Evaluation of the compression characteristics and physical properties of the newly invented one-step dry-coated tablets.

This study was conducted in order to clarify the compression characteristics, and to confirm the superiority of the physical properties, of the newly invented One-Step DRy-Coated tablets (OSDRC). We compared both the compression characteristics and the physical properties of OSDRC with those of physical-mixture tablets (PM) that were prepared with the same ingredients, quantity, and compression pressures. We selected potassium chloride (KCl) and acetaminophen (AAP) as the model drugs, since the former is known for its appropriate compression characteristics and the latter for its brittleness. The advantage of OSDRC is that they are capable of maintaining any kind of drug in their core, because the core is tightly surrounded by the outer layer, even when the drugs in the core have poor compression characteristics, which causes difficulties in forming a solid core tablet using conventional dry-coated tablet methods. The radial tensile strength of OSDRC was the same as, or superior to, that of PM containing of AAP. The results were in accordance with the compression process analysis performed according to Kawakita's equation. The friability of OSDRC was also superior to that of PM. These preferable characteristics were attributable to the high intensity of the OSDRC outer layer surface in comparison to that of PM. It was difficult to clarify the difference between OSDRC and PM in their physical properties when KCl was applied, since the tabletability of the whole tablet was high due to KCl's physical properties. The OSDRC containing AAP in their cores showed a controlled release pattern, though no other materials that have been known to influence drug release was present. It was considered that this controlled release pattern was caused by a reduced AAP particle surface area due to compression. It was confirmed with these experiments that the compression characteristics and the physical properties of AAP-OSDRC were superior to those of PM. These results indicated that it is possible to produce tablets that have materials with poor compression characteristics in the core portion, and high tabletability materials for the outer layers. In other words, it is possible to produce capsule-like tablets using the OSDRC compression method.