Synthetic ghrelin-receptor agonist. Approved in Japan only as a one-time IV test for growth hormone deficiency.
Also called Pralmorelin, Pralmorelin hydrochloride, Growth hormone-releasing peptide-2, KP-102, GPA-748, GHRP Kaken 100
GHRP-2 is a six-amino-acid synthetic peptide from Cyril Bowers' lab at Tulane, a stronger successor to GHRP-6. It switches on the ghrelin receptor, so the pituitary releases a large pulse of growth hormone within an hour. Under the name pralmorelin it is the only one of the classic GHRPs (GHRP-2, GHRP-6, hexarelin) with a regulatory approval: Japan approved GHRP Kaken 100 in October 2004 as a single 100 microgram IV injection used to diagnose growth hormone deficiency. A healthy pituitary pushes GH well above 9 ng/mL after the shot; a GH-deficient one does not.
Beyond diagnosis, the human record is a handful of small studies. Children with short stature grew faster during months of intranasal or injected GHRP-2, but IGF-1 did not rise and the trials had no placebo group. Critically ill ICU patients given a GHRP-2 plus TRH infusion for five days shifted toward protein building on blood markers. In healthy and obese adults, a GHRP-2 infusion made people eat about a third more at a buffet meal, which is the ghrelin effect showing up.
No published trial has tested GHRP-2 for muscle, fat loss or recovery in healthy adults, which is how it is used outside medicine. It also raises cortisol and ACTH. FDA says it is aware of serious adverse event reports in people given GHRP-2, including increased insulin needs, infection, pancreatitis and deaths of critically ill study subjects, though cause was not established. It is banned in sport by WADA.
What it binds to, and what happens inside the body after that, step by step.
GHRP-2 is a potent agonist of the ghrelin receptor (GHS-R1a) on pituitary somatotrophs and hypothalamic neurons. It releases GH by a route separate from GHRH, so a working pituitary responds strongly while a damaged one does not, which is the basis of the Japanese diagnostic test. Activating the same receptor also stimulates hunger and the ACTH-cortisol axis.
Human results and animal results are kept apart below. A result in rats tells you a mechanism is plausible. It does not tell you what happens in a person.
Strong human evidence exists for one thing: a single IV dose reliably separates GH-deficient patients from healthy people, which is why Japan approved it as a diagnostic. Small randomized studies show it increases food intake in lean and obese adults, and small uncontrolled studies show faster growth in short children and better metabolic markers in ICU patients. There are no trials in healthy adults for muscle, fat loss, recovery or anti-aging.
77 healthy adults and 58 adults with confirmed GH deficiency (Japan, KP-102 Study Group)
After 100 micrograms IV, peak GH was 84.6 micrograms/L in healthy subjects vs 1.36 in GH-deficient patients; a 15 micrograms/L cutoff matched the insulin tolerance test.
Read the study19 healthy adults (10 lean, 9 obese), double-blind, randomized, 3 visits
A 270-minute subcutaneous infusion raised buffet food intake by 10.2 percent at the low dose and 33.5 percent at the high dose vs placebo, in lean and obese people alike.
Read the study7 lean healthy men, GHRP-2 vs saline infusion on separate days
Every subject ate more on GHRP-2, an average of 35.9 percent more at an ad libitum buffet.
Read the study14 ICU patients ill for about 40 days, randomized crossover of 5 days placebo vs 5 days GHRP-2 plus TRH
IGF-1 reached near-normal levels from day 2, osteocalcin rose 19 percent vs a 6 percent fall on placebo, and protein breakdown markers fell.
Read the study15 children with short stature, 6 followed for 18 to 24 months
Height velocity rose from 3.7 to 6.1 cm/year at 6 months with no significant change in IGF-1.
Read the study6 prepubertal children with GH deficiency
Subcutaneous GHRP-2 raised overnight GH in a dose-dependent way and growth velocity increased, but IGF-1 and IGFBP-3 did not rise and the GH effect was brief.
Read the study36 patients with hypothalamic-pituitary disorders (Japan)
An ACTH rise under 1.55-fold during the GHRP-2 test flagged pituitary adrenal insufficiency with 83 percent sensitivity and 88 percent specificity.
Read the studyNo preclinical studies are listed as key studies here. The human data above carries the evidence.
These are questions the published research has not answered.
Japan's approval (October 22, 2004) covers diagnosis only, not treatment. Kaken also ran trials for short stature and licensed US rights to Wyeth, whose GH-deficiency program appears to have been discontinued. Not FDA-approved. WADA lists GHRP-2 (pralmorelin) by name under S2.2.4, prohibited at all times.
No human half-life has been published for GHRP-2, so we do not draw a clearance curve. Half-lives quoted online for it are usually estimates from animal data.
This table records the doses that trials and approved labels used, with the source for each row. It is a record of research, not a recommendation, and it is open to free members.
Which symptoms are expected and which mean stop and get help: side effects and red flags.
Tap a claim to see what the studies found.
It is approved only in Japan, only as a single-dose diagnostic test. FDA has never approved it.
No published study in healthy adults has measured muscle or fat after a course of GHRP-2. The ICU study showed shifts in blood markers of protein turnover, not muscle gain.
No head-to-head human appetite trial against GHRP-6 exists. GHRP-2 is the one with randomized human data on hunger: an infusion raised meal intake by about 34 percent.
Continuous infusion in ICU patients brought IGF-1 to near-normal, but daily injections and intranasal doses in children did not raise IGF-1.
It reliably raises ACTH and cortisol, to the point that Japanese endocrinologists use the GHRP-2 test to screen for adrenal insufficiency.
These pairings come up often. Almost none have been tested together in a trial, and the evidence note on each says so plainly.
Ghrelin-receptor agonists and GHRH act on separate pathways, so together they produce larger GH pulses.
EvidenceHuman data are limited to acute GH responses and one 2-month period in six GH-deficient children who received GHRP-2 plus GHRH. No trial has tested GHRP-2 with CJC-1295 or measured body-composition outcomes.
The approved Japanese product is a dry powder vial stored per its Japanese label. No published stability data exist for research-grade GHRP-2.
The approved product is dissolved in 10 mL of saline immediately before IV injection and used at once. No published in-use stability data exist for multi-dose research vials.
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