross the blood-brain barrier and reach the ghrelin receptors within various parts of the brain, including the ghrelin receptors (aka GHS receptors) in the pituitary gland. This results in increased GH synthesis and a spike in serum GH levels.

    Based on the available data, MK-677 appears to be well tolerated even in long-term trials. Thus, despite not being a peptide, MK-677 is classified as GHS and has effectiveness and safety that are comparable to that of peptide-based medications.

  • How Does MK-677 Work?

    MK-677 works by activating the ghrelin receptors throughout the body. This results in increased GH secretion as well as elevated appetite levels.

    Clinical studies report that the peptide can increase the mean 24-hour GH levels by 57% when taken at 10 mg a day and by 97% when dosed at 25mg daily. Peak GH levels were also increased by 170%.

    The peaks in GH levels can reach up to 55.9 ng/ml after 25 mg of MK-677, which is over 6 times higher than the average GH peaks in the placebo group.

    The increase in GH levels occurs soon after oral administration, and GH levels are expected to remain elevated for several hours, as the half-life of MK-677 is 5-6 hours.

    Furthermore, the research shows that the increase in GH levels is sufficient to upregulate the main anabolic mediator of GH’s effects – insulin-like growth factor-1 (IGF-1).

    Mean IGF-1 levels increased by 55% after 2 weeks and by 88% after 4 weeks of therapy at 25 mg a day.

    Research in young obese individuals suggests that 2 weeks of therapy at 25 mg per day of MK-677 can also lead to notable results, such as increase in fat-free mass (FFM). The researchers did not share the specific increase in FFM at 2 weeks. FFM increased even further at 8 weeks, reaching a total of +6.6 lbs for the whole period.

    At our clinic, MK-677 is administered by highly skilled medical professionals who follow stringent safety protocols to ensure a secure and effective treatment experience.

    Utilizing a comprehensive assessment process, we tailor the dosing regimen of MK-677 to meet the individual needs of each patient while continuously monitoring and managing any potential side effects.

  • Benefits of MK-677

    The main benefit of MK-677 appears to be the increase in lean body mass, which is a result of the increased GH and IGF-1 levels, as well as the transient increase in appetite.

    As noted, the peptide can lead to +6.6 lbs in lean mass within 8 weeks. Moreover, the peptide did not affect fat mass. Thus, MK-677 may help increase muscle growth without affecting adiposity.

    Other benefits related to MK-677 therapy may include:

    • Reduced muscle loss during low-calorie dieting. Studies report reduced nitrogen losses compared to placebo in individuals taking MK-677 and following restrictive dietary regimes.
    • Improved cholesterol levels. MK-677 therapy at 25 mg daily reduced LDL (bad) cholesterol by -0.14 mmol/l from baseline, which experienced a +0.12 mmol/ increase.
    • Better sleep. MK-677 taken at 25 mg a day can improve both rapid-eye movement (REM) sleep and slow-wave non-REM sleep (deep sleep) by 20% and 50% respectively,
    • Improved bone health. MK-677 produced a 29.4% increase in mean serum osteocalcin, which indicates improved bone resorption and formation.

  • Side Effects of MK-677

    MK-677 can lead to mild and transient side effects, which had the following incidence in the treatment group:

    • 67% of subjects experienced increased appetite
    • 58% had joint pain
    • 44% had mild leg edema
    • 33% had mild muscle pains

    These side effects can be observed at 25 mg of MK-677 administered daily. Trials in higher doses (50 mg) also report potential risk for diarrhea and dry skin.

    Some studies suggest that MK-677 may also lead to a transient increase in cortisol and prolactin and an increase in insulin resistance.

    Despite its favorable safety profile, MK-677 is contraindicated for certain groups of the population, primarily due to a lack of research on such individuals:

    • history of cancer or active malignancies
    • pregnancy and lactation

  • How to Use MK-677

    MK-677 is a GHS that can be effectively administered orally as a pill, as it has a favorable rate of absorption in the digestive system.

    Based on the available scientific evidence, MK-677 appears to be safe and effective when administered in doses of 10-25 mg per day for periods of up to 24 months.

    The safety and effectiveness of MK-677 have not been studied for longer than 2 years of daily use

    Short-term trials lasting only a few days have also employed higher doses, reaching up to 50 mg daily.

    MK-677 is usually available in the form of capsules, which can be administered at any time during the day, as its absorption is not influenced by food intake.

    Thus, it may be optimal to take MK-677 late in the evening before bed to mimic the natural release of GH from the pituitary gland.

    The fact that the compound is available in capsule form also prolongs its shelf life compared to injectable peptides reconstituted with bacteriostatic water.

    When stored properly in a cool, dry place, away from light and heat, MK-677 capsules can have a shelf-life of 24 months.


How long does MK-677 stay in your system?

MK-677 has an elimination half-life of 5-6 hours. This is the time it takes for half of the compound to be excreted from the human body, and it usually takes 4-5 half-lives until a xenobiotic is completely eliminated. Thus, MK-677 may stay in your system for roughly 30 hours after each dose. It is important to note that MK-677 is banned by the World Anti-Doping Agency (WADA), and it can be detected via drug tests in both blood and urine samples.

What happens when you stop taking MK-677?

MK-677 has not been reported to pose a risk of psychological or physical addiction, and stopping it cold turkey does not pose any risk of withdrawal. Furthermore, GHSs do not suppress the function of the pituitary gland, so the GH levels in the body will return to pretreatment levels.

Does MK-677 affect other hormones?

Studies suggest that MK-677 causes a significant increase in GH and IGF-1 while also causing a mild, transient increase in prolactin and adrenocorticotropic hormone (ACTH). Thus, MK-677 appears to be more selective compared to other GHSs, such as GHRP-2 and GHRP-6. The available evidence does not suggest that MK-677 may affect testosterone levels in adults.


"MK-677 has been a fantastic addition to my routine. I've seen impressive muscle gains and my sleep quality has improved dramatically. What really stood out was the constant support from the medical team who monitored me closely for any side effects. "


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