STABILIZATION OF SALMON-CALCITONIN BY POLYSTYRENE NANOPARTICLES HAVING SURFACE HYDROPHILIC POLYMERIC CHAINS, AGAINST ENZYMATIC DEGRADATION

The effect of polystyrene nanoparticles having surface hydrophilic pol ymeric chains on the stability of salmon calcitonin (sCT) in the prese nce of digestive enzymes was investigated in vitro. sCT was protected against pepsin-or trypsin-catalyzed degradation by nanoparticles other than those with surface poly(N-vinylacetamide) chains, which do not e nhance sCT absorption via the gastrointestinal tract in vivo. This sta bilizing effect was affected by the structure of the polymeric chains. Nanoparticles whose surface was covered by poly(N-isopropylacrylamide ) inhibited completely sCT degradation by pepsin. However, they did no t increase sCT stability in the presence of trypsin. The degradation o f sCT by trypsin was inhibited totally by nanoparticles with surface p oly(methacrylic acid) chains, even though sCT stability in the presenc e of pepsin was only slightly improved by them. Nanoparticles having p oly(vinylamine) chains on their surfaces stabilized sCT in the presenc e of either enzyme. It is probable that the stabilizing effect results mainly from the physicochemical interaction between the enzyme and th e nanoparticles. These results demonstrated that nanoparticles have th e property of stabilizing peptide drugs in the gastrointestinal tract, and that this property affects the absorption enhancement of orally a dministered sCT. (C) 1997 Elsevier Science B.V.