1998 Volume 35 Issue 6 Pages 439-442
A new aqueous polymeric enteric coating system was developed with the aqueous dispersions of hydroxypropylmethylcellulose phthalate (HPMCP) nanoparticles prepared by the emulsion solvent diffusion method. The average diameter of HPMCP nanoparticles (pseudolatex) was 120nm with a polydispersity index of 0.172. The enteric coating of riboflavin granules with the present system was successfully conducted using a fluidized bed coating.
To obtain satisfactory acid resistance (i. e. enteric properties) of the coated granules with HPMCP nanoparticles, the coating film thickness needed to be 10μm or more. The coating amount required to obtain satisfactory acid resistance of the coated granules with HPMCP nanoparticles was found to be much smaller than with the pulverized HPMCP available on the market. This is because the coating film with HPMCP nanoparticles was closer and more uniform than that with pulverized HPMCP particles. The equation to predict the amount of polymer required for satisfactory enteric coating was proposed in the present study.
