Overview
Overview
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified analog of human IGF-1 with significantly extended half-life, studied for its anabolic and metabolic effects[1]. This synthetic variant exhibits reduced binding to IGF binding proteins, allowing enhanced bioavailability and systemic activity[2]. This educational protocol presents a once-daily subcutaneous approach with conservative titration for research applications. Reconstitute: Add 3.0 mL bacteriostatic water → ~0.333 mg/mL conce
- Category
- Growth Hormone
- Routes
- subcutaneous
Mechanism
IGF-1 LR3
Mechanism of action
Mechanism of action
IGF-1 LR3 binds to the IGF-1 receptor (IGF-1R) , a tyrosine kinase receptor present on most tissues — skeletal muscle, bone, liver, kidney, nerve, and connective tissue. When the receptor is engaged, it kicks off intracellular signaling cascades that drive both protein-building activity and cell proliferation. PI3K → Akt → mTOR. This is the protein-synthesis arm. It increases muscle protein synthesis, reduces protein breakdown, supports glucose and amino acid uptake, and suppresses programmed cell death. It is also the pathway that drives IGF-1 LR3's insulin-like glucose-lowering effect — the same mechanism that creates hypoglycemia risk. RAS → RAF → MEK → ERK (MAPK). This is the proliferation arm. It supports cell division and tissue growth. In skeletal muscle this pathway can support satellite cell activation and possible hyperplasia (creation of new muscle fibers). The same mitogenic activity is the basis of long-term cancer concern, because IGF-1 signaling is one of the more well-documented growth pathways studied in tumor biology. Native IGF-1 is largely sequestered in circulation by IGF binding proteins (IGFBPs) — a family of six proteins that escort IGF-1 around the body and limit how much is free to engage receptors. The structural changes in IGF-1 LR3 (the arginine substitution and 13-amino-acid extension) drop binding-protein affinity sharply. More peptide stays free, and the half-life stretches from roughly 12-15 hours for native IGF-1 to about 20-30 hours for IGF-1 LR3. Tomas et al. (1996) reported the analog was 1.5-2x more potent than equimolar IGF-1 in catabolic rat models, and broader pharmacology literature places it at roughly 3x potency overall. These same pharmacology properties — direct receptor activation, reduced binding-protein clearance, and the long half-life — explain both the anabolic interest researchers have in IGF-1 LR3 and its primary safety liabilities.
Key research findings
- 01
Long R3 insulin-like growth factor-1: an 83-amino-acid recombinant IGF-1 analog with an Arg-for-Glu substitution at position 3 plus a 13-amino-acid N-terminal extension (protein engineering).
- 02
These modifications markedly reduce binding to IGF-binding proteins (IGFBPs), increasing free, bioactive IGF-1 and prolonging/raising potency relative to native IGF-1 (in vitro).
- 03
Acts as an agonist at the IGF-1 receptor (IGF-1R), driving downstream PI3K/Akt and MAPK proliferation/growth signaling (in vitro / cell biology).
- 04
Its principal established, legitimate application is as a cell-culture supplement to promote proliferation and productivity in mammalian bioprocessing (e.g., CHO cells) and in stem-cell/tissue-culture research (in vitro / biotechnology).
- 05
Human in-vivo data on 'IGF-1 LR3' specifically are minimal; systemic IGF-1R agonism is potent and is studied cautiously, mainly in animal models (limited human evidence).
