MK-677 (Ibutamoren) 25mg capsules, 60 per bottle

Last reviewed: 16 October 2026 · sources and prices checked by Free Muscle.

Key facts

Where to buy MK-677 in the UK: what to check

Whichever seller you consider, check these five points:

1. Stated strength and capsule count. Here: 25 mg per capsule, 60 capsules, 1,500 mg per bottle.
2. A batch number on the pack. Here: printed on every bottle we ship.
3. A certificate for that batch from a named independent laboratory. Here: Janoshik Analytical; we email the certificate for your batch on request.
4. Tracked delivery in plain packaging and a written returns policy. Here: every order ships in plain packaging, UK delivery is free and tracked, EU delivery usually takes 3 to 7 working days after dispatch, and unopened items can be returned within 30 days.
5. Sold for laboratory research only, to adults aged 18 or over. Here: no instructions for human use are given.

Our UK supplier checklist explains each point, and How we test sets out what a certificate does and does not prove.

Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice.

MK-677 in the UK: buying, legal status and what to check

UK searches for MK-677 come down to three questions: is it legal to buy, who is a trustworthy supplier, and what should a listing show. Ibutamoren has never held a marketing authorisation from the MHRA, so it is not a licensed medicine in the UK, and it is not an authorised food supplement ingredient, so it cannot lawfully be sold or labelled for consumption. Free Muscle supplies it strictly as a research compound to adults aged 18 or over. Growth hormone secretagogues also sit on the WADA Prohibited List. A fuller account of the UK position is on our MK-677 legal status page.

What separates a credible UK listing from a poor one is documentation. Look for a stated strength and capsule count, a batch number on the pack, a certificate of analysis for that batch rather than for the product line in general, a named independent laboratory, plain packaging, tracked delivery and a written returns policy. This listing is our 25mg strength, the highest of the three we make alongside 10mg and 12.5mg. Every batch is assayed by Janoshik Analytical, the batch number is on the label, and the certificate for your batch is sent by email on request. UK delivery is free and tracked, orders placed before 2pm Monday to Friday are processed the same working day, EU orders arrive in three to seven working days, and unopened items can be returned within 30 days. See shipping and our guarantee.

Capsules compared with other forms

MK-677 circulates as capsules, tablets, liquids and raw powder. Ibutamoren is a small non-peptide molecule that the published studies gave by mouth, so the differences between forms concern measurement rather than pharmacology. Two points carry most weight. Raw powder has to be weighed on an analytical balance, where small errors are large in percentage terms, and a research liquid depends on the compound staying evenly dispersed, which a certificate for the starting powder cannot confirm. A capsule is a weighed fill that the batch certificate measures directly. Our 12.5mg listing sets out, form by form, what a certificate can and cannot confirm. None of this is a claim that one form produces a different outcome.

MK-677 compared with ipamorelin

Both compounds act at the same target, the growth hormone secretagogue receptor GHS-R1a, and both fall under growth hormone secretagogues on the WADA list, but they differ in almost every practical respect. Ipamorelin is a pentapeptide, a chain of five amino acids, which is broken down in the digestive tract and has therefore been studied by injection; MK-677 is a non-peptide molecule designed to be active by mouth. Ipamorelin's terminal half-life was about two hours in a human infusion study (Gobburu 1999); for MK-677 we have found no verified human half-life in the published trial reports, which gave it by mouth for periods from one week to two years. MK-677 has a two-year randomised trial in older adults, a large Alzheimer's disease trial and studies in obesity, catabolism and hip fracture; ipamorelin has early-phase and preclinical work, with a post-operative ileus programme that did not proceed to approval. Neither is a licensed medicine in the UK. The MK-677 trials recorded increased appetite, raised fasting glucose and reduced insulin sensitivity; the ipamorelin literature is too thin to make an equivalent list. Read about ipamorelin on its own page. This is a pharmacological and regulatory comparison, not a recommendation of either compound.

Reading the certificate of analysis for this product

Every batch of Free Muscle MK-677 is assayed by Janoshik Analytical, and the certificate is tied to the batch number on your bottle. Identity is established by chromatography with mass spectrometric or ultraviolet detection, so the certificate should name the method (HPLC, LC-MS or similar) and confirm that the substance detected is ibutamoren rather than something else. Purity is expressed as a percentage of the material tested, and for a capsule product the more useful figure is the measured quantity per capsule set against the label claim, since a pure compound underfilled into a capsule is still a mislabelled product. The batch number on the certificate must match the pack, and the test date must make sense for that batch. A document with no batch number, method, date or laboratory name is a marketing sheet, not an analytical one. To request the certificate for your batch, email us the batch number and the product name. See our lab tests page and How to read a certificate of analysis.

Detection, sport and testing

Ibutamoren is listed by WADA under S2, peptide hormones, growth factors, related substances and mimetics, as a growth hormone secretagogue, and is prohibited at all times, in and out of competition. Laboratories screen for it and its metabolites in urine, and a finding is a violation regardless of intent or source. We have not found a peer-reviewed human excretion study that fixes a detection window, so the honest statement is that it is detectable and the window is not established in the published literature. For anyone subject to anti-doping rules, the conservative position is to regard it as detectable.

