The short version

Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.

What GHRP-2 is

A synthetic hexapeptide — six residues, C-terminally amidated — whose proper name is pralmorelin. We do not sell it; this is a reference entry.

Identity taken from FDA's Global Substance Registration System — a federal substance registry rather than a vendor catalogue. FDA publishes the formula but not the molecular weight, so the 817.99 figure is ours, computed with standard atomic weights: (45 × 12.011) + (55 × 1.008) + (9 × 14.007) + (6 × 15.999).

Telling the three GHRPs apart

This library also carries GHRP-6 and Hexarelin as reference entries. They share a scaffold — GHRP-6 is the parent, hexarelin is GHRP-6 with a methyl added at position 2, and GHRP-2 swaps the opening pair entirely. One 1997 paper calls GHRP-2 and hexarelin “synthetic, non-natural super-analogs of GHRP-6.”

The cleanest discriminator is the nitrogen count. GHRP-2 has nine; the other two have twelve, because GHRP-2 alone lacks the histidine imidazole and the second tryptophan indole. Any formula claiming to be GHRP-2 with twelve nitrogens is not GHRP-2.

Two naming traps that cost real time. GHRP-6's registry name is “Hexapeptide-2,” a cosmetic-ingredient designation — so a database search for “GHRP-6” can return nothing while the substance is fully registered. And hexarelin appears on the anti-doping list only as “examorelin.” A page concluding hexarelin is unlisted because it could not find “hexarelin” has made an avoidable error.

What the salt costs, and why it costs more here

The licensed Japanese product is the hydrochloride. Research-market material is normally an acetate or trifluoroacetate salt — the counterions left behind by reverse-phase purification. GHRP-2 has two basic sites, so 1:1 and 2:1 are both plausible. House arithmetic:

The approved-drug fact

This is the most interesting thing about GHRP-2 and almost nobody selling it mentions it — which is understandable, because it cuts against them.

Pralmorelin hydrochloride is a licensed prescription medicine in Japan. It is marketed by Kaken Pharmaceutical as GHRP Kaken 100 for Injection. Here is the licensed product, from its own package insert:

On the approval date specifically: the records give a February 2005 sales start and an authorisation number whose leading digits would place the authorisation in 2004. We could not find a document stating the approval date explicitly — the manufacturer's interview form, which would settle it, returns a 404. So this page says marketed from February 2005 and does not print a bare approval date.

The arithmetic that follows, and it is not close

So the honest headline is not “unapproved research chemical.” It is that a real drug, approved for a one-hour hospital test, is being taken daily at up to three times the entire licensed dose per day — on the strength of an approval for something else entirely. Approval for a diagnostic is not evidence about repeated dosing. The gap is two orders of magnitude in cumulative dose and five hundredfold in concentration.

And the corollary cuts the same way. The one-hour diagnostic safety record describes sixty minutes after one injection — and it gets cited as though it established that daily use is safe. It cannot do that.

The near-miss, which is the kind of thing this library exists to find

In January 2021 a university regulatory-science centre produced a summary report “Prepared for: Food and Drug Administration,” supporting FDA's evaluation of GHRP-2. It concluded, verbatim:

Both halves have to be said. The report is not wrong: its finding is scoped to the nominated dosage forms, and the nomination was for oral tablets, capsules, aqueous solutions, inhaled aerosols and an injectable solution — so a 100 µg intravenous diagnostic genuinely is not the nominated product.

And the omission still matters. The public conversation about GHRP-2 runs on “no regulator anywhere has approved this” — and an FDA-commissioned report searched twelve foreign registries without searching the one country that holds an approved pralmorelin product.

How it works, stated exactly

GHRP-2 is a ghrelin receptor agonist. It is not a GHRH analogue, and the distinction is routinely blurred in marketing even though it decides what else the compound does.

