What it is
Hexarelin is a synthetic hexapeptide, His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2, an analogue of GHRP-6 with a methylated tryptophan. It was studied widely in human endocrine research in the 1990s as a potent growth hormone secretagogue, and later for direct effects on the heart. It is not an approved medicine in any major market.
How it works
Hexarelin is an agonist at the ghrelin receptor GHS-R1a, releasing growth hormone and, to a lesser degree, prolactin, ACTH and cortisol. In rat hearts it also binds the scavenger receptor CD36, which is proposed to mediate its cardiovascular effects separately from growth hormone release.
Regulatory status
- Cosmetic ingredient
- Research compound
- In clinical trials
- Approved medicine
Not approved as a medicine by the FDA or the EMA. Some are registered in individual countries. Supplied for laboratory research only.
What published research is studying
- Growth hormone release by intravenous, subcutaneous, intranasal and oral routes in healthy adults
- Attenuation of the growth hormone response during months of repeated dosing
- Linear growth in short prepubertal children (small uncontrolled study)
- Acute left ventricular function in growth hormone deficiency and coronary artery disease
Key findings
In 12 healthy young volunteers, intravenous hexarelin released about twice as much growth hormone as the same dose of GHRH (area under the curve 3175 versus 1544), and estimated bioavailability was 77% subcutaneous, 4.8% intranasal and 0.3% oral.
Ghigo E et al., J Clin Endocrinol Metab 1994In adults given twice-daily subcutaneous hexarelin for 16 weeks, the growth hormone response to a test dose fell from 19.1 to 10.5 micrograms per litre-hour and returned to 19.4 four weeks after stopping, while IGF-I, body composition and bone mineral density did not change significantly.
Rahim A et al., J Clin Endocrinol Metab 1998In an uncontrolled study of 8 prepubertal short children given intranasal hexarelin for up to 8 months, mean growth velocity rose from 5.3 to 8.3 cm per year and IGF-I from 10.4 to 14.1 nmol per litre.
Laron Z et al., Clin Endocrinol (Oxf) 1995In 7 men with growth hormone deficiency and 9 controls, a single intravenous dose raised left ventricular ejection fraction from 50% to a peak of 57% and from 63% to 70% respectively, even though growth hormone barely rose in the deficient group.
Bisi G et al., Eur J Pharmacol 1999In 24 men with coronary artery disease undergoing bypass surgery, intravenous hexarelin raised left ventricular ejection fraction, cardiac index and cardiac output for up to 90 minutes, while GHRH, recombinant growth hormone and placebo had no haemodynamic effect.
Broglio F et al., Eur J Pharmacol 2002
What the studies measured
Study durations
- Long-term adult study: 16 weeks of twice-daily subcutaneous dosing, with a retest 4 weeks after stopping (Rahim et al. 1998).
- Paediatric growth study: intranasal dosing three times daily for up to 8 months (Laron et al. 1995).
- Bypass surgery study: haemodynamics followed for 90 minutes after a single intravenous dose (Broglio et al. 2002).
- Rat post-infarction study: 2 weeks of twice-daily dosing starting 4 weeks after coronary ligation (Tivesten et al. 2000).
Endpoints
- Area under the growth hormone curve and bioavailability by route
- Prolactin, ACTH and cortisol responses
- Serum IGF-I and IGFBP-3
- Linear growth velocity in children
- Left ventricular ejection fraction, cardiac index and cardiac output
How strong is the evidence?
Human studies are numerous but small and mostly single-dose; the longest adult study ran 16 weeks and found the growth hormone response partly blunted, and the cardiac data are acute measurements only.
Common questions
Is Hexarelin an approved medicine?
Research compound. Not approved as a medicine by the FDA or the EMA. Some are registered in individual countries. Supplied for laboratory research only.
How much human research is there on Hexarelin?
Human studies are numerous but small and mostly single-dose; the longest adult study ran 16 weeks and found the growth hormone response partly blunted, and the cardiac data are acute measurements only.
Does UU supply Hexarelin?
Yes, as premium-grade research material for laboratory use. Every batch is tested by an independent lab and the certificate of analysis is published.