Name: IGF-1 LR3
Brand: PeptidesDirect
SKU: PD-IGF1LR3-1MG
Price: 74.99 EUR
Availability: InStock

Question 1

What is IGF-1 LR3?

Accepted Answer

IGF-1 LR3 (Long R3) is a modified 83-amino-acid analog of Insulin-like Growth Factor 1 with reduced IGFBP binding and an extended half-life of approximately 20 to 30 hours. It is the preferred IGF-1 variant for most research applications.

Question 2

How should I store IGF-1 LR3?

Accepted Answer

Store lyophilized IGF-1 LR3 at -20°C for long-term storage or 2-8°C for short-term use. After reconstitution with bacteriostatic water, keep refrigerated at 2-8°C and use within 14 days. Avoid repeated freeze-thaw cycles.

Question 3

What purity is your IGF-1 LR3?

Accepted Answer

Every batch of IGF-1 LR3 ships with a certificate of analysis from Janoshik Analytical, an independent third-party laboratory, at a minimum purity of 98%. We do not run a lab ourselves: the manufacturer commissions this test, and we pass the report on unchanged, with an online verification link on the product page.

Question 4

Why IGF-1 LR3 instead of native IGF-1?

Accepted Answer

Native IGF-1 has a very short half-life (~20 minutes) due to rapid binding by IGF-binding proteins. The LR3 modifications reduce this binding, providing 2 to 3 times higher bioactivity and a much longer half-life, making the peptide far more practical for research.

Question 5

What has IGF-1 LR3 actually been studied for, in terms of species and models?

Accepted Answer

IGF-1 LR3 has been studied almost entirely in animals and cell culture, not in people. Published work covers growth and the growth hormone/IGF axis in finisher pigs (PMID 9488001), intestinal epithelial proliferation in rats (PMID 8549937), whole body and organ growth in guinea pigs (PMID 7561636), and cell proliferation potency in rat lung fibroblasts (PMID 15204833) and rat ovarian theca interstitial cells (PMID 9096870). No published study has tested IGF-1 LR3 in humans.

Question 6

What dose did the IGF-1 LR3 studies use, and is there a published human dosing protocol?

Accepted Answer

In Dunaiski et al., finisher pigs received 0.18 mg/kg/day (180 micrograms/kg/day) by continuous infusion for 4 days (PMID 9488001). In Steeb et al., female rats received 2.5 mg/kg/day by continuous infusion for 3 days (PMID 8549937). That is what those studies administered to animals, not a treatment protocol for a person. No human dosing protocol has been published for IGF-1 LR3 itself; the only human dosing data in the IGF-1 receptor family belongs to a different, unmodified molecule, native recombinant IGF-1 (mecasermin), and it does not carry over to LR3.

Question 7

What did the IGF-1 LR3 studies actually observe, and how quickly did effects appear?

Accepted Answer

The results are mixed rather than uniformly positive, and they appeared within each study's short window of 3 to 7 days. In pigs, 4 days of IGF-1 LR3 decreased average daily weight gain and feed intake and lowered plasma growth hormone by about 23% (PMID 9488001). In rats, 3 days of IGF-1 LR3 increased intestinal wet weight by about 20% and crypt cell proliferation by up to 14% (PMID 8549937). In guinea pigs, 7 days of IGF-1 LR3 increased the fractional weight of specific organs (adrenals, gut, kidneys, spleen) but did not change whole body weight gain and lowered circulating IGF-I and IGF-II (PMID 7561636).

Question 8

What side effects or adverse events were reported in the IGF-1 LR3 studies?

Accepted Answer

None of the published studies used human style adverse event reporting; what exists is animal physiology data, not a safety profile. In pigs, IGF-1 LR3 suppressed the animals' own growth hormone (about 23% lower plasma GH, about 60% lower area under the GH peaks) and reduced plasma IGFBP-3, IGF-I and insulin, alongside decreased weight gain and feed intake (PMID 9488001). In guinea pigs, it raised the fractional weight of the adrenals, gut, kidneys and spleen while lowering circulating IGF-I, IGF-II and IGF binding protein (PMID 7561636). Because every one of these findings comes from animals, there is no human side effect data for IGF-1 LR3.

Question 9

Does IGF-1 LR3 carry a hypoglycemia risk, since IGF-1 can activate the insulin receptor?