Regulators keep them apart too. The anti-doping list has “GHRH and analogues” and “GH-Releasing Peptides” as separate example groups in the same subsection, and FDA has GHRP-2 and GHRP-6 on its do-not-compound list while CJC-1295 and sermorelin are not.

Worth noting what the licensed label itself says: the mechanism is “an action mediated principally via the hypothalamus.” Even the licence holder does not describe this as a straightforward direct effect on the pituitary.

Combining it with a GHRH analogue — the good argument, and the missing half

The combination is how this class is usually sold, and there is a real quantified human result behind it. In a 1996 dose-response study, hexarelin plus a GHRH fragment produced “massive GH release (115 ± 32.8 mU/L), a moderate rise in serum PRL (84.9 ± 27.5%), and no rise in serum cortisol” — against a hexarelin-alone plateau of 140 mU/L.

“It releases growth hormone” is an observation, not an outcome

The GH release is real and should not be undersold — one crossover study measured a 13.5-fold increase in GH area-under-curve over saline. But a GH pulse measures the drug acting on the pituitary, not anything happening to the person. Four unbridged steps sit between that pulse and any claim made for it:

The honest sentence: the pulse is real, well measured and reproducible. Every step after it is either unmeasured, or has been measured and did not go the way the marketing says.

The human evidence

Unlike most of this library, real human data exists — including regulator-accepted pharmacokinetics. The point of this section is precision about what was measured, and the answer is almost always hormone concentrations.

Pharmacokinetics, from the licensed label

Appetite — the best-controlled human GHRP-2 study, and what it found

Seven lean healthy men, crossover, infused with GHRP-2 or saline for 270 minutes and then given an ad libitum buffet meal. Verbatim from the paper:

And hunger is a labelled adverse reaction of the licensed product, listed after a single 100 µg diagnostic dose. The orexigenic effect is fast enough and strong enough to show up after one injection in a hospital.

For a compound bought to change body composition, a 34–36% increase in food intake is plausibly the dominant determinant of what actually happens to the user's weight — in the opposite direction to the one intended. This is not a side effect. It is what a ghrelin mimetic is.

The five-day study, which used exactly the licensed dose

Nine healthy young men, 100 µg subcutaneously every day for five days — the entire licensed adult dose, repeated. Peak GH ran 83, 59 and 51 µg/L on days 1, 3 and 5.

Be fair to the compound: the authors note GH release was “maintained,” and osteocalcin — a downstream marker of GH activity in tissue — did move. The attenuation is significant, not total. But the study's own title says it: a five-day course “causes response attenuation and does not stimulate insulin-like growth factor-I secretion.”

The rest of the adult evidence, and what it is

• GH release versus GHRH. A 1997 study of twelve people found the GH response to 2 µg/kg intravenous GHRP-2 “higher (p < 0.05) than that to GHRH.” The direction is established. The abstract carries no individual hormone values and we did not open the full text, so we are not printing numbers for it.
• Critical illness. Fourteen patients ill for around forty days, given GHRP-2 plus a second hormone by continuous infusion for five days against placebo. The best-designed GHRP-2 study that exists — randomised, placebo-controlled, crossover — and it measured biochemical markers. Its own claim is “metabolic effectiveness,” not clinical benefit: no survival, ventilator-day, muscle-mass or functional endpoint. It cannot separate the two agents, and its population — people whose GH axis was suppressed — is the furthest imaginable from a healthy adult.
• The IGF-1 study everyone cites. Fourteen hypogonadal men, IGF-1 up 49.8%. It is a retrospective chart review, not randomised, with no control group, of men taking three peptides at once — so it cannot attribute anything to GHRP-2. The authors' own listed limitations include that it “lack[ed] anthropomorphic data, lacked direct GH measurement, and did not evaluate metabolic endpoints.” The GHRP-2 dose alone was 300 µg/day, three times the licensed dose, for a mean of 134 days.
• Children. The longest human exposures on record — 18 to 24 months — are in small groups of children who were growth-hormone-deficient or short, measuring linear growth in open epiphyses, an endpoint an adult does not have. We reached these through secondary accounts only. They are frequently gestured at as “long-term human data” and they are not evidence about adults.

