MK-677 (ibutamoren) studies and research data

Ibutamoren (MK-677, MK-0677, L-163,191, LUM-201) is a small molecule, C27H36N4O5S, 528.7 Da, with one defined stereocentre (R). It is a spiro[indoline-3,4'-piperidine] compound that Merck described in 1995 as a potent, orally active growth hormone secretagogue (PMID 7624358). It is an agonist of the growth hormone secretagogue receptor 1a (GHSR, the ghrelin receptor). A 2021 title reports a structure of the human receptor with ibutamoren bound (PMID 34737341; RCSB entry 7NA8 holds the ibutamoren ligand code 1KD). The mesylate salt (MK-0677, USAN ibutamoren mesylate, EU name ibutamoren mesilate) is the form that was developed. Merck ran phase 2 trials in Alzheimer's disease (NCT00074529, completed 2006; the paper reports no clinical effect on progression, PMID 19015485) and in older adults after hip fracture (NCT00128115 'Treatment of Sarcopenia in Post-Hip Fracture Patients', terminated; a 123-patient phase IIb paper is PMID 21067829). A separate 2-year randomized trial in healthy older adults was done at a university hospital (PMID 18981485). FDA cites a hip-fracture trial that 'was terminated early due to a potential safety signal of congestive heart failure'. Merck licensed the compound to Ammonett Pharma on 2013-10-22. Lumos Pharma bought the assets in July 2018 and calls the compound LUM-201. Double Point Ventures bought Lumos Pharma on 2024-12-12. Lumos runs the OraGrowtH program in children with growth hormone deficiency. Its phase 3 trial (NCT06948214, 1.6 mg/kg/day by mouth, 150 children planned) started on 2026-05-20 and is recruiting. FDA and EMA have not approved ibutamoren for any use. FDA lists ibutamoren mesylate in category 2 (significant safety risks) of both the 503A and 503B compounding lists and has said that products with ibutamoren cannot be sold as dietary supplements. The EU gave it an orphan designation for growth hormone deficiency in 2017, which is not a marketing authorisation. WADA lists it in S2.2.4 (prohibited at all times). People also buy it online for muscle gain, sleep and appetite. Sellers often list it with SARMs, but it is not a SARM and does not act on the androgen receptor.

Kind

Small molecule

Formula

C₂₇H₃₆N₄O₅S

Identifiers

ChEMBLCHEMBL13817 (opens in a new tab)CHEMBL2105872 (opens in a new tab)CHEMBL542653 (opens in a new tab)PubChem CID178024 (opens in a new tab)6450830 (opens in a new tab)UNIIGJ0EGN38UL (opens in a new tab)R90JB6QJ2B (opens in a new tab)CAS159634-47-6159752-10-0PDB7NA8 (opens in a new tab)KEGGD04491 (opens in a new tab)IUPHAR5867 (opens in a new tab)

Development

Phase 3Lumos Pharma (Austin, Texas) develops it as LUM-201. Double Point Ventures has owned Lumos Pharma since 2024-12-12. Merck (Merck Sharp & Dohme) discovered it as MK-0677 and licensed it to Ammonett Pharma on 2013-10-22. Lumos bought LUM-201 from Ammonett in July 2018 (Lumos 10-Q).Phase 3: NCT06948214, 'OraGrowtH Phase 3', a 12-month randomized, double-blind, placebo-controlled trial of daily oral LUM-201 (1.6 mg/kg/day) in treatment-naive, prepubertal children with growth hormone deficiency. Sponsor Lumos Pharma. Start 2026-05-20, status RECRUITING, 150 children planned, primary completion 2027-12 (estimated), record updated 2026-10-09. The record keywords include 'ibutamoren mesylate'. Other Lumos trials on ClinicalTrials.gov: phase 2 OraGrowtH210 (NCT04614337, completed), OraGrowtH212 (NCT04806854, active, not recruiting), OraGrowtH213 (NCT05250063, completed), long-term safety (NCT05796440, enrolling by invitation), phase 3 extension (NCT07129759, not yet recruiting, start 2027-02) and a phase 2 trial of LUM-201 plus semaglutide (NCT07754045, not yet recruiting, start 2027-02-15). Merck-era and academic trials listed for these names: Alzheimer's disease NCT00074529 (Merck, phase 2, completed, 512 enrolled by the registry; the paper PMID 19015485 reports no effect on progression); post hip fracture NCT00128115 (Merck, phase 2, terminated, 83 enrolled, started 2005-09); University of Virginia NCT00474279 (phase 1/2, older adults, 1998), NCT00395291 (dialysis patients, IGF-1) and NCT01343641 (withdrawn); fibromyalgia NCT00116129 (phase 2, completed, drug named Ibutamoren Mesylate (MK-0677)); Massachusetts General Hospital fatty liver NCT05364684 (phase 2, completed). Papers: hip fracture phase IIb in 123 patients (PMID 21067829), earlier hip fracture trial (PMID 15066065), healthy older adults randomized trial (PMID 18981485). FDA says a hip fracture trial was terminated early over a possible congestive heart failure signal. FDA does not name the trial. PubMed lists NCT00128115 as the registry entry of PMID 21067829, and that paper says the trial was 'terminated early due to a safety signal of congestive heart failure'. No Merck phase 3 trial was found. No involvement of Eli Lilly was found in the sources read. Status in other databases is out of date: ChEMBL max_phase is 2.0 and the Wikipedia article says 'As of June 2017, ibutamoren is in the preclinical stage'. Meaning of 'phase_3': a phase 3 trial in children with growth hormone deficiency is recruiting. No marketing application is known. The 'Detecting and Treating Growth Hormone Deficiency' patent expires in 2036 and a formulation patent runs to 2042 (Lumos 10-Q, 2024). Source (opens in a new tab)

• Tesamorelin evidence
• Ipamorelin evidence
• CJC-1295 (with DAC) evidence
• Mod GRF (1-29) (CJC-1295 without DAC) evidence