MK-677 Guía & Tabla de Dosis

What is MK-677?

MK-677 — also called Ibutamoren — is a research compound that belongs to a class called growth hormone secretagogues (GHS). That's a fancy way of saying it tells your body to release more of its own growth hormone (GH). What makes MK-677 stand out is that it works when taken by mouth, as a pill or liquid, rather than by injection.^[6] Most compounds in this class are peptides that break down in the stomach. MK-677 is a small non-peptide molecule, so it survives digestion and reaches the bloodstream intact.^[1] It is strictly a research compound — not approved for human medical use — and all studies cited here are laboratory or clinical research contexts only.

How MK-677 Works

Think of growth hormone release like a locked door. Your body normally uses a signalling molecule called ghrelin (your hunger hormone) as a key to open that door and let GH out. MK-677 is a ghrelin mimic — it fits the same lock (the ghrelin receptor, formally called GHSR) and turns it without being ghrelin itself.^[6] Once the door opens, the pituitary gland pulses out GH. That GH then travels to the liver and other tissues, prompting them to make IGF-1 (insulin-like growth factor 1), which is what actually drives many of the downstream effects researchers are interested in, such as protein building and tissue repair.^[1] Importantly, because MK-677 works through the body's own feedback system, GH levels can't go infinitely high — the body can still pump the brakes.^[6]

What the Research Shows

Reversing Protein Loss

One of the earliest and most-cited human studies gave 25 mg of MK-677 once daily for 7 days to healthy volunteers who were on a calorie-restricted diet. The diet alone caused the body to burn protein for fuel — a state called negative nitrogen balance (negative nitrogen balance simply means the body is breaking down more protein than it's building). MK-677 flipped that balance back to positive, meaning protein was being preserved rather than lost. IGF-1 levels also rose significantly compared to placebo.^[1]

Body Composition in a Real-World Case

A case report followed a 25-year-old male who took MK-677 (15 mg/day) together with LGD-4033 (a selective androgen receptor modulator) for 5 weeks. Body mass, lean mass, and trunk lean mass all increased. However, the same subject saw worrying changes too: liver enzymes spiked, cholesterol worsened, total testosterone dropped sharply, and bone mineral density dipped — though most markers returned to baseline after stopping.^[5] This case illustrates why research into safety signals is ongoing.

Somatic Growth in Rats

A 6-week rat study gave 4 mg/kg of MK-677 daily and measured GH, body weight, bone length, and IGF-1. GH spiked by about 1.8-fold initially — but after 6 weeks of continuous dosing, the GH response essentially disappeared. The rats did not show meaningful gains in body length or IGF-1 over the full period. Researchers found that the hypothalamus ramped up production of somatostatin — a natural GH-braking molecule — which appeared to dampen the long-term response.^[3] This desensitisation effect is an important open question for researchers.

Hair Detection and Forensic Science

Sports anti-doping researchers need to know how long compounds can be detected. A forensic study gave a single 10 mg dose to a volunteer and collected hair 4 weeks later — MK-677 was still detectable in that hair sample. A second subject who took 10 mg daily for 90 days showed much higher concentrations in a 0–4 cm hair segment collected after stopping, confirming that hair testing can reveal prolonged use.^[4] These data are now being used to help courts and arbitration panels interpret hair-test results fairly.

Liver Safety Signal

A 2025 case report described a healthy man in his early 30s who developed elevated liver enzymes (transaminitis) after taking MK-677 for about 2 months. His liver function returned to normal after stopping the compound.^[2] This adds to earlier case data showing liver enzyme elevations with use.^[5]

What MK-677 Is Being Studied For

• Reversing diet- or disease-related protein catabolism (muscle wasting)^[1]
• Stimulating GH and IGF-1 secretion in GH-deficient states^[6]
• Body composition changes including lean mass^[5]
• Appetite stimulation and metabolic effects^[6]
• Somatic growth in animal models^[3]
• Anti-doping detection methods and forensic reference ranges^[4]

How MK-677 Is Dosed in Research

Research protocols have used a range of doses depending on the scientific question being asked. See the dosage chart on this page for a full breakdown of doses, frequencies, and durations drawn from published studies — and use the calculator to explore weight-based scaling. In brief, human studies have used as little as 10 mg as a single forensic reference dose up to 25 mg once daily for short-term nitrogen-balance work, while the animal study used 4 mg/kg daily for 6 weeks.^[1][3][4][5] Dosing context matters enormously — duration, population, and co-administered compounds all affect outcomes and risk profiles.

Mixing and Storing MK-677

In research settings, MK-677 is often supplied as a powder or pre-dissolved liquid. If working with powder, researchers typically dissolve it in a carrier such as DMSO (dimethyl sulfoxide) or a PEG-400/water blend, depending on the assay requirements — always follow your supplier's certificate of analysis for solubility guidance. Once reconstituted into solution, store it in a sealed, amber vial away from light, heat, and moisture; most labs refrigerate solutions at 2–8 °C and use them within 30 days, or freeze aliquots at −20 °C for longer-term storage. Label every vial with the compound name, concentration, solvent, date prepared, and lot number. Never use a solution that appears cloudy, discoloured, or has visible particulates. All handling should follow your institution's chemical safety protocols.

Sources

1. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. — The Journal of clinical endocrinology and metabolism, 1998. PMID 9467534.
2. Hepatotoxicity induced by MK-677. — BMJ case reports, 2025. PMID 40675653.
3. Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats. — Yonsei medical journal, 2018. PMID 30450851.
4. Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue. — Clinica chimica acta; international journal of clinical chemistry, 2026. PMID 40882886.
5. LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report. — Experimental physiology, 2022. PMID 36303408.
6. The Safety and Efficacy of Growth Hormone Secretagogues. — Sexual medicine reviews, 2018. PMID 28400207.