Dual-Responsive Ion-Exchange Resin Encapsulated Atomoxetine Hydrochloride for Taste-Masking and Biphasic Release

Atomoxetine hydrochloride (ATH) is a first-line medication used to treat Attention Deficit Hyperactivity Disorder (ADHD) in children. However, it poses challenges such as a bitter taste and difficulties in dose adjustment. While once-daily administration may result in excessive drug exposure, twice-daily dosing improves plasma drug concentration stability but can reduce patient compliance, especially in school-aged children. To address these challenges, a novel strategy was proposed that involves encapsulating ATH into ion exchange resins (IERs) (referred to as ATH@IER). The pH-responsive release of ATH from the ATH@IER exhibited a limited release rate in neutral conditions, effectively masking the bitter taste, which was evaluated through electronic tongue analysis. The cation-responsive release of ATH from the ATH@IER demonstrated immediate-release (IR) property, which was combined with Eudragit