PRODUCTION AND CHARACTERIZATION OF ENTERIC BEADS

Enteric beads have been produced using a purely aqueous system. The me thod relies on the precipitation of the enteric polymer hydroxypropylm ethylcellulose phthalate (HPMCP), when its solutions in Bn aqueous alk aline media are dropped into an acidic environment. Two compounds, rib oflavin and riboflavin 5-phosphate, representing a poorly soluble and readily soluble compound respectively, have been successfully incorpor ated in the beads. Drug release studies show that the relatively insol uble compound is well protected in an acidic environment but rapid rel ease occurs when the pH is raised. Solute migration during drying form s a high surface concentration with the soluble material allowing some release in acid.