GHRP-2
GHRP-2 (also called pralmorelin or KP-102) is a synthetic hexapeptide growth hormone secretagogue developed in the early 1990s. It is one of the most studied GHRPs in humans, with published phase I pharmacokinetic data, pediatric short-stature trials, and appetite studies. In Japan it was approved as a diagnostic agent for testing growth hormone deficiency, which is why the human dosing literature for GHRP-2 is unusually well characterized compared to most research peptides.
- class
- GHRP (hexapeptide secretagogue)
- half-life
- ~30 minutes
- route
- subcutaneous (intranasal in trials)
- cadence
- 1–3x daily, fasted
- typical dose
- 100–300 mcg per injection
- cycle
- 12–16 weeks, then 4-week break
- storage
- refrigerated · 28-day max (reconstituted)
GHRP-2 Reconstitution & Dosage Protocol
weekly dose · reduces side effects| Phase | Window | Weekly dose | Draw (U-100, 2.5mL BAC) | Note |
|---|---|---|---|---|
| Introduction | Weeks 1–2 | 0.10 mg | 5 units· 0.05 mL | 100 mcg once daily, fasted, to gauge appetite and flush response |
| Standard | Weeks 3–12 | 0.20 mg | 10 units· 0.10 mL | 200 mcg 2x daily (morning fasted and pre-sleep); stack with a GHRH analog |
| High output | Weeks 4–12 | 0.30 mg | 15 units· 0.15 mL | Optional 300 mcg ceiling; above this GH response plateaus while cortisol rises |
| Maintenance | Weeks 13–16 | 0.10 mg | 5 units· 0.05 mL | Taper to 100 mcg once daily before a 4-week washout |
What is GHRP-2?
GHRP-2 (also called pralmorelin or KP-102) is a synthetic hexapeptide growth hormone secretagogue developed in the early 1990s. It is one of the most studied GHRPs in humans, with published phase I pharmacokinetic data, pediatric short-stature trials, and appetite studies. In Japan it was approved as a diagnostic agent for testing growth hormone deficiency, which is why the human dosing literature for GHRP-2 is unusually well characterized compared to most research peptides.
GHRP-2 works by binding the growth hormone secretagogue receptor (GHS-R1a), the same receptor targeted by endogenous ghrelin. Activation in the anterior pituitary triggers a pulse of growth hormone, and activation in the arcuate nucleus of the hypothalamus suppresses somatostatin, the brake on GH release. Because it both stimulates the accelerator and releases the brake, GHRP-2 produces a larger GH pulse than a GHRH analog used alone.
The distinguishing practical feature of GHRP-2 is appetite stimulation. A 2005 JCEM study showed that intravenous GHRP-2 increased ad libitum food intake by roughly 35% in healthy men, mirroring the orexigenic effect of ghrelin itself. This is useful for individuals in a bulking phase or dealing with poor appetite, and a real drawback for anyone in a caloric deficit. Ipamorelin is the standard substitute when appetite stimulation is unwanted.
Cortisol and prolactin elevation with GHRP-2 sits between ipamorelin (essentially none) and GHRP-6 (the most pronounced). At 100 mcg per injection the spillover is minimal in most people. At doses above 300 mcg the GH response begins to plateau while cortisol and prolactin continue climbing, which is why 300 mcg is the practical per-injection ceiling rather than a hard pharmacological limit.
The most common protocol pairs GHRP-2 with a GHRH analog such as CJC-1295 without DAC or sermorelin. The GHRH analog loads the somatotroph cells with releasable GH while GHRP-2 triggers the release and suppresses somatostatin. A typical stack is 100 mcg GHRP-2 plus 100 mcg CJC-1295 drawn into the same syringe, injected subcutaneously 1–2 times daily on an empty stomach.