Growth hormone secretagogues
"GH secretagogue" is an umbrella term for compounds that cause the pituitary to release endogenous growth hormone — as opposed to exogenous recombinant hGH itself. They split cleanly along two receptor axes: GHRH analogs (sermorelin, tesamorelin, CJC-1295) hit the growth-hormone-releasing-hormone receptor, while ghrelin mimetics / GHRPs (ipamorelin, hexarelin, GHRP-2, GHRP-6, MK-677) hit the growth-hormone secretagogue receptor (GHSR-1a). The two axes are synergistic, which is why research protocols frequently combine them.
The two receptor axes at a glance
| Class | Receptor | Effect on pituitary | Examples |
|---|---|---|---|
| GHRH analogs | GHRHR | Amplifies natural pulsatile GH release; preserves feedback | Sermorelin, Tesamorelin, CJC-1295 |
| Ghrelin mimetics (GHRPs) | GHSR-1a | Triggers GH pulse; suppresses somatostatin "brake" | Ipamorelin, Hexarelin, GHRP-2/6, MK-677 |
Stacking one of each (e.g. CJC-1295 + ipamorelin) is the canonical research combination because the two arms reinforce each other: the GHRH analog raises the pulse ceiling, the ghrelin mimetic releases the somatostatin brake, and the result in research models is a larger, cleaner GH pulse than either alone.
GHRH analogs in detail
Sermorelin (GRF 1–29)
The first 29 amino acids of native GHRH — the minimal fragment that retains full GHRH-receptor activity. Half-life is minutes. Preserves the natural pulsatile pattern of GH release, which is why it has historically been studied in pediatric and adult GH-deficiency research as the "gentlest" of the GH secretagogues.
Tesamorelin
Stabilized GHRH analog with a trans-3-hexenoyl group on the N-terminus to resist DPP-IV cleavage. Half-life ~26 minutes after subcutaneous dosing. The only GHRH analog with completed Phase III trials and an approved indication (HIV-associated lipodystrophy) — and the only one with published data showing a sustained reduction in visceral adipose tissue. Often used in research on visceral fat and cognitive aging.
CJC-1295 (with vs without DAC)
A GHRH analog modified with four amino-acid substitutions for protease resistance. Comes in two forms:
- CJC-1295 without DAC (a.k.a. Mod GRF 1-29): half-life ~30 minutes. Behaves like a stronger sermorelin — pulsatile, washes out between doses.
- CJC-1295 with DAC: includes a Drug Affinity Complex (maleimide linker) that covalently binds albumin in plasma. Half-life extends to 6–8 days, producing a sustained elevation in GH/IGF-1 baseline rather than discrete pulses — the "GH bleed" pattern that fundamentally changes feedback behavior compared with the non-DAC version.
Ghrelin mimetics / GHRPs in detail
Ipamorelin
The cleanest of the GHRPs — selective for GHSR-1a with negligible cross-activation of cortisol, prolactin, or ACTH release in research models. Half-life ~2 hours. The default "stack partner" for CJC-1295 because of its specificity profile.
Hexarelin
Six-residue GHRP that produces the strongest GH pulse of the class but also the most desensitization with chronic dosing, and modest prolactin/cortisol elevation. Of interest in cardiac research because of GHSR-1a expression in the myocardium.
GHRP-2 and GHRP-6
Earlier-generation GHRPs. GHRP-6 is notorious for ghrelin-mediated appetite stimulation (hunger pangs in research models within ~15 minutes); GHRP-2 is more selective for GH release with less hunger but more cortisol/prolactin elevation than ipamorelin. Both have been largely superseded by ipamorelin in modern research protocols where selectivity matters.
MK-677 (ibutamoren)
Not a peptide — a small-molecule, orally bioavailable ghrelin-receptor agonist. Half-life ~24 hours, producing a sustained elevation of GH and IGF-1 over weeks. Useful in research where injectable dosing is impractical, but the always-on signaling is mechanistically distinct from pulsatile peptide protocols and warrants separate consideration.
Half-life reference
| Compound | Half-life | Typical research cadence |
|---|---|---|
| Sermorelin | ~10 min | Pre-sleep, daily |
| Tesamorelin | ~26 min | Daily SC |
| CJC-1295 (no DAC) | ~30 min | 1–3× daily SC |
| CJC-1295 with DAC | ~6–8 days | Weekly SC |
| Ipamorelin | ~2 h | 1–3× daily SC |
| Hexarelin | ~70 min | 1–2× daily SC |
| GHRP-2 / GHRP-6 | ~15–60 min | 1–3× daily SC |
| MK-677 | ~24 h | Daily oral |
The canonical stack and why it works
The most-studied GH-secretagogue research combination is CJC-1295 (no DAC) + ipamorelin, typically dosed pre-sleep to align with the natural overnight GH pulse. Mechanistically:
- CJC-1295 raises the GHRH-receptor signal at the somatotrophs.
