Bottom line
Hexarelin (INN: examorelin) is a synthetic hexapeptide GH secretagogue developed as a more potent and metabolically stable analog of GHRP-6, distinguished by a D-2-methyltryptophan substitution at position 2. It advanced to Phase II trials for GH deficiency and heart failure but was discontinued before Phase III. Hexarelin activates both GHS-R1a and CD36, giving it a unique dual-receptor pharmacology among GHRPs. It also stimulates ACTH, cortisol, and prolactin more than GHRP-2 or ipamorelin. The published human evidence base consists of small endocrine pharmacology studies (each n < 30) and no efficacy trial.
Identity and composition
| Field | Verified information |
|---|---|
| Preferred name | Hexarelin |
| Key aliases | Examorelin (INN), MF-6003 |
| Molecular/sequence identity | Hexapeptide: His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH2 (where D-2-Me-Trp = D-2-methyltryptophan) |
| Modifications/form | D-2-methyltryptophan at position 2 (vs D-Trp in GHRP-6); D-Phe at position 5; C-terminal amidation |
| Stable identifiers | PubChem CID: 6918297; CAS: 140703-51-1; MW ~887 Da |
| Identity caveats | Distinguished from GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) by the 2-methyl substitution on D-Trp². Hexarelin is not interchangeable with GHRP-6 or GHRP-2. The INN examorelin is rarely used in the research chemical market. |
Development and approval status
| Jurisdiction | Status and indication | Product/source | As of |
|---|---|---|---|
| US (FDA) | No approved indication; development discontinued | — | 2026-08-06 |
| EU (EMA) | No marketing authorization | — | 2026-08-06 |
| Registers reviewed | No FDA-approved product or EMA-authorized medicine identified; status elsewhere requires a current national-register check | — | 2026-08-06 |
Mechanism and pharmacology
Hexarelin is a potent GHS-R1a (ghrelin receptor) agonist, stimulating GH release from pituitary somatotrophs. Unlike ipamorelin, hexarelin also binds CD36, a scavenger receptor expressed on cardiomyocytes, macrophages, and vascular endothelium, mediating GH-independent cardiac effects. The D-2-Me-Trp substitution confers enhanced metabolic stability relative to GHRP-6. Hexarelin significantly elevates ACTH, cortisol, and prolactin.
Evidence by claim
| Claim/indication | Stage | Grade | Best human evidence | Main result | Important limitations |
|---|---|---|---|---|---|
| GH release (acute pharmacology) | Phase I | C | Imbimbo et al., Eur J Clin Pharmacol 1994; multiple small human studies | Dose-dependent GH elevation | Pharmacology only; each n < 30 |
| GH deficiency diagnosis | Phase II | D | Laron et al., 1995; intranasal hexarelin in short children | GH secretion measurable | Small N; diagnostic only |
| Congestive heart failure | Phase II (discontinued) | D | Preclinical cardiac data; no published human efficacy trial | CD36 binding shown in animal models | No human efficacy data published |
| Body composition | Marketing | E | No controlled human trials | No adequate evidence | Marketing extrapolation only |
Key studies
| Study | Design/population | Exposure studied | Endpoints and result | Limitations |
|---|---|---|---|---|
| Imbimbo et al., Eur J Clin Pharmacol 1994; PMID: 7957536 | PK/PD study; healthy adults | SC, IV, intranasal hexarelin | Dose-dependent GH release; bioavailability ~77% SC; half-life ~55 min | Small N; pharmacology only |
| Arvat et al., J Clin Endocrinol Metab 1995 | Crossover; healthy adults | IV hexarelin vs GHRH | GH, ACTH, cortisol, prolactin responses characterized | Small; acute only |
| Laron Z et al., 1995 | Children with short stature | Intranasal hexarelin | GH secretion measurable | Small; not confirmatory efficacy |
Dose and administration evidence
Approved labeled regimen
Not applicable.
Studied regimens (not recommendations)
No established or recommended human dose. In published human studies: SC doses of approximately 1.5–2.0 mcg/kg; IV 1–2 mcg/kg.
What is not established
Effective therapeutic dose for any indication
Long-term dosing safety or efficacy
Any dosing protocol validated beyond acute administration
Appropriate frequency of administration
Safety
Established label risks
No approved label exists.
Human-study signals
Hexarelin elevates cortisol and prolactin more than most other GHRPs. GH response attenuates within days of daily dosing (receptor desensitization). In small Phase I/II studies (total published N < 100), acute tolerability was acceptable.
Unknowns and product-quality risks
No long-term safety data. Receptor desensitization suggests chronic use would have diminishing efficacy. CD36-mediated cardiac effects have not been evaluated for safety in humans. Research-grade material is unregulated; DAC-like modifications are often falsely claimed by vendors.
Interactions and special populations
No human drug-interaction data exist. Contraindications theoretically include active malignancy, cardiovascular disease, uncontrolled hypertension, diabetes, pregnancy, and lactation.
Regulatory, compounding, and sport notes
Hexarelin (examorelin) is prohibited by WADA under S2.2.4. No FDA-approved product was identified as of 2026-08-06. US compounding eligibility or legality cannot be inferred from market listings and requires a current substance-, facility-, prescription-, and product-specific assessment under sections 503A/503B.
Evidence gaps
No completed Phase II efficacy trial with published results
No Phase III program
No long-term safety data in any population
No human cardiovascular efficacy trial
No dose-ranging for chronic use
No pharmacokinetic data in women, elderly, or disease states
Search notes
Databases and registries: PubMed, ClinicalTrials.gov, FDA Drugs@FDA, PubChem
Search terms: "hexarelin", "examorelin", "MF-6003", "GHRP hexarelin"
Last searched: 2026-08-06
Inclusion emphasis: Primary human data; peer-reviewed endocrine studies; regulatory documents
Sources
Imbimbo BP et al. Growth hormone-releasing activity of hexarelin in humans. Eur J Clin Pharmacol. 1994;46(5):421-425. https://pubmed.ncbi.nlm.nih.gov/7957536/
Arvat E et al. Comparison of hexarelin and GHRH on GH, ACTH, cortisol and prolactin. J Clin Endocrinol Metab. 1995. https://pubmed.ncbi.nlm.nih.gov/7714095/
Bodart V et al. CD36 is a binding site for hexarelin. Circ Res. 2002;90(8). https://pubmed.ncbi.nlm.nih.gov/11988492/
WADA Prohibited List 2026. https://www.wada-ama.org/en/prohibited-list
PubChem CID 6918297. Hexarelin. https://pubchem.ncbi.nlm.nih.gov/compound/6918297
FDA. Drugs@FDA. No listing for hexarelin. https://www.accessdata.fda.gov/scripts/cder/daf/