The class problems

These apply to GHRP-6 and hexarelin as well as to GHRP-2, and one of them is the most repeated unsourced claim in the category.

Cortisol and prolactin — and a ranking nobody can source

All three compounds raise prolactin and activate the corticotroph axis to some degree. A 2026 review describes GHRP-2 and GHRP-6 as producing “transient increases in cortisol and prolactin” and hexarelin as activating “the corticotropic axis, leading to increases in ACTH and cortisol levels.”

What we can source has a number on it, and it is not what people expect. The 1996 hexarelin dose-response study found a GH ED₅₀ of 0.48 µg/kg and a prolactin ED₅₀ of 0.39 µg/kg.

House arithmetic: the prolactin curve is left-shifted relative to the GH curve — ratio 0.81. That destroys the standard harm-reduction advice, “use a low enough dose to get GH without prolactin.” On these data, for hexarelin, there is no dose window below which prolactin is spared and GH is not, and if anything the reverse. Cortisol behaves differently, stepping to about 40% at 0.5 µg/kg — more like a threshold than a curve.

Desensitisation — the best-evidenced problem in the class

The five-day GHRP-2 study above lost 46.7% of its GH response in four days. A 16-week hexarelin study lost 45.0% — and then recovered to 101.6% of baseline four weeks after stopping. Its authors' words: “a partial and reversible attenuation.”

Reversible is the operative word and it belongs on the page as a point in the compound's favour. The same study also found that over twenty weeks “serum IGF-I and IGF binding protein-3 did not change significantly.”

Glucose

Three independent sources converge, which is unusual in this catalogue. A peer-reviewed review notes “some concern for increases in blood glucose due to decreases in insulin sensitivity”; FDA's GHRP-6 listing names the same thing as a listing reason; and FDA's GHRP-2 listing names “increased insulin requirement to maintain the blood glucose level” among reported serious adverse events. The best-corroborated metabolic concern in the class.

IGF-1, and why it cuts both ways

Reconstitution

A microgram-scale compound packaged at milligram scale, and the arithmetic runs the opposite way to the intuition.

House arithmetic. 10 mg vial, U-100 syringe, 1 unit = 0.01 mL.

The right-hand column treats half a unit as the smallest reliably readable increment, which is generous — most U-100 barrels are graduated in whole units.

What the 28-day clock costs here

House arithmetic. Under our 28-day in-use convention, a 10 mg vial used at 100 µg/day delivers 2.8 mg and discards 7.2 mg — 72% of the vial. At 300 µg/day it delivers 8.4 mg and discards 16%.

For a microgram-scale compound in a milligram-scale vial, the calendar rather than the protocol decides how much of the vial is ever used. That is our 28-day rule argument in its most extreme form anywhere in this library.

Storage

The licensed product is stored “avoid freezing, store at 10 °C or below,” with a three-year shelf life unreconstituted. After reconstitution its instruction is one line, and it is worth quoting rather than summarising:

Our house convention is 28 days reconstituted at 2–8 °C in bacteriostatic water, and we publish that it is a convention — “a handling convention that has become repeated as though it were data.” We found no published stability study of reconstituted GHRP-2 in any diluent at any temperature.

The two positions are not in conflict once both are stated plainly, and we are not going to pretend either settles the other. The licensed product is saline, preservative-free and intravenous, so “use immediately” is at least as much a microbiological instruction as a chemical-stability one. Bacteriostatic water contains benzyl alcohol, which is what the 28-day convention is built around. The Japanese label neither supports nor contradicts our 28 days — it is a different formulation by a different route.

Reported effects

There is a labelled adverse-reaction list here, which is more than almost anything else in this catalogue has — and it describes a single dose.