Accepted Answer

No study has measured this for IGF-1 LR3 itself, but the closest related molecule with human data, native recombinant IGF-1 (mecasermin, FDA approved as Increlex), documented hypoglycemia in 30 of 71 subjects (42%) at least once during treatment, including 5 subjects with severe hypoglycemia and 4 with hypoglycemic seizures or loss of consciousness, which is why its label requires dosing around meals and glucose monitoring (INCRELEX FDA label, DailyMed). This happens because IGF-1 cross reacts with the insulin receptor at sufficient exposure. IGF-1 LR3 is engineered to stay active in circulation far longer than native IGF-1, so the same insulin receptor cross reactivity is a reasonable mechanistic concern, but it has not been directly studied or quantified for LR3 itself.

Question 10

What is not known about IGF-1 LR3's long term safety?

Accepted Answer

There is no published human clinical trial of IGF-1 LR3, so there is no long term human safety data, no data on chronic or repeated dosing, and no data on interactions with other substances in people. Every study that exists is short term animal or cell culture work (3 to 7 days), and in two of the five studies the compound reduced growth markers rather than enhancing them (PMID 9488001, PMID 7561636). Sustained activation of the IGF-1 receptor also carries a well documented, general proliferative and oncogenic concern in the cancer literature (PMID 36017326), a concern none of the short LR3 studies were designed to test. Animal-only evidence plus an unstudied long term signaling risk is the honest state of the science here.

Question 11

Is IGF-1 LR3 approved by the FDA, EMA, or any regulator?

Accepted Answer

No. IGF-1 LR3 has no marketing authorization from the FDA, EMA or any other medicines regulator anywhere, and it is sold and used strictly as a research reagent, not a medicine. A related but different, unmodified molecule, native recombinant IGF-1 (mecasermin), is FDA approved under the brand Increlex for one narrow pediatric indication, severe primary IGF-1 deficiency, but that approval does not extend to the LR3 analog. No regulator has evaluated IGF-1 LR3 for safety or efficacy in humans.

Question 12

Is IGF-1 LR3 banned by WADA or other anti doping bodies?

Accepted Answer

Yes. IGF-1 and its analogs LongR3-IGF-I, Des(1-3)-IGF-I and R3-IGF-I are listed as prohibited substances in sport, and a 2021 anti doping detection paper notes they are never approved for human use yet are sold on the black market for bodybuilding (PMID 33587816). The WADA Prohibited List bans exogenous IGF-1, in the peptide hormones and growth factors category, at all times, both in competition and out of competition. Anyone subject to WADA, USADA or a similar code should treat IGF-1 LR3 as banned.

Question 13

How much bacteriostatic water should be used to reconstitute IGF-1 LR3, and does the ratio matter?

Accepted Answer

A common ratio for a 1 mg vial is 1 mL of bacteriostatic water for a 1 mg/mL solution, or 2 mL for 0.5 mg/mL; the ratio is a concentration choice, not a chemical requirement, and by itself it does not change how long the peptide stays intact. What actually determines stability after reconstitution is temperature and time, which is why the existing storage guidance (2-8°C, use within 14 days, avoid repeated freeze-thaw) applies regardless of dilution. Bacteriostatic water, not plain sterile water, is the standard choice for a multi use vial because its benzyl alcohol preservative is what allows the vial to be kept beyond a single draw.

Question 14

What does your own third party CoA show for IGF-1 LR3, and how can a specific batch be verified?

Accepted Answer

Our current 1 mg IGF-1 LR3 batch, labeled Black Cap, was tested by Janoshik Analytical on 25 November 2025 and reports 99.5% purity and 1.19 mg content for the 1 mg labeled vial, with identity and purity confirmed; this particular report does not cover microbial, endotoxin or heavy metal testing. That test was commissioned by the manufacturer, not by us: we do not operate our own laboratory and do not independently verify these certificates ourselves. Anyone can check this exact result at verify.janoshik.com using the batch's test ID (89869-IGF_LR3_1mg_LB7H22VJ8JAD), the same link published on the product page.

Question 15

How does IGF-1 LR3 compare to native recombinant IGF-1 (mecasermin) in evidence and approval?

Accepted Answer

Mecasermin is the unmodified molecule, FDA approved as Increlex for severe primary IGF-1 deficiency in children, and it has real human trial data, including a 42% hypoglycemia rate (30 of 71 subjects) in its clinical program (INCRELEX FDA label, DailyMed). IGF-1 LR3 is a different, engineered molecule, with an Arg substitution at position 3 and an N-terminal extension that make it escape IGF binding proteins, giving it a longer active half life and roughly 2 to 3 times more potency in cell culture assays (PMID 15204833), but it has never been tested in a human trial. The two get confused because both are called IGF-1, but only mecasermin carries any regulatory approval or human safety data, and none of that data transfers to LR3.

