IGF-1 LR3
Hormonal and Signaling
ABOUT
IGF-1 LR3 (LongR3-IGF-I) is a modified IGF-1 analogue. An analytical study describes detection and metabolite work, including rodent experiments; it is not a clinical efficacy study.
EVIDENCE OVERVIEW
Too little published work to judge either way
WHAT THIS MEANS
Insufficient evidence. Review the research and limitations before relying on this record.
IDENTITY
HALF-LIFE
HOW IT IS THOUGHT TO WORK
Long R3 IGF-1 is a research-reagent analogue of IGF-1 carrying an arginine substitution at position 3 plus a 13-amino-acid N-terminal extension. Both changes reduce binding to IGF binding proteins, which is what raises free, receptor-available peptide and increases apparent potency in cell culture. It is sold as a cell-culture supplement.
PHARMACOKINETICS
No human pharmacokinetic data exists. The analogue has not been characterised in people by any route, so its exposure profile is unknown.
REVIEW
PUBLISHED PAIR RECORDS
with CJC-1295 (without DAC)
Additive IGF-1 receptor signallingCJC-1295 (without DAC) raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with CJC-1295 with DAC
Additive IGF-1 receptor signallingCJC-1295 with DAC raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with Sermorelin
Additive IGF-1 receptor signallingSermorelin raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with Tesamorelin
Additive IGF-1 receptor signallingTesamorelin raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with Ipamorelin
Additive IGF-1 receptor signallingIpamorelin raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with GHRP-2
Additive IGF-1 receptor signallingGHRP-2 raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with GHRP-6
Additive IGF-1 receptor signallingGHRP-6 raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with Hexarelin
Additive IGF-1 receptor signallingHexarelin raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with MK-677
Additive IGF-1 receptor signallingMK-677 raises IGF-1 indirectly by stimulating growth-hormone release, while IGF-1 LR3 is an IGF-1 analogue that acts directly at the IGF-1 receptor. The two therefore converge on the same downstream signalling. Regulatory labelling for recombinant IGF-1 records that the IGF-1 receptor is homologous to the insulin receptor, that IGF-1 has insulin-like hypoglycaemic effects, and that hypoglycaemia is among its most common adverse effects; doses of insulin or other hypoglycaemic products may need reducing. Growth hormone itself moves blood glucose in the opposite direction, so the net glycaemic effect of the pair is not predictable from either agent alone. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with IGF-1 DES
Overlapping IGF-1 pathway activityIGF-1 LR3 and IGF-1 DES are both IGF-1-pathway analogues or splice variants, so their activity converges on IGF-1 receptor signalling rather than on separate mechanisms. Regulatory labelling for recombinant IGF-1 records insulin-like hypoglycaemic effects arising from IGF-1 receptor homology with the insulin receptor. No human study has characterised these specific research analogues in combination, so the size of any combined effect is uncharacterised rather than known to be small. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with MGF
Overlapping IGF-1 pathway activityIGF-1 LR3 and MGF are both IGF-1-pathway analogues or splice variants, so their activity converges on IGF-1 receptor signalling rather than on separate mechanisms. Regulatory labelling for recombinant IGF-1 records insulin-like hypoglycaemic effects arising from IGF-1 receptor homology with the insulin receptor. No human study has characterised these specific research analogues in combination, so the size of any combined effect is uncharacterised rather than known to be small. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with peg-mgf
Overlapping IGF-1 pathway activityIGF-1 LR3 and PEG-MGF are both IGF-1-pathway analogues or splice variants, so their activity converges on IGF-1 receptor signalling rather than on separate mechanisms. Regulatory labelling for recombinant IGF-1 records insulin-like hypoglycaemic effects arising from IGF-1 receptor homology with the insulin receptor. No human study has characterised these specific research analogues in combination, so the size of any combined effect is uncharacterised rather than known to be small. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 19 Aug 2026with follistatin-344
