GHRP-2

Also known as: Growth Hormone Releasing Peptide 2, GHRP2, Pralmorelin, KP-102, GPA-748, GHRP Kaken 100

Evidence: Clinical

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Overview

Synthetic hexapeptide ghrelin-receptor agonist (pralmorelin, KP-102) that raised GH and food intake 36% in healthy men (n=7); approved in Japan as a single-dose GH-deficiency diagnostic (GHRP Kaken 100).

GHRP-2 (pralmorelin, KP-102) is a second-generation GHRP from the Bowers series. In children, 1 mcg/kg IV gave a predictable GH rise with a 33 min plasma half-life (Pihoker 1998), and intranasal 5-20 mcg/kg was active (Pihoker 1995). Six GH-deficient children treated SC for 8 months grew faster, though IGF-1 did not rise and the effect of each injection was brief (Mericq 1998). In older adults, 30 days of continuous SC infusion at 1 mcg/kg/h sustained GH secretion at 1.8-fold and raised IGF-1 to a stable plateau (Bowers 2004). A 270 min SC infusion increased ad libitum food intake 36% in healthy men (Laferrere 2005). In Japan a 100 mcg IV test with a 15 mcg/L GH cut-off diagnoses severe adult GH deficiency (Chihara 2007) and it is approved there as a diagnostic. US development was discontinued. No body-composition or sleep trial exists.

Benefits

Sustained GH and IGF-1 elevation over 30 days of SC infusion (human, older adults, n=17), increased food intake (human, n=7), validated GH-deficiency diagnostic (human, approved in Japan), growth velocity in GH-deficient children (human, n=6, open label)

Dosing reference

Research dose: 1 mcg/kg IV or 100 mcg IV fixed dose (diagnostic); 1 mcg/kg/h SC infusion (30-day study); 0.3-3 mcg/kg/day SC in children; research-community range 100-300 mcg SC 1-3x daily
Range: 100 to 300 mcg, 2-3x daily
Reconstitution: 2 mL bacteriostatic water
Common vial sizes: 5 mg, 10 mg

IV bolus in diagnostic use, SC injection or infusion in research. GH peaks within 60 min and the GH effect of a single SC dose is brief (Chihara 2007; Mericq 1998). GHRP-2 raised ACTH and cortisol in swine where ipamorelin did not (Raun 1998). Continuous 30-day SC infusion in older adults kept safety screening tests normal (Bowers 2004).

Mechanism

GHRP-2 is an agonist at the ghrelin receptor GHS-R1a on pituitary somatotrophs and in the hypothalamus. It releases GH through a pathway distinct from GHRH, and the two synergize in children and adults (Pihoker 1995; Bowers 2004). Like ghrelin it increases food intake in humans (Laferrere 2005). It also stimulates ACTH and cortisol release (Raun 1998, swine), which ipamorelin does not. GH responses are lower in GH-deficient patients than in healthy subjects regardless of age or adiposity, the basis of its diagnostic use (Chihara 2007).

Evidence

Clinical: at least one published human trial or an approved drug

1 mcg/kg IV: predictable GH rise, plasma half-life 33 min, in 10 children (Pihoker et al., 1998)
Intranasal 5-20 mcg/kg released GH in children; IV GHRP-2 + GHRH was synergistic (Pihoker et al., 1995)
8 months of SC 0.3-3 mcg/kg/day raised growth velocity in 6 GH-deficient children without raising IGF-1 (Mericq et al., 1998)
30-day continuous SC infusion at 1 mcg/kg/h sustained GH secretion and IGF-1 in 17 older adults (Bowers et al., 2004)
SC infusion increased ad libitum food intake 36% in 7 healthy men (Laferrere et al., 2005)
Human-trial status: approved in Japan as a GH-deficiency diagnostic (100 mcg IV, 15 mcg/L cut-off; Chihara et al., 2007); US development discontinued; no approved therapeutic use

References

Side effects

No side effects or toxicities were observed over 8 months in GH-deficient children (Mericq 1998) and safety tests stayed normal over a 30-day infusion in older adults (Bowers 2004). Increased food intake is a documented human effect (Laferrere 2005). ACTH and cortisol rise acutely (Raun 1998, swine). Water retention, tingling in the hands, joint aches and reduced insulin sensitivity are commonly reported (anecdotal). Regulatory: GHRP-2 (injectable and nasal) is on FDA's 503B category 2 (significant safety risks) table, added 2023-09-29, page content as of 2026-04-22: https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks

Storage

Storage: Refrigerate 2-8°C (36-46°F)
Lyophilized: 2+ years at room temp, 3+ years refrigerated
Reconstituted: 28-30 days refrigerated

Pharmacology

Half-life: ~33 min (t1/2 beta; children, IV bolus; Pihoker 1998)
Bioavailability: Intranasal: GH response at 5-20 mcg/kg in children (Pihoker 1995); no absolute bioavailability figure located
Molecular weight: 817.96 Da
Sequence: [D-A][D-2-Nal]AW[D-F]K[NH2]