GHR-2 (GHRP-2)

What is GHR-2 (GHRP-2)?

GHRP-2 (Growth Hormone Releasing Peptide-2) is a synthetic hexapeptide that acts as a potent growth hormone secretagogue. It stimulates the pituitary gland to release growth hormone through the ghrelin receptor (GHS-R1a). It is one of the most studied GHRPs and has been used as a diagnostic tool for growth hormone deficiency.

What GHR-2 (GHRP-2) Is Investigated For

GHRP-2 is investigated for growth hormone optimization, body composition improvement, recovery from training, and sleep quality, with a well-characterized ghrelin-receptor (GHS-R1a) mechanism that stimulates pulsatile GH release. The strongest evidence is for its diagnostic use — it is formally approved in Japan as pralmorelin for intravenous GH-stimulation testing, one of the few GHRPs worldwide to achieve any regulatory indication. Human clinical data on chronic wellness dosing is moderate: well-characterized GH release kinetics and IGF-1 elevation in the 3–6 week range, with stacking against GHRH analogs like CJC-1295 producing synergistic pulses. The honest caveats are meaningful: no FDA approval exists for any indication in the US, long-term human safety data beyond the diagnostic-use population is essentially absent, and GHRP-2 elevates cortisol and prolactin more than ipamorelin though less than GHRP-6. It is explicitly prohibited under WADA S2 at all times, and LC-MS/MS urinary detection is routine. The 503A compounding pathway that has historically supplied US users is narrowing under FDA review.

History & Discovery

GHRP-2, also known as pralmorelin, was developed in the 1990s building on the original GHRP series pioneered by Cyril Bowers and colleagues at Tulane University, whose work in the 1980s established that short synthetic enkephalin-derived peptides could release growth hormone through a distinct receptor from GHRH. GHRP-2 (sometimes designated KP-102 in early Japanese literature) was advanced by Kaken Pharmaceutical in partnership with Sumitomo Pharmaceuticals as a diagnostic agent for growth hormone deficiency, and it received approval in Japan for intravenous use in GH-stimulation testing — one of the few GHRPs worldwide to achieve a formal regulatory indication. The Japanese diagnostic preparation is marketed as GHRP Kaken. Outside Japan, GHRP-2 was never approved as a therapeutic drug. It migrated into the wellness, bodybuilding, and research-chemical markets during the 2000s, where it became a common component of GH-optimization stacks, typically paired with a GHRH analog such as CJC-1295 or sermorelin to exploit the dual-pathway rationale described in the GHRP literature. The identification of GHS-R1a as the ghrelin receptor in 1999, and the subsequent discovery of endogenous ghrelin as its natural ligand, reframed GHRP-2 as an early synthetic ghrelin mimetic rather than the orphan peptide it had been for its first decade.

How It Works

GHRP-2 tells your pituitary gland to release more growth hormone by mimicking a natural hunger hormone called ghrelin. This results in a pulse of growth hormone similar to what your body produces naturally during deep sleep.

GHRP-2 binds to the growth hormone secretagogue receptor (GHS-R1a), the same receptor targeted by endogenous ghrelin. This triggers calcium influx in somatotroph cells, leading to GH release. Unlike direct GH administration, GHRP-2 maintains the pulsatile nature of GH secretion and preserves negative feedback mechanisms. It also has mild effects on ACTH and cortisol release.

Evidence Snapshot

Research Gaps & Open Questions

What the current literature has not yet settled about GHR-2 (GHRP-2):

• 01Long-term (>12 month) human safety data outside the diagnostic-use population is essentially absent — Japanese diagnostic-use experience informs single-dose IV safety, not chronic subcutaneous wellness dosing.
• 02Whether GHRP-2's mild cortisol and prolactin elevation carries clinically meaningful consequences at chronic wellness doses has not been quantified in a dedicated long-duration trial.
• 03Optimal dosing cadence (two vs. three times daily) and the dose-response curve for IGF-1 at chronic wellness-range doses have not been compared head-to-head in published human work.
• 04Whether stacking with a GHRH analog meaningfully improves clinical endpoints over monotherapy — as opposed to just amplifying the acute GH pulse — has not been tested with body-composition or functional endpoints in a controlled human study.
• 05Pituitary desensitization with chronic use — GHRP-2 is often described as less desensitizing than hexarelin but this comparison rests on short-duration studies rather than long-duration human data.
• 06Independent replication of cardiovascular and tissue-repair findings outside the Japanese and European GHRP research programs is thin.

Forms & Administration

GHRP-2 is administered via subcutaneous injection, typically 2-3 times daily. It is often combined with a GHRH analog for enhanced effect. Timing around meals and sleep is important for optimal results. All injectable peptides should only be administered under the guidance of a qualified healthcare provider. Never self-administer without clinician oversight.

Dosing & Protocols

The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.

GHRP-2 is not FDA-approved for any indication in the United States; its only current regulatory approval is as an intravenous diagnostic agent for GH deficiency in Japan. The numbers above describe commonly-referenced wellness protocols, not a prescription. Use should be supervised by a qualified clinician with appropriate IGF-1, glucose, cortisol, and prolactin monitoring.

Timeline of Effects

Common Questions

Who GHR-2 (GHRP-2) Is NOT For

Drug & Supplement Interactions

Documented clinical drug interactions for GHRP-2 outside the diagnostic setting are sparse; most of what follows is theoretical and derived from GH-pathway overlap with known drug classes. Glucose-regulating medications — insulin, sulfonylureas, and GLP-1 receptor agonists — interact with GH's counter-regulatory effect on glucose and may require dose adjustment as IGF-1 rises over weeks of use. Corticosteroids (prednisone, dexamethasone) complicate the picture in both directions: acute glucocorticoid administration can actually enhance GH response to GHRP-2, while chronic glucocorticoid exposure suppresses spontaneous GH secretion and may blunt cumulative IGF-1 gains. This pharmacological quirk is part of why GHRP-2 is used in Cushing's-disease workup. Somatostatin analogs (octreotide, lanreotide) directly oppose GH release and will pharmacologically antagonize GHRP-2. Thyroid hormone status matters — uncorrected hypothyroidism blunts the GH response. Estrogens modulate GH/IGF-1 coupling, with oral estrogens in particular reducing hepatic IGF-1 generation, which affects interpretation of IGF-1 monitoring labs. Dopamine agonists used for hyperprolactinemia may attenuate GHRP-2's small prolactin-elevating effect. Patients on any regular medication should disclose GHRP-2 use to their prescribing clinician; absence of documented interaction is not evidence of absence.

Safety Profile

Legal Status

Regulatory status changes over time. Verify current local rules with a qualified professional.

Myths & Misconceptions