GHRP-6 Pharmacokinetics
GHRP-6 half-life, absorption, routes of administration, and clearance.
Half-Life & Dosing Cadence
GHRP-6 has a reported elimination half-life of ~15-30 min. The half-life is the time it takes for blood levels to fall by half, and it's the single biggest driver of how often you dose. That's why the typical schedule lands around 1-3x daily at 100–300 mcg — frequent enough to keep levels in a useful range without stacking up. Shorter half-lives mean more frequent dosing and faster clearance if you stop; longer ones mean steadier levels but a slower washout.
Administration & Absorption
GHRP-6 is administered by subcutaneous injection (into the fat layer just under the skin). The primary route is subcutaneous. Subcutaneous delivery is absorbed steadily from the fat depot, giving smoother peaks than intramuscular dosing. Whichever route you use, rotate sites and follow sterile technique.
Reconstitution & Handling
GHRP-6 ships as a lyophilized (freeze-dried) powder that you reconstitute before use — a common starting point is a 5 mg vial with 2.5 mL of bacteriostatic water. Add the water slowly down the vial wall, swirl (don't shake), and let it fully dissolve. Reconstituted peptide is refrigerated and used within its stability window; unmixed powder keeps far longer when stored cold and dark. Always confirm exact dosing math against your own vial and concentration.
Onset & Clearance
Because of its ~15-30 min half-life, GHRP-6 reaches steady levels after a few consistent doses and clears the system within roughly four to five half-lives once you stop. Track how you respond over a defined block rather than judging any single dose, and give the compound enough consistent days before deciding whether it's working. This is educational information, not medical advice — review your protocol with a clinician.
Physicochemical and PK profile
- Molecular Formula
- C46H56N12O6
- Molecular Weight
- 873.01 g/mol
- CAS Number
- 87616-84-0
- Half-Life
- 15-60 minutes
- Sequence
- His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
- Solubility
- Soluble in water and bacteriostatic water
- Storage
- Store lyophilized at -20°C. Reconstituted solution at 2-8°C.
References
- GHRP-6 and the discovery of the ghrelin receptor · Bowers CY · 2012
- Bowers CY, et al. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984;114(5):1537-1545. · Bowers CY, Momany FA, Reynolds GA, Hong A · 1984
- Acute dexamethasone administration enhances GH responsiveness to GH releasing peptide-6 (GHRP-6) in man. · Pinto AC, Finamor FE Jr, Lengyel AM · 1999
- Howard AD, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974-977. · Howard AD, Feighner SD, Cully DF, Arena JP, Liberator PA, Rosenblum CI, Hamelin M, Hreniuk DL, Palyha OC, Anderson J, Paress PS, Diaz C, Chou M, Liu KK, McKee KK, Pong SS, Chaung LY, Elbrecht A, Dashkevicz M, Heavens R, Rigby M, Sirinathsinghji DJ, Dean DC, Melillo DG, Patchett AA, Nargund R, Griffin PR, DeMartino JA, Gupta SK, Schaeffer JM, Smith RG, Van der Ploeg LH · 1996
- Growth hormone response to GHRH, GHRP-6 and GHRH + GHRP-6 in patients with polycystic ovary syndrome. · Micić D, Kendereski A, Popović V et al. · 1996
- Synthetic Growth Hormone-Releasing Peptides (GHRPs) - NIH · Berlanga-Acosta J, Abreu-Cruz A, Herrera DGB, Mendoza-Marí Y, Rodríguez-Ulloa A, García-Ojalvo A, Falcón-Cama V, Hernández-Bernal F, Beichen Q, Guillén-Nieto G · 2017
- Kojima M, Kangawa K. Ghrelin: structure and function. Physiological Reviews. 2005;85(2):495-522. · Kojima M, Kangawa K · 2005
- Growth hormone secretion elicited by GHRH, GHRP-6 or GHRH plus GHRP-6 in patients with microprolactinoma and macroprolactinoma before and after bromocriptine therapy. · Popovic V, Simic M, Ilic L et al. · 1998
- Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 ...
- Blocked growth hormone-releasing peptide (GHRP-6)-induced GH secretion and absence of the synergic action of GHRP-6 plus GH-releasing hormone in patients with hypothalamopituitary disconnection: evidence that GHRP-6 main action is exerted at the hypothalamic level. · Popovic V, Damjanovic S, Micic D et al. · 1995
- Growth hormone releasing peptide-6 (GHRP-6) prevents ... · Berlanga-Acosta J, Cibrian D, Valiente-Mustelier J, Suárez-Alba J, García-Ojalvo A, Falcón-Cama V, Jiang B, Wang L, Guillén-Nieto G · 2024
- Leal-Cerro A, et al. Growth hormone (GH)-releasing peptide-6 requires endogenous hypothalamic GH-releasing hormone for maximal GH stimulation. J Clin Endocrinol Metab. 1998;83(4):1186-1189. · Pandya N, DeMott-Friberg R, Bowers CY, Barkan AL, Jaffe CA · 1998