Primary source: Direct human evidence on IGF-1 LR3 Preclinical potency benchmark: Tomas et al. (1996, Journal of Endocrinology) reported IGF-1 LR3 was 1.5-2x more potent than equimolar native IGF-1 for body weight gain, organ growth, and anti-catabolic effects when continuously infused in normal and dexamethasone-treated rats. Preclinical anabolic effect in catabolic states: Tomas et al. (1992, Biochemical Journal) showed IGF-1 LR3 produced larger anabolic responses than native IGF-1 in dexamethasone-induced muscle catabolism in rats. Preclinical mitogenic concern: Tomas et al. (1997, Journal of Endocrinology) reported that IGF-1 LR3 supported protein turnover in tumor-bearing catabolic rats but also increased tumor growth in that model. Vascular biology: von der Thusen et al. (2011, American Journal of Pathology) reported that IGF-1 had plaque-stabilizing effects in a mouse atherosclerosis model — useful as a half-life reference (~20-30 hours) and pathway marker. Adjacent human safety: Increlex (mecasermin) FDA label: 71 pediatric patients with severe primary IGFD treated for a mean of 3.9 years. Hypoglycemia in 42%, tonsillar hypertrophy in 15%, intracranial hypertension in 3 subjects. This is the closest human dataset informing IGF-1 LR3 risk. Adjacent human efficacy in non-growth indications: Borasio et al. (1998, Neurology) and Sorenson et al. (2008, Neurology) tested SubQ native rhIGF-1 in adult ALS patients. Neither trial showed primary-endpoint benefit. These trials inform what native IGF-1 does in adults at clinical-grade doses, even though they target a different indication. Cancer epidemiology context: LeRoith & Roberts (2003) and Pollak (2008) summarize the body of evidence linking elevated circulating IGF-1 to risk of certain cancers. Not specific to IGF-1 LR3 but pathway-relevant. Anti-doping detection: Mongongu et al. (2020, Drug Testing and Analysis) developed an immunopurification + high-resolution mass spectrometry method to detect Long R3-IGF-I and Des(1-3)-IGF-I in athlete samples — establishing that IGF-1 LR3 is detectable by current anti-doping methods.
Protocol Reference
Protocol reference
Commonly cited research range: 20–50 mcg, daily.
Reference figures reported in the research literature — not a dosing recommendation. For interactive vial math and scheduling, see the Calculator and Schedule tabs.
Cited protocol & reconstitution guide
Source-backed reference fields by phase, including any volume fields authored in the cited guide.
Assessment
20 mcg/day
Low range
20-40 mcg/day
Moderate range
40-80 mcg/day
High range
80-100 mcg/day
| Phase | Reference amount | Units / volume |
|---|---|---|
| Assessment | 20 mcg/day | 6 units (0.06 mL) |
| Low range | 20-40 mcg/day | 6–12 units (0.06–0.12 mL) |
| Moderate range | 40-80 mcg/day | 12–24 units (0.12–0.24 mL) |
| High range | 80-100 mcg/day | 24–30 units (0.24–0.30 mL) |
Titration protocol
- AssessmentStart20 mcg/day
Once daily — used to gauge tolerance and hypoglycemic response.
- Low rangeBuild20-40 mcg/day
Once daily — most-cited starting range; the lower end (10-20 mcg/day) is also commonly used.
- Moderate rangeBuild40-80 mcg/day
Once daily — community protocols commonly hold at ~50-60 mcg/day before moving higher.
- High rangeBuild80-100 mcg/day
Once daily — upper limit of reported protocols (100 mcg/day max); side-effect frequency rises in this range.
- Cycle structureBuild—
Standard: 4 weeks on / 4 weeks off minimum. Conservative: 3-4 weeks on / 4-6 weeks off. Extended: 5-6 weeks on / 6 weeks off minimum, only after prior cycles confirmed glucose tolerance.
- Timing (all phases)Maintenance—
Once daily (20-30 hour half-life). Commonly paired with 30-50 g fast-acting carbohydrates within ~30 minutes. Avoid fasted dosing and dosing within 2 hours of bedtime — schedule at least 2-3 hours before bed. Post-workout on training days, morning with food on rest days. Skip missed doses and resume the next day; do not double-dose. Rotate sites — do not reuse the same square inch within a 7-day window.
Storage & Handling
Storage requirements(typical for most peptides)
Can be stored for extended periods. Protect from moisture.
Store in refrigerator door. Never freeze after reconstitution.
Label vials with reconstitution date. Discard if cloudy.
