Ipamorelin vs GHRP-2 vs GHRP-6 | Growth Hormone Peptide Comparison | QSC
Ipamorelin vs GHRP-2 vs GHRP-6 — Growth Hormone Releasing Peptide Comparison
Ipamorelin, GHRP-2, and GHRP-6 are all GH-releasing peptides (GHRPs) acting through ghrelin receptor (GHSR1a) — but with meaningfully different selectivity profiles for cortisol, prolactin, and appetite. Selecting the right GHRP depends on whether these off-target effects are experimental confounds or research targets.
Side-by-Side Comparison
Property
Ipamorelin
GHRP-2
GHRP-6
CAS
170851-70-4
158861-67-7
87616-84-0
Sequence
Aib-His-D-2Nal-D-Phe-Lys-NH2
D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2
His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
GH release potency
Moderate — selective GHSR1a
High — strong GHSR1a agonist
High — strong GHSR1a agonist
Cortisol increase
Minimal (<10% above baseline)
Moderate increase
Moderate increase
Prolactin increase
Minimal
Moderate increase
Moderate increase
Appetite stimulation
Minimal
Moderate
Strong (via ghrelin axis)
Selectivity
High — GH specific
Low — cortisol/prolactin/appetite
Lowest — strong ghrelin/appetite effects
Research advantage
Clean GH stimulus, no confounds
Strong GH release when confounds acceptable
Maximum GHSR1a + appetite/ghrelin research
Typical combination
CJC-1295 No-DAC + Ipamorelin
GHRH + GHRP-2 for maximum GH
GHRH + GHRP-6 when appetite is an endpoint
QSC purity
≥99% HPLC — Janoshik COA
≥99% HPLC — Janoshik COA
≥99% HPLC — Janoshik COA
Ipamorelin selectivity — why it matters for clean GH research
In most GH axis research, cortisol and prolactin are confounds — they have independent effects on muscle, fat, and bone that complicate attribution of phenotypes to GH. Ipamorelin produces equivalent or near-equivalent GH pulse amplitude to GHRP-2/6 without the cortisol/prolactin increase — making it the default GHRP for most research designs.
When to choose GHRP-6 — appetite/ghrelin research
GHRP-6 strongly activates the ghrelin axis — significantly stimulating appetite in addition to GH release. For researchers studying ghrelin receptor pharmacology, appetite-GH crosstalk, or cachexia models where appetite stimulation is a therapeutic target (not a confound), GHRP-6 is the appropriate choice over ipamorelin.
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Frequently Asked Questions
Which GHRP is best for GH pulse research without confounds?
Ipamorelin — it produces selective GH release with minimal cortisol, prolactin, or appetite effects. For research where GH is the sole variable of interest, ipamorelin avoids confounds that GHRP-2 and GHRP-6 introduce.
What is the difference between GH release potency of these three peptides?
In most comparative studies, GHRP-2 and GHRP-6 produce slightly higher GH release than ipamorelin at equivalent doses. However, the magnitude difference is smaller than the selectivity difference — making ipamorelin preferable for most GH-focused research despite marginally lower peak GH.
Can these GHRPs be combined with each other?
Combining two GHRPs does not produce additive GH release — they act on the same receptor (GHSR1a). The synergy is between GHRH analogues (CJC-1295, sermorelin) and GHRPs. For maximum GH pulse amplitude, the combination of one GHRH analogue + one GHRP is the standard approach.
