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IGF-1 LR3 Reconstitution Calculator & Guide
Long R3 Insulin-Like Growth Factor-I Analog
IGF-1 LR3, also called Long R3 IGF-I, is a synthetic analog of insulin-like growth factor 1 designed to bind IGF-binding proteins much less strongly than native IGF-1. It is widely discussed in bodybuilding and performance communities, but human clinical evidence for the LR3 analog itself is essentially absent. This page explains what is actually known from laboratory and animal research, how LR3 differs from approved recombinant IGF-1, safety and sports considerations, and educational reconstitution math.
Evidence Snapshot
IGF-1 LR3 research at a glance
Standardized regulatory and evidence context so research compounds, investigational drugs, and approved medications are not treated as if they have the same level of human evidence.
Regulatory status
Not FDA-approvedDevelopment / evidence stage
Preclinical / no established human program
No established development program
Human evidence level
No meaningful direct human therapeutic evidencePrimary mechanism
Modified long-acting IGF-1 analogue intended to signal through the IGF-1 receptor.
WADA context
Explicitly prohibited — S2Human intervention evidence
No peer-reviewed human clinical program establishing safety or effectiveness for IGF-1 LR3 was identified in the 2026 review used for this comparison.
Human biology evidence
The biological rationale is largely extrapolated from established IGF-1 physiology and receptor signaling rather than direct clinical evidence for LR3.
Key takeaway
The compound is often discussed as if IGF-1 biology directly proves LR3 outcomes, but the direct human evidence base is extremely weak.
Evidence labels describe the research base and regulatory context; they are not treatment, dosing, or use recommendations. Review dates describe the last BACToBasics source check for this evidence summary. Anti-doping rules can change and should be verified with the applicable authority.
IGF-1 LR3 Reconstitution Calculator
Enter the vial amount, liquid volume, and amount you want to calculate. BACToBasics will automatically calculate concentration, liquid volume, and U-100 syringe-unit equivalents.
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Calculator values are educational math inputs only. They are not recommended preparation amounts, doses, or use protocols.
IGF-1 LR3 Reconstitution Math
Reconstitution math starts with the amount contained in the vial and the liquid volume used in the calculation. Dividing the vial amount by the liquid volume gives the resulting concentration.
Example vial amount
1 mg
| Liquid Volume | Calculation | Concentration |
|---|---|---|
| 1 mL | 1 mg ÷ 1 mL | 1 mg/mL |
| 2 mL | 1 mg ÷ 2 mL | 0.5 mg/mL |
| 3 mL | 1 mg ÷ 3 mL | 0.3333 mg/mL |
This table demonstrates concentration math only. The liquid volumes shown are examples for comparison and are not preparation recommendations.
More Reconstitution Tools
Need to compare different liquid volumes or convert between mg, mcg, mL, and U-100 units? Use the dedicated BACToBasics calculator tools.
What is IGF-1 LR3?
IGF-1 LR3 is a modified form of insulin-like growth factor 1. It contains an arginine substitution at position 3 and an additional N-terminal peptide extension. These changes were developed to reduce binding to IGF-binding proteins, which normally regulate how much free IGF-1 is available to interact with receptors. IGF-1 LR3 is not an FDA-approved medication.
How is IGF-1 LR3 different from native IGF-1?
Native IGF-1 circulates largely bound to IGF-binding proteins, which influence its distribution, half-life, and biological availability. Long R3 IGF-I was engineered to have dramatically lower affinity for several IGF-binding proteins while retaining activity at the IGF-1 receptor. This can make it behave differently from native IGF-1 in laboratory and animal models, so evidence from standard recombinant IGF-1 should not automatically be applied to LR3.
What does laboratory research show?
Cell-culture studies show that Long R3 IGF-I can activate IGF-1 receptor signaling and can promote proliferation or differentiation in some experimental systems. Its reduced interaction with IGF-binding proteins can increase apparent activity in certain models. These findings demonstrate biological activity but do not establish clinical benefits in humans.
What does animal research show?
Animal studies have produced mixed and species-dependent findings. Long R3 IGF-I has altered organ growth, IGF-binding proteins, endogenous IGF concentrations, food intake, and growth-related signaling in different animal models. In some studies it increased tissue or organ growth without increasing overall body growth, while in others it reduced weight gain or food intake. This variability is one reason animal results should not be translated directly into human bodybuilding claims.
Are there human clinical trials of IGF-1 LR3?
Published human therapeutic trials specifically evaluating Long R3 IGF-I are not established in the clinical literature. Most published work involving LR3 is laboratory, cell-culture, or animal research rather than Phase 1, Phase 2, or Phase 3 human drug development. Claims about muscle gain, recovery, fat loss, anti-aging, or performance therefore lack validated human clinical-trial support for the LR3 analog itself.
