PRODUCTION AND CHARACTERIZATION OF ENTERIC BEADS

Enteric beads have been produced using a purely aqueous system. The method relies on the precipitation of the enteric polymer hydroxypropylmethylcellulose phthalate (HPMCP), when its solutions in Bn aqueous alkaline media are dropped into an acidic environment. Two compounds, riboflavin and riboflavin 5-phosphate, representing a poorly soluble and readily soluble compound respectively, have been successfully incorporated in the beads. Drug release studies show that the relatively insoluble compound is well protected in an acidic environment but rapid release occurs when the pH is raised. Solute migration during drying forms a high surface concentration with the soluble material allowing some release in acid.