Investigation of the nasal absorption of biosynthetic human growth hormone in sheep—use of a bioadhesive microsphere delivery system

Abstract

This paper describes an assessment of the potential of using bioadhesive microspheres as a nasal delivery system for biosynthetic human growth hormone (hGH) in sheep. The microsphere system was used alone and in combination with a biological surfactant, lysophosphatidylcholine (LPC). For comparison, hGH was also administered nasally as a solution and subcutaneously as an injection. The levels of hGH in the blood samples obtained were determined by an ELISA technique. The hGH was absorbed to only a very low extent when administered as a nasal solution. However, the microsphere delivery system without added enhancer was capable of considerably enhancing the nasal absorption of hGH. A delay in absorption was observed with the microspheres alone, which may be partially due to low aqueous solubility of hGH. Rapid and much higher absorption was observed when hGH was administered in combination with the microspheres and LPC as an enhancer.