# IGF-1 LR3

IGF-1 LR3 has no registered human trials in the registries we track. It is marketed for 3 different uses.

**In short**

- No registered human trial exists for IGF-1 LR3 in the registries we track.
- IGF-1 LR3 is not FDA-approved for any use.
- Last checked against ClinicalTrials.gov on 2026-07-30.

## What it is

IGF-1 LR3 is a modified version of insulin-like growth factor 1: arginine replaces glutamate at position 3 and a thirteen-residue extension is added at the N-terminus. Those changes reduce how tightly it binds the carrier proteins that normally limit it, so it stays active far longer. It was developed as a reagent for industrial cell culture, never as a human drug.

## Where the claims come from

The interest is extrapolated from IGF-1’s genuine role in muscle growth, combined with the analogue’s longer half-life. Three different things are routinely called "IGF-1" in marketing: the natural hormone, the FDA-approved drug mecasermin (Increlex), and this research analogue. Evidence or approval for one does not transfer to the others, and only mecasermin has registered trials — fourteen of them.

## What evidence exists outside the registry

Published work on the LR3 analogue is animal and laboratory only: fetal sheep infusion studies, mouse work, and recombinant-expression papers. One mouse study of intranasal LongR3 failed to preserve cognition. The analogue does appear in doping-control literature, which is evidence that people use it, not evidence that it works.

**Sources for the above**

- [Increlex (mecasermin) FDA label](https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22Increlex%22) — The approved IGF-1 product — a different molecule from the LR3 analogue, approved for severe primary IGF-1 deficiency in children.
- [LongR3 IGF-1 in fetal sheep](https://pubmed.ncbi.nlm.nih.gov/37114757/) — Representative of the animal literature that exists for the analogue.
- [Detection of LongR3 IGF-1 in doping control](https://pubmed.ncbi.nlm.nih.gov/38197510/) — Evidence of human use; not evidence of effect.

## Approved for

Not approved by the FDA for any use. Nothing has been reviewed for safety, effectiveness or manufacturing quality.

## Studied for

No registered trial on ClinicalTrials.gov lists a studied condition for this compound. That is a gap in the registry, not a finding that it was tested and failed. Published human research may exist without a registry entry — registration only became standard in the mid-2000s.

## Marketed for

- Muscle growth
- Recovery
- Nutrient partitioning

## What regulators have said

We searched FDA's list of bulk drug substances nominated for use in pharmacy compounding and did not find IGF-1 LR3 on it, in any category. There is no published FDA safety assessment to report — that is not the same as having been reviewed and cleared.


## Every trial on record

No registered interventional human study found on ClinicalTrials.gov. That is not proof the compound does nothing, and not proof it was never given to a human — trial registration only became standard in the mid-2000s, so older published work often has no registry entry.

## Common questions

**How many human trials does IGF-1 LR3 have?**
None in the registries we track.

**Is IGF-1 LR3 FDA approved?**
No. It is not approved by the FDA for any indication.

**Where does this data come from?**
ClinicalTrials.gov. We count interventional human studies only. Every trial
links to its original record.

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*Automated aggregation from public registries. Not medical advice. No physician
has reviewed this page. Source: https://www.whatsactuallyknown.com/compounds/igf-1-lr3*