Growth hormone-releasing activity of hexarelin in humans. A dose-response study.
Imbimbo. B P BP; Mant. T T; Edwards. M M; Amin. D D; Dalton. N N; Boutignon. F F; Lenaerts. V V; Wüthrich. P P; Deghenghi. R R
Key Findings
- IV hexarelin produces a rapid, dose‑dependent increase in plasma GH (Cmax up to ~55 ng/mL at 2 µg/kg).
- Peak GH levels occur ~30 minutes after injection; the effect wanes to baseline by ~240 minutes.
- Estimated ED50 for GH release is ~0.5‑0.6 µg/kg, indicating low doses are already effective.
Practical Outcomes
- For biohackers aiming to boost GH, a single IV dose of about 0.5‑1 µg/kg of hexarelin should elicit a substantial hormone surge, while 2 µg/kg approaches the maximal response. The short half‑life means the effect is brief, so timing relative to training or sleep matters. Because the study used IV administration, subcutaneous or oral routes may require different dosing and further safety data.
Summary
Hexarelin is a tiny peptide that makes the pituitary release a burst of growth hormone (GH) when given by IV. In healthy men, doses from 0.5 to 2 µg per kg caused a dose‑dependent rise in GH that peaked around 30 minutes and fell back to baseline within 4 hours. The half‑life of the peptide’s effect is roughly 55 minutes, and the dose that gives half the maximal GH response (ED50) is about 0.5‑0.6 µg/kg.
Abstract
Hexarelin is a new hexapeptide (His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2) that stimulates the release of growth hormone both in vitro and in vivo. In this double-blind, placebo-controlled, rising-dose study we evaluated the growth hormone releasing activity of hexarelin in healthy human subjects. Twelve adult male volunteers received single intravenous boluses of 0.5, 1 and 2.micrograms.kg-1 hexarelin as well as placebo. For safety, drug doses were given in a rising-dose fashion with placebo randomly inserted into the sequence. Plasma growth hormone concentrations increased dose-dependently after the injection of the peptide, peaking at about 30 min and then decreasing to baseline values within 240 min with a half-life of about 55 min. The mean peak plasma growth hormone concentrations (Cmax) were 3.9, 26.9, 52.3, 55.0 ng.ml-1 after 0, 0.5, 1 and 2 micrograms.kg-1, respectively. The corresponding areas under the curve of growth hormone plasma levels from drug injection to 180 min (AUC0-180) were 0.135, 1.412, 2.918 and 3.695 micrograms.min.ml-1. The theoretical maximum response (Emax) and the dose that produces half of the maximum response (ED50) were estimated using logistic regression. The calculated ED50 values were 0.50 and 0.64 microgram.kg-1 for Cmax and AUC0-180, respectively. The corresponding Emaxs were 55.1 ng.ml-1 and 3936 ng.min.ml-1, thus indicating that the effect after the 2 micrograms.kg-1 dose is very close to the maximal response.(ABSTRACT TRUNCATED AT 250 WORDS)
Study Information
pubmed
1994
10.1007/bf00191904