Reconstitution steps
- 01🌡️Wash hands thoroughly. Lay out a clean surface with the IGF-1 LR3 vial, bacteriostatic water, alcohol swabs, and a sterile syringe.
- 02🧴Wipe the rubber stoppers of the IGF-1 LR3 vial and the bacteriostatic water vial with separate alcohol swabs. Let them air-dry for 10-15 seconds.
- 03💉Draw 3 mL bacteriostatic water into a sterile syringe — this 1 mg vial yields 0.333 mg/mL.
- 04💧Slowly inject the water against the inner wall of the IGF-1 LR3 vial — never directly onto the lyophilized powder.
- 05🔄Gently swirl or roll the vial between your palms until the powder fully dissolves. Do not shake — shaking introduces foam and can damage the peptide structure.
- 06🏷️Inspect before any draw: the solution should be clear and free of particles. If cloudy or with visible debris, do not use.
- 07❄️Refrigerate at 2-8 °C (36-46 °F) and use within roughly 28-30 days. Do not freeze the reconstituted solution.
- 08💉Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.
Additional storage notes
Store at −20 °C (−4 °F) or colder (−80 °C optimal) in dry, dark conditions for up to 12 months [4] ; short-term storage at 2–8 °C (35.6–46.4 °F) for several months is acceptable.
Refrigerate at 2–8 °C (35.6–46.4 °F) immediately after mixing; use within 30 days for optimal potency [9] .
Extended storage of reconstituted solution: For storage beyond 30 days, prepare sterile aliquots and freeze at −20 °C (−4 °F); aliquots remain stable for 3–6 months [4] . Never refreeze a thawed vial.
Allow frozen vials to reach room temperature before opening to minimize condensation; always inspect solution for clarity (discard if cloudy or contains particles) [10] .
Keep all vials protected from light and maintain cold chain during storage.
Clinical Evidence
Clinical evidence
Studied for anabolic and growth-promoting activity in cell and animal models; human data are limited.
Direct human evidence on IGF-1 LR3 Preclinical potency benchmark: Tomas et al. (1996, Journal of Endocrinology) reported IGF-1 LR3 was 1.5-2x more potent than equimolar native IGF-1 for body weight gain, organ growth, and anti-catabolic effects when continuously infused in normal and dexamethasone-treated rats. Preclinical anabolic effect in catabolic states: Tomas et al. (1992, Biochemical Journal) showed IGF-1 LR3 produced larger anabolic responses than native IGF-1 in dexamethasone-induced muscle catabolism in rats. Preclinical mitogenic concern: Tomas et al. (1997, Journal of Endocrinology) reported that IGF-1 LR3 supported protein turnover in tumor-bearing catabolic rats but also increased tumor growth in that model. Vascular biology: von der Thusen et al. (2011, American Journal of Pathology) reported that IGF-1 had plaque-stabilizing effects in a mouse atherosclerosis model — useful as a half-life reference (~20-30 hours) and pathway marker. Adjacent human safety: Increlex (mecasermin) FDA label: 71 pediatric patients with severe primary IGFD treated for a mean of 3.9 years. Hypoglycemia in 42%, tonsillar hypertrophy in 15%, intracranial hypertension in 3 subjects. This is the closest human dataset informing IGF-1 LR3 risk. Adjacent human efficacy in non-growth indications: Borasio et al. (1998, Neurology) and Sorenson et al. (2008, Neurology) tested SubQ native rhIGF-1 in adult ALS patients. Neither trial showed primary-endpoint benefit. These trials inform what native IGF-1 does in adults at clinical-grade doses, even though they target a different indication. Cancer epidemiology context: LeRoith & Roberts (2003) and Pollak (2008) summarize the body of evidence linking elevated circulating IGF-1 to risk of certain cancers. Not specific to IGF-1 LR3 but pathway-relevant. Anti-doping detection: Mongongu et al. (2020, Drug Testing and Analysis) developed an immunopurification + high-resolution mass spectrometry method to detect Long R3-IGF-I and Des(1-3)-IGF-I in athlete samples — establishing that IGF-1 LR3 is detectable by current anti-doping methods.