From the licensed label, after one 100 µg injection

Two things on that list belong on the page. Hunger appears after a single diagnostic dose — the orexigenic effect is that fast. And 16% report a sensation of heat, a marked acute subjective effect that is very likely part of why the compound is perceived to be working.

What FDA says, quoted in full including the part that helps the compound

Two honest caveats we owe you. FDA's entry cites nothing for those adverse events, and we could not trace them. The critical-illness literature is the plausible origin, but that is a hypothesis and we are not going to assert it. And the “causality has not been established” clause is FDA's own — omitting it would be exactly the selective quoting these pages exist to correct.

What has been found in products

One published analytical finding exists, and it is not about a research vial: a 2010 paper identified and quantified GHRP-2 at about 50 µg per tablet in a product sold over the counter as a nutritional supplement. A prohibited peptide in something that did not declare it.

We found no published analytical survey of GHRP-2 vials sold as research chemicals, no case report of harm from self-administration, and no poison-centre dataset covering GHRPs — searches named in our references note. Absence of harm reports for a compound almost nobody reports on is not evidence of safety, and we would rather say that plainly than let an empty search look like a clean bill of health.

Regulatory status

This is why this compound was next in the queue. GHRP-2 is on FDA's Category 2 list — and almost every other page in this library correctly says its compound is not.

Category 2 held fourteen substances when we read it: cesium chloride, chloral hydrate, diethylstilbestrol, domperidone, edetate disodium, germanium sesquioxide, GHRP-2, GHRP-6, ibutamoren mesylate, ipamorelin acetate, kisspeptin-10, neomycin sulfate, quinacrine hydrochloride and tranilast.

Six things to get right about that listing

• It is 503B only, not 503A. Some entries on that list are flagged for both; GHRP-2 is not. Saying “banned from compounding” without the qualifier overstates it.
• It is route-scoped — “for injectable and nasal routes of administration.”
• The reasons are process reasons first. Immunogenicity and characterisation difficulty are statements about manufacturing and analysis, not about pharmacology.
• FDA disclaims causality on the adverse events, and the disclaimer is part of the quote.
• The adverse events are unsourced in the entry, and we did not trace them.
• It is not a Canadian legal statement. FDA's compounding lists govern US compounding pharmacies.

Also worth recording: GHRP-2 and GHRP-6 were not among the seven peptides heard at FDA's July 2026 compounding advisory committee — that meeting covered BPC-157, KPV, TB-500, MOTS-c, DSIP, Semax and Epitalon. Both GHRP entries stand unchanged.

Canada — two advisories, two different answers

We checked both rather than assuming either. And the general rules in the April 2026 advisory reach this compound regardless of whether it is named: “In Canada, peptides are generally regulated as prescription drugs”, and on research-use-only labelling, “This type of labelling does not make these products legal or exempt from regulatory requirements.”

The Alberta one is close to home. Our own provincial medical regulator has named this compound to every physician in the province, telling them to “ask patients about the use of non-prescribed injectable products” bought online. We are in Medicine Hat.

Sport

GHRP-2 is prohibited at all times, in and out of competition, under the peptide hormones class — listed by name, with its INN in brackets, in the growth-hormone-releasing peptides group. GHRP-6 and hexarelin sit on the same line, hexarelin appearing only as examorelin.

The detail usually left out of vendor copy: everything in that class is a non-Specified substance, which attracts the standard sanction and puts a heavier burden on the athlete to reduce it. We read the list through a national anti-doping organisation's verbatim reproduction; the official file did not open for us.

Sentient Biogenix does not sell GHRP-2.

Questions we actually get

Is GHRP-2 an approved drug?

In Japan, yes — as a diagnostic. One 100 µg vial in 10 mL of saline, slow intravenous injection, five blood draws over an hour, to test whether someone is growth hormone deficient. That is the whole approved use. It is not an approval for repeated dosing, and a 10 mg vial holds a hundred of those doses.

Is it a GHRH analogue like sermorelin or CJC-1295?