Converging on muscle growth from two different directionsFollistatin-344 antagonises myostatin and activin A, removing a brake on skeletal-muscle growth through the SMAD2/3 pathway. IGF-1 LR3 pushes the accelerator instead, acting on IGF-1-receptor signalling. These are genuinely distinct pathways converging on the same tissue outcome, which is why the combination is attractive in principle and why its size cannot be predicted from either alone. The evidence does not support treating it as characterised: human follistatin data comes from AAV-delivered gene therapy in open-label muscular-dystrophy trials of a handful of patients, not from injected follistatin protein, and a case series reported central serous chorioretinopathy in bodybuilders using subcutaneous FS-344. Growth factors affecting muscle regeneration are prohibited at all times in sport. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 21 Aug 2026with CJC-1295 / Ipamorelin blend
Inherited from a component of this blendCJC-1295 / Ipamorelin blend contains CJC-1295 (without DAC) and Ipamorelin, and the catalogue holds a curated pair record between those components and IGF-1 LR3: CJC-1295 (without DAC) (additive igf-1 receptor signalling); Ipamorelin (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026with CJC-1295 with DAC / Ipamorelin blend
Inherited from a component of this blendCJC-1295 with DAC / Ipamorelin blend contains CJC-1295 with DAC and Ipamorelin, and the catalogue holds a curated pair record between those components and IGF-1 LR3: CJC-1295 with DAC (additive igf-1 receptor signalling); Ipamorelin (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026with Sermorelin / Ipamorelin blend
Inherited from a component of this blendSermorelin / Ipamorelin blend contains Sermorelin and Ipamorelin, and the catalogue holds a curated pair record between those components and IGF-1 LR3: Sermorelin (additive igf-1 receptor signalling); Ipamorelin (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026with CJC-1295 / GHRP-2 blend
Inherited from a component of this blendCJC-1295 / GHRP-2 blend contains CJC-1295 (without DAC) and GHRP-2, and the catalogue holds a curated pair record between those components and IGF-1 LR3: CJC-1295 (without DAC) (additive igf-1 receptor signalling); GHRP-2 (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026with CJC-1295 / GHRP-6 blend
Inherited from a component of this blendCJC-1295 / GHRP-6 blend contains CJC-1295 (without DAC) and GHRP-6, and the catalogue holds a curated pair record between those components and IGF-1 LR3: CJC-1295 (without DAC) (additive igf-1 receptor signalling); GHRP-6 (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026with CJC-1295 / Hexarelin blend
Inherited from a component of this blendCJC-1295 / Hexarelin blend contains CJC-1295 (without DAC) and Hexarelin, and the catalogue holds a curated pair record between those components and IGF-1 LR3: CJC-1295 (without DAC) (additive igf-1 receptor signalling); Hexarelin (additive igf-1 receptor signalling). Taking the blend therefore carries the same consideration as taking that component on its own, with the difference that a fixed-ratio vial cannot be adjusted independently of the rest of its contents. The evidence and citations here are the component record's; nothing has been studied about the blend itself. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 25 Aug 2026HUMAN EVIDENCE
No human clinical trial of Long R3 IGF-1 has been conducted. Clinical evidence exists only for recombinant human IGF-1 (mecasermin, Increlex), which is a different molecule with intact binding-protein affinity and an approved label. Findings from mecasermin do not transfer, because reduced binding-protein affinity is precisely the property that was engineered out.
REPORTED EFFECTS
No human safety data exists for this analogue. The hazards that apply to IGF-1 pharmacology apply here with less restraint from binding proteins: hypoglycaemia is the acute concern, and sustained IGF-1 receptor activation carries a theoretical mitogenic risk. Increlex labelling for the approved recombinant peptide carries hypoglycaemia warnings. No regulator has approved this substance for the use described here, so there is no label-verified dose, purity standard, or safety monitoring requirement behind it.
RESEARCH LIMITATIONS
The source is analytical and preclinical, not a formulation-specific clinical profile. Do not treat this analogue as interchangeable with licensed recombinant human IGF-1 medicines or endogenous IGF-1.
CURATED SOURCES · 3