Storage, stability and handling

Ibutamoren is supplied here as a dry capsule fill, and the main threats to a dry solid are moisture, heat and light. Keep the bottle tightly closed in a cool, dry place away from direct sunlight, and do not decant capsules into another container, because the batch number stays with the original label and traceability is lost without it. Handle with clean, dry gloves and clear any spilt powder promptly. Record the batch number and date of opening in the laboratory notebook. Keep out of the reach of children and pets. Refer to any date printed on the label rather than assuming a shelf life.

Glossary

• Growth hormone secretagogue (GHS): a substance that stimulates the pituitary to release growth hormone.
• GHS-R1a: the ghrelin receptor, the G-protein-coupled receptor through which ibutamoren and ghrelin act.
• Ghrelin: the 28-amino-acid stomach peptide identified in 1999 as the endogenous ligand of GHS-R1a.
• IGF-1: insulin-like growth factor 1, a hormone made mainly in the liver whose blood level rises when growth hormone secretion rises; used in trials as a marker of drug effect.
• Visceral fat: fat stored around the organs inside the abdomen, measured separately from total body fat in the two-year trial.
• Oedema: swelling caused by fluid collecting in the tissues; in the MK-677 trials it was usually mild, transient and in the legs.
• Congestive heart failure: a state in which the heart cannot pump enough blood for the body's needs, so fluid builds up; a signal of it ended the hip fracture trial early.
• Phase IIb trial: a mid-stage clinical trial in patients, run to look for evidence of efficacy and to gather safety data before any large phase III study.
• Bone mineral density: the mineral content of bone per unit area, measured by X-ray absorptiometry and used to diagnose osteoporosis.
• Femoral neck: the narrow part of the thigh bone just below the ball of the hip joint, a common site of hip fracture.
• Certificate of analysis (COA): a laboratory report of identity and purity for one specific batch.
• WADA S2: the section of the Prohibited List covering peptide hormones, growth factors and their mimetics, including GH secretagogues.

What the published research reports

MK-677 has a substantial clinical literature, and it cuts both ways. In a two-year randomised, placebo-controlled trial in 65 healthy adults aged 60 to 81, daily ibutamoren raised growth hormone and IGF-1 to young-adult levels, and after one year fat-free mass had risen by about 1.1 kg against a 0.5 kg fall on placebo, with no difference in visceral or total fat. Body weight rose more on the drug (2.7 kg against 0.8 kg), fasting glucose increased, insulin sensitivity fell and cortisol rose; the most frequent side effects were increased appetite that subsided within a few months, mild transient leg oedema and muscle pain, and the extra fat-free mass did not translate into better strength or function, although the authors noted the study was too small to assess function (Nass 2008). An eight-week trial in 24 obese men reported roughly a 40 percent rise in IGF-1 and an increase in fat-free mass, with no change in total or visceral fat and an impairment of glucose tolerance on oral testing at both two and eight weeks (Svensson 1998). In a phase IIb trial in 123 older people after hip fracture, walking speed improved alongside the rise in IGF-1, while stair-climbing power showed no significant difference from placebo and neither did most other measures of function. The study was ended early because of a safety signal of congestive heart failure in a small number of patients; the authors described the safety profile in that population as unfavourable (Adunsky 2011). In 563 patients with mild to moderate Alzheimer's disease, a year of treatment raised IGF-1 by about 73 percent yet produced no difference from placebo on any cognitive or functional measure (Sevigny 2008). Over 18 months, a trial in 292 postmenopausal women with osteoporosis, aged 64 to 85, found that ibutamoren raised IGF-1 by 39 to 45 percent and increased markers of both bone formation and bone resorption; given with alendronate, it lifted femoral neck bone mineral density by 4.2 percent compared with 2.5 percent for alendronate alone, with no comparable gain at the lumbar spine, the total hip or the whole body, and growth hormone related side effects were noted; the authors saw the absence of gains at other sites as a concern given those side effects (Murphy 2001). None of these findings is a claim about this product, which is supplied for laboratory research only.

• Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149(9):601-611. PMID: 18981485.
• Svensson J, et al. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. J Clin Endocrinol Metab. 1998;83(2):362-369. PMID: 9467542.
• Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011;53(2):183-189. PMID: 21067829.
• Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008;71(21):1702-1708. PMID: 19015485.
• Murphy MG, et al. Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women. J Clin Endocrinol Metab. 2001;86(3):1116-1125. PMID: 11238495.
• Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-1416. PMID: 10496658.

Related compounds and reading

All strengths and brands of ibutamoren we stock are compared on the MK-677 collection page. Related pages: all three Free Muscle MK-677 strengths, MK-777 (Acetamoren) and ipamorelin. Further reading: MK-677: what the research says, MK-677 by brand, What is Janoshik Analytical and Price per milligram.

Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice.