Sermorelin: Growth Hormone Releasing Hormone (1-29)
The native, unmodified GHRH(1-29) sequence – the biologically active fragment of human growth hormone releasing hormone.
Quick Reference
| Research Dosage | 200-500mcg per administration |
|---|---|
| Frequency | 1-3 times daily |
| Administration | Subcutaneous injection |
| Half-Life | 10-20 minutes |
| FDA History | Previously approved (Geref) |
| Reconstitution | 2-3mL bacteriostatic water per vial |
Sermorelin is the native, unmodified GHRH(1-29) sequence – the biologically active fragment of growth hormone releasing hormone. Unlike CJC-1295 which has four stability-enhancing amino acid modifications, Sermorelin represents the natural human sequence exactly as it exists in the body.
This distinction matters because Sermorelin was FDA-approved in the 1990s under the brand name Geref for diagnosis and treatment of growth hormone deficiency. This approval means Sermorelin has more clinical documentation, established safety data, and regulatory history than most research peptides.
The trade-off for being the "natural" sequence: Sermorelin has a shorter half-life (~10-20 minutes vs. ~30 minutes for CJC-1295 No DAC) because it lacks modifications protecting against enzymatic degradation by DPP-IV.
The Native GHRH Fragment
Why GHRH(1-29)?
Full-length growth hormone releasing hormone is 44 amino acids, but research in the 1980s established that only positions 1-29 are required for complete biological activity:
- Positions 1-29: Contain the full receptor binding domain and all biological activity
- Positions 30-44: Not required for GHRH receptor activation
- Practical advantage: Shorter sequence means simpler synthesis while retaining identical function
This discovery led to the development of Sermorelin as a more practical pharmaceutical form of GHRH – maintaining the exact human sequence in a minimal active fragment.
The Unmodified Sequence
Unlike modified GHRH analogues, Sermorelin is biochemically identical to positions 1-29 of human GHRH:
- No amino acid substitutions
- No chemical modifications
- Identical to the endogenous signalling molecule
- Subject to the same enzymatic degradation as natural GHRH
This "naturalness" is both Sermorelin's defining characteristic and its limitation. The native sequence is rapidly recognised and cleaved by DPP-IV, resulting in a short half-life but ensuring the research involves the exact human signalling molecule.
Historical FDA Approval
Geref: The Approved Product
Sermorelin was FDA-approved in the 1990s under the brand name Geref (also known as Gerel in some markets). This approval was granted for two primary indications:
- Diagnostic use: Assessment of growth hormone secretory capacity and pituitary function
- Therapeutic use: Treatment of idiopathic growth hormone deficiency in paediatric patients
Clinical Documentation
The FDA approval process generated substantial clinical data that remains valuable for researchers:
- Established safety profiles from controlled clinical trials
- Documented pharmacokinetic parameters
- Standardised dosing protocols for various applications
- Long-term safety data from paediatric use
- Published adverse event profiles
Discontinuation
Geref was later discontinued by the manufacturer for commercial reasons – not due to safety concerns. The emergence of recombinant human growth hormone (rhGH) as a more direct treatment option reduced the market for GH secretagogues. However, the clinical data generated during its approved period continues to inform research.
Paediatric Use History
Growth Hormone Deficiency Treatment
Sermorelin's primary therapeutic application was in paediatric patients with idiopathic growth hormone deficiency. The rationale for using Sermorelin rather than direct GH administration was to stimulate the patient's own pituitary gland:
- Preserved natural pulsatile GH release patterns
- Maintained physiological feedback mechanisms
- Supported natural GH axis development
- Avoided supraphysiological GH levels associated with direct administration
Diagnostic Applications
Beyond treatment, Sermorelin served important diagnostic functions:
- GH Reserve Testing: Assessing the pituitary's capacity to produce growth hormone
- Differential Diagnosis: Distinguishing between pituitary and hypothalamic causes of GH deficiency
- Treatment Monitoring: Evaluating response to growth hormone deficiency interventions
A robust GH response to Sermorelin indicated intact pituitary function, suggesting the deficiency originated at the hypothalamic level. Poor response suggested pituitary dysfunction.
