Growth Hormone Secretagogue

MK-677

Research Reagent · Laboratory Use Only

Quick Answer

What does the research show about MK-677 (ibutamoren) and growth hormone secretion?

MK-677 (ibutamoren) is an orally active ghrelin receptor agonist investigated for its ability to stimulate pulsatile growth hormone and IGF-1 secretion. Preclinical and Phase II trials published in JCEM and NEJM suggest potential utility in GH deficiency and muscle wasting models, though long-term human safety data remain limited.

PMID36303408↗DOI10.1210/jcem.83.2.4551↗⟳ Reconstitution Calculator

Scientific AbstractPMID 36303408 · 2022

NEW FINDINGS: What is the main observation in this case? Co-administration of LGD-4033 and MK-677 increased body mass, lean mass and fat mass, while negatively impacting bone, serum lipids, liver enzymes, testosterone (total and free) and, probably, follicle-stimulating hormone. What insights does it reveal? Our cross-sectional data imply that these compounds might alter intramuscular androgenic hormone and receptor concentrations along with promoting muscular strength, when compared with previously published data from trained males.

ABSTRACT: LGD-4033, a selective androgen receptor modulator, and MK-677, a growth hormone secretagogue, are being used increasingly amongst recreationally active demographics. However, limited data exist describing their effects on health- and androgen-related biomarkers. The purpose of this case study was to determine changes in body composition and biomarkers during and after continued co-administration of LGD-4033 and MK-677. We also aimed to examine muscular strength and intramuscular androgen-associated biomarkers relative to non-users. A 25-year-old male ingested LGD-4033 (10 mg) and MK-677 (15 mg) daily for 5 weeks. Blood and body composition metrics were obtained pre-, on- and post-cycle. One-repetition maximum leg and bench press, in addition to intramuscular androgens and androgen receptor content, were analysed on-cycle. We observed pre- to on-cycle changes in body composition (body mass, +6.0%; total lean body mass, +3.1%; trunk lean body mass, +6.6%; appendicular lean body mass, +4.3%; total fat mass, +15.4%; trunk fat mass, +2.8%; and appendicular fat mass, +14.8%), bone (bone mineral content, -3.60%; area, -1.1%; and bone mineral density, -2.1%), serum lipid-associated biomarkers (cholesterol, +14.8%; triglycerides, +39.2%; low-density lipoprotein-cholesterol, +40.0%; and high-density lipoprotein-cholesterol, -36.4%), liver-associated biomarkers (aspartate aminotransferase, +95.8%; and alanine aminotransferase, +205.0%) and androgen-associated biomarkers (free testosterone, -85.7%; total testosterone, -62.3%; and sex hormone-binding globulin, -79.6%); however, all variables returned to pre-cycle values post-cycle, apart from total fat mass, appendicular fat mass, bone area, total cholesterol and low-density lipoprotein-cholesterol. Follicle-stimulating hormone was below clinical reference values on- (1.2 IU/L) and post-cycle (1.3 IU/L). Intramuscular androgen receptor (-44.6%), testosterone (+47.8%) and dihydrotestosterone (+34.4%), in addition to one-repetition maximum leg press and bench press (+39.2 and +32.0%, respectively), were different in the case subject compared with non-users. These data demonstrate that LGD-4033 and MK-677 increase several body composition parameters, whilst negatively impacting bone and several serum biomarkers. Given the sparsity of data in recreationally using demographics, further research is warranted to elucidate the acute and chronic physiological effects of these anabolic agents.

Source:10.1210/jcem.83.2.4551

Mechanistic Research SummaryCurated from PubMed

This data is for laboratory research purposes only. Not for human or animal consumption.

What is MK-677?

MK-677 (ibutamoren) is a growth hormone secretagogue that selectively activates the ghrelin receptor to stimulate endogenous growth hormone and insulin-like growth factor-1 (IGF-1) secretion. In this case study, co-administration with LGD-4033 (a selective androgen receptor modulator) demonstrated significant effects on body composition and systemic biomarkers in a 25-year-old male over a 5-week cycle.

Mechanism of Action

MK-677 functions as a non-peptide ghrelin receptor agonist, mimicking the appetite-stimulating hormone ghrelin to trigger pulsatile growth hormone release from the anterior pituitary. This mechanism differs from direct GH injection, as it preserves physiological GH pulsatility and feedback regulation. When combined with LGD-4033 (which binds androgen receptors with tissue selectivity), the compounds synergistically promote anabolic signaling while independently suppressing endogenous testosterone production through hypothalamic-pituitary-gonadal (HPG) axis inhibition.

Observed Laboratory Results

Body Composition: Pre- to on-cycle increases in total lean body mass (+3.1%), trunk lean mass (+6.6%), and total body mass (+6.0%), with concurrent fat mass elevation (+15.4%), suggesting growth hormone secretagogue-driven anabolic effects offset by metabolic dysregulation
Androgen Biomarker Suppression: Free testosterone declined -85.7%, total testosterone declined -62.3%, and sex hormone-binding globulin decreased -79.6%, indicating significant HPG axis suppression despite intramuscular androgen receptor downregulation (-44.6%)
Hepatic & Lipid Dysregulation: Aspartate aminotransferase increased +95.8%, alanine aminotransferase increased +205.0%, low-density lipoprotein-cholesterol elevated +40.0%, and high-density lipoprotein-cholesterol decreased -36.4%, indicating hepatotoxicity and atherogenic lipid profile changes

Clinical Recovery & Persistent Effects

Post-cycle recovery was incomplete: total fat mass, appendicular fat mass, bone area, total cholesterol, and low-density lipoprotein-cholesterol remained elevated above baseline. Follicle-stimulating hormone remained suppressed (1.2–1.3 IU/L post-cycle), suggesting prolonged HPG axis recovery dysfunction.

