The purpose of this study was to develop and test a novel and simple method for evaluating the disintegration time of rapidly disintegrating tablets (RDTs) in vitro, since the conventional disintegration test described in the pharmacopoeia produces poor results due to the difference of its environmental conditions from those of an actual oral cavity. Six RDTs prepared in our laboratory and 5 types of commercial RDTs were used as model formulations. Using our original apparatus, a good correlation was observed between in vivo and in vitro disintegration times by adjusting the height from which the solution was dropped to 8 cm and the weight of the load to 10 or 20 g. Properties of RDTs, such as the pattern of their disintegrating process, can be assessed by verifying the load. These findings confirmed that our proposed method for an in vitro disintegration test apparatus is an excellent one for estimating disintegration time and the disintegration profile of RDTs.
Key words rapidly disintegrating tablets; disintegration test; disintegration time; disintegrating profileIn recent years, several types of dosage forms have been developed for a variety of demands such as improvement in patient compliance. Among them, rapidly disintegrating tablets (RDTs) are a convenient dosage form for elderly people or children who have difficulty swallowing conventional tablets or capsules, as RDTs are disintegrated within several tens of seconds with a small amount of saliva in the oral cavity. [1][2][3][4][5] RDTs are also applicable for drug administration through an enteral feeding tube without crushing the tablets, since RDTs are easily dispersible into an aqueous solution.Two main factors are important for disintegration of RDTs in the oral cavity: the absorption of saliva and the destruction by external pressure between the tongue and the upper palate. Evaluating the disintegration profile of RDTs is important in their development and quality assurance. Many studies have recorded disintegration times in the human mouth.6,7) However, evaluating the disintegration time in the human mouth entails the following problems: 1) the disintegration time in the mouth tends to depend on oral environments and conditions, and thus, results are scattered; and 2) the human sensory test has risks for healthy volunteers. Many other disintegration test methods have been proposed such as a modified disintegration test and a modified dissolution test.8,9) However, the evaluation of various RDTs using these methods is ultimately flawed because their environments differ from that of the oral cavity. Some researchers reported disintegration test for RDTs using a loading apparatus.10-12) These apparatuses still have some problems, such as wetting of the tablet only on one side and the requirement of a special apparatus such as a texture analyzer to load.The purpose of this study was to develop a novel and simple method to simulate the disintegration time and profiles of RDTs in the oral cavity. The developed method has several advantages: 1) it invo...