LongR3-IGF-1
Exact PubMed and ClinicalTrials.gov searches found no human administration study of LongR3-IGF-1 (checked 2026-08-26). PMID 33427051 compared eight treated fetal sheep with eight saline controls. Heart weight was higher after one week. Adrenal-gland weight was higher. Spleen weight was higher. Skeletal-muscle myoblast proliferation was higher. Total fetal weight was not significantly different (3.682 versus 3.260 kg; p=0.15). Crossref lists funding from NIDDK, NICHD, NHLBI, and the NIH Office of the Director.
What exactly is LongR3-IGF-1?
LongR3-IGF-1 is an IGF-1 analogue. It has arginine at position 3. It also has a 13-residue extension at its N terminus (PMID 10744677; checked 2026-08-26).
| Identity field | Verified value |
|---|---|
| Register name | LongR3-IGF-1 |
| Register aliases | IGF-1 LR3; Long R3 insulin-like growth factor-I; Long-(Arg3)insulin-like growth factor-I |
| Register class | IGF-1 analogue with arginine at position 3 and a 13-residue N-terminal extension |
| GSRS display name | LONG-(ARG3)INSULIN-LIKE GROWTH FACTOR-I |
| GSRS systematic name | 1-13-SOMATOTROPIN (SWINE REDUCED), 1-L-METHIONINE-12-L-VALINE-, (13->1')-PROTEIN WITH 3-L-ARGININE INSULIN-LIKE GROWTH FACTOR I (HUMAN) |
| GSRS substance class | Protein |
| GSRS sequence length | 83 residues |
| Molecular formula | C400H623N111O115S9 |
| Estimated molecular weight | 9,120 Da |
| UNII | M9L22Y19H9, checked 2026-08-26 |
| CAS | 143045-27-6, checked in the same GSRS record on 2026-08-26 |
The 13-residue extension in the GSRS systematic name comes from the start of swine growth hormone. This record is not native human IGF-1.
What did animal studies measure?
The findings differ by species and model.
| Primary record | Animal sample | Measured finding | Funding and limit |
|---|---|---|---|
| PMID 33427051 | 8 treated fetal sheep; 8 saline controls | Heart weight was higher after one week. Adrenal-gland weight was higher. Spleen weight was higher. Skeletal-muscle myoblast proliferation was higher. Total fetal weight was not significantly different (3.682 versus 3.260 kg; p=0.15). Amino-acid uptake was lower. | Crossref lists NIDDK, NICHD, NHLBI, and NIH Office of the Director awards. This was a fetal-sheep study. Checked 2026-08-26. |
| PMID 39679943 | 7 growth-restricted fetal sheep; 7 vehicle controls | Body weight did not differ after one week. Insulin did not differ. Glucose did not differ. Oxygen did not differ. Glucose-stimulated insulin secretion did not differ. Amino-acid concentrations fell in the treated group (p=0.0232). | PubMed and Crossref list NIH support. This result is from growth-restricted fetal sheep. Checked 2026-08-26. |
| PMID 39610283 | 19-27 male mice per group | Seven months of treatment improved body composition. Filamentous amyloid plaques fell in the cortex. Inert plaques rose. Low-molecular-weight amyloid-beta oligomers fell. Cognitive measures did not significantly change. | Crossref lists NIA, NIGMS, and NCI support. This was a mouse model of Alzheimer's disease. Checked 2026-08-26. |
| PMID 7561636 | Female guinea pigs; group count not stated in the opened abstract | Fractional weights of the adrenals, gut, kidneys, and spleen increased. Overall growth did not increase. Body-weight gain did not significantly change. Feed intake did not significantly change. | PubMed has no GrantList. Crossref lists no funder. PubMed tags the paper as Research Support, Non-U.S. Gov't. Checked 2026-08-26. |
| PMID 9488001 | Finisher pigs; sample count not stated in the opened abstract | Average daily gain fell during the four-day infusion. Feed intake fell. Mean growth hormone fell 23%. Area under the growth-hormone peaks fell 60%. | PubMed has no GrantList. Crossref lists no funder. PubMed tags the paper as Research Support, Non-U.S. Gov't. Checked 2026-08-26. |
How strong is the evidence?
Evidence tier C means animal and laboratory evidence is available, but no human administration study was found (checked 2026-08-26).
Every result from the PubMed title-and-abstract query was screened. None administered LongR3-IGF-1 to people. Each exact ClinicalTrials.gov name search also returned no study. A mecasermin control resolved.
What do current United States product records show?
| Search checked August 26, 2026 | Result | Boundary |
|---|---|---|
| DailyMed exact name | No result | |
DailyMed UNII M9L22Y19H9 | One SPL: D-136, published January 15, 2025. It is a multi-ingredient sublingual product. The SPL marks its marketing category as unapproved homeopathic. | |
| openFDA Drugs@FDA exact name and UNII | No matching application | The DailyMed SPL is not a Drugs@FDA approval record. |
What do the central EU and country fields show?
| Field | Current primary record |
|---|---|
Central EU status: unclear | The EMA report generated August 26, 2026 contains 2,732 medicine rows. No row contains the six searched LongR3 names or identifiers. Mecasermin and somatropin controls resolved. The central file does not cover every national authorization. |
Germany: unclear | The current German source contains a broad IGF-1 Analoga line and gives no examples. The register does not decide whether LongR3-IGF-1 belongs inside that category. Checked 2026-08-26. |
Sweden: unclear | The product file dated August 26, 2026 contains 38,382 rows. No row contains the six searched LongR3 names or identifiers. Mekasermin and somatropin controls resolved. This exact-term absence does not settle classification. |
Status and evidence tier answer different questions.
What has been measured in submitted products?
PMID 33587816 names LongR3-IGF-I among the IGF-I analogues it tested (checked 2026-08-26). The paper reports abundant signs of oxidized peptide forms in the black-market products it examined. The Agence Française de Lutte contre le Dopage funded the paper.
In the rat experiment from the same paper, unchanged LongR3-IGF-I disappeared rapidly after 4 hours. One LongR3 degradation product remained detectable for 16 hours. These are rat findings, not human-use results.
The register stores first_observed: 2021-02 because PMID 33587816 was published online on February 22, 2021. This source examined products; it did not merely propose an assay. It does not supply an earlier product date.
The 2026 submitted-vial preprint, DOI 10.20944/preprints202604.1748.v1, tested fourteen other compounds. LongR3-IGF-1 is not among them. That paper supplies no LongR3 identity result. It supplies no LongR3 amount result. It supplies no LongR3 purity result. It supplies no LongR3 endotoxin result.