Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man.
Ghigo. E E; Arvat. E E; Gianotti. L L; Imbimbo. B P BP; Lenaerts. V V; Deghenghi. R R; Camanni. F F
Key Findings
- IV hexarelin (1‑2 µg/kg) produced 2‑3 times more GH than an equivalent dose of GHRH.
- Sub‑cutaneous injection had good bioavailability (~77%) and a clear dose‑response.
- Intranasal delivery gave modest GH release with low bioavailability (~5%).
- Oral doses (20‑40 mg) showed a dose‑related GH rise but very poor bioavailability (~0.3%).
Practical Outcomes
- For biohackers aiming to boost GH, the most reliable method is sub‑cutaneous injection of about 1.5‑3 µg/kg, which offers high bioavailability and a strong, reproducible response. Intranasal sprays can be used for a milder effect without needles, but expect only ~5% of the dose to reach circulation. Oral tablets are largely ineffective unless taken in very high doses, making them impractical for regular use.
Summary
Hexarelin is a synthetic six‑amino‑acid peptide that strongly stimulates growth hormone (GH) release in healthy people. It works best when given by injection (IV or sub‑cut), but also has measurable effects when taken as a nasal spray or even a pill, though the oral route is barely effective. Compared to the natural GH‑releasing hormone, hexarelin produces about twice as much GH at the same dose.
Abstract
We evaluated the GH-releasing activity of hexarelin, a new synthetic hexapeptide, after i.v. (1 and 2 micrograms/kg), sc (1.5 and 3 micrograms/kg), intranasal (20 micrograms/kg), and oral (po; 20 and 40 mg) administration to 12 healthy young volunteers. Reference treatments were i.v. saline and GH-releasing hormone (GHRH; 1 microgram/kg). GH release (mean +/- SEM) after the i.v. dose of 1 microgram/kg hexarelin [area under the curve (AUC), 3175 +/- 506 micrograms/min.L] was about 2 times higher than that induced by 1 microgram/kg GHRH (AUC, 1544 +/- 161 micrograms/min.L; P < 0.001). Hexarelin (2 micrograms/kg, i.v.) elicited a further increase in GH levels (AUC, 4422 +/- 626 micrograms/min.L) compared to the 1 microgram/kg dose. The GH response to 2 micrograms/kg hexarelin, i.v., was very reproducible (AUC, 4016 +/- 563 vs. 3959 +/- 803 micrograms/min.L). The sc administration of hexarelin produced a dose-dependent GH response (AUC, 3180 +/- 392 and 4459 +/- 566 micrograms.min.L with 1.5 and 3 micrograms/kg, respectively). Intranasal administration of 20 micrograms/kg hexarelin induced GH release (AUC, 2642 +/- 452 micrograms/min.L) similar to that caused by 1 microgram/kg, i.v. Twenty and 40 mg hexarelin, po, produced a dose-related increase in GH levels (AUC, 2278 +/- 442 and 4079 +/- 514 micrograms/min.L). Biological bioavailabilities were 77.0 +/- 10.5%, 4.8 +/- 0.9%, and 0.3 +/- 0.1% for the sc, intranasal, and po routes, respectively. This study shows that the GH response to hexarelin administered by the i.v. route has a limited variability and is superior to the response to GHRH. The GH-releasing activity appeared to be dose dependent. Thus, hexarelin could be clinically useful to stimulate GH secretion in humans.
Study Information
pubmed
1994
10.1210/jcem.78.3.8126144