MK-677 (Ibutamoren): Reference Overview and Reconstitution Notes

MK-677 (Ibutamoren)

What it is

MK-677, also known as Ibutamoren, is a non-peptide, orally active small molecule of the spiroindoline class. It acts as a growth-hormone secretagogue and ghrelin mimetic, meaning it binds the growth-hormone secretagogue receptor (GHSR-1a), the same receptor targeted by the hormone ghrelin.

Research context and categorization

MK-677 is generally grouped under growth-hormone secretagogues, a subset of the broader metabolic and growth-hormone-axis research category. Because it is not a peptide, it is chemically distinct from injectable peptide secretagogues even though it is often discussed alongside them.

In neutral research terms, MK-677 is studied in the context of the growth-hormone and insulin-like growth factor 1 (GH/IGF-1) axis, since it is reported to raise circulating GH and IGF-1 levels through receptor activity rather than through direct hormone replacement. It has been investigated in the context of body composition, lean mass, and bone-mineral-density research, including studies in older adults and in populations at risk for reduced bone density. It is also commonly discussed in relation to sleep and appetite because of its activity at the ghrelin receptor.

These uses are investigational. MK-677 has not completed the trials required for approval, and none of the outcomes described above are confirmed or approved benefits. They represent research and discussion context only, not established results.

Status

  • Regulatory status: Research-only, not FDA-approved. MK-677 reached mid-stage (Phase II) clinical investigation for indications such as growth-hormone deficiency, muscle wasting, and osteoporosis, but commercial development was discontinued and it has never been approved for any human indication. It is treated as an investigational compound.
  • Sport status: Prohibited under the WADA Prohibited List. It is classified within class S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), specifically as a growth-hormone secretagogue, and is prohibited both in-competition and out-of-competition.

Reconstitution notes (general)

For lyophilized research powders that are reconstituted, the working concentration equals the milligrams in the vial divided by the millilitres of bacteriostatic water added. For example, 10 mg in 1 mL gives a concentration of 10 mg/mL. A reconstitution calculator is available at /pages/tools.

Dilution and handling notes (compound-specific)

MK-677 is not a reconstituted lyophilized peptide, so the standard bacteriostatic-water reconstitution workflow does not apply to it. It is an orally active small molecule and is typically supplied either as capsules or as a ready-to-use oral liquid solution, with a common solution concentration around 25 mg/mL.

MK-677 is poorly soluble in plain water, which is why finished liquid products are usually prepared in a solvent system rather than in water alone. When a laboratory starts from raw powder, the material is commonly dissolved in carriers such as DMSO, ethanol, or PEG-400 rather than bacteriostatic water, because these solvents dissolve it more readily. If a water-based preparation is attempted at higher concentrations, the compound can fail to fully dissolve and may cloud or leave undissolved particles, so a suitable solvent and thorough mixing are the practical fix. Because MK-677 is measured and handled as an oral-form reagent, there are no reconstitution-for-injection steps to follow.

Handling and storage

Store finished solutions refrigerated at 2 to 8 C and keep them out of direct light. Wipe any bottle or vial closure with an alcohol pad before accessing it, and label the container with the preparation or mix date. As a general guideline, a refrigerated working solution is often used within roughly a four-week window. Discard any material that becomes cloudy, discolored, or shows floaters or particulates.

Related reading

Tools and supplies

For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.