IN-VIVO AND IN-VITRO EVALUATION OF 4 DIFFERENT AQUEOUS POLYMERIC DISPERSIONS FOR PRODUCING AN ENTERIC-COATED TABLET

The human in vivo single dose pharmacokinetics of a model tablet coated with four different aqueous enteric coat polymeric dispersions were assessed, using an uncoated tablet core as a-control. In vitro release properties were also investigated. The four aqueous polymeric dispersions were cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), 50:50 CAP/CAT, and methacrylic acid copolymer. Naproxen sodium was the model drug. Polymer pH dissolution profiles showed that CAT dissolved at the most acidic pH, followed by 50:50 CAP/CAT, and then by CAP and methacrylic acid copolymer. It was found that all of the enteric coat formulations performed satisfactorily during initial in vitro disintegration and dissolution testing. Human in vivo testing showed that all of the enteric coat formulations were bioequivalent to the standard (uncoated) tablet with respect to AUG, half-life, and C-max. However, the CAP, 50:50 CAP/CAT, and methacrylic acid copolymer formulations had T-max values that were significantly longer than the uncoated tablet (p < 0.001), while the CAT formulation was statistically similar to the standard tablet (p = 0.130). Therefore, the CAT formulation may not have adequately protected the tablet in the upper gastrointestinal tract. After being stored for 9 months at room temperature, none of the enteric coat formulations studied passed USP disintegration testing.