No, and this is the single most-blurred fact about it. Those act at the GHRH receptor. GHRP-2 acts at the ghrelin receptor — it is a ghrelin mimetic, which is why it moves appetite and touches cortisol and prolactin in a way GHRH analogues do not.

Does it raise growth hormone?

Yes, clearly and reproducibly — a 13.5-fold rise in one crossover study. What that does not tell you is whether anything happens to the person. Half-life is under 45 minutes, the response falls by nearly half within five days of daily dosing, and IGF-1 stayed flat on every subcutaneous or repeated-bolus regimen ever tested.

Will it make me hungry?

Almost certainly. Seven of seven subjects in the best-controlled study ate more — about 36% more at a buffet meal. Hunger is a labelled adverse reaction after a single diagnostic dose. For anyone taking it to change body composition, that is likely the dominant effect and it points the wrong way.

Is GHRP-2 cleaner than GHRP-6 or hexarelin for cortisol and prolactin?

We could not find the study. All three raise both; the ranking that everyone repeats traces to vendor comparison pages, not to a head-to-head human comparison. And the one dose-response study with real numbers found, for hexarelin, that the prolactin curve sits below the GH curve — so there is no low-dose window that spares prolactin.

How much water should I use?

More than feels convenient. A 100 µg dose from a 10 mg vial in 1 mL is one unit on an insulin syringe, where no useful precision exists. Five millilitres puts it at five units. For reference, the licensed product is given at 10 µg/mL — that same vial in 2 mL is five hundred times more concentrated.

Is it on FDA's do-not-compound list?

Yes. Unusually for this library, this one really is on Category 2 — added 29 September 2023, for injectable and nasal routes, under the 503B pathway. That is a different list from the “nominated but withdrawn” one where most of our catalogue sits, and the difference matters: one is FDA's judgement, the other is somebody withdrawing a form.

Why is it in your library if you do not sell it?

Because people ask about it, and because the most interesting thing about it — that it is an approved diagnostic being used as a daily performance drug — is not something anyone selling it has an incentive to explain.

