Bones & muscles IGF-1 analog
IGF-1 LR3
Regulatory status
Status at a glance
503A compounding status
Not nominated
We found no pending nomination for the 503A bulks list. Unless the substance has another legal pathway (for example, a USP monograph or use in an FDA-approved drug), 503A pharmacies generally may not compound with it.
- FDA approval
- Not FDA-approved for any use
- 503B outsourcing
- Not determined
- Anti-doping (WADA)
- On the WADA Prohibited List
- DEA schedule
- Not a controlled substance
About peptide status
Most peptides discussed here are not FDA-approved for any use, and products labeled “research use only” are not for human use. Removal from Category 2 does not authorize compounding. PCAC votes are non-binding recommendations; FDA and HHS make the final decisions.
This is not medical or legal advice, and we do not publish dosing, sourcing or reconstitution information. Talk with a licensed clinician before using any peptide.
If you think you are having a medical emergency, call 911.
Key takeaway
IGF-1 LR3 is a long-acting laboratory analog of insulin-like growth factor-1 (IGF-1), sold as a "research chemical" and performance drug for muscle growth. Its evidence is entirely animal and cell-based, with no human trials, and laboratory work has flagged a tumor-growth concern tied to IGF signaling. As of 2026 it is not FDA-approved and is banned in sport.
At a glance
- FDA status
- Non-FDA-approved IGF-1 analog sold as a research chemical/performance drug
- What it is
- Long-acting, modified version of IGF-1
- Research
- Evidence is animal and cell-based only; no human efficacy trials exist
- Sport
- Prohibited by WADA at all times
- Evidence strength
- Low research
Summary
IGF-1 LR3 is a long-acting IGF-1 analog sold as a research chemical. Its evidence is animal and cell-based, it is not FDA-approved, and sport bans it.
What is IGF-1 LR3?
IGF-1 LR3 (Long R3 IGF-1) is a chemically modified version of insulin-like growth factor-1 with an amino-acid substitution and an added N-terminal extension. These changes lower its binding to carrier proteins and extend its activity, and it is widely sold as a laboratory cell-culture supplement. In the performance market it is used as a muscle-growth drug; it is not an approved medicine.
How does it work?
IGF-1 LR3 activates the IGF-1 receptor, driving the growth signaling that promotes muscle protein synthesis in cell and animal models. Its modifications are proposed to prolong its activity in the body. In laboratory work it increased muscle-cell differentiation, and in a mouse model of cancer-related muscle wasting it limited muscle loss, but at the cost of accelerated tumor growth, illustrating the mitogenic (growth-promoting) concern that comes with strong IGF signaling. These are animal and cell findings. This describes the proposed mechanism, separate from proven outcomes in people.
Is it FDA-approved?
Safety note
Status: Non-FDA-approved IGF-1 analog sold as a research chemical/performance drug
Category: Wellness and performance · Primary body area: Bones & muscles
No. IGF-1 LR3 is not approved by the FDA; it is a research chemical and performance-enhancing drug with no approved compounding status. In sport, IGF-1 and its analogs are prohibited at all times under the WADA list.
What does the research show?
Editor’s note
Evidence strength: Low research
There is no human efficacy evidence; the anabolic rationale rests on animal and cell studies, which also include an explicit tumor-growth signal.
The evidence is preclinical. According to PubMed, a mouse study found IGF-1 LR3 limited muscle loss in cancer cachexia but accelerated tumor growth, and laboratory assays show it stimulates muscle-cell growth. There are no human clinical trials supporting muscle or performance use, and the tumor-growth signal is a specific preclinical concern. Its marketed benefit is unproven in people.
Sources: a mouse study of IGF-1 LR3 in muscle wasting and tumor growth (Levolger et al., Scientific Reports, 2019, DOI: 10.1038/s41598-019-46178-9) and a review of performance peptides (Dominikowski et al., Frontiers in Endocrinology, 2026, DOI: 10.3389/fendo.2026.1822475), indexed on PubMed; and the WADA Prohibited List. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product.
Registered human trials
0 registered human trials on ClinicalTrials.gov that we reviewed
Sources
- [1]
- PMID 29535161
- [2]
- [3]
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