Question 16

Is IGF-1 LR3 the same thing as MGF (mechano growth factor)?

Accepted Answer

No, they are different molecules with different origins. IGF-1 LR3 is a synthetic analog of the mature IGF-1 peptide, engineered with an Arg substitution at position 3 and a 13 residue N-terminal extension to reduce IGF binding protein affinity. MGF, also called IGF-1Ec, is instead a naturally occurring, alternatively spliced isoform of the IGF-1 gene that carries its own distinct C-terminal E-peptide domain, not present in mature IGF-1 or in LR3 (PMID 24146828). They are often confused because both get described as IGF-1 variants, but one is a lab made analog and the other is a naturally occurring gene product.

Question 17

Is IGF-1 LR3 the same as Des(1-3)-IGF-I, or are these different analogs?

Accepted Answer

They are different but related engineered analogs, both designed to reduce binding to IGF binding proteins so more IGF-1 activity stays free in circulation. Des(1-3)-IGF-I removes the first three N-terminal amino acids of native IGF-1, while IGF-1 LR3 instead substitutes an Arg for Glu at position 3 and adds a 13 residue N-terminal extension, a different structural change aimed at the same functional goal. A 1997 study comparing both directly in rat ovarian theca interstitial cells found that both analogs produced greater DNA synthesis stimulation than native IGF-I, with no meaningful difference reported between the two analogs themselves (PMID 9096870). Neither analog has published human trial data.

Question 18

Would IGF-1 LR3 show up on a standard drug test?

Accepted Answer

No. Routine workplace or medical urine and blood panels do not screen for IGF-1 or its analogs at all. Detecting LongR3-IGF-I, Des(1-3)-IGF-I or R3-IGF-I requires specialized anti doping methods, immunopurification followed by high resolution mass spectrometry, the kind of testing only WADA accredited sports laboratories run (PMID 33587816). Outside of competitive sports anti doping testing, there is no realistic chance of a standard drug test detecting it.

Question 19

Does IGF-1 LR3 raise cancer or tumor growth risk, since elevated IGF-1 is linked to cancer in epidemiological research?

Accepted Answer

Epidemiological research does associate higher circulating IGF-1 with increased risk across several cancer types, and IGF-1 receptor signaling is a well documented driver of cell proliferation, migration and metastasis in the cancer literature (PMID 36017326). IGF-1 LR3 adds a real mechanistic reason for extra caution: it is engineered to escape IGF binding proteins, so more IGF-1 receptor activity stays available in circulation than with native IGF-1. That said, no published study has tested whether IGF-1 LR3 itself increases tumor growth or cancer risk. This is a theoretical, mechanism based concern extrapolated from the broader IGF-1 literature, not a direct finding about this analog.

Question 20

Should IGF-1 LR3 be reconstituted with plain bacteriostatic water, or does it need an acidified diluent to stay in solution?

Accepted Answer

For the concentrations and short term use covered in our standard reconstitution guidance, bacteriostatic water is the right choice, exactly as our existing storage answer describes. IGF-1 LR3 does have a known tendency toward limited solubility and aggregation in near neutral aqueous solution, more so than most peptides in our catalogue, which is why manufacturer and research documentation for this specific analog often specifies a dilute acidified diluent, commonly a small amount of acetic acid, as the standard alternative when keeping it fully in solution for in-vitro use is a concern. This is reconstitution chemistry for a research sample, not a dosing instruction.

Question 21

How should unopened, lyophilized IGF-1 LR3 be stored, and how long does it stay stable once reconstituted?

Accepted Answer

Unopened, lyophilized IGF-1 LR3 is stable for the long term when kept frozen and protected from light and moisture, and like other lyophilized peptides in our catalogue, it tolerates brief periods at cooler ambient temperature during shipping without meaningful loss. Once reconstituted, keep the vial refrigerated at 2-8°C, protect it from light, and use it within about 14 days, avoiding repeated freeze-thaw cycles, which degrades the peptide, the same reconstituted-solution window we already give for this product. This is sample-handling guidance for a research reagent, not instructions for use in a person.

Question 22

Is it legal to buy and hold IGF-1 LR3 as a research chemical in Germany or the EU?

