Poly(palmitoyl-L-hydroxyproline ester) microspheres as potential oral controlled drug delivery system

A new type of carrier using poly(palmitoyl-L-hydroxyproline ester) (PPH) [IUPAC name: poly((l-palmitoyl-4,2-pyrrolidinediyl)carbonyloxy)], a poly(amino acid) is described. The polymer is synthesized by conventional method and the microspheres were prepared by solvent evaporation technique for application in drug delivery system. Microspheres with different sizes were prepared by varying certain formulation and technological parameters and their distributive stabilities under physiological conditions were studied. The microspheres were characterized by DSC, optical and laser particle size analysis. A model drug, rifampicin (antituberculosis drug) was entrapped in the microspheres and the in vitro release studies were performed in pH 7.4 and pH 1.5 buffer media. The pH value seemed to have some influence on the dissolution rate of the rifampicin-containing microspheres. Dissolution experiments using rifampicin indicated the possibility of using PPH microspheres with other hydrophobic drugs.