A tiny peptide called hexarelin, when sprayed into the nose three times a day at about 60 µg per kilogram of body weight, raised IGF‑1 levels and sped up linear growth in short kids without obvious side‑effects, showing it can act like a growth‑hormone releaser when taken nasally.

Hexarelin is a recently synthesized small growth hormone releasing peptide (GHRP) (His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys- NH2). It is active by intravenous, oral and intranasal administration in animals and man. The aim of this study was to find out whether long-term administration of this peptide would promote growth in short children. Intranasal hexarelin was administered in a dose of 60 micrograms/kg thrice daily to 8 prepubertal short children aged 4-11.6 years for periods of up to 8 months. Hexarelin treatment stimulated insulin-like growth factor-I (IGF-I) secretion raising the level from 10.4 +/- 3.9 (SD) to 14.1 +/- 4.6 nmol/l (P < 0.004). The rise in IGF-I led to a significant increase in the mean (+/- SD) linear growth velocity from 5.3 +/- 0.8 to 8.3 +/- 1.7 cm/year (P < 0.0001). There was also a significant decrease in skinfold thickness despite increase in body weight and an increase in head circumference. Additional findings were a rise in serum phosphate from 1.5 +/- 0.1 to 1.8 +/- 0.1 mmol/l (P < 0.004) and of alkaline phosphatase from 219 +/- 74 to 261 +/- 75 U/l (P < 0.05). The long-term GH/IGF-I stimulating, anabolic and growth promoting effects achieved by intranasal administration of this hexapeptide, seemingly without undesirable side-effects, suggests clinical potential for this new class of drugs.