Safety Profile in Paediatric Populations
Clinical trials and post-marketing surveillance established Sermorelin's safety profile in children, documenting:
- Common injection site reactions (redness, swelling) – generally mild and transient
- Occasional facial flushing
- Rare instances of headache
- No significant long-term adverse effects identified during the approval period
Sermorelin vs CJC-1295 No DAC
Understanding when to use the native sequence versus the modified analogue:
| Property | Sermorelin | CJC-1295 No DAC |
|---|---|---|
| Sequence | Native GHRH(1-29) | Modified (4 substitutions) |
| Half-Life | ~10-20 minutes | ~30 minutes |
| FDA History | Previously approved | Never approved |
| Modifications | None | Stability-enhancing |
| Dosing Frequency | More frequent (1-3x daily) | Less frequent (1-2x daily) |
| Sequence Identity | Identical to human GHRH | Modified sequence |
When to Choose Sermorelin
- Research requiring the native, unmodified human sequence
- Studies comparing natural vs. modified GHRH analogues
- When FDA-approval history and clinical documentation matter for research context
- GHRH receptor pharmacology studies requiring the endogenous ligand
When to Choose CJC-1295 No DAC
- Longer half-life preferred for practical reasons
- Better timing coordination with Ipamorelin combination protocols
- Fewer daily administrations desired
- Research where enhanced stability is advantageous
Research Applications
Native GHRH Research
Sermorelin allows research with the exact human sequence:
- GHRH receptor pharmacology and binding studies
- Comparison with modified analogues to assess impact of modifications
- Natural GH axis stimulation without sequence alterations
- Studies of endogenous GHRH signalling pathways
Clinical Research Context
Sermorelin's FDA history provides researchers with:
- Published safety data from controlled clinical trials
- Established dosing protocols validated in human subjects
- Known pharmacokinetic profile including absorption, distribution, metabolism
- Clinical trial documentation available in regulatory submissions
Diagnostic Research Applications
Historically used to assess GH axis function:
- GH reserve testing protocols
- Pituitary function assessment methodologies
- GH deficiency diagnostic criteria research
- Hypothalamic-pituitary axis evaluation
Dosage Information
Standard Research Dosages
Dosages commonly referenced in clinical and research literature range from 200-500mcg per administration. The short half-life necessitates consideration of timing and frequency.
Dosing Frequency Considerations
Due to the 10-20 minute half-life, Sermorelin protocols typically involve multiple daily administrations:
- Once daily: Typically administered before bed to coincide with natural nocturnal GH pulsatility
- Twice daily: Morning and evening administrations for more sustained stimulation
- Three times daily: Used in protocols seeking maximum GH axis stimulation
Timing Considerations
Research protocols commonly time Sermorelin administration to optimise GH response:
- Pre-sleep: Capitalises on natural nocturnal GH release patterns
- Fasted state: GH response may be attenuated by recent food intake
- Post-exercise: Some protocols utilise post-training timing
Comparison with Historical Clinical Dosing
When FDA-approved as Geref, paediatric dosing was typically 30mcg/kg body weight administered subcutaneously at bedtime. Adult research protocols have generally utilised fixed doses in the 200-500mcg range.
Reconstitution Guide
Required Materials
- Sermorelin lyophilised powder (5mg or 10mg vial)
- Bacteriostatic water (water containing 0.9% benzyl alcohol)
- Sterile insulin syringe for reconstitution
- Alcohol swabs for sterile technique
Reconstitution Steps
- Allow the Sermorelin vial to reach room temperature before reconstitution
- Draw the appropriate volume of bacteriostatic water into the syringe:
- For 5mg vial: 2mL bacteriostatic water recommended
- For 10mg vial: 2-3mL bacteriostatic water recommended
- Insert the needle into the Sermorelin vial and direct the stream of water down the inside wall of the vial – do not spray directly onto the powder
- Allow the powder to dissolve naturally without shaking. Gentle swirling is acceptable if needed. Complete dissolution typically occurs within a few minutes. The solution should be clear with no visible particles.
