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Performance & Musclephase_2_3

MK-677

Ibutamoren
Performance & Muscle · CAS 159752-10-0
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Category
Performance & Muscle
Evidence grade
B
PubMed records
117
Female-tagged
25
Sex-analysis
1
CAS
159752-10-0
B
Evidence grade B, Phase 2/3 human trial evidence across 117 indexed studies (mixed-sex). How grades work →
Female evidence: Extrapolated
MK-677: of 117 PubMed records, 25 are tagged as including female subjects and 1 carry a sex-analysis tag.Counts reflect PubMed records as of 2026-07-17. “Female” uses the Female MeSH filter and “sex-analysis” the Sex Factors MeSH filter, automated proxies pending manual study-level review. Methodology →

Overview

MK-677, also known as ibutamoren, is an orally active, non-peptide agonist of the ghrelin receptor. Its oral bioavailability distinguishes it from injectable growth-hormone secretagogues and gives it a research-friendly profile as a tool compound in growth-hormone-axis studies.

MK-677 has been studied for its activity at the ghrelin, or growth-hormone-secretagogue, receptor (GHS-R1a), where it is characterized for stimulating pulsatile growth-hormone release and raising IGF-1. It has been investigated in clinical trials in contexts such as growth-hormone deficiency, frailty, and catabolic states, although it is not an approved drug and those studies do not establish sex-specific regimens.

What makes MK-677 notable for a performance and endocrine catalog is the combination of an oral route with a defined secretagogue mechanism. Some of its trials included women; our evidence review tracks how many of the underlying studies reported outcomes by sex, an open research question at this stage.

Summary

MK-677 (ibutamoren) is an orally active ghrelin-receptor agonist that raises growth hormone and IGF-1. It has been investigated in clinical trials, for growth-hormone deficiency, frailty, and catabolic states, but is not an approved drug. Some of those trials included women; none establish female-specific dosing.

Evidence in women

Menstrual cycle
Unstudied
No studies examine menstrual cycle interactions.
Pregnancy & lactation
Unstudied
No pregnancy or lactation safety data exist; absence of harm data is not evidence of safety.
Hormonal interactions
Unstudied
Estrogen modulates the GH/IGF-1 axis, but MK-677's interaction with estrogen status is not characterized.
Perimenopause & menopause
No evidence
Some trials in older adults included women, but menopause-specific dosing or response was not established.
Sex differences
No evidence
Clinical studies have included female participants, but sex-stratified dosing and response are not established; figures circulating online are not female-specific.

Mechanism

Agonist at the ghrelin / growth-hormone-secretagogue receptor (GHS-R1a). Stimulates pulsatile GH release and raises IGF-1, with the practical distinction of oral bioavailability.

Reported dosing & routes

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We don't give dosing or medical advice. The figures below describe what was used in published research, not a recommendation. Decide with your clinician.

Reported range (literature)Once-daily oral dosing has been used in clinical studies (literature figures, not advice).
Routesoral
Female-specific dosingNot established

Contraindications: conditions affected by elevated IGF-1 (per clinical judgment); not established in pregnancy

Side effects

Reported in the research literature. Sex-specific incidence has not been separately analysed in the available records.

increased appetitefluid retention / edematransient rise in blood glucosefatigue

MK-677 reconstitution calculator

Enter this vial's amount, the bacteriostatic water you add, and a target amount to get the concentration and the U-100 syringe units to draw. Handling arithmetic for research use, not a dose recommendation.

Reconstitution

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Draw for MK-677

5
units on a U-100 insulin syringe
020406080100
U-100 insulin syringe — 1 mL = 100 units
That's 0.05 mL drawn to the 5-unit mark.
Concentration5 mg/mL (5,000 mcg/mL)
Volume to draw0.05 mL
Doses per vial40

Reference chart at 5 mg/mL

Target amountVolume (mL)U-100 units
100 mcg0.02 mL2
250 mcg0.05 mL5
500 mcg0.1 mL10
750 mcg0.15 mL15
1000 mcg0.2 mL20

Research-use arithmetic only. This tool converts a vial amount, diluent volume, and a target amount into a concentration and syringe draw for laboratory handling. It is not dosing guidance, a recommendation, or a claim of safety or efficacy, and it does not account for overfill, dead space, or peptide purity. Nothing here is medical advice. “U-100” means 100 units = 1 mL; confirm your syringe graduation before measuring. See the reconstitution & storage handbook for handling detail.

