Evaluation of Acid-Resistance of Enteric Coated Film and Dissolution of Futraful Enteric Coated Granules

The acid-resistance of enteric coated films and the dissolution pattern of Futraful enteric coated granules were monitored with the U. S.P. dissolution tester in various pH test solutions: a) pH 1.2, 5.0, 6.0, 6.5, and 7.5 test solutions, and b) pH shift test solution in consideration of gastrointestinal coated films were found to show satisfactory acid-resistance in the test solutions at pH 1.2 and 5.0, because the rate of dissolution measured 120 min after the onset of the test was less than 10%. In the pH 6.0 solution. the time required to achieve 100% dissolution rate was 140 min after the onset of the test, whereas the times for the 100% dissolution rate in the pH 6.5 and pH 7.5 test solutions were 50 and 10 min, respectively. For the pH shift solution, the rate of dissolution increased gradually in the first 280 min, and then the rate increased rapidly, when pH of dissolution medium exceeded 6.4. Therefore, the rate of dissolution was slightly low.