INFLUENCE OF FORMULATION VARIABLES ON PLASMA GROWTH-HORMONE LEVELS FOLLOWING INTRANASAL ADMINISTRATION OF GROWTH HORMONE-RELEASING PEPTIDE IN ANESTHETIZED RATS

Growth hormone releasing peptide (GHRP-6) is a synthetic hexapeptide t hat 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 var iables on growth hormone (GH) release following intranasal administrat ion of GHRP-6 was examined in anesthetized rats. Pharmacologic availab ility of the peptide was significantly increased by reducing formulati on tonicity (hypotonic solution) and incorporation of the preservative benzalkonium chloride. Alteration of formulation pH from 5 to 7 did n ot demonstrate significant changes in pharmacologic response. GH relea se decreased as solution viscosity was increased, suggesting a slower rate of peptide absorption across the nasal epithelium.