- Store reconstituted solution refrigerated at 2-8°C immediately after reconstitution
Concentration Reference Table
| Vial Size | Water Added | Concentration | 200mcg Dose | 500mcg Dose |
|---|---|---|---|---|
| 5mg | 2mL | 2.5mg/mL | 8 units (0.08mL) | 20 units (0.2mL) |
| 10mg | 2mL | 5mg/mL | 4 units (0.04mL) | 10 units (0.1mL) |
| 10mg | 3mL | 3.33mg/mL | 6 units (0.06mL) | 15 units (0.15mL) |
Storage Guidelines
Lyophilised (Powder) Form
- Stable at room temperature for short periods (days to weeks)
- Refrigeration (2-8°C) recommended for storage beyond a few weeks
- Freezing (-20°C) extends stability for long-term storage
- Protect from light and moisture
- Keep vial sealed until ready for reconstitution
Reconstituted Solution
- Must be refrigerated at 2-8°C
- Stable for 3-4 weeks when stored correctly
- Do not freeze after reconstitution – freezing can damage the peptide structure
- Avoid repeated temperature fluctuations
- Use sterile technique when drawing doses to prevent contamination
- If solution becomes cloudy or contains particles, discard and reconstitute a fresh vial
Note: Sermorelin may be somewhat less stable than modified GHRH analogues due to its native sequence. Prompt refrigeration after reconstitution is particularly important.
The Science: GHRH(1-29) Mechanism
GHRH Receptor Activation
Sermorelin acts as an agonist at the growth hormone releasing hormone receptor (GHRHR), a G protein-coupled receptor located on somatotroph cells in the anterior pituitary:
- Binding activates adenylyl cyclase via Gs protein coupling
- Increased intracellular cAMP activates protein kinase A
- Downstream signalling promotes GH gene transcription and GH release
- Calcium influx through voltage-gated channels triggers GH exocytosis
Physiological GH Release Pattern
Unlike direct GH administration, Sermorelin stimulates endogenous GH production:
- Preserves pulsatile GH release patterns
- Maintains negative feedback regulation via IGF-1 and somatostatin
- Avoids supraphysiological GH levels
- Supports natural GH axis homeostasis
DPP-IV Degradation
The short half-life of Sermorelin is due to rapid cleavage by dipeptidyl peptidase-4 (DPP-IV):
- DPP-IV cleaves the N-terminal Tyr-Ala dipeptide
- This cleavage inactivates the peptide
- Modified analogues like CJC-1295 have substitutions at positions 2, 8, 15, and 27 that resist DPP-IV
- Sermorelin's native sequence lacks these protective modifications
Synergy with GHRPs
GHRH and growth hormone releasing peptides (GHRPs) act through distinct mechanisms that produce synergistic effects:
- GHRH (Sermorelin): Stimulates GH synthesis and primes somatotrophs for release
- GHRPs (Ipamorelin, GHRP-6): Amplify GH release through the ghrelin receptor pathway
- Combined effect: Greater GH release than either peptide alone
Frequently Asked Questions
Common questions about Sermorelin research
What is the difference between Sermorelin and CJC-1295 No DAC?
Sermorelin is the native, unmodified GHRH(1-29) sequence identical to human GHRH, while CJC-1295 No DAC (Mod GRF 1-29) has four amino acid substitutions that enhance stability. Sermorelin has a shorter half-life (~10-20 minutes vs ~30 minutes) but has FDA approval history. CJC-1295 No DAC offers longer duration of action and requires less frequent dosing.
Was Sermorelin FDA approved?
Yes. Sermorelin was FDA-approved in the 1990s under the brand name Geref for diagnosis and treatment of growth hormone deficiency, particularly in paediatric populations. This approval provides Sermorelin with more clinical documentation, established safety data, and regulatory history than most research peptides. The drug was later discontinued for commercial reasons, not safety concerns.
Why does Sermorelin have a short half-life?
Sermorelin is rapidly degraded by the DPP-IV (dipeptidyl peptidase-4) enzyme in the bloodstream. Unlike modified analogues such as CJC-1295 which have amino acid substitutions protecting against enzymatic degradation, Sermorelin retains the native human sequence and is therefore subject to natural breakdown processes. This is the trade-off for using the "natural" unmodified sequence.
Why is Sermorelin called GHRH(1-29)?
Full-length GHRH is 44 amino acids, but research determined that only positions 1-29 are required for full biological activity. Positions 30-44 are not necessary for receptor activation. Sermorelin represents this minimal active fragment – a shorter sequence that is simpler to produce while retaining complete biological function.
Can Sermorelin be combined with Ipamorelin?
Yes. Combining a GHRH analogue like Sermorelin with a GHRP like Ipamorelin is a common research protocol. The two peptides work synergistically – GHRH stimulates GH synthesis and release while GHRPs amplify the release signal. However, due to Sermorelin's short half-life, timing coordination may be more challenging compared to using CJC-1295 No DAC with Ipamorelin.