Accepted Answer

IGF-1 LR3 has no approval as a medicine, supplement or food product anywhere in the EU: we sell it strictly as an unlabeled research chemical for in-vitro laboratory use, not for human or animal use. Import, possession and research-chemical rules differ by EU member state and can change, and we cannot give country specific legal advice. Buyers are responsible for checking their own country's rules before ordering. Our terms (AGB) set out the research-use-only basis of every sale. Where the legal status in a specific country is unclear, a local customs authority or legal advisor is the right source, not a vendor FAQ.

Question 23

Is adding IGF-1 LR3 to CJC-1295 or Ipamorelin known to be redundant, or has no combination study tested that?

Accepted Answer

No published study has tested IGF-1 LR3 combined with CJC-1295 or Ipamorelin: the three have only ever been studied separately, never together. The research-market habit of stacking them rests on two different signaling pathways, not any tested protocol. CJC-1295 and Ipamorelin act upstream, prompting the body's own growth hormone release, while IGF-1 LR3 acts downstream, engaging the IGF-1 receptor directly (PMID 15204833). Pairing two separately studied pathways is not the same as a studied combination, and no data exists on how the three interact together, in any model.

Question 24

Does IGF-1 LR3 actually work for muscle growth, or is it overhyped?

Accepted Answer

There is no published human study of IGF-1 LR3, so no research-based expectation for muscle gain, timeline, or before/after result in a person can be given here. This is research use only, not medical advice. What the published research shows is signaling activity in cell and tissue models over short windows: increased crypt cell proliferation and intestinal growth within 3 days in rats (PMID 8549937), and about 2 to 3 times greater potency than native IGF-I in stimulating DNA synthesis in cultured rat cells (PMID 15204833). Neither result translates into a human amount or timeline. See our /research/igf-1-lr3 page and the original PubMed papers for the full picture.

Question 25

Where should I keep the vial before I reconstitute it?

Accepted Answer

In the fridge, from the day it arrives. This is the step people skip most often, because a sealed freeze-dried vial looks robust enough to leave in a drawer. The dry cake in these GHRH-family vials is thin and porous, and warmth combined with humidity makes it slump and densify. A collapsed cake then dissolves slowly or incompletely and can leave a haze or floating particles when you finally add water, even when the powder itself still assays perfectly. So put the vial in the fridge at 2 to 8 degrees Celsius on the day the parcel arrives, or in the freezer at -20 degrees if it will sit unused for more than a couple of weeks, and keep it dark either way. Let it come back to room temperature before you add water. Once reconstituted it stays in the fridge and never goes into the freezer, because freeze-thaw cycles are harder on a dissolved peptide than steady cold. The few days in transit at ambient temperature are expected and fine; it is the weeks afterwards that decide how well it dissolves.

Question 26

Does the bacteriostatic water I use actually matter?

Accepted Answer

More than most people expect, and the reason is the specification rather than the brand. Bacteriostatic water is permitted a wide window: the USP range is pH 4.5 to 7.0, so two bottles that both say 0.9% benzyl alcohol can sit at opposite ends of it. Most labels state the benzyl alcohol and nothing else, so you cannot tell where yours sits. That matters because a peptide is least soluble near its own isoelectric point, and a water that drifts to one edge of the range can push a sensitive peptide toward it, which shows up as haze or particles that no amount of swirling fixes. We know this first-hand: one of our own past water batches measured pH 3.8 on a meter, below the permitted floor, and it turned GLP-1 peptides milky regardless of technique. Our own bacteriostatic water now comes from a European manufacturer whose batches run pH 6.2 to 6.4, with the measured value for the specific batch stated on its certificate rather than just a pass mark. Whichever water you use, take a freshly opened vial, keep it at room temperature and out of the light, and do not reuse a bottle that has been open for months.

Question 27

Does unrefrigerated shipping affect the quality of this product?

Accepted Answer

No. This product ships as a lyophilized (freeze-dried) powder in a sealed vial. Freeze-drying removes the water that drives peptide degradation, so the dry powder remains stable at room temperature for extended periods, longer than any normal parcel transit. Ambient shipping is standard practice across the peptide industry, and a peer-reviewed study reported months of room-temperature stability for a lyophilized therapeutic peptide (teriparatide, PMID 26620825). For comparison, FDA labeling allows an Ozempic (semaglutide) pen, after first use, to be kept out of the fridge for 56 days at 15 to 30°C, and a Mounjaro (tirzepatide) pen for up to 21 days at up to 30°C, even though these are ready-mixed solutions rather than sealed dry powder. Store the sealed vial in the fridge or freezer for long-term storage, and always refrigerate after reconstitution.

Question 28

Why might IGF-1 LR3 sting, itch, or cause a lump or welt at the injection site?

