MK-677
Also known as: Ibutamoren · Nutrobal · MK-0677
Contents
MW
528.67 Da
Half-Life
24 hours (effective)
Route
Oral
CAS
159634-47-6
Formula
C27H36N4O5S
Mechanism of Action
MK-677 (Ibutamoren) is a non-peptide, orally active ghrelin mimetic that activates GHS-R1a. It is unique among GH secretagogues in being available as an oral compound — all peptide GHRPs require injection.
PRIMARY MECHANISM: Oral GHS-R1a activation → same Gq/PLC/calcium pathway as injectable GHRPs → GH release. Produces sustained GH and IGF-1 elevation over 24 hours due to long half-life (~6 hours with active metabolites lasting longer).
SUSTAINED ELEVATION: Unlike injectable GHRPs which produce short GH pulses, MK-677's long half-life creates a more sustained GH elevation profile — increased GH pulse amplitude AND elevated trough GH throughout the day.
APPETITE: Significant appetite stimulation via ghrelin receptor activation in gut and hypothalamus. More pronounced than ipamorelin.
2-YEAR DATA: Murphy et al. 1998 (PMID 10352464) showed sustained IGF-1 elevation for 2 years without tachyphylaxis (tolerance) — rare for any GH secretagogue. Also improved lean mass and bone density in elderly.
INSULIN RESISTANCE: The major clinical concern. MK-677 consistently worsens fasting glucose and insulin sensitivity — potentially pushing pre-diabetics toward diabetes.
Dosing Protocol
Low Dose
███ – ███ mcg/day
Standard Dose
███ mcg/day
High Dose
███ – ███ mcg/day
Dosing protocols are for paid members
Get exact dosing ranges, injection frequency, timing rationale, and reconstitution math.
Get Clinical Access — $79/moFrequency
Once daily oral — no injection.
Half-Life
24 hours (effective)
Reconstitution Guide
Full reconstitution protocol with BAC water volumes, concentration math, and units-to-draw per dose is available on the Clinical plan.
Unlock reconstitution guide →Clinical Warnings
INSULIN RESISTANCE — worsens fasting glucose. Contraindicated in diabetics without careful monitoring.
Water retention/edema common.
Increased appetite (difficult for weight management).
Lethargy/fatigue.
Numbness/tingling = dose too high.
WADA prohibited.
Not FDA approved.
Contraindications
Absolute
Active cancer
Uncontrolled diabetes
Pregnancy
Relative Cautions
Diabetes/insulin resistance
History of cancer
CHF
Edema
Side Effect Profile
Mild
- ●Increased appetite
- ●Water retention
- ●Mild lethargy
- ●Vivid dreams
Moderate
- ●Elevated fasting glucose
- ●Joint swelling
- ●Numbness/tingling
- ●Muscle pain
Severe (Rare)
- ●Insulin resistance
- ●Edema in CHF patients
- ●Potential tumor growth
Synergistic Peptides
Common Stacks
CJC-1295
Ipamorelin
Research Status
WELL-STUDIED. PMID 9467543 (Chapman 1996): GH/IGF-1 elevation in elderly RCT. PMID 10352464 (Murphy 1998): 2-year sustained IGF-1, lean mass, bone density in elderly without tolerance. One of the best-studied GH secretagogues.
Frequently Asked Questions
How does MK-677 work?
MK-677 (Ibutamoren) is a non-peptide, orally active ghrelin mimetic that activates GHS-R1a. It is unique among GH secretagogues in being available as an oral compound — all peptide GHRPs require injection. PRIMARY MECHANISM: Oral GHS-R1a activation → same Gq/PLC/calcium pathway as injectable GHRPs → GH release. Produces sustained GH and IGF-1 elevation over 24 hours due to long half-life (~6 hours with active metabolites lasting longer). SUSTAINED ELEVATION: Unlike injectable GHRPs which produ
What is the standard dose of MK-677?
MK-677 dosing protocols are available with a ClinPep Clinical subscription. Dosing varies by indication and patient factors — consult a licensed healthcare provider. General frequency: Once daily oral — no injection.
