Objectives: We examined the usability of theophylline extended-release dry syrups, including their powder fluidity and ingestibility using one branded and six generic formulations (formulations A, B, C, D, E, F, and G, respectively). Methods: To evaluate the ease of handling by pharmacists, powder fluidity was evaluated by measuring the repose angle, whereas to determine ingestibility, the viewpoints of patients or caregivers were evaluated using a questionnaire survey. Results and discussion: The repose angles of formulations A, B, C, D, E, and F were approximately 30-40. These formulations had sufficient powder fluidity, indicating the ease of weighing for most pharmacists. However, the repose angle of formulation G was <30. Formulation G had high fluidity, suggesting its high rolling property. Thus, powder handling for formulation G may be more difficult than that for other six formulations. The ingestibility, such as the ease of mixing the dry syrup with water and odor intensity, was different between the formulations. Conclusions: The present study provides useful information for selecting branded or generic theophylline extended-release dry syrups.

Objectives: In this study, we examined the taste and dissolution of theophylline extended-release dry syrups using one branded and six generic formulations. Methods: Healthy volunteers underwent sensory testing to assess the syrup taste. Drug dissolution was examined using in vitro dissolution tests. Results and discussion: Syrup taste, including sweetness, bitterness, and aftertaste, was different between formulations. These differences can likely be attributed to the presence of different pharmaceutical additives between formulations. Our results indicated that syrup aftertaste was dependent on the level of sweetness and bitterness. In addition, dissolution behaviors were different between formulations, suggesting bio-inequivalence between formulations. These differences likely reflect the use of different controlledrelease technologies between formulations. Conclusions: This study provides useful information for selecting branded or generic theophylline extendedrelease dry syrups for individualized treatments.