- 01Long R3 insulin-like growth factor-1: an 83-amino-acid recombinant IGF-1 analog with an Arg-for-Glu substitution at position 3 plus a 13-amino-acid N-terminal extension (protein engineering).
- 02These modifications markedly reduce binding to IGF-binding proteins (IGFBPs), increasing free, bioactive IGF-1 and prolonging/raising potency relative to native IGF-1 (in vitro).
- 03Acts as an agonist at the IGF-1 receptor (IGF-1R), driving downstream PI3K/Akt and MAPK proliferation/growth signaling (in vitro / cell biology).
- 04Its principal established, legitimate application is as a cell-culture supplement to promote proliferation and productivity in mammalian bioprocessing (e.g., CHO cells) and in stem-cell/tissue-culture research (in vitro / biotechnology).
- 05Human in-vivo data on 'IGF-1 LR3' specifically are minimal; systemic IGF-1R agonism is potent and is studied cautiously, mainly in animal models (limited human evidence).
Evidence maturity varies by compound; much peptide research is preclinical (in vitro or animal-model). Where human data are limited, findings should be read as research observations, not clinical conclusions.
References
Literature references
Published research articles and sources related to IGF-1 LR3.
- 01Biomolecules (MDPI) — Insulin-Like Growth Factor-1 (IGF-1) and Its Monitoring in Medical Diagnostic and in Sports View Source
- 02Dopinglinkki (FINCIS Anti-Doping Authority) — Insulin-like growth factor 1 (IGF-1) and long chain IGF (LR3IGF-1): Medical information and safety overview View Source
- 03Mayo Clinic / IBM Micromedex — Mecasermin (Subcutaneous route): Proper Use and Handling – guidance on IGF-1 administration timing with meals View Source
- 04Cell Sciences (Research Reagents) — Recombinant Human LR3 IGF-1: Product technical datasheet including storage and stability specifications View Source
- 05Centers for Disease Control and Prevention (CDC) — Preventing Unsafe Injection Practices: One Needle, One Syringe, Only One Time View Source
- 06Drugs.com — Increlex (mecasermin) Dosage Guide: Clinical dosing and hypoglycemia management for IGF-1 therapy View Source
- 07AnabolicMinds Community Research Forum — Storage and cycle considerations for IGF-1 LR3: Practical protocol discussions View Source
- 08Immunize.org (Immunization Action Coalition) — How to Administer Subcutaneous Vaccine Injections: Site selection and rotation guidance View Source
- 09ReliaTech GmbH — Human IGF-1 LR3 Protein Technical Specifications: Reconstitution and storage protocols View Source
- 10Mayo Clinic — Mecasermin (subcutaneous route): Side effects and proper handling – solution inspection guidelines View Source
- 11Frontiers in Bioengineering & Biotechnology — Insulin-Like Growth Factor-1: A Promising Therapeutic Target for Peripheral Nerve Injury View Source
- 12Drug Testing and Analysis (PubMed) — Detection of LongR3-IGF-I, Des(1-3)-IGF-I, and R3-IGF-I using immunopurification and high resolution mass spectrometry for antidoping purposes View Source
- 13Centers for Disease Control and Prevention (CDC) — Chapter 6: Vaccine Administration (Pink Book): Comprehensive subcutaneous injection technique guidance View Source
- 14NCBI Bookshelf — 5.6 Administering Subcutaneous Medications: Clinical best practices for subcutaneous injection technique View Source
- 15Pure Lab Peptides — IGF-1 LR3 (1 mg) Product Page: Supplier specifications, purity documentation, and COA access View Source
Observed Effects
Observed effects in cited research
Hypoglycemia (the primary acute risk)
- In the Increlex program, hypoglycemia was reported in 30 of 71 subjects (42%) . Most events were mild or moderate. Five subjects had severe hypoglycemia requiring assistance, and four experienced hypoglycemic seizures or loss of consciousness on at least one occasion . The rate was highest in the first month of treatment. Symptoms include shakiness, sweating, hunger, anxiety, confusion, dizziness, blurred vision, and at the severe end, seizure or loss of consciousness.
