For laboratory research use only. Not for human consumption. Sold by Explicit SARMs solely as reference material for in-vitro and animal research by qualified professionals. Not evaluated by the FDA and not intended to diagnose, treat, cure or prevent any disease.
MK-677 is ibutamoren, Merck’s compound L-163,191 (also written MK-0677). Each bottle holds 90 capsules at 10mg per capsule, made in the US and tested three times per batch.
What MK-677 is, and isn’t
MK-677 is sold alongside SARMs and often called one. It isn’t. It has no androgen receptor activity. It’s a small nonpeptide agonist of the growth hormone secretagogue receptor, GHS-R1a, the receptor later shown to bind ghrelin (Howard et al., Science 1996, PMID 8688086; Kojima et al., Nature 1999, PMID 10604470).
Chemistry
The free base is CAS 159634-47-6, C27H36N4O5S, MW 528.7. Most research material and most of the clinical literature use the mesylate salt: CAS 159752-10-0, C28H40N4O8S2, MW 624.8. That difference of about 96 matters when you calculate molar concentrations, so check which form your COA reports.
What the literature reports
Patchett et al. (PNAS 1995, PMID 7624358) described the compound’s design and its GH-releasing activity in rat pituitary cells (EC50 1.3 nM). Merck’s beagle work showed GH elevated for up to six hours after a single gavage administration, followed by a rise in IGF-1 (Jacks et al., Endocrinology 1996, PMID 8940347). Later clinical studies reported changes in GH, IGF-1 and fasting glucose and reduced insulin sensitivity (Chapman et al. 1996, PMID 8954023; Nass et al., Ann Intern Med 2008, PMID 18981485). Trials by Adunsky (2011, PMID 21067829) and Sevigny (2008, PMID 19015485) did not show clinical benefit, and the compound has never been approved.
For the full write-up, read our MK-677 (Ibutamoren) Research Review. Working with the newer analog? See MK-777 (acetamoren). Prefer a liquid? See MK-677 Liquid.
Specifications
- Compound: ibutamoren (MK-677, MK-0677, L-163,191)
- CAS: 159634-47-6 (free base); 159752-10-0 (mesylate)
- MW: 528.7 (free base); 624.8 (mesylate)
- Target: GHS-R1a (ghrelin receptor) agonist
- Format: 90 capsules, 10mg per capsule
- WADA: named in S2.2.4, prohibited at all times
How we source and test it
MK-677 is made by US domestic manufacturing partners. Every batch is tested three separate times: when the raw ingredient arrives at the lab, after processing, and again when it arrives at our facility. The first two tests are run by our manufacturer, and the final test is run independently by Accumark on our behalf. The lot COA is available on request. Email [email protected] with your order or lot number, or see how to read a COA.
FAQ
Is MK-677 a SARM?
No. It’s a ghrelin-receptor (GHS-R1a) agonist with no androgen receptor activity.
Is MK-677 a peptide?
No. It’s a small nonpeptide molecule.
Free base or mesylate?
Most of the clinical literature used ibutamoren mesylate. Your lot COA states which form you have.
Capsules or liquid?
It’s the same compound. Capsules give a fixed 10mg per unit; the liquid suits protocols that need volumetric measurement. See MK-677 Liquid.
Is it for human use?
No. It’s sold only as reference material for laboratory research.
For laboratory research use only. Not for human consumption. Sold by Explicit SARMs solely as reference material for in-vitro and animal research by qualified professionals. Not evaluated by the FDA and not intended to diagnose, treat, cure or prevent any disease.
Who tests MK-677?
Every batch of MK-677 sold by Explicit SARMs is tested twice by our manufacturer, then independently tested by Accumark, a third-party analytical lab, on our behalf before it ships. The lot COA is available on request through our contact page.
What payment methods does Explicit SARMs accept?
We accept debit and credit cards, Zelle, Cash App, and ACH bank transfer.
Does Explicit SARMs ship internationally?
Yes. We ship inside and outside the United States. Available destinations and shipping options are shown at checkout.
