Growth Peptide Comparison

A comprehensive side-by-side comparison of the six growth factor and signaling peptides covered in this database: MK-677 (Ibutamoren), Ipamorelin, GHRP-2, GHRP-6, CJC-1295, and Sermorelin.

Overview¶

Feature	MK-677 (Ibutamoren)	Ipamorelin	GHRP-2 (Pralmorelin)	GHRP-6	CJC-1295 (DAC-GHRH)	Sermorelin
Class	Non-peptide GHSR agonist	Peptide GHSR agonist	Peptide GHSR agonist	Peptide GHSR agonist	GHRH analogue (DAC)	GHRH fragment (1–29)
CAS Number	159634-47-0	170851-70-4	157026-82-1	142640-99-9	863288-34-8	86168-78-7
Molecular Weight	528.7 Da	711.9 Da	786.9 Da	873.0 Da	~3315.7 Da	3357.9 Da
Route	Oral	Subcutaneous	Subcutaneous	Subcutaneous	Subcutaneous	SC, IV
Half-life	~24 h	~2 h	~30 min	~30 min	~6–8 days	~12 min
Mechanism	GHSR-1a agonist	GHSR-1a agonist	GHSR-1a agonist	GHSR-1a agonist	GHRH-R agonist	GHRH-R agonist

Chemical Profile Comparison¶

Property	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
Molecular Formula	C₂₇H₂₈F₂N₄O₂S	C₃₈H₄₉N₉O₅	C₄₄H₅₄N₁₀O₆	C₄₆H₅₆N₁₂O₆	C₁₅₂H₂₅₂N₄₄O₄₂	C₁₅₃H₂₅₃N₄₅O₄₂S
Sequence Length	N/A (non-peptide)	5 aa	6 aa	6 aa	30 aa	29 aa
Purity (HPLC)	≥ 98%	≥ 98%	≥ 98%	≥ 98%	≥ 98%	≥ 98%
Solubility	Poor (water)	Freely soluble	Freely soluble	Freely soluble	Soluble	Soluble
logP	~3.2	~ −1.5	~ −1.2	~ −1.0	~ −2.0	~ −2.5

Mechanism of Action Comparison¶

Pathway	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
Receptor	GHSR-1a	GHSR-1a	GHSR-1a	GHSR-1a	GHRH-R	GHRH-R
G-Protein	Gαq/11	Gαq/11	Gαq/11	Gαq/11	Gαs	Gαs
Second Messenger	Ca²⁺, IP₃	Ca²⁺, IP₃	Ca²⁺, IP₃	Ca²⁺, IP₃	cAMP, PKA	cAMP, PKA
GH Release	++++	+++	+++++	++++	++++	+++
IGF-1 Increase	+++	++	+++	++	++++	++
Prolactin	Minimal	Minimal	Mild	Significant	None	None
Cortisol	Minimal	Minimal	Minimal	Mild	None	None
Appetite	Strong	Minimal	Moderate	Strong	None	None
Oral Activity	Yes	No	Limited	Limited	No	No

Pharmacological Comparison¶

Parameter	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
Half-life	~24 h	~2 h	~30 min	~30 min	~6–8 d	~12 min
Bioavailability	> 60% (oral)	~80–90% (SC)	~70–80% (SC)	~70–80% (SC)	~70–80% (SC)	~60–70% (SC)
Tmax	1–2 h	15–30 min	15–20 min	15–20 min	12–24 h	15–30 min
Dosing Frequency	Daily	2–3×/day	2–3×/day	2–3×/day	Every 5–8 d	Daily
Metabolism	Hepatic (CYP3A4)	Proteolytic	Proteolytic	Proteolytic	Proteolytic	Proteolytic