Frequently asked questions

Answers drawn only from MK-677's research facts and, where reviewed, its sex-disaggregated evidence. Nothing here is medical advice, dosing, or a claim of safety or efficacy.

What is MK-677?

MK-677, also known as Ibutamoren, is a research compound in our performance muscle category. MK-677 (ibutamoren) is an orally active ghrelin-receptor agonist that raises growth hormone and IGF-1.

Is MK-677 studied in women?

MK-677: of 117 PubMed records, 25 are tagged as including female subjects and 1 carry a sex-analysis tag. We grade this extrapolated: women appear in the record, but no study is tagged for a sex-specific analysis, so female-relevant conclusions are inferred from mixed or male data rather than measured in women. See our methodology.

Has MK-677 been studied during pregnancy or breastfeeding?

Unstudied. No pregnancy or lactation safety data exist; absence of harm data is not evidence of safety. This is not a safety clearance or a recommendation. Vera, our research chat, deliberately hard-stops on pregnancy, breastfeeding, and trying-to-conceive questions rather than answer them.

What evidence grade does MK-677 have, and why?

MK-677 carries evidence grade B. Phase 2/3 human trial evidence across 117 indexed studies (mixed-sex).. Grades are derived from the research record, never hand-assigned; see how grades work.

Is there a female-specific dose for MK-677?

No. A female-specific dose for MK-677 is not established, and this site does not provide dosing or medical advice. Any figures we show describe what published research used, not a recommendation. Decide anything about use with a qualified clinician.

How is MK-677 administered in research?

In the published literature, MK-677 is administered via oral. Reported dose ranges on the Dosing tab describe what studies used for laboratory research, not a protocol for people. We don't provide dosing.

What side effects have been reported for MK-677?

Effects reported in the research literature include increased appetite, fluid retention / edema, transient rise in blood glucose, fatigue. Sex-specific incidence has not been separately analysed in the available records, so these are not broken out for women.

What is the CAS number for MK-677?

The CAS registry number for MK-677 is 159752-10-0. It is also referred to as Ibutamoren, MK-0677, L-163,191. Use it to confirm identity against a Certificate of Analysis.

How should MK-677 be stored and handled?

MK-677 sold for research is supplied as a lyophilized (freeze-dried) powder. Lyophilized peptides are generally kept cold and dry, at roughly -20°C for longer-term storage and 2-8°C short-term, protected from light. Once reconstituted they are typically refrigerated and used within a short window, avoiding repeated freeze-thaw cycles. This is general laboratory handling for research use only, not a directive for human use. Always follow the handling and purity details on the product's Certificate of Analysis.

Where can I buy MK-677 for research?

MK-677 is not currently listed by our research-use partner, Aurevena Research, but their catalog carries related compounds. Code research15 applies 15% off. We may earn a commission when you purchase through this link, at no extra cost to you. Products are for laboratory research use only.

Browse the Aurevena catalog
Research-use supplier: MK-677 isn't currently listed by our research-use vendor. Their catalog carries related compounds. Code research15 for 15% off, applied automatically at checkout. We may earn a commission when you purchase through this link, at no extra cost to you. Products are for laboratory research use only.
Browse the catalog →

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CJC-1295 with DAC: of 32 PubMed records, 2 are tagged as including female subjects and 0 carry a sex-analysis tag.

Educational information for laboratory and research use only. Not medical advice, a recommendation, or a claim of safety or efficacy; no personal dosing. “Unstudied” means no qualifying study was found, not that a compound is safe or unsafe.