Method-dependent release kinetics of the sustained-release bolus tablets: a comparative study using daisy II...

This study aimed to compare the dissolution kinetics of sustained-release bolus tablets formulated with different pharmaceutical binders using two systems-the continuous-flow artificial saliva rig and the Ankom Daisy II incubator-to evaluate how the experimental setup influences the interpretation of release behavior and kinetic modeling.

A precise understanding of method-dependent variations is critical for designing reliable sustained-release veterinary formulations. By isolating the effect of the testing environment itself, this study provides a methodological perspective that enhances the predictive accuracy of in vitro systems and supports the development of cost-effective, sustainable approaches in ruminant drug delivery research.

Bolus tablets containing 1% or 2% binder (starch, polyvinylpyrrolidone-PVP, or gum acacia-GA) were tested using a continuous-flow artificial saliva system and the Daisy II incubator with real rumen liquor. Granule morphology, particle size, bulk density, and mechanical strength were characterized. Dissolution kinetics were analyzed through standard models, and the model fits were evaluated using R² and AIC parameters.

The binder composition and test environment had a significant impact on the release profiles. Starch-based bolus tablets dissolved rapidly, PVP showed moderate release, and GA provided prolonged, steady release. The Daisy II incubator produced stronger model correlations, with the 2% GA formulation showing the best fit (R²=0.9909, AIC=-71.08). The higher binder concentrations improved granule compactness and hardness.

The binder type and concentration strongly influence dissolution kinetics, while the testing environment determines release predictability. Gum acacia at 2% concentration achieved the most controlled and stable release, and the Daisy II incubator most accurately simulated rumen conditions for predictive in vitro evaluation.