HomePeptide dosagesIGF-1 LR3
IGF-1 LR3 dosage: chart, reported range and vial math
The range reported for IGF-1 LR3 is 20 to 100 mcg a day. No human study of IGF-1 LR3 was found, so it has no tested dose, half-life or safety data. It was made as a laboratory reagent and is a different molecule from mecasermin, the approved form of IGF-1.
IGF-1 LR3 dosage chart
Reported range, not a label dosePick your vial size. Each row shows the dose in milligrams or micrograms, the volume to draw and the mark on a U-100 syringe.
| Dose | Volume | Syringe units |
|---|---|---|
| 20 mcg | 0.06 mL | 6 units |
| 40 mcg | 0.12 mL | 12 units |
| 100 mcg | 0.30 mL | 30 units |
Source Reported range, not a label dose. Reports describe starting at 20 to 40 mcg, in 4 to 6 week cycles. No human study has been published. Vial math is arithmetic.
Which syringe fits each dose
For the 1 mg vial at 0.3333 mg/mL.
| Dose | Volume | Units | 0.3 mL syringe | 0.5 mL syringe | 1 mL syringe |
|---|---|---|---|---|---|
| 20 mcg | 0.06 mL | 6 units | Yes | Yes | Yes |
| 40 mcg | 0.12 mL | 12 units | Yes | Yes | Yes |
| 100 mcg | 0.30 mL | 30 units | Yes | Yes | Yes |
How long a vial lasts
Whole doses in one vial. The row for the size picked above is marked.
| Vial | 20 mcg | 40 mcg | 100 mcg |
|---|---|---|---|
| 1 mg vial | 50 doses | 25 doses | 10 doses |
How to mix a IGF-1 LR3 vial
These steps are for the 1 mg vial picked in the chart. Change the size there and the amounts here change with it.
- Wash your hands. Wipe the stopper of the peptide vial and the water vial with an alcohol swab.
- Draw 3 mL of bacteriostatic water into a syringe.
- Push the needle through the stopper of the peptide vial and let the water run slowly down the glass, not straight onto the powder.
- Swirl the vial gently until the powder is gone. Do not shake it.
- Write the date and 0.3333 mg/mL on the vial, then put it in the fridge.
| Vial | Bacteriostatic water | Concentration |
|---|---|---|
| 1 mg vial | 3 mL | 0.3333 mg/mL |
What IGF-1 LR3 is
IGF-1 LR3 (Long [Arg3]-IGF-I) is a laboratory-made analog of human IGF-1: the IGF-1 chain with arginine in place of glutamate at position 3 and an extra 13 amino acid piece on the front end. It binds the body's IGF binding proteins only weakly. It was made as a research reagent and cell culture supplement, not as a medicine. [2]
Other names: Long R3 IGF-I, Long [Arg3]-IGF-I, LR3IGF-I, LongR3-IGF-I, LONG R3IGF-I.
How it has been given to people: no human use on record.
What to know before reading a dose
- No human study of IGF-1 LR3 was found. No human dose, half-life or safety data exist for it. Any dose quoted for it does not come from a human trial.
- IGF-1 LR3 is not mecasermin. Mecasermin (Increlex) has the same 70 amino acid sequence as natural human IGF-1 [12]. IGF-1 LR3 has an arginine swapped in at position 3 and a 13 amino acid extension [2], and it binds IGF binding proteins about 1000 times more weakly [4]. Mecasermin label doses must not be carried over to it.
- It was built as a laboratory reagent and cell culture supplement [1], [10]. It was never approved for use in humans [8].
- In animals it lowers blood sugar more strongly and for longer than IGF-I [5]. Mecasermin, the approved form of IGF-1, already carries a label warning for severe hypoglycemia [12].
- Animal results conflict between species: growth increased in rats [3], organs enlarged without overall growth in guinea pigs [7], and growth, growth hormone and the animal's own IGF-I all fell in pigs [6].
- In rats it leaves the blood faster than IGF-I, not slower [4], [8], and a 2026 review found no documented half-life [11]. Any half-life figure quoted for it is not from a human measurement.
- Black market products tested by anti-doping laboratories were of poor quality, and one vial held His-tagged laboratory material [8], [9].
What the evidence shows
Each finding is tagged by the kind of study it comes from. Human trials are listed first.
Animal study
In rats it is cleared from the blood much faster than IGF-I, because it does not stay attached to the binding proteins. [4]
Animal study
After an intramuscular injection in rats, intact LR3 was no longer detectable in blood after 4 hours, while two other IGF-I analogs were detected until 24 hours. [8]
Animal study
In growing female rats, a 14-day infusion under the skin increased weight gain and nitrogen retention; 44 mcg a day of LR3 matched 278 mcg a day of IGF-I. [3]
Animal study
In pigs, IGF-I variants including LR3 lowered blood sugar 2 to 3 times more strongly than IGF-I, and for much longer. [5]
Animal study
The low blood sugar lasted far longer than with IGF-I. [5]
Animal study
In pigs it did the opposite of what it did in rats: a 4-day infusion reduced daily weight gain and food intake and lowered the animals' own IGF-I, IGFBP-3 and insulin. [6]
Animal study
The same pig study found it suppressed the animals' own growth hormone release. [6]
Animal study
In guinea pigs a 7-day infusion enlarged the adrenals, gut, kidneys and spleen without increasing overall growth. [7]
Lab study
The analog was first described in 1992 as one of a set of IGF-I fusion proteins made in E. coli, which the authors presented as reagents for studying how IGF-I works. [1]
Lab study
In cells that release IGF binding proteins it was more potent than IGF-I, but in a cell line that releases none it was less potent than IGF-I. Its extra strength comes from escaping the binding proteins, not from a stronger action at the receptor. [1]
Lab study
IGF-I binds the binding proteins about 1000 times more tightly than LR3 does. [4]
Lab study
A paper from the company that supplies it for cell culture describes it as engineered for use in biopharmaceutical protein production in mammalian cells. [10]
Lab study
A French anti-doping laboratory found black market IGF-I analog products to be of poor quality, with oxidised forms of the peptide. [8]
Lab study
A black market injection vial analysed in Germany contained His-tagged Long R3 IGF-I, a form normally made for laboratory work; the authors judged it a by-product of biochemical studies, not something made for injection. [9]
Side effects and warnings
No side effect data from human studies was found for IGF-1 LR3. That is a gap in the research, not a sign that it is safe.