IGF-1 LR3 and muscle growth claims
IGF-1 signaling is involved in muscle-cell growth, differentiation, protein synthesis, and other anabolic processes, which is why IGF-1 LR3 is often discussed in bodybuilding communities. However, demonstrating receptor activity or anabolic effects in cells and animals is not the same as proving that nonmedical IGF-1 LR3 use increases muscle mass safely or predictably in humans.
IGF-1 LR3 and growth hormone pathways
Growth hormone stimulates production of IGF-1, particularly in the liver, and many effects of the growth-hormone axis are mediated partly through IGF-1 signaling. CJC-1295, Ipamorelin, and Tesamorelin act upstream by influencing growth-hormone secretion, whereas IGF-1 LR3 is an IGF-1 analog acting further downstream at IGF-related signaling pathways.
IGF-1 LR3 vs Mecasermin (Increlex)
Mecasermin is recombinant human IGF-1 and is FDA-approved under the brand name Increlex for a narrow pediatric indication involving severe primary IGF-1 deficiency or certain children with GH-gene deletion and neutralizing antibodies to GH. IGF-1 LR3 is a different modified molecule and should not be treated as equivalent to mecasermin or as an approved version of IGF-1 therapy.
What safety information exists for IGF-1 LR3?
A validated human safety profile for IGF-1 LR3 has not been established. Because LR3 activates IGF-related signaling, concerns often discussed by clinicians and researchers include glucose lowering, edema, headaches, soft-tissue effects, and unwanted growth signaling, but these risks are not characterized for LR3 through controlled human trials. Safety information from approved mecasermin can provide biological context but cannot be assumed to define the risk profile of LR3.
Hypoglycemia and IGF signaling
Approved recombinant IGF-1 can produce clinically important hypoglycemia because IGF-1 has insulin-like metabolic effects. Severe hypoglycemia, including seizures, appears in mecasermin prescribing information. Whether the frequency or severity of this risk is the same with IGF-1 LR3 is unknown because LR3 lacks an established human clinical safety dataset.
IGF signaling and cancer concerns
IGF-1 receptor signaling can promote cell survival and proliferation, which makes growth signaling an important safety consideration. Approved mecasermin is contraindicated in pediatric patients with malignant neoplasia or a history of malignancy. In a mouse cancer-cachexia model, Long R3 IGF-I limited muscle loss but was associated with accelerated tumor growth. This animal result does not quantify human risk, but it reinforces why unmonitored growth-factor exposure should not be treated as benign.
Black-market and research-product concerns
A published anti-doping laboratory report identified a His-tagged Long R3 IGF-I research reagent in a black-market injection vial. The authors noted that the effects of that tagged product in humans had not been established. This illustrates a broader problem with products sold as research peptides: identity, purity, formulation, sterility, and manufacturing quality may not match what the label claims.
Is IGF-1 LR3 FDA-approved?
No FDA-approved drug product containing IGF-1 LR3 has been established. FDA's Global Substance Registration System recognizes Long-(Arg3) insulin-like growth factor-I as a defined ingredient substance and lists IGF-1 LR3 as a synonym, but FDA explicitly notes that assignment of a UNII does not imply regulatory review or approval.
Is IGF-1 LR3 banned in competitive sports?
Yes. The World Anti-Doping Agency prohibits IGF-1 and other growth factors that affect muscle, tendon, ligament, protein synthesis, vascularization, regenerative capacity, or energy use. The 2026 Prohibited List identifies insulin-like growth factor-1 within the growth-factor category prohibited at all times.
IGF-1 LR3 reconstitution math
Reconstitution calculations depend on the labeled amount in a vial and the liquid volume used. As a mathematical example, a 1mg vial combined with 1mL of liquid produces a concentration of 1mg per mL, or 1,000mcg per mL. BACToBasics uses examples like this only to demonstrate concentration, liquid-volume, and U-100 syringe-unit calculations rather than to recommend a preparation or dosing protocol.
Explore more about IGF-1 LR3
11 linksComparisons, research records, development tracking, blends, and related guides are available here when you want to go deeper.
Explore more about IGF-1 LR3
11 linksComparisons, research records, development tracking, blends, and related guides are available here when you want to go deeper.
Compare IGF-1 LR3
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Research, updates & development
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IGF-1 LR3 research & development updates
Open the public timeline of sourced research records and material development changes tracked by BACToBasics.
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ResearchIGF-1 LR3 research sources
Open 1 curated research record for IGF-1 LR3.
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DevelopmentIGF-1 LR3 clinical development
Preclinical / no established human program · No established development program. No established direct human therapeutic development milestone identified.
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Relevant glossary concepts
Definitions are matched against the guide's structured title, subtitle, description, and educational sections.
FDA-Approved
A status indicating that the FDA has approved a specific drug product for one or more labeled uses after reviewing the required evidence and manufacturing information.
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GlossaryMilliliter (mL)
A metric unit of liquid volume equal to one-thousandth of a liter.
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GlossaryConcentration
The amount of a substance contained in a given volume of liquid, such as mg/mL or mcg/mL.
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IGF-1 LR3 FAQ
Tap a question to expand only the answer you want to read.
Is IGF-1 LR3 FDA-approved?
No FDA-approved IGF-1 LR3 drug product has been established. FDA recognizes the substance in its registration system, but explicitly states that a UNII does not imply regulatory review or approval.
Is IGF-1 LR3 the same as Increlex?
No. Increlex contains mecasermin, recombinant human IGF-1, and is FDA-approved for specific pediatric growth disorders. IGF-1 LR3 is a modified analog with altered binding characteristics and is not an approved substitute for mecasermin.
Why is IGF-1 LR3 called Long R3 IGF-I?
The name refers to an IGF-1 analog with an arginine substitution at position 3 plus an N-terminal peptide extension. These changes reduce binding to IGF-binding proteins compared with native IGF-1.
Are there human trials showing IGF-1 LR3 builds muscle?
Published controlled human trials specifically establishing muscle-building efficacy for IGF-1 LR3 are not available. Most evidence for LR3 comes from cell and animal studies.
Does IGF-1 LR3 increase IGF signaling?
Yes. Laboratory studies show that Long R3 IGF-I can activate IGF-1 receptor signaling. Its reduced affinity for IGF-binding proteins can change its apparent biological activity compared with native IGF-1.
Can IGF-1 LR3 cause low blood sugar?
The human risk has not been quantified for LR3, but IGF signaling can lower blood glucose. Approved recombinant IGF-1 has a well-established hypoglycemia warning, so glucose effects are a biologically plausible concern for an IGF-1 analog.
Is IGF-1 LR3 safe?
Its safety in humans has not been established through controlled clinical trials. Product-quality uncertainty and the potent growth-factor biology add additional concerns beyond the absence of efficacy data.
Is IGF-1 LR3 linked to cancer?
No controlled human LR3 data quantify cancer risk. IGF signaling can promote cell survival and proliferation, approved mecasermin is contraindicated in malignancy, and one mouse cancer model found accelerated tumor growth with LR3. These findings justify caution but do not establish a specific human risk estimate.
Is IGF-1 LR3 banned by WADA?
Yes. IGF-1 falls within WADA's prohibited growth-factor category and is prohibited at all times for athletes subject to the World Anti-Doping Code.
How do you calculate IGF-1 LR3 concentration?
Divide the labeled amount in the vial by the liquid volume. For example, 1mg divided by 1mL equals 1mg/mL, or 1,000mcg/mL. This is mathematical concentration conversion rather than a preparation recommendation.
Can BACToBasics calculate IGF-1 LR3 reconstitution math?
Yes. Enter the labeled vial amount and liquid volume to calculate concentration, equivalent liquid volume, U-100 syringe units, and approximate amounts per vial. The calculator provides educational math rather than medical or dosing advice.
Sources & References
7 sourcesOpen the references when you want to inspect the research and regulatory sources behind this guide.
Sources & References
7 sourcesOpen the references when you want to inspect the research and regulatory sources behind this guide.
FDA substance-registration record identifying IGF-1 LR3 / Long R3 IGF-I as a defined ingredient substance and explicitly noting that UNII assignment does not imply regulatory review or approval.
Official U.S. prescribing information for FDA-approved recombinant human IGF-1, including its narrow pediatric indication, hypoglycemia warning, and malignancy contraindication. Used for biological context, not as evidence that LR3 has the same safety profile.
Official WADA list identifying insulin-like growth factor-1 within the prohibited growth-factor category.
Peer-reviewed anti-doping laboratory report identifying a tagged Long R3 IGF-I research reagent in an injection vial and noting that its effects in humans were not established.
Animal study showing substantial endocrine and growth-related effects, including reduced food intake, weight gain, IGFBP-3, endogenous IGF-I, insulin, and growth-hormone signaling.
Animal study showing altered organ growth and circulating IGF/IGF-binding-protein biology without increased overall body growth.
Preclinical mouse study in which Long R3 IGF-I limited muscle loss but was associated with accelerated tumor growth.
BACToBasics provides educational information and math tools only. This content is not medical advice, dosing advice, injection instruction, or a recommendation to use any peptide or medication.