Influence of formulation variables on plasma growth hormone levels following intranasal administration of growth hormone-releasing peptide in anesthetized rats

Abstract

Growth hormone releasing peptide (GHRP-6) is a synthetic hexapeptide that stimulates the release of growth hormone in several animal species. The feasibility of developing an efficacious intranasal formulation of GHRP-6 is currently under consideration for clinical and commercial applications. In this study, the influence of several formulation variables on growth hormone (GH) release following intranasal administration of GHRP-6 was examined in anesthetized rats. Pharmacologie availability of the peptide was significantly increased by reducing formulation tonicity (hypotonie solution) and incorporation of the preservative benzalkonium chloride. Alteration of formulation pH from 5 to 7 did not demonstrate significant changes in pharmacologie response. GH release decreased as solution viscosity was increased, suggesting a slower rate of peptide absorption across the nasal epithelium.