- Mitigation in the Increlex label is straightforward: administer with food, never on an empty stomach, monitor glucose during titration, and keep fast-acting carbohydrates available. The IGF-1 LR3 research community uses the same rule set, with the additional precaution of avoiding pre-bed dosing because of overnight hypoglycemia risk.
Tonsillar and lymphoid hypertrophy
- Tonsillar hypertrophy was reported in roughly 15% of Increlex subjects. Adenoidal hypertrophy and snoring/sleep apnea were also documented. The mechanism is consistent with general lymphoid tissue growth under elevated IGF-1 exposure.
Intracranial hypertension (papilledema)
- Intracranial hypertension occurred in 3 of the 71 Increlex subjects. The label recommends funduscopic examination at the start of therapy and periodically. New, severe, or persistent headache — especially with visual changes — warrants medical evaluation.
Organ growth and visceral hypertrophy
- Increlex labeling notes rapid increases in renal and splenic length in some patients. In the research community, sustained or supraphysiologic IGF-1 exposure is associated with progressive abdominal distension (sometimes called 'GH gut') and concern for cardiac hypertrophy. Organ-growth changes are believed to be largely irreversible, which is the strongest argument behind the 4-6 week cycle ceiling.
Fluid retention, joint discomfort, headache
- Mild edema, joint stiffness, and headaches are commonly reported in the IGF-1 pathway literature, including IGF-1 LR3 community reports. These are typically dose-dependent and reversible with dose reduction or cycle discontinuation.
Injection site reactions
- Lipohypertrophy, irritation, redness, and bruising can occur at injection sites. Site rotation and proper technique reduce frequency. The Increlex label also identifies injection-site lipohypertrophy as a recognized adverse reaction.
Cancer-pathway concern
- IGF-1 signaling is mitogenic and anti-apoptotic, two properties relevant to cancer biology. In 2-year rat carcinogenicity studies referenced in the Increlex label, increased mammary and skin tumor incidence occurred at high IGF-1 exposure. Tomas et al. (1997) reported that IGF-1 LR3 supported protein turnover in tumor-bearing rats but also increased tumor growth in that model. Broader epidemiology (LeRoith 2003; Pollak 2008) has linked higher circulating IGF-1 to elevated risk of certain cancers in human cohorts. This is not the same as proving short-term IGF-1 LR3 use causes cancer in healthy adults — it is a real biological-mechanism concern that supports cycle limits and absolute contraindication in anyone with cancer history.
Endogenous GH suppression
- Exogenous IGF-1 can suppress pituitary GH secretion through hypothalamic-pituitary feedback. This is one reason most IGF-1 LR3 protocols avoid late-evening dosing — dosing close to bedtime is more likely to coincide with the natural overnight GH pulse.
Research Considerations
Research considerations
Research Use Only - not for human or veterinary therapeutic use. Current evidence is limited to in vitro and/or animal-model research; human data are minimal or absent. Consult a licensed healthcare professional for any clinical decisions.
- IGF-1 LR3 has no FDA-approved human indication. It is studied as a research compound and used in research-community protocols only. The Increlex (mecasermin) FDA label, which covers native rhIGF-1 in pediatric severe primary IGFD, is the closest human reference and informs the contraindications below.
- Active or prior cancer, or strong family history of cancer. IGF-1 signaling is mitogenic and anti-apoptotic. The Increlex label explicitly contraindicates use in patients with active or suspected neoplasia and notes that active or suspected malignancy should prompt discontinuation. Epidemiological studies have repeatedly linked elevated circulating IGF-1 to risk of certain cancers (LeRoith & Roberts 2003; Pollak 2008).
