GHRP-2 — also called pralmorelin — is a small peptide that reliably triggers the body to release a pulse of its own growth hormone. It is a close cousin of GHRP-6, and it holds a distinction none of the other peptides in this family can claim: it is the only growth-hormone-releasing peptide that has been approved anywhere — as a diagnostic test in Japan.
In plain terms: the GHRP that made it into real clinical medicine, but as a *test*, not a treatment.
What it is
GHRP-2 is a synthetic peptide in the growth-hormone secretagogue class — compounds that make the pituitary gland release growth hormone rather than supplying it directly. Its name follows the family convention: Growth-Hormone-Releasing Peptide, number 2.
Like GHRP-6, it copies the natural hunger hormone ghrelin, discovered in 1999 as the body's own trigger for this receptor5. GHRP-2 is generally described as a more potent, somewhat "cleaner" growth-hormone releaser than GHRP-6 — it still raises appetite, but with less of GHRP-6's heavy hunger signature.
How it works
GHRP-2 switches on the GHS-R1a receptor (the growth-hormone-secretagogue receptor), the same lock used by ghrelin and the other GHRPs5. That releases a burst of growth hormone from the pituitary, and — because it can add to the separate GHRH lever — it produces a larger response when the two are combined1.
The ghrelin mechanism also means an appetite effect. In a controlled human study, healthy men given GHRP-2 ate about 36% more at a buffet meal than when given saline — direct evidence that, like ghrelin, GHRP-2 drives hunger2.
In plain terms: same lever as GHRP-6 — growth hormone up, appetite up — but generally a stronger, tidier growth-hormone push.
Pharmacokinetics — the diagnostic pulse
GHRP-2 is short-acting, and that is exactly what makes it a good diagnostic. Given as a single injection, it drives growth hormone to a peak within about 60 minutes, then clears3. A doctor measures that peak: a healthy pituitary produces a big growth-hormone spike, while a growth-hormone-deficient one cannot3. Its plasma half-life is on the order of tens of minutes — a quick pulse, not a lasting elevation.
GHRP-2 at a glance
| Property | GHRP-2 (Pralmorelin) |
|---|---|
| Type | Synthetic peptide (growth-hormone secretagogue) |
| Route studied | Injection (also intranasal in some diagnostic work) |
| Target | Ghrelin / GHS-R1a receptor |
| Signature use | Diagnostic GH-stimulation test (GH peak within ~60 min) |
| Appetite effect | Present (raises food intake), milder than GHRP-6 |
| Duration | Short — pulse then cleared |
| Regulatory status | Approved in Japan as a diagnostic only; research compound elsewhere |
What the studies actually found
GHRP-2 has an unusually concrete evidence base for a "peptide," because it was developed and tested as a real diagnostic drug:
| Study | Model | Key result | Year |
|---|---|---|---|
| Bowers et al.1 | Human (normal men) | GHRP reliably released growth hormone; synergistic with GHRH | 1990 |
| Laferrère et al.2 | Human (7 healthy men) | GHRP-2 increased food intake by ~36% versus saline | 2005 |
| Pralmorelin approval4 | Japan (regulatory) | Approved as a diagnostic agent for growth-hormone secretion capacity | 2004 |
| Asakura et al.3 | Human (children) | Single-injection GHRP-2 test reliably separated GH-deficient from GH-sufficient children | 2010 |
In plain terms: GHRP-2 does two well-documented things in people — it provokes a clean growth-hormone pulse used to diagnose deficiency3, and it makes people hungrier2. Its diagnostic use is genuinely approved (in Japan); its use as a *treatment* is not.
The honest limitations
- "Approved" means approved as a test. Japan's approval of pralmorelin is for diagnosing growth-hormone deficiency, not for treating aging, body composition, or anything else4. That distinction is the one most easily blurred.
- Outside that narrow diagnostic role, it is a research compound. There are no large human trials establishing GHRP-2 as a therapy.
- It raises appetite, which may be unwanted2.
- This page describes GHRP-2's studied mechanism and effects — not how to use it — and takes no position on sourcing.
Latest research
- The diagnostic use is the durable, evidence-backed story. Pediatric and adult validation work continues to support single-injection GHRP-2 as a safe, fast alternative to the older insulin-tolerance test for probing growth-hormone reserve3.
- The appetite mechanism keeps GHRP-2 in metabolism research as a human-usable tool for studying ghrelin's effects on eating behaviour2.
- No new approval has broadened it beyond diagnostics. We update this section as results report.
The short version
GHRP-2 (Pralmorelin) is a ghrelin-mimetic peptide that reliably provokes a growth-hormone pulse and, like ghrelin, raises appetite. It is the only growth-hormone-releasing peptide approved anywhere — Japan approved it as a diagnostic test for growth-hormone deficiency, not as a treatment. Everywhere else it is a research compound. Educational overview only, not medical advice. Compare with GHRP-6 and the oral MK-677.