What is the half-life of MK-677?
The half-life of MK-677 is 24 hours (effective). This determines optimal dosing frequency and timing.
Who should not use MK-677?
MK-677 is absolutely contraindicated in: Active cancer; Uncontrolled diabetes; Pregnancy. Use with caution in: Diabetes/insulin resistance; History of cancer; CHF.
What are the side effects of MK-677?
Common mild side effects include: Increased appetite, Water retention, Mild lethargy, Vivid dreams. Moderate effects: Elevated fasting glucose, Joint swelling, Numbness/tingling, Muscle pain.
What peptides stack well with MK-677?
MK-677 is commonly stacked with: CJC-1295, Ipamorelin, Tesamorelin.
How do you reconstitute MK-677?
MK-677 is reconstituted with bacteriostatic water. Exact volumes, concentrations, and units-to-draw calculations are available in the ClinPep Clinical plan. Always follow your compounding pharmacy's instructions.
How long should you cycle MK-677?
MK-677 cycle protocols vary by indication. Detailed cycle length, on/off schedules, and monitoring guidelines are available with ClinPep Clinical access. Consult your healthcare provider for personalized cycling guidance.
References & Citations
5 PubMed studies · 3 clinical trials
Detection of the growth hormone secretagogue MK-0677 in equine hair following oral administration.
Viljanto Marjaana, Cutler Charlotte, Taylor Polly, Habershon-Butcher Jocelyn et al.. Drug testing and analysis. 2023
MK-0677 (ibutamoren) is an orally active non-peptide growth hormone secretagogue that binds to the ghrelin receptor stimulating the secretion of endogenous growth hormone. It is one of the most preval
Brain and kidney GHS-R1a underexpression is associated with changes in renal function and hemodynamics during neurogenic hypertension.
Sales da Silva Elder, Ferreira Patrícia Maria, Castro Carlos Henrique, Pacheco Lilian Fernanda et al.. Molecular and cellular endocrinology. 2020
Ghrelin is a peptide hormone whose effects are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), mainly expressed in the brain but also in kidneys. The hypothesis herein raise
MK0677, a Ghrelin Mimetic, Improves Neurogenesis but Fails to Prevent Hippocampal Lesions in a Mouse Model of Alzheimer's Disease Pathology.
Tian Jing, Wang Tienju, Wang Qi, Guo Lan et al.. Journal of Alzheimer's disease : JAD. 2019
Hippocampal lesions including synaptic injury, neuroinflammation, and impaired neurogenesis are featured pathology closely associated with neuronal stress and cognitive impairment in Alzheimer's disea
Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats.
Lee Junghun, Kwon Ahreum, Chae Hyun Wook, Lee Woo Jung et al.. Yonsei medical journal. 2018
Growth hormone secretagogues (GHSs) possess the ability to release growth hormone (GH) in the body. This study aimed to investigate the effects of MK-677, an orally active GHS, on somatic growth in ra
MK-0677, a Ghrelin Agonist, Alleviates Amyloid Beta-Related Pathology in 5XFAD Mice, an Animal Model of Alzheimer's Disease.
Jeong Yu-On, Shin Soo Jung, Park Jun Yong, Ku Bo Kyeong et al.. International journal of molecular sciences. 2018
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive deficits, neuroinflammation, and neuronal death. The primary pathogenic cause is believed to be t
Registered Clinical Trials
Effects of an Oral GH Secretagogue (MK-677) on Body Composition and Functional Ability of Older Adults
Growth Hormone Secretagogue MK-0677's Effect on Lean Body Mass in Chronic Kidney Disease Stage 4/5 Subjects
The Impact of Ibutamoren on Nonalcoholic Fatty Liver Disease
Symptom Indications
Full Clinical Access
Complete MK-677 Protocol
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This information is for educational and research reference purposes only. ClinPep does not provide medical advice, diagnosis, or treatment recommendations. All protocols should be reviewed by a licensed healthcare provider.