Ibutamoren MK-677 Nutrobal 10mg 90 Capsules

MK-677, also written ibutamoren or nutrobal and coded L-163,191 by Merck when it was first developed, is an orally active growth hormone secretagogue rather than a SARM. This bottle contains 90 capsules at 10mg of MK-677 per capsule, made in the United Kingdom with batch specific third party analysis. It is supplied as laboratory research material and is not for human consumption.

Product specification

What the research says about MK-677

MK-677 is unusual among compounds sold as research chemicals because it went through real human trials. It is a non peptide agonist at the growth hormone secretagogue receptor GHS-R1a, the receptor that ghrelin binds. Being a small molecule rather than a peptide, it survives digestion, which is why Merck developed it as a once daily oral alternative to injected growth hormone in the 1990s. It does not touch the androgen receptor and the trials did not report suppression of testosterone.

The central paper is Nass and colleagues in Annals of Internal Medicine in 2008. Sixty five healthy adults aged 60 to 81 took 25mg of MK-677 or placebo daily for a year. IGF-1 rose to levels typical of young adults and fat free mass increased by about 1.1kg relative to placebo, while fat mass did not change significantly and measures of strength and function did not improve in step with body composition. Svensson and colleagues, writing in the Journal of Clinical Endocrinology and Metabolism in 1998, found increased fat free mass and basal metabolic rate in obese men over two months, alongside raised fasting glucose and reduced insulin sensitivity. Copinschi and colleagues reported increased stage IV and REM sleep in a crossover study in 1997.

The counterweight is equally well documented. A 24 week study in older patients recovering from hip fracture, reported by Adunsky and colleagues, was stopped early because of a higher rate of congestive heart failure in the treated group. Increased appetite was recorded in every trial, which is expected for a ghrelin receptor agonist, along with transient lower limb oedema, muscle pain and lethargy in the early weeks. Reduced insulin sensitivity was consistent and is the principal reason the compound was never approved. Doses used in the published research ranged from 10mg to 50mg once daily.

Quality and testing

Dexterz Labs products are manufactured in the UK to a fixed strength per capsule with the batch number printed on every bottle. Every batch is independently tested and its certificate of analysis is published on the product page and on the Lab Testing page. If you need the batch report for research records, contact sales@sarmsstore.co.uk with your batch number.

Frequently asked questions

Is MK-677 legal in the UK in 2026? MK-677 is not a controlled substance under the Misuse of Drugs Act 1971 and is not scheduled as an anabolic steroid, so it is lawful to buy and hold as a research chemical in the United Kingdom. The MHRA treats it as an unlicensed medicine if it is sold or advertised for human use, which is why it is listed here strictly for laboratory research.

How fast is delivery? Orders placed before the daily cut off are despatched the same working day by tracked delivery, with UK orders usually arriving within two to three working days and a next day upgrade available at checkout. Everything leaves in plain outer packaging with no reference to the contents or to the compound on the outside of the parcel. International delivery is available to most countries, although some destinations are restricted because of local customs rules, and restricted countries are listed at checkout.

How should the capsules be stored? Store sealed, below 25C, in a dry place away from sunlight and heat. Under those conditions the material is stable to the expiry date shown on the bottle. Humidity is the usual problem with capsules, so a cupboard is better than a windowsill or a bathroom shelf.

Is MK-677 banned in sport? Yes. Growth hormone secretagogues are prohibited at all times under section S2 of the WADA prohibited list, and ibutamoren has been detectable in anti doping testing since 2015. Its long half life means the detection window is not short.

How is MK-677 different from a SARM? It works on a different receptor entirely. SARMs such as ostarine and LGD-4033 bind the androgen receptor. MK-677 binds the ghrelin receptor and raises the body's own pulsatile release of growth hormone, with IGF-1 rising downstream. That is why the published trials do not describe androgenic suppression, and why the reported issues centre on appetite, fluid retention and glucose handling instead.

Research use only. This product is supplied strictly for laboratory and research purposes and is not for human consumption. It is not a medicine, it is not a food supplement, and it is not intended to diagnose, treat, cure or prevent any disease. Sold to persons aged 18 or over only.