- Diabetes (type 1 or type 2) or any condition involving glucose dysregulation. IGF-1 LR3 lowers blood glucose. Adding it to existing insulin therapy or impaired glucose handling can produce unpredictable, severe hypoglycemia. The 2025 Increlex label requires meal/snack pairing and dose titration starting from a low dose specifically because hypoglycemia is so consistent.
- Pregnancy and breastfeeding. No human safety data exists. The Increlex label specifies it should not be used by pregnant women.
- Closed or near-closed epiphyses being a goal of approved use. Mecasermin loses approved indication once growth plates close. For IGF-1 LR3, that means there is no validated 'normal-adult' indication at all. Adolescents with open growth plates are not appropriate research subjects in unsupervised settings due to disproportionate-growth concerns.
- Concurrent insulin or insulin secretagogue therapy. Combining IGF-1 LR3 with insulin or sulfonylureas produces additive hypoglycemia. Multiple research-community sources flag this combination as having been associated with hospitalizations. There is no protocol justification for combining the two outside direct clinician supervision.
- Pre-existing cardiac, kidney, liver, or splenic conditions. IGF-1 supports growth in many organ systems. Increlex labeling notes rapid increases in renal and splenic length in some treated patients. Pre-existing organ disease is widely treated as a hard contraindication.
- Competitive athletes in tested sports. IGF-1 LR3 is prohibited at all times by the World Anti-Doping Agency (WADA) and by all major professional sports organizations. Detection assays for LR3 have been published in peer-reviewed analytical literature (Mongongu et al. 2020).
Factors noted in the research literature; not patient-specific medical advice.
Regulatory Status
Regulatory status
RUO
Comparisons
Comparisons
| Compound | Mechanism | Route | Status |
|---|---|---|---|
| IGF-1 LR3this | A modified analog of insulin-like growth factor-1 with reduced binding to IGF-binding proteins, giving a markedly extended half-life and prolonged activation of IGF-1 receptor anabolic signaling. | subcutaneous | Investigational / RUO |
| Ipamorelin | Binds to ghrelin receptors to stimulate pituitary gland to release growth hormone. Highly selective with minimal side effects. | subcutaneous | Investigational / RUO |
| Sermorelin | Binds to GHRH receptors to stimulate pulsatile GH release, mimicking natural patterns. Preserves feedback mechanisms. | subcutaneous | Investigational / RUO |
| Tesamorelin | Binds to GHRH receptors to stimulate endogenous GH production. Preferentially reduces abdominal fat accumulation. | subcutaneous | Investigational / RUO |
| CJC-1295 | Binds to GHRH receptors to stimulate GH release. Modified structure provides extended duration of action (up to 7 days). | subcutaneous | Investigational / RUO |
| Kisspeptin | A neuroendocrine peptide that activates KISS1R (GPR54) on GnRH neurons to stimulate gonadotropin-releasing hormone secretion, a key upstream regulator of the reproductive axis. | subcutaneous | Investigational / RUO |
| KPV | A C-terminal tripeptide fragment of alpha-melanocyte-stimulating hormone (Lys-Pro-Val) studied for anti-inflammatory activity, proposed to act through intracellular pathways (e.g., NF-kB modulation) without melanocortin pigmentary activity. | subcutaneous | Investigational / RUO |
Attributes shown for research comparison only; not a statement of efficacy or therapeutic equivalence.
FAQ
Frequently asked questions
IGF-1 LR3 (Long Arginine-3 IGF-1) is a synthetic, longer-acting analog of human insulin-like growth factor 1. It carries an arginine substitution at position 3 and a 13-amino-acid N-terminal extension, giving it 83 amino acids total versus 70 for native IGF-1. The structural changes lower its affinity for IGF binding proteins and stretch its half-life to roughly 20-30 hours. It is sold as a research reagent and is not FDA-approved for any human use.