Accepted Answer

No published study, human or animal, has measured injection-site reactions for IGF-1 LR3 itself, so there is no direct answer, only two documented neighbours. First, the approved unmodified relative: the Increlex (mecasermin, recombinant human IGF-1) label documents lipohypertrophy at the injection site in at least 5 percent of trial subjects and, post-marketing, local allergic reactions including pruritus and urticaria. Mecasermin is a different, unmodified molecule, so none of that transfers to IGF-1 LR3; it shows what documented local-reaction data look like for an IGF-1 class molecule. Second, formulation physics: the general literature ties injection pain to pH and osmolality outside the physiological range, concentration and preservatives (PMID 31587143); a controlled human comparison found pH 10 protein solution significantly more painful than pH 7.4 (PMID 22568666), and a randomized trial found buffer choice alone changed injection pain for a growth-hormone formulation (PMID 16445598). IGF-1 LR3 is relevant here because it has documented limited solubility near neutral pH, which is why manufacturer datasheets specify acidified diluents, and bacteriostatic water is permitted anywhere in the pH 4.5 to 7.0 window. A causal link between any of this and stinging for IGF-1 LR3 specifically is plausible, not proven. No human protocol exists; laboratory research use only.

Question 29

Do compounds like enclomiphene, GHK-Cu, or berberine lower IGF-1 and work against a GH-axis or IGF-1 LR3 stack?

Accepted Answer

No study has tested any of the three alongside a GH secretagogue or IGF-1 LR3, so the stack-interference question itself is unstudied; what exists is single-compound data of very mixed quality. The strongest signal is for the clomiphene family: in 20 hypogonadal men on clomiphene citrate (the racemic drug of which enclomiphene is one isomer), 75 percent showed a decrease in serum IGF-1 over about 14 months, with a proposed estrogen-mediated mechanism (SOCS-3 inhibition of GH signalling; PMID 40421427); no study tests isolated enclomiphene on IGF-1. For GHK-Cu, no study shows it lowers circulating IGF-1 in any species; its documented in-vitro skin biology runs through local growth-factor signalling and says nothing about serum IGF-1. For berberine, the human data point is oblique: a trial of barberry juice (a whole-fruit preparation, not the isolated supplement) in 85 women reported IGF-1 effects (PMID 31752829), while a rat exercise study found berberine INCREASED muscle IGF-1 expression, so even the direction is inconsistent across models. Separately worth knowing: IGF-1 LR3 itself suppresses the body's own GH secretion in animal studies (about 23 percent lower in continuously infused pigs, PMID 9488001), a documented negative feedback that community stack-logic usually ignores. Net: one plausible IGF-1-lowering candidate (clomiphene-class), indirect and mixed evidence for berberine (a whole-fruit human trial reporting an IGF-1 reduction versus a rat study showing the opposite), none for GHK-Cu, and zero data on any actual combination.

Question 30

Does injecting IGF-1 LR3 into one muscle grow only that muscle, or does it act systemically throughout the body?

Accepted Answer

A frequently cited source, and the likely origin of the idea, is a study that did not inject the peptide at all: the localized-growth result (Barton-Davis 1998, PMID 9861016) used a viral gene-transfer vector producing sustained IGF-1 inside mouse muscle, a completely different delivery than a bolus peptide injection. For injected peptides, the documented physiology points systemic: subcutaneously injected native IGF-1 in humans produces measurable systemic blood levels with defined pharmacokinetics (PMID 7752586); subcutaneously injected proteins of similar size reach circulation in substantial fractions via capillaries and lymphatics; the IGF-1 receptor is expressed across essentially all tissues (review, PMID 39638246); and IGF-1 LR3's reduced binding-protein affinity is documented at the receptor level (rat ovarian-cell work, PMID 9096870); systemic action for injected LR3 is therefore an inference from analog pharmacology and general mechanisms, and its actual injection-site distribution has never been measured. The three published IGF-1 LR3 animal studies all used continuous systemic infusion, none tested single-muscle injection against a distant muscle, and no human study of IGF-1 LR3 exists by any route. So the honest answer: never tested directly for this molecule, but every documented mechanism predicts systemic action, and the community practice of injecting bilaterally into a trained muscle has no published support. All of the above is study-register information about animal and mechanistic research; no human protocol exists.

IGF-1 LR3

What is IGF-1 LR3

How it works

Often studied alongside

Documentation

Storage and stability

Reviews

Frequently Asked Questions

Technical data sheet

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