Evaluation of novel one-step dry-coated tablets as a platform for delayed-release tablets.

Using a novel one-step dry-coated tablets (OSDRC) manufacturing method, which we have recently invented, we evaluated the possibility of its application to delayed-release tablets. The manufacturing method for OSDRC is different from conventional methods in that dry-coated tablets can be made with only one process. One of the major advantages of OSDRC is that we can expect to produce tablets, which always contain the core exactly in the center of the whole tablet. This characteristic means that the thickness of outer layer is constantly uniform, which is difficult to achieve with the conventional dry-coated tablets. The effects of different outer layer thicknesses and various compression pressures were examined using HPMC to evaluate OSDRC applicability to delayed-release tablets. We proved that the lag-time can be adjusted only by changing the thickness of the outer layer without any arrangement of its ingredients, which is quite different from the conventional approach. Further, the lag-time of each OSDRC prepared in the 100-200 MPa compression pressure range was almost the same, indicating the lag-time of OSDRC under these compression pressures does not vary. The release rate of the drug (acetaminophen) from the OSDRC with 0.5 and 1.0 mm outer layer thicknesses was almost constant independent of compression pressure. On the other hand, the release rate of the OSDRC with a 2.0 mm outer layer thickness was delayed compared to that of other thicknesses. That is, in the tablets with 2.0 mm outer layer thickness, the release rate declined since its outer layer thickness was sufficient to form a gel-layer. In conclusion, OSDRC could be a platform for delayed-release tablets, which do not utilize the conventional method used for dry-coated tablets.