Preparation and release profile of colon-targeting drug delivered as novel One-Step Dry-Coated tablets (OSDrC®)

One-Step Dry-Coated tablets (OSDrC) of a colon-targeting drug were prepared using Eudragit L 100-55 (Eud-L) and chitosan (Chit) as the outer layer. Lag time in the 1st fluid, which simulated the stomach, was affected by differences in the pores occurring as a result of Chit dissolution. The dissolution rate of Chit was decreased by the addition of Eud-L. On the other hand, lag times in phosphate buffer (pH 7.4) simulating the small intestine, and in the 2nd fluid simulating the colon, were affected by differences in the pores occurring as a result of Eud-L dissolution and Chit swelling. The lag time of OSDrC with an outer layer of Eud-L : Chit at a ratio of 3 : 1 in each test medium was greater than the gastric emptying time in the 1st fluid and the small intestine transit time in phosphate buffer (pH 7.4). Furthermore, lag times were similar when test media were changed sequentially. Therefore, it is possible to deliver colon-targeting drugs as OSDrC with an outer layer of Eud-L : Chit at 3 : 1.