Overview
GHRP-6 is a growth hormone-related peptide. Growth hormone releasing hexapeptide with ghrelin-mimetic activity.
With a half-life of ~20 minutes, GHRP-6 requires daily administration in most observed protocols. Administered via SubQ injection, it has a bioavailability of approximately 95% via its primary route.
Half-life approximately 20 minutes. Activates ghrelin receptors in addition to GH secretagogue receptor. Subcutaneous administration. One-compartment model.
Mechanism of Action
GHRP-6's pharmacological activity involves the following key pathways:
Ghrelin Receptor Agonism
GHRP-6 acts as a growth hormone secretagogue by binding to the ghrelin (GHS-R1a) receptor, triggering GH release from the pituitary.
Synergy with GHRH
GH secretagogues like GHRP-6 work synergistically with GHRH analogs — co-administration amplifies GH release beyond what either produces alone.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
100 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
4-12 weeks
Dose
300 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
4-12 weeks
Reconstitution Steps
GHRP-6 is supplied as a lyophilized (freeze-dried) powder and requires reconstitution before use. Common vial sizes: 2 mg, 5 mg, 10 mg.
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1
Gather supplies
You will need the GHRP-6 vial, bacteriostatic water (BW), a sterile syringe for reconstitution, insulin syringes for dosing, and alcohol swabs.
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2
Clean both vial tops
Wipe the rubber stopper of both the GHRP-6 vial and the bacteriostatic water vial with separate alcohol swabs. Allow to air dry for 10 seconds.
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3
Draw bacteriostatic water
For a 5 mg vial, draw 2.5 mL of bacteriostatic water. This yields a concentration of 2,000 mcg/mL, so each 0.1 mL (10 units on an insulin syringe) contains 200 mcg.
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4
Inject slowly down the vial wall
Angle the needle so the water flows down the inside wall of the GHRP-6 vial rather than directly onto the lyophilized powder. This prevents foaming and protects peptide integrity.
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5
Gently swirl to dissolve
Roll the vial gently between your palms until the powder is fully dissolved — do not shake. GHRP-6 dissolves readily and should produce a clear solution.
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6
Store correctly
Refrigerate the reconstituted vial at 2–8°C. Bacteriostatic water extends stability to approximately 28 days post-reconstitution when kept refrigerated and away from light. Do not freeze the reconstituted solution.
Quick Reconstitution Math
5 mg vial + 2.5 mL BW = 2,000 mcg/mL. A 100 mcg dose = 0.05 mL (5 units on an insulin syringe). A 200 mcg dose = 0.10 mL (10 units). Use the Milligram reconstitution calculator for custom vial sizes.
Store lyophilized powder at −20°C for long-term storage, or at 2–8°C for shorter periods. After reconstitution with bacteriostatic water, refrigerate at 2–8°C and use within 28 days. Do not freeze reconstituted solution.
Frequently Asked Questions
What is GHRP-6 and how does it work?
GHRP-6 is a synthetic hexapeptide that mimics ghrelin by binding to the GHS-R1a receptor on pituitary somatotroph cells, triggering a strong, pulsatile release of growth hormone. It was one of the first synthetic GHRPs developed and is notable for its dual action – stimulating both GH secretion and a pronounced appetite response through activation of orexin-containing neurons in the lateral hypothalamus. The appetite effect is the strongest of any commonly used GHRP.
Why does GHRP-6 cause such intense hunger?
GHRP-6 activates the ghrelin receptor (GHS-R1a) with high affinity, and this receptor is expressed in hypothalamic appetite centres as well as the pituitary. Activation triggers orexigenic (appetite-stimulating) signalling through orexin-containing neurons in the lateral hypothalamus, producing intense hunger typically within 15–30 minutes of injection. This hunger effect is significantly more pronounced than with GHRP-2 or ipamorelin and is considered a distinguishing characteristic of GHRP-6.
What is the half-life of GHRP-6?
Clinical pharmacokinetic studies have observed a distribution half-life of approximately 7.6 minutes and an elimination half-life of approximately 2.5 hours for GHRP-6. Despite the short distribution phase, the GH pulse triggered by each injection peaks within 15–30 minutes and typically returns to baseline within 90–120 minutes. This rapid on/off profile makes multiple daily injections the standard approach to sustain GH elevation across the day.
How does GHRP-6 compare to GHRP-2?
Both peptides bind to the same GHS-R1a receptor and produce strong GH pulses with moderate cortisol and prolactin co-elevation. GHRP-6 is the go-to choice for bulking phases due to its aggressive appetite stimulation, while GHRP-2 is generally preferred for recomposition or cutting where hunger management matters. GHRP-2 is considered to maintain maximum GH elevations over longer repeated dosing, while GHRP-6's distinguishing advantage is its caloric intake facilitation.
What protocols is GHRP-6 commonly used in?
GHRP-6 is most commonly observed in bulking protocols where caloric surplus is a goal – the appetite stimulation becomes a feature rather than a side effect. It is frequently stacked with CJC-1295 (no DAC) for synergistic GH output, as the combined GHRH + GHRP approach produces GH peaks 2–3 times higher than either alone. Typical protocols run 12–16 weeks followed by a break period of 4–6 weeks.
Does GHRP-6 affect cortisol and prolactin?
Like GHRP-2, GHRP-6 produces dose-dependent increases in cortisol and prolactin alongside GH release – an effect mediated by non-selective GHS-R1a activation beyond the pure GH pathway. These co-elevations are transient, corresponding to the GH pulse window, and are more pronounced at doses above 300 mcg per injection. Ipamorelin is the preferred alternative when cortisol sensitivity is a concern.