Understand the source comparison
GHRP-2 Acetate Ghrelin Receptor Agonism: Agonist vs Partial Agonist Comparison
Understanding receptor pharmacology requires distinguishing between full agonists, partial agonists, and inverse agonists. GHRP-2 is classified as a full agonist at GHS-R1a. It produces maximal receptor activation and downstream signaling equivalent to the end
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- Understanding receptor pharmacology requires distinguishing between full agonists, partial agonists, and inverse agonists. GHRP-2 is classified as a full agonist at GHS-R1a. It produces maximal receptor activation and downstream signaling equivalent to the endogenous ligand ghrelin. This is distinct from partial agonists, which bind the receptor but produce submaximal responses even at saturating concentrations.
- GHRP-2
- GHS-R1a (ghrelin receptor)
- Full agonist
- 100% (reference)
- Mild cortisol/ACTH elevation at >1 mcg/kg; minimal appetite stimulation
- Gold standard for GH pulse amplification with acceptable selectivity. Ideal for short-term studies requiring maximal GH output per dose
- GHRP-6
- GHS-R1a + CD36
- 95–105%
- Significant appetite stimulation via CD36; cortisol elevation
- Comparable GH efficacy to GHRP-2 but orexigenic effects complicate metabolic research. Useful when appetite stimulation is a desired variable
- Hexarelin
- 120–140%
- Cardiac hypertrophy via CD36; desensitization with chronic use
- Highest GH output but cardiac tropism limits long-term research applications. Preferred when cardioprotective effects are under investigation
- Ipamorelin
- GHS-R1a
- 70–85%
- Minimal. No cortisol, prolactin, or appetite effects
- Most selective GHS-R1a agonist; lower GH output per microgram but cleanest endocrine profile. Preferred for multi-week protocols where off-target effects are unacceptable
- MK-677
- Full agonist (non-peptide)
- 60–80% (sustained over 24h)
- Sustained ghrelin-like appetite stimulation; mild insulin resistance with chronic use
- Orally bioavailable and long-acting but lacks pulsatility. Fundamentally different pharmacokinetics than injectable peptides
- Ghrelin (endogenous)
- Full agonist (endogenous ligand)
- 100% (physiological reference)
- Appetite stimulation; rapid enzymatic degradation (half-life ~30 min)
- Natural comparator; GHRP-2 mimics ghrelin's GH effects while resisting proteolytic breakdown