✓ Medically reviewed by  ·  Last reviewed: May 2026

Morgan Ellis

Pharmacy Researcher · 8 years experience

Pharmacy researcher with 8 years reviewing clinical drug information, generic formulation equivalence, and international pharmaceutical standards. Focuses on patient-facing accuracy in medication education.

Researchers studying growth hormone (GH) release discovered something counterintuitive early on: triggering a single receptor — either the GHRH receptor or the ghrelin receptor (GHS-R1a) — produces a modest, short-lived GH pulse. Activating both simultaneously, however, creates a response up to ten times larger than either alone. That finding is the pharmacological rationale behind the CJC-1295 and ipamorelin combination: one peptide occupies the GHRH receptor, the other occupies the ghrelin receptor, and together they produce a synergistic GH release that neither achieves independently. This guide covers the mechanism, the practical protocols used in research, the DAC vs no-DAC question, and what the published evidence actually supports.

CJC-1295 and Ipamorelin: The Complete Peptide Stack Guide for Growth Hormone Research (2026)

Last updated: May 10, 2026 · Reviewed by a licensed pharmacist (MedsBase Medical Team)

What Is CJC-1295?

CJC-1295 is a synthetic analogue of growth-hormone-releasing hormone (GHRH), the 44-amino-acid hypothalamic peptide that signals the anterior pituitary to release growth hormone. The native GHRH molecule degrades rapidly in plasma — half-life is roughly 7 minutes — because serine protease enzymes quickly cleave it. CJC-1295 was developed to solve that limitation.

There are two commercially distributed forms:

• CJC-1295 without DAC (also called Modified GRF 1-29, or Mod GRF 1-29): a 29-amino-acid GHRH fragment with four amino-acid substitutions that resist enzymatic degradation. Half-life is approximately 25–30 minutes — long enough to sustain a GH pulse, short enough to preserve pulsatile physiology.
• CJC-1295 with DAC: the same 29-residue sequence with an added Drug Affinity Complex that binds albumin in the bloodstream, extending the effective half-life to approximately 6–8 days. This allows twice-weekly or even weekly dosing at the cost of a more sustained — rather than pulsatile — GH elevation.

Both forms bind the pituitary GHRH receptor (GHRHR) and increase cyclic AMP signalling, leading to synthesis and secretion of GH. In a published clinical study (Walker et al., 2006, JCEM), CJC-1295 with DAC produced sustained, dose-dependent increases in plasma GH and IGF-1 lasting several days from a single injection, with mean IGF-1 levels rising 1.5- to 3-fold above baseline in healthy adults.

What Is Ipamorelin?

Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) is a pentapeptide growth-hormone secretagogue developed in the late 1990s. It acts as a selective agonist at the ghrelin receptor (GHS-R1a), the pathway through which acylated ghrelin — the “hunger hormone” — stimulates GH release from the pituitary somatotrophs.

What distinguishes ipamorelin from earlier GHS-R agonists (GHRP-2, GHRP-6) is its receptor selectivity. Older compounds triggered meaningful cortisol and prolactin release alongside GH, complicating their use in longer-term research protocols. Ipamorelin, by contrast, stimulates GH release with minimal activation of the HPA axis. In rat studies directly comparing GH secretagogues (Raun et al., 1998, Eur J Endocrinol), ipamorelin achieved equivalent GH release to GHRP-6 while producing less than one-third the cortisol elevation and statistically negligible prolactin changes.

Ipamorelin also differs from ghrelin itself: it does not increase appetite or gastric motility at standard research doses, and it does not bind the GHS-R splice variants that mediate ghrelin’s cardiovascular effects. That selective pharmacological fingerprint explains why ipamorelin became the preferred GHRP-class partner in most modern GH secretagogue stacks.

Why Combine CJC-1295 and Ipamorelin?

The two receptor pathways the combination exploits are genuinely independent:

• GHRH receptor / CJC-1295 — Gs-protein coupled; increases cAMP → PKA → CREB → GH gene transcription and vesicle release
• GHS-R1a / ipamorelin — Gq-protein coupled; increases IP₃ and DAG → PKC → separate calcium-mediated GH secretion pathway

Because the pathways converge at the somatotroph but originate from distinct receptor families, co-activation is approximately additive-to-synergistic rather than redundant. Neither peptide competes with the other for receptor binding. The combination therefore allows a researcher to achieve a meaningful GH pulse at lower individual doses than would be required using either peptide alone — a practical advantage when designing and titrating research protocols.

The CJC-1295 + ipamorelin combination also partially mirrors the physiological architecture of GH regulation: the hypothalamus releases GHRH while ghrelin (gut-derived) amplifies somatotroph sensitivity. Using an exogenous GHRH analogue alongside a ghrelin-receptor agonist recapitulates that two-signal mechanism at the pituitary level.

DAC vs No-DAC: Which CJC-1295 for This Stack?

