There are several modified disintegration test methods for ODTs. In one involving a Petri dish, a given volume of water is used as a medium to mimic physiological conditions. A 10-cm diameter Petri dish is filled with 10 mL of water containing eosin, a water soluble dye. A 10-cm diameter circular tissue paper is placed in the Petri dish. The tablet is carefully placed in the center of the dish and the time for the tablet to completely disintegrate into fine particles is noted as the disintegration time (7). Another popular in vitro method involves a texture analyzer instrument to accurately determine the disintegration time. In this test, a flat-ended cylindrical probe penetrates into the disintegrating tablet immersed in a defined volume of water. As the tablet disintegrates, the instrument is set to maintain a small force for a determined period of time. The plot of the distance traveled by the probe generated with the instrument's software provides a disintegration profile of the tablet as a function of time. The plot facilitates calculation of the start and end point of the tablet disintegration (8, 9). Other modified disintegration test methods for ODTs have been suggested (10–12). None of these methods provides a good in vitro–in vivo correlation (IVIVC) for the disintegration time of an ODT. The main reason is that the experimental conditions used do not simulate the wet tongue surface condition or the amount of saliva in the mouth at a given time. Therefore, it is very desirable to develop a simple alternative method for evaluating the disintegration time of ODTs with these specific attributes:

• Testing conditions closely simulate the physiological conditions in the mouth, specifically the wet tongue surface and the volume of saliva
• Good reproducibility by various operators
• Reasonable IVIVC
• Suitable as a quick screening tool for discerning if a dosage form should be labeled as an ODT.

In this article, the authors propose a new alternative in vitro disintegration test method closely simulating placing an ODT on the tongue as compared with the current USP disintegration test method. We also compared our proprietary ODT formulations with the commercial ODT products using the proposed test. Although we do not have extended in vivo data for all ODTs discussed in this study to fully demonstrated IVIVC, the limited in vivo evaluation results of selected preparations in the study indicated the feasibility and usefulness of the alternative test method.

Materials