IGF-1 LR3 has no approved label in the US or Canada for this use, so there is no official list of who should not use it, no interaction list and no missed-dose rule.
Storage
Keep an unmixed vial the way its label says. Once it is mixed, keep it in the fridge, do not freeze it, and write the mixing date on the vial.
IGF-1 LR3 dosage questions
How many units is 40 mcg of IGF-1 LR3 from a 1 mg vial?
Mixed with 3 mL of bacteriostatic water, a 1 mg vial is 0.3333 mg/mL. 40 mcg is 0.12 mL, which is 12 units on a U-100 syringe.
How much water goes in a 1 mg IGF-1 LR3 vial?
3 mL gives 0.3333 mg/mL. At that strength the doses in the chart sit at 6, 12, 30 units on a U-100 syringe.
How many doses are in a 1 mg vial?
Whole doses in one vial: 50 at 20 mcg, 25 at 40 mcg, 10 at 100 mcg.
Is IGF-1 LR3 approved in the US?
Not FDA approved: Drugs@FDA holds no IGF-1 LR3 product, and the only IGF-1 products it lists are mecasermin products, which are a different molecule.
Is IGF-1 LR3 authorized in Canada?
No IGF-1 LR3 product is in Health Canada's Drug Product Database; the IGF-1 product it lists is Increlex (mecasermin, DIN 02509733), which is a different molecule.
What human dosing data is there for IGF-1 LR3?
No human study of IGF-1 LR3 was found. No human dose, half-life or safety data exist for it. Any dose quoted for it does not come from a human trial.
Sources
Each one was opened on 10 Oct 2026 and matched to the line it supports.
- Francis GL et al. Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency. J Mol Endocrinol 1992. PubMed 1378742.
- Laajoki LG et al. Secondary structure determination of 15N-labelled human Long-[Arg-3]-insulin-like growth factor 1 by multidimensional NMR spectroscopy. FEBS Lett 1997. PubMed 9450557.
- Tomas FM et al. Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats. J Endocrinol 1993. PubMed 8371075.
- Ballard FJ et al. Effects of interactions between IGFBPs and IGFs on the plasma clearance and in vivo biological activities of IGFs and IGF analogs. Growth Regul 1993. PubMed 7683526.
- Tomas FM et al. IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys. J Endocrinol 1997. PubMed 9415072.
- Dunaiski V et al. Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs. J Endocrinol 1997. PubMed 9488001.
- Conlon MA et al. Long R3 insulin-like growth factor-I (IGF-I) infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig. J Endocrinol 1995. PubMed 7561636.
- Mongongu C et al. Detection of LongR(3) -IGF-I, Des(1-3)-IGF-I, and R(3) -IGF-I using immunopurification and high resolution mass spectrometry for antidoping purposes. Drug Test Anal 2021. PubMed 33587816.
- Kohler M et al. Detection of His-tagged Long-R3-IGF-I in a black market product. Growth Horm IGF Res 2010. PubMed 20675162.
- Voorhamme D et al. LONG R3IGF-I as a more potent alternative to insulin in serum-free culture of HEK293 cells. Mol Biotechnol 2006. PubMed 17172665.
- Dominikowski A et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne) 2026. PubMed 42395176.
- INCRELEX (mecasermin) injection: US prescribing information (a different molecule, cited only for comparison) via openFDA and DailyMed 2026-05-18. api.fda.gov.
- ClinicalTrials.gov searches: IGF-1 LR3, IGF-I LR3, Long R3, LongR3, LR3 IGF (0 studies each) clinicaltrials.gov.
- Drugs@FDA lookups via openFDA: no record for LR3 or Long R3; mecasermin returns Increlex and Iplex only US Food and Drug Administration. api.fda.gov.
- Health Canada Drug Product Database: active ingredient search for mecasermin (1 record, INCRELEX); no record for IGF-1 LR3 Health Canada. health-products.canada.ca.
- The Prohibited List (2026 list as shown on the WADA website) World Anti-Doping Agency. wada-ama.org.
Looked for and not found
- Any human study of IGF-1 LR3. A PubMed search across its name variants (Long R3, LR3 IGF, LR3IGF, LongR3, Long Arg3, IGF-1 LR3) returned 175 records; the 55 indexed under Humans were checked by title and are cell culture, assay or doping-detection papers, not dosing studies.
- Any registered trial: five ClinicalTrials.gov searches returned 0 studies [13]. A search for LR3 alone returns acupuncture trials, because LR3 is also the name of an acupuncture point.
- A 2026 peer-reviewed review ([11], full text) reaches the same result, placing IGF-1 LR3 among compounds 'for which no peer-reviewed human studies exist at all'.
- Human dose, human half-life, human side effects: none on record.
- A half-life figure in any species: the abstracts read give clearance comparisons and detection times in rats, not a half-life.
- Any approved product or label anywhere, so no official contraindications, interaction list or storage instructions.
- A Health Canada advisory or FDA compounding entry naming IGF-1 LR3.
Change log
10 Oct 2026Page published. 16 sources checked. Vial math added for the 1 mg vial.
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