References

1. Japanese package insert for pralmorelin hydrochloride injection (GHRP Kaken 100), JAPIC 00050479, revision of July 2022 — read via KEGG MEDICUS and the JAPIC product record, cross-read against a Japanese prescribing reference. Indication, dose, procedure, pharmacokinetics, adverse reactions, storage and the “use as promptly as possible” instruction all come from here.
2. University of Maryland Center of Excellence in Regulatory Science and Innovation. Summary report: growth hormone-releasing peptide-2, January 2021, prepared for the Food and Drug Administration — the twelve searched registries, and the prescriber interviews.
3. US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks — content current 22 April 2026. fda.gov — both tables read directly. GHRP-2 and GHRP-6 in Category 2; hexarelin on neither.
4. Nijland EA, Strasburger CJ, Popp-Snijders C, van der Wal PS, van der Veen EA. A five day treatment with daily subcutaneous injections of growth hormone-releasing peptide-2 causes response attenuation and does not stimulate insulin-like growth factor-I secretion in healthy young men. European Journal of Endocrinology 1998;139(4):395–401. DOI 10.1530/eje.0.1390395 — the five-day study, at exactly the licensed dose.
5. Jaffe CA, Ho PJ, Demott-Friberg R, Bowers CY, Barkan AL. Effects of a prolonged growth hormone (GH)-releasing peptide infusion on pulsatile GH secretion in normal men. Journal of Clinical Endocrinology and Metabolism 1993;77(6):1641–1647. DOI 10.1210/jcem.77.6.7903313 — GHRP-6, 34 hours of continuous intravenous infusion, and the one regimen in which IGF-1 did rise. Added 4 September 2026, correcting an earlier version of this page that said IGF-1 had not risen in any prospective study.
6. Laferrère B, Abraham C, Russell CD, Bowers CY. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. Journal of Clinical Endocrinology and Metabolism 2005;90(2):611–614. PMID 15699539 — the appetite crossover.
7. Massoud AF, Hindmarsh PC, Brook CG. Hexarelin-induced growth hormone, cortisol, and prolactin release: a dose-response study. Journal of Clinical Endocrinology and Metabolism 1996;81(12):4338–41 — the ED₅₀ figures, and the combination result.
8. Rahim A, O'Neill PA, Shalet SM. Growth hormone status during long-term hexarelin therapy. Journal of Clinical Endocrinology and Metabolism 1998;83(5):1644–1649 — sixteen weeks, and the reversibility. Abstract only; the sample size is not in it, which is why no n appears above.
9. Maccario M, Veldhuis JD, Broglio F, et al. Impact of two or three daily subcutaneous injections of hexarelin on 24-h GH, prolactin, adrenocorticotropin and cortisol secretion in humans. European Journal of Endocrinology 2002;146(3):310–318 — the three desensitisation rates.
10. Arvat E, di Vito L, Maccagno B, et al. Effects of GHRP-2 and hexarelin on GH, prolactin, ACTH and cortisol levels in man. Peptides 1997;18(6):885–91. PMID 9285939 — abstract only, and it carries no individual hormone values, which is why no numbers from it appear above.
11. Van den Berghe G, Wouters P, Weekers F, et al. Reactivation of pituitary hormone release and metabolic improvement by infusion of growth hormone-releasing peptide and thyrotropin-releasing hormone in patients with protracted critical illness. Journal of Clinical Endocrinology and Metabolism 1999;84(4):1311–1323.
12. Sigalos JT, Pastuszak AW, Allison A, et al. Growth hormone secretagogue treatment in hypogonadal men raises serum insulin-like growth factor-1 levels. American Journal of Men's Health 2017;11(6):1752–1757 — the retrospective chart review, and the authors' own limitations.
13. Thomas A, Kohler M, Mester J, et al. Identification of the growth-hormone-releasing peptide-2 (GHRP-2) in a nutritional supplement. Drug Testing and Analysis 2010;2(3):144–148 — about 50 µg per tablet, undeclared.
14. Health Canada. Unauthorized injectable peptide drugs seized and sold by Canada Peptide, 1 August 2025 — GHRP-2, GHRP-6 and hexarelin all named. And: Think twice before injecting peptides bought online, 9 April 2026 — none of the three named, checked by direct read.
15. College of Physicians & Surgeons of Alberta. Unauthorized injectable peptides and their potential serious health risks, 9 April 2026 — names GHRP-2, GHRP-6 and hexarelin to Alberta physicians.
16. The 2026 Prohibited List, World Anti-Doping Code, subsection on growth hormone releasing factors — read through a national anti-doping organisation's verbatim reproduction; the official file did not open for us.
17. Mear Y, Enjalbert A, Thirion S. GHS-R1a constitutive activity and its physiological relevance. Frontiers in Neuroscience 2013;7:87 — the 50%-constitutive-activity finding.
18. Dominikowski A, Rékoś Z, Olejarz M, et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis. Frontiers in Endocrinology 2026;17:1822475.

What we could not check, listed rather than hidden. The single most consequential gap is the provenance of FDA's adverse-event claims — the entry cites nothing and we could not trace the reports behind “death of critically ill study subjects, infection and pancreatitis.” We could not open the manufacturer's interview form, which would have given the exact Japanese approval date and the approval dossier's clinical data; the full texts of the 1997 comparison and the 16-week hexarelin study, which is why this page prints no hormone numbers for the first and no sample size for the second; a paper on detecting these compounds in athlete urine; the only located analytical survey of black-market growth-promoting products; a follow-up appetite study in obese subjects; and the two hexarelin cardiomyopathy papers. Six negatives are reported above with the searches behind them — most importantly that the cortisol/prolactin potency ranking everyone repeats returned vendor blogs and nothing else, and that no published stability study of reconstituted GHRP-2 exists in any diluent at any temperature.