{"id":"igf-1-lr3","name":"IGF-1 LR3","aliases":["Long R3 IGF-1","LR3 IGF-1","insulin-like growth factor 1 analogue"],"url":"https://lyoresearch.com/compounds/igf-1-lr3","class":{"id":"growth-hormone-and-igf","name":"Growth hormone, IGF-1 and growth factors","url":"https://lyoresearch.com/classes/growth-hormone-and-igf"},"summary":"IGF-1 LR3 is a modified version of insulin-like growth factor 1, engineered so that it evades the binding proteins that normally control IGF-1 and therefore stays active far longer. It was designed as a cell-culture reagent for laboratories, not as a medicine, and no controlled human trial has ever tested it. Natural IGF-1 is available as an approved drug, mecasermin, for a rare severe deficiency — the LR3 analogue is a different molecule with no clinical file at all.","overall_grade":"D","overall_grade_meaning":"no human evidence","human_trials":"0 controlled","regulatory_status":"Not approved; research reagent","molecule":{"formula":null,"molecular_weight":null,"cas":null,"pubchem_cid":null,"note":"An 83-residue protein analogue; not in PubChem Compound at review"},"pharmacokinetics":{"basis":"none","route":"Injected as sold; no human study (mecasermin is a different, approved product)","half_life":"No human pharmacokinetic data","licensed_regimen":null,"product":null,"source":null},"outcomes":[{"outcome":"Muscle growth","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"0 controlled","evidence":"No controlled human trial of IGF-1 LR3 exists for muscle, strength or body composition. The claims extrapolate from IGF-1's known role in tissue growth and from animal and cell work.","references":[]},{"outcome":"Any clinical outcome","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"0 controlled","evidence":"A PubMed search for the compound and its aliases returns recombinant-expression papers, rodent studies and reviews of self-administration — no human trial.","references":[]},{"outcome":"Safety in humans","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":true,"human_studies":"None","evidence":"No human dosing study exists. The theoretical concerns are hypoglycaemia, because IGF-1 has insulin-like activity, and the long-term effect of sustained growth signalling — neither measured in people for this analogue.","references":[{"citation":"Dominikowski A, et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.","where":"Front Endocrinol, 2026","url":"https://pubmed.ncbi.nlm.nih.gov/42395176/"}]}],"regions":[{"region":"European Union","status":"Unauthorised medicinal product","note":"No marketing authorisation. Sold as a research reagent; supplying it for human use is an offence under national medicines law."},{"region":"United States","status":"Not approved","note":"Not an approved drug. Mecasermin (recombinant human IGF-1) is approved for severe primary IGF-1 deficiency; the LR3 analogue is a different, unapproved molecule."},{"region":"United Kingdom","status":"Unlicensed medicine","note":"No MHRA licence; supply for human use is an offence."},{"region":"Australia","status":"Prescription-only / unapproved","note":"Not on the ARTG; imports are seized."},{"region":"Canada","status":"Not authorised","note":"No Drug Identification Number."},{"region":"Sport (WADA)","status":"Prohibited at all times","note":"IGF-1 and its analogues are prohibited in and out of competition as growth factors."}],"faq":[{"q":"Does IGF-1 LR3 build muscle?","a":"No controlled human trial has tested it. Every claim rests on IGF-1's known biology and on animal work, not on evidence in people."},{"q":"Is it the same as the approved IGF-1 drug?","a":"No. Mecasermin is recombinant human IGF-1, approved for a rare severe deficiency. LR3 is a modified analogue built to evade the body's control mechanisms, and it has no approval or clinical trial anywhere."},{"q":"Why is it sold as 'research use only'?","a":"Because that is what it was made for — a cell-culture reagent. The label is not a loophole that makes human use lawful or studied."}],"references":[{"cite":"Dominikowski A, et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.","where":"Front Endocrinol, 2026","url":"https://pubmed.ncbi.nlm.nih.gov/42395176/","note":"Review of the gap between evidence and self-administration in this class."},{"cite":"Mecasermin (Increlex) prescribing information — recombinant human IGF-1 for severe primary IGF-1 deficiency.","where":"FDA product information","url":"https://www.accessdata.fda.gov/scripts/cder/daf/","note":"The approved IGF-1 product, for contrast."}],"last_reviewed":"2026-09-03","literature_searched_to":"2026-09-03","changelog":[{"date":"2026-09-03","note":"Initial publication. All outcomes graded D on the absence of any human trial of the LR3 analogue."}],"license":"CC BY 4.0 — cite as “LYO Research” with a link.","methodology":"https://lyoresearch.com/methodology"}