Research Evidence Comparison¶

Key Studies¶

Compound	Primary Finding	Reference
MK-677	+1.5 kg lean mass in elderly (2-year study)	DOI: 10.1210/jc.2004-0333
Ipamorelin	Selective GH release, minimal prolactin	DOI: 10.1016/j.peptides.2004.12.005
GHRP-2	Potent GH pulse amplification	DOI: 10.1159/000069222
GHRP-6	First GH secretagogue with oral activity	DOI: 10.1210/jcem.79.4.7962278
CJC-1295	Sustained GH/IGF-1 for 6+ days	DOI: 10.1210/jc.2004-2195
Sermorelin	GH secretagogue; studied in GH deficiency research	DOI: 10.1210/jcem.68.6.2656709

Dosing Comparison¶

Parameter	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
Typical Dose	10–25 mg	200–500 μg	100–300 μg	100–300 μg	1–2 mg	200–500 μg
Frequency	Daily	2–3×/day	2–3×/day	2–3×/day	Every 5–8 d	Daily
Route	Oral	SC	SC	SC	SC	SC

Safety Profile Comparison¶

Category	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
Injection Reactions	N/A (oral)	Mild	Mild	Mild	Mild	Mild
Appetite Increase	Strong	Minimal	Moderate	Strong	None	None
Prolactin	None	Minimal	Mild	Significant	None	None
Cortisol	None	None	Minimal	Mild	None	None
Glucose Impact	Transient elevation	Minimal	Minimal	Minimal	Minimal	None
Immunogenicity	None	Low	Low	Low	Low–Moderate	Low

Selection Considerations¶

Choose MK-677 when:¶

Oral administration is required
Long-term GH axis modulation is the target
Research on appetite and GH interaction is planned

Choose Ipamorelin when:¶

Selective GH release with minimal hormonal crosstalk is needed
Twice-daily injection protocol is acceptable
Cleanest side-effect profile among GHRPs is desired

Choose GHRP-2 when:¶

Maximum GH pulse amplification is required
Potency is the primary consideration
Research focus is on acute GH response

Choose GHRP-6 when:¶

Studying the prototypical GHRP mechanism
Appetite stimulation is a research endpoint
Historical comparator compound is needed

Choose CJC-1295 when:¶

Sustained GH/IGF-1 elevation is the goal
Infrequent dosing is required (once weekly)
Long-duration GHRH receptor activation is studied

Choose Sermorelin when:¶

GHRH receptor mechanism without GHSR activity is the focus
GH deficiency diagnostic protocols are being studied
Physiologic GHRH signaling is the research target

Analytical Method Comparison¶

Parameter	MK-677	Ipamorelin	GHRP-2	GHRP-6	CJC-1295	Sermorelin
HPLC Gradient	30–70% B (20 min)	10–45% B (25 min)	15–50% B (25 min)	15–50% B (25 min)	20–60% B (30 min)	20–55% B (30 min)
Retention Time	~10–12 min	~12–14 min	~13–15 min	~14–16 min	~16–18 min	~15–17 min
Detection	UV 220 nm	UV 214 nm	UV 214 nm	UV 214 nm	UV 214 nm	UV 214 nm
Detected (M+H)+	~529.7 Da	~712.9 Da	~787.9 Da	~874.0 Da	~3316.7 Da	~3358.9 Da

References¶

Nass R, et al. (2008). MK-677 in elderly. Journal of Clinical Endocrinology & Metabolism. DOI: 10.1210/jc.2004-0333
Raun K, et al. (2005). Ipamorelin selectivity. Peptides. DOI: 10.1016/j.peptides.2004.12.005
Chapman IM, et al. (1997). GHRP-2 in humans. Journal of Clinical Endocrinology & Metabolism. DOI: 10.1210/jcem.82.8.4183
Bowers CY, et al. (1994). GHRP-6 in humans. Journal of Clinical Endocrinology & Metabolism. DOI: 10.1210/jcem.79.4.7962278
Teichman SL, et al. (2006). CJC-1295 sustained GH release. Journal of Clinical Endocrinology & Metabolism. DOI: 10.1210/jc.2004-2195
Thorner MO, et al. (1989). Sermorelin diagnostic test. Journal of Clinical Endocrinology & Metabolism. DOI: 10.1210/jcem.68.6.2656709
Patchett AA, et al. (1998). MK-677 design. Journal of Medicinal Chemistry. DOI: 10.1021/jm970457k

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