IGF-1 LR3
Long R3 IGF-1
Modified long-acting IGF-1 used in cell culture; never tested in humans. Mecasermin (Increlex) is the approved IGF-1.
Not FDA-approved. LR3 is not approved for human use. WADA-prohibited. Mecasermin is FDA-approved for primary IGF-1 deficiency. This page describes research and public discussion; it is not a recommendation to use.
Overview
IGF-1 LR3 has an extended N-terminus and an amino-acid substitution that reduce binding to IGF-binding proteins, prolonging activity. It was developed as a cell-culture reagent.
Mechanism of action
Activates the IGF-1 receptor (anabolic, insulin-like effects) with reduced IGFBP binding.
Benefits & evidence ratings
Dosing
Doses show what has been studied or discussed — not guidance. Always follow your prescriber.
| Source | Dose | Frequency | Duration | Route |
|---|---|---|---|---|
Mecasermin label (different molecule) A Established / approved | 0.04–0.12 mg/kg | Twice daily with meals | Chronic (pediatric) | Subcutaneous |
Online / clinic protocols D Anecdotal / community Not derived from controlled human trials. Reported for transparency, not recommendation. | 20–50 mcg | Daily | 4 weeks | Subcutaneous |
Clinical trials & studies
- LabelCurrentIncrelex (mecasermin) prescribing information
Hypoglycemia, intracranial hypertension, and neoplasia warnings.
Safety
Side effects
- Hypoglycemia
- Jaw/organ growth, edema (IGF class)
- Theoretical cancer promotion
Contraindications
- Active or suspected malignancy
- Diabetes (caution)
- Pregnancy
Interactions
- Insulin and oral hypoglycemics
Long-term safety
Unknown; IGF-1 elevation associated with certain cancers epidemiologically.
Regulatory status
Unapproved / research
LR3 is not approved for human use. WADA-prohibited. Mecasermin is FDA-approved for primary IGF-1 deficiency.
FAQ
Commonly discussed alongside
Listing a combination does not mean it has been studied or is safe.