The choice depends on the research protocol’s timing objectives:

In most published CJC-1295 + ipamorelin combination protocols, CJC-1295 without DAC (Mod GRF 1-29) is the more widely studied variant for stacking, because its short half-life produces a discrete GH pulse per injection rather than a tonically elevated GH level. Researchers studying circadian GH physiology — including the large GH pulse that naturally occurs 60–90 minutes after sleep onset — tend to prefer the no-DAC form for that reason.

What Does the Research Show?

Human and animal data on the combination are more limited than on each peptide individually, but the mechanistic rationale is well-established in peer-reviewed endocrinology literature:

• Walker et al. (2006, JCEM): Healthy adults receiving CJC-1295 with DAC (subcutaneous, 30 or 60 µg/kg) showed mean GH AUC increases of 200–400% over 6 days post-injection, with IGF-1 elevations persisting 14+ days. No serious adverse events were recorded across 28 subjects.
• Raun et al. (1998, Eur J Endocrinol): Ipamorelin produced dose-dependent GH release in rats with a selectivity profile clearly superior to GHRP-6, showing no significant cortisol or ACTH elevations at effective GH-stimulating doses.
• Combination mechanistic studies: Multiple in-vitro and rodent in-vivo experiments demonstrate that GHRH + GHRP co-stimulation produces GH release greater than additive, consistent with cross-pathway somatotroph sensitisation.

It is important to contextualise this evidence: the bulk of research is preclinical (rodent) or early-phase human pharmacokinetic data. Large randomised controlled trials on outcomes such as body composition, muscle mass, recovery, or longevity are absent. Researchers should treat preclinical findings as hypothesis-generating rather than definitive.

Dosing Protocols Used in Research

CJC-1295 without DAC + Ipamorelin (pulsatile stack):

• CJC-1295 without DAC: 100 µg per injection
• Ipamorelin: 100–200 µg per injection
• Timing: 30–60 minutes before sleep (to align with natural nocturnal GH pulse)
• Frequency: once daily (5 days on, 2 days off in many protocols)
• Route: subcutaneous injection into abdomen or thigh
• Reconstitution: bacteriostatic water (BAC water); see the product pages for volume guidance

CJC-1295 with DAC + Ipamorelin (sustained + pulse hybrid):

• CJC-1295 with DAC: 1–2 mg per injection, twice weekly
• Ipamorelin: 100–200 µg, 1–3× daily, independent schedule
• The DAC form provides a sustained GH/IGF-1 elevation baseline; ipamorelin injections layer additional pulsatile events on top

Peptides must be reconstituted before use. Standard protocol: draw the stated volume of bacteriostatic water into a U-100 insulin syringe, inject slowly into the lyophilised peptide vial — do not shake, roll gently — and store refrigerated for up to 30 days after reconstitution. Detailed reconstitution charts are available on the individual product pages.

Side Effect Profile

Based on available clinical and preclinical data, the combination’s observed side-effect profile is modest compared to exogenous GH administration or earlier GHRP compounds:

• Injection-site reactions: mild redness or transient swelling — the most commonly reported effect in Phase I CJC-1295 studies
• Water retention / oedema: consistent with GH elevation; more prominent with CJC-1295 with DAC protocols than with pulsatile no-DAC approaches
• Flushing: mild, transient; reported by a subset of ipamorelin users in the minutes following injection; typically resolves within 15–20 minutes
• Fatigue or sedation: sometimes reported after evening injections; may be an incidental effect of GH elevation coinciding with sleep onset
• Cortisol / prolactin elevation: minimal with ipamorelin at standard doses — this is the key advantage over GHRP-6 and GHRP-2, both of which elevate cortisol dose-dependently
• Appetite increase: unlike GHRP-6 and ghrelin itself, ipamorelin does not substantially increase appetite at doses used in most research protocols

The Walker et al. (2006) Phase I CJC-1295 human trial found no serious adverse events across 28 healthy subjects at doses up to 60 µg/kg. Long-term human safety data on chronic combination use does not exist in the peer-reviewed literature.

CJC-1295 + Ipamorelin vs Alternatives

Researchers evaluating GH secretagogue protocols have several combination options:

• Sermorelin + ipamorelin: Sermorelin is a truncated 29-residue GHRH analogue (GRF 1-29 without the DAC-stabilising substitutions). Its half-life is even shorter (~6–8 minutes) and it is typically dosed multiple times daily. CJC-1295 without DAC (Mod GRF 1-29) is structurally similar but with four amino acid substitutions that extend its half-life to ~30 minutes — more practical for most research schedules.
• Tesamorelin + ipamorelin: Tesamorelin is an FDA-approved GHRH analogue (Egrifta, for HIV-associated lipodystrophy). It has the strongest clinical evidence base of any GHRH analogue currently available, and its combination with ipamorelin is studied in similar research contexts.
• CJC-1295 + GHRP-2 or GHRP-6: These older pairings predate ipamorelin. GHRP-2 and GHRP-6 are potent GH releasers but carry meaningful cortisol and prolactin elevations, and GHRP-6 produces significant appetite stimulation. Ipamorelin’s cleaner receptor profile makes it the preferred modern pairing for CJC-1295.