Approximately 20-30 hours, compared to roughly 12-15 hours for native IGF-1. The longer half-life is the reason once-daily dosing is the standard schedule across research-community protocols.
Research-community sources cluster between 20 and 100 mcg per day, given as one daily SubQ or IM injection. Lower-end ranges (20-40 mcg/day) are most commonly cited for tolerance assessment and women's protocols. Above roughly 50-60 mcg/day, observed effect frequency rises faster than the perceived signaling benefit. None of these ranges are validated clinical doses.
Add bacteriostatic water to the lyophilized vial, pouring slowly down the inside wall — never directly onto the powder. Swirl gently, do not shake. Refrigerate immediately at 2-8°C. A 1 mg vial reconstituted with 2 mL of BAC water gives 500 mcg/mL; a 50 mcg dose at that concentration is 0.10 mL (10 units on a U-100 insulin syringe). For custom math, use the Pep Pal calculator .
Most research-community protocols cap on-time at 4-6 weeks with at least equal time off between cycles. The ceiling reflects observed patterns of progressive insulin resistance, organ-growth concern, and IGF-1 receptor desensitization. Continuous multi-month use is widely discouraged.
Very real. In the Increlex (native mecasermin) FDA-approved program, hypoglycemia was reported in 42% of subjects, with five subjects experiencing severe episodes requiring assistance and four experiencing seizures or loss of consciousness. The rate was highest in the first month. Mitigation is consistent across all sources: eat 30-50 grams of fast-acting carbohydrates within 30 minutes of every injection, never inject fasted, never inject before sleep, and keep glucose tablets accessible during cycles.
Both routes are used in research protocols. SubQ is simpler and is the most-cited default. IM injection into a freshly trained muscle is reported in research interest in localized hyperplasia signaling, though the long half-life means the peptide distributes systemically regardless of site. Same hypoglycemia rules apply to both routes.
No. The combination produces additive hypoglycemia and has been associated with hospitalizations in research-community reporting. Both compounds lower blood glucose and the combined effect is unpredictable. This is treated as an absolute contraindication across virtually every published research-community source.
IGF-1 signaling is mitogenic and anti-apoptotic — both relevant to cancer biology. The Increlex label cites preclinical 2-year rat carcinogenicity studies in which increased mammary and skin tumor incidence occurred at high IGF-1 exposure. Tomas et al. (1997) reported that IGF-1 LR3 increased tumor growth in tumor-bearing catabolic rats. Epidemiological literature (LeRoith 2003; Pollak 2008) has linked elevated circulating IGF-1 to higher risk of certain cancers in human cohorts. Anyone with active or prior cancer, or strong family history, should not use IGF-1 LR3.
Two reasons. First, hypoglycemic episodes during sleep are harder to detect and respond to. Second, exogenous IGF-1 can suppress the natural overnight GH pulse through hypothalamic-pituitary feedback. Most research protocols schedule injections at least 2-3 hours before bedtime.
1 mg (1,000 mcg) and 0.1 mg (100 mcg) lyophilized vials are the most common research-grade sizes. The 1 mg vial is more practical for full cycles; 0.1 mg vials are usually used for short cycles or first-time tolerance assessment.
No. IGF-1 LR3 is not FDA-approved for any human therapeutic use. The closest FDA-approved IGF-1 product is mecasermin (Increlex) , native recombinant human IGF-1, approved only for the long-term treatment of growth failure in pediatric patients with severe primary IGF-1 deficiency or GH gene deletion with neutralizing antibodies. There is no adult or performance-related FDA indication for any IGF-1 product.
Yes. IGF-1 LR3 falls under the World Anti-Doping Agency's S2 category (peptide hormones, growth factors, related substances, and mimetics) and is prohibited at all times — both in and out of competition. Mongongu et al. (2020) published a validated detection method for IGF-1 LR3 in athlete samples.
Research-use notice
Research Use Only. This educational content and calculation support is intended for private research documentation. It does not provide medical advice, human-use directions, or claims of safety or effectiveness.