- Ipamorelin simultaneously hits GHSR-1a, which both adds a pulse trigger and suppresses somatostatin tone.
- The result is a larger pulse than either component alone, while preserving pulsatility and feedback — in contrast to CJC-1295-with-DAC + MK-677, which both flatten the curve into sustained elevation.
Pulsatile-vs-sustained is the central design choice in any GH-secretagogue research protocol: pulsatile preserves receptor sensitivity and feedback over time; sustained desensitizes faster but produces a higher integrated AUC of GH/IGF-1 exposure.
Reconstitution and storage
Standard cold-chain peptides — reconstitute with BAC water, store at 2–8 °C, use within 30 days. Example: 5 mg CJC-1295 (no DAC) + 2.5 mL BAC water = 2 mg/mL; a 100 µg research dose is 0.05 mL = 5 units on a U-100 syringe. Full per-vial math is in the dosage protocols guide; cold-chain rules in the storage & handling guide.
Safety, risks & legal notice
Read before ordering or conducting any research
For laboratory research only
Every compound described on this page is sold and provided strictly as a research-grade reagent for in-vitro and animal-model studies. These products are not intended for human consumption, cosmetic use, dietary supplementation, or any clinical or therapeutic application. By purchasing, you represent that you are a qualified researcher, laboratory, or educational institution with appropriate facilities and oversight.
Not FDA-approved or evaluated
Some compounds in this class have limited regulatory approvals for specific indications (tesamorelin for HIV-associated lipodystrophy). However, the research-grade materials supplied here are not manufactured, labelled, or verified for those approved uses, and we make no claims regarding their safety or efficacy outside laboratory research.
No medical, clinical, or dosing advice
Dr Jays Peptides does not employ physicians, pharmacists, or clinical researchers. Nothing on this page — including dosage figures, reconstitution math, or mechanism descriptions — constitutes medical advice, a prescribing recommendation, or instructions for self-administration. If you are considering any peptide for personal use, consult a licensed healthcare provider who can evaluate your individual risk factors, medication interactions, and monitoring needs.
Class-specific risk signals
- "GH bleed" and receptor desensitization: CJC-1295 with DAC and MK-677 produce sustained GH/IGF-1 elevation rather than physiological pulses. Chronic exposure leads to GH-receptor downregulation, insulin resistance, and elevated fasting glucose in research models.
- Insulin resistance and hyperglycemia: elevated IGF-1 antagonizes insulin signaling at the cellular level. Research subjects with metabolic syndrome or diabetes risk factors may experience worsened glucose control.
- Fluid retention and carpal tunnel: GH is natriuretic and promotes sodium/water retention. Peripheral edema, joint pain, and carpal tunnel syndrome are commonly reported side effects in GH-exposure research.
- Acromegalic changes: prolonged supraphysiological GH exposure thickens soft tissues, enlarges extremities, and can promote organomegaly and cardiomegaly in chronic animal studies.
- Prolactin and cortisol elevation: non-selective GHRPs (hexarelin, GHRP-2/6) can raise prolactin and ACTH/cortisol, with potential downstream effects on mood, libido, and immune function.
- Cancer risk theoretical concern: GH and IGF-1 are mitogenic. Any research model with active neoplasia, or a history of hormonally sensitive tumors, requires heightened scrutiny.
Prohibited by WADA and most sporting bodies
Compounds in this class are explicitly listed on the World Anti-Doping Agency (WADA) Prohibited List under S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). They are also banned by the IOC, NCAA, USADA, UKAD, and virtually all national anti-doping agencies. Athletes subject to drug testing should not purchase, possess, or use these substances.
General risk factors
- Purity and contamination: Research peptides are not manufactured to pharmaceutical-grade GMP standards. Even high-purity lots may contain trace endotoxins, residual solvents, or unrelated peptide sequences.
- Stability and degradation: Improper storage, repeated freeze–thaw cycles, or use beyond recommended reconstitution windows can produce degraded products with unknown toxicology.
- Immunogenicity: Foreign peptides can elicit antibody responses; repeated administration may cause allergic reactions or neutralizing antibodies that alter pharmacokinetics in unpredictable ways.
- Drug interactions: Peptides may potentiate or antagonize prescription medications, herbal supplements, or other research compounds. No systematic interaction data exists for most of these molecules.
- Pregnancy, lactation, and pediatric populations: Zero safety data. Absolute contraindication for use in these populations.
Legal status & buyer responsibility
The legal status of research peptides varies by country, state, and municipality. It is the buyer's sole responsibility to understand and comply with all applicable laws, regulations, and institutional policies in their jurisdiction before ordering. Dr Jays Peptides ships products with accurate customs declarations; buyers are responsible for any import duties, inspections, or seizures. We reserve the right to cancel any order where we believe the buyer lacks legitimate research intent or where shipment would violate local law.
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