For background on related peptide research, see the BPC-157 healing peptide guide and the GHK-Cu copper peptide guide.

Research-Grade Sourcing

The quality of lyophilised peptides varies substantially between suppliers. Research-grade CJC-1295 and ipamorelin should meet the following minimum specifications:

• Purity ≥99% by HPLC (high-performance liquid chromatography)
• Certificate of Analysis (COA) from an independent third-party laboratory
• Ipamorelin CAS 170851-70-4; confirmed by MS/HPLC on the COA
• Lyophilised powder in sealed, sterile vials — not pre-mixed or pre-dissolved solutions
• Cold-chain compatible packaging to preserve peptide integrity during shipping

MedsBase carries both CJC-1295 variants — CJC-1295 without DAC (Mod GRF 1-29) and CJC-1295 with DAC — alongside Ipamorelin, all manufactured to research-grade purity specifications with COA-verified batches. Worldwide Shipping available. The full peptide catalogue — including stacks, BAC water, and reconstitution supplies — is at medsbase.com/peptides/.

For researchers working with multiple peptides simultaneously, the Peptide Healing Stack provides a convenient pre-assembled kit for common combination protocols.

Frequently Asked Questions

What is the difference between CJC-1295 with DAC and without DAC?

CJC-1295 with DAC binds albumin in the bloodstream, extending its half-life to approximately 6–8 days and allowing twice-weekly dosing with sustained IGF-1 elevation. CJC-1295 without DAC (Mod GRF 1-29) has a ~30-minute half-life and produces a discrete, pulsatile GH release event per injection, better preserving the natural circadian GH rhythm. Most CJC-1295 + ipamorelin combination protocols use the no-DAC form for this reason.

Can CJC-1295 and ipamorelin be mixed in the same syringe?

In research protocols using CJC-1295 without DAC, both peptides are commonly reconstituted separately and drawn into the same insulin syringe immediately before injection. They do not chemically interact at physiological pH. CJC-1295 with DAC, given its different dosing schedule, is typically administered in a separate injection on its own twice-weekly timetable.

Why is ipamorelin preferred over GHRP-6 in modern stacks?

Ipamorelin’s high selectivity for GHS-R1a means it stimulates GH release without the cortisol and prolactin elevations seen with GHRP-6 and GHRP-2, and without the pronounced appetite stimulation that GHRP-6 produces via off-target ghrelin receptor activity in the gut. For combination stacks in recovery and body-composition research, ipamorelin’s cleaner side-effect profile makes it the preferred choice.

Does ipamorelin suppress natural GH production?

Available preclinical evidence does not show significant suppression of endogenous GHRH or ghrelin production at standard ipamorelin research doses. Ipamorelin acts downstream of hypothalamic GHRH to amplify pituitary GH release rather than replacing it. Long-term suppression data in humans is not established in the literature.

What purity standards should research-grade CJC-1295 and ipamorelin meet?

Research-grade specifications require HPLC purity ≥99%, an independent third-party COA confirming purity and molecular weight, and lyophilised powder in sealed sterile vials. Pre-dissolved or pre-mixed peptide solutions are not suitable for serious research use.

Is CJC-1295 the same as Mod GRF 1-29?

“CJC-1295 without DAC” and “Modified GRF 1-29” (Mod GRF 1-29) refer to the same 29-residue GHRH fragment with four substitutions at positions 2, 8, 15, and 27 that resist serine protease degradation. The two terms are used interchangeably in the research literature.

The Bottom Line

The CJC-1295 + ipamorelin combination is one of the most mechanistically well-founded peptide stacks in GH secretagogue research. CJC-1295 activates the GHRH receptor; ipamorelin simultaneously activates the ghrelin receptor (GHS-R1a). The two pathways amplify each other at the pituitary somatotroph level, producing GH pulses substantially larger than either peptide achieves alone. Ipamorelin’s exceptional receptor selectivity — no meaningful cortisol, prolactin, or appetite elevation — makes it the preferred modern partner for CJC-1295 among researchers studying GH-related physiology.

The choice between CJC-1295 with DAC (twice-weekly, sustained IGF-1) and without DAC (daily, pulsatile GH) is a protocol design decision: the no-DAC form is better suited to circadian GH physiology research, the DAC form offers convenience and is the version with published Phase I human pharmacokinetic data. Most combination stacking protocols in the literature use the no-DAC form.

Both variants are available as research-grade lyophilised peptides with HPLC ≥99% purity and COA verification. Browse CJC-1295 without DAC, CJC-1295 with DAC, and Ipamorelin — or view the complete peptides catalogue.

Written by

Sophie Chen

Pharmaceutical Content Researcher · 8 years experience

Sophie Chen is a pharmaceutical content researcher with 8 years covering generic medication access and clinical pharmacology. She specialises in international regulatory frameworks, bioequivalence standards, and patient-facing education on therapeutic drug classes. She is not a clinician.