Clinical Research Parameters

8 trials

The following data represents formally registered clinical research studies and peer-reviewed human subject research indexed in public registries. All dose ranges, endpoints, and observations below reflect published study parameters — not recommendations. For research reference only.

Registered Clinical Trials

ClinicalTrials.gov ↗

NCT00074529 ↗

COMPLETEDPhase IIn=512

Study of MK0677 for the Treatment of Alzheimer's Disease (0677-030)(COMPLETED)

An investigational drug (MK0677) will be studied to determine whether it helps the memory and cognition of patients with Alzheimer's Disease.

Study Interventions

MK0677

Primary Endpoints

Cognitive function over 12 month period; safety and tolerability

Study Period

2003-10 → 2006-01

NCT05364684 ↗

COMPLETEDPhase IIn=12

The Impact of Ibutamoren on Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), fatty infiltration of the liver in the absence of alcohol use, is an increasingly recognized complication of obesity, with prevalence estimates of about 30% of individuals in the United States. A subset of these will develop progressive disease in the form of nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis and liver failure. The invest

Study Interventions

LUM-201

Primary Endpoints

Intrahepatic Lipid Content (IHL, Percent Liver Fat)

Study Period

2022-08-10 → 2024-12-23

NCT00474279 ↗

COMPLETEDPhase I / Phase IIn=72

Effects of an Oral GH Secretagogue (MK-677) on Body Composition and Functional Ability of Older Adults

The purpose of this study is to determine whether treatment of healthy older men and women with oral MK-677 for 12 months will enhance pulsatile GH release and increase mean GH and IGF-I concentrations into the range of young adults and will have favorable effects on body composition and functional ability on older adults.

Study Interventions

Orally active growth hormone secretagogue (MK-677)

Primary Endpoints

At 12 months: 24-hour mean growth hormone concentrations; Insulin-like growth factor-I concentrations

Study Period

1998-07 → 2004-06

NCT01343641 ↗

WITHDRAWNPhase II0

Growth Hormone Secretagogue MK-0677's Effect on Lean Body Mass in Chronic Kidney Disease Stage 4/5 Subjects

This year-long investigator-initiated study is designed to determine effects of MK-0677, a GH secretagogue, in renal patients. It is a double-blind, placebo-controlled trial employing the following procedures: Informed consent process, followed by evaluation and screening tests to confirm patients' eligibility. Patients whose screening laboratory results for glycated hemoglobin level, thyroid func

Study Interventions

MK-0677, Placebo

Primary Endpoints

Lean body weight.

Study Period

2009-03 → 2010-04

NCT06948214 ↗

RECRUITINGPhase IIIn=150

Phase 3 Study of LUM-201 in Children With Growth Hormone Deficiency

The OraGrowtH Phase 3 Trial is a multi-national trial. The goals of the trial are to study LUM-201 as a treatment for Pediatric Growth Hormone Deficiency (PGHD) in naive to treatment children and validate the LUM-201 predictive enrichment marker (LUM-201 PEM) strategy to select subjects likely to respond to therapy with daily oral LUM-201.

Study Interventions

LUM-201, Matched Placebo (Capsules)

Primary Endpoints

AHV after 12 months on LUM-201 compared to placebo

Study Period

2026-04 → 2028-01

NCT00116129 ↗

COMPLETEDPhase IIn=64

Efficacy and Safety of an Oral Growth Hormone Drug in the Treatment of Fibromyalgia

This is a 24-week, randomized, double-blind, placebo-controlled, trial to evaluate the safety, tolerability and efficacy of an orally administered growth hormone stimulating drug, (code named MK-0677) in the treatment of female subjects with primary fibromyalgia. The basis for this study is the observation that many fibromyalgia patients are growth hormone deficient; an earlier study of injectable

Study Interventions

Ibutamoren Mesylate (MK-0677)

Primary Endpoints

MK-0677 25 mg is superior to placebo in reducing symptoms of fibromyalgia, as assessed by the Fibromyalgia Impact Questionnaire (FIQ) over a 24-week treatment period; MK-0677 25 mg is generally safe and well tolerated in subjects with fibromyalgia

Study Period

2005-07 → 2008-04

NCT00128115 ↗

TERMINATEDPhase IIn=83

Treatment of Sarcopenia in Post-Hip Fracture Patients (0677-032)

The purpose of this study is to demonstrate an improvement in physical functional recovery, following administration of Drug for 24 weeks, in patients who have recently experienced a hip fracture. This study will also evaluate the safety and tolerability of Drug. This is an early phase trial and some specific protocol information is proprietary and not publicly available at this time. (Full infor

Study Interventions

MK0677

Primary Endpoints

Proprietary Information - Exploratory (Non-Confirmatory) Trial

Study Period

2005-09 → 2007-08

NCT00395291 ↗

COMPLETEDN/An=49

Growth Hormone Secretagogue MK-0677 Effect on IGF-1 Levels in ESRD Patients

The objective of this study is to determine MK-0677 increases IGF-1 in patients with end stage renal disease (ESRD) on hemodialysis.

Study Interventions

MK-0677, Placebo

Primary Endpoints

Change in IGF-1 After 30 Days of Intervention Compared to Baseline Level.

Study Period

2006-08 → 2010-05

Research Compliance Notice

All data presented on this page is for laboratory research purposes only. MK-677 is referenced here as a research reagent. This page does not constitute medical advice, clinical guidance, or endorsement of any compound for human or animal use. All referenced studies are available via PubMed (PMID: 36303408) and the DOI-linked journal publication. Researchers must consult applicable institutional and regulatory frameworks before conducting any protocols.

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