What is the optimal dosing frequency for Sermorelin?
Due to its short half-life of 10-20 minutes, Sermorelin research protocols typically involve 1-3 administrations daily. Common timing is before bed to coincide with natural GH pulsatility, or multiple times daily for more sustained stimulation. The short duration of action means more frequent dosing is required compared to modified GHRH analogues.
What is the molecular weight of Sermorelin?
Sermorelin has a molecular weight of 3357.9 Da (Daltons).
How should Sermorelin be stored?
Lyophilised (powder) form: stable at room temperature short-term; refrigeration (2-8°C) recommended for storage of weeks to months. Reconstituted solution: must be refrigerated (2-8°C), stable for 3-4 weeks. Do not freeze reconstituted solution. Sermorelin is somewhat less stable than modified analogues due to its native sequence.
Technical Specifications
| Systematic Name | GHRH(1-29) |
|---|---|
| Other Names | Sermorelin Acetate, GRF(1-29), Growth Hormone Releasing Factor 1-29, Geref, Gerel |
| Amino Acid Count | 29 |
| Sequence | YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL |
| Molecular Formula | C149H246N44O42S |
| Molecular Weight | 3357.9 Da |
| CAS Number | 86168-78-7 |
| Isoelectric Point | ~10.0 |
| Net Charge (pH 7) | +3 |
| Appearance | White to off-white lyophilised powder |
| Solubility | Freely soluble in water and aqueous buffers |
| Purity (PurposeLabs) | ≥99% (HPLC verified) |
| Storage (Lyophilised) | -20°C long-term, 2-8°C short-term |
| Storage (Reconstituted) | 2-8°C, use within 4-6 weeks |
Quality: Australian University Testing
Why Peptide Quality Matters
The research peptide market contains products of highly variable quality. Independent testing of products from various suppliers has revealed significant issues:
- Purity levels as low as 50% in products claiming "99% purity"
- Incorrect amino acid sequences (entirely wrong peptides)
- Truncated sequences (missing amino acids)
- Bacterial endotoxin contamination
- Oxidised or degraded peptides with reduced activity
Our Testing Protocol
Every batch of Sermorelin from PurposeLabs undergoes comprehensive testing at a leading proteomics laboratory based at an Australian university in Sydney – one of Australia's premier analytical facilities.
Confirms purity levels of ≥99%, identifies any impurities or degradation products.
Verifies exact molecular weight, confirms correct amino acid sequence.
Determines actual peptide content versus salt, moisture, and counter-ions.
Why Australian University Testing?
Our testing partner is an established, verifiable proteomics facility at a major Australian university, with published research credentials, transparent methodology, and no commercial conflict of interest. This contrasts with overseas "certificates of analysis" from unknown or unverifiable laboratories.
Shop Sermorelin
Australian university tested. 99%+ purity verified by HPLC and mass spectrometry. Fast shipping from Sydney.
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References
Key studies and documentation for researchers:
- Thorner MO, et al. "Growth hormone-releasing hormone and growth hormone-releasing peptide as therapeutic agents to enhance growth hormone secretion in disease and aging." Recent Progress in Hormone Research, 1997.
- Walker RF. "Sermorelin: A better approach to management of adult-onset growth hormone insufficiency?" Clinical Interventions in Aging, 2006.
- Prakash A, Goa KL. "Sermorelin: A review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency." BioDrugs, 1999.
- Corpas E, et al. "Human growth hormone and human aging." Endocrine Reviews, 1993.
- Frohman LA, et al. "Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive product cleaved at the NH2 terminus." Journal of Clinical Investigation, 1986.
- Gelato MC, Merriam GR. "Growth hormone releasing hormone." Annual Review of Physiology, 1986.
- FDA. "Geref (Sermorelin Acetate for Injection) Prescribing Information." Serono Laboratories, 1997.
- Svensson J, et al. "Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure." Journal of Clinical Endocrinology and Metabolism, 1998.
Disclaimer
All products sold by PurposeLabs are intended for laboratory and research use only. They are not intended for human or animal consumption. The information provided is for educational purposes only and should not be construed as medical advice. Consult with qualified healthcare professionals for any health-related decisions.
Sermorelin is not approved by the TGA for therapeutic use in Australia. Products are sold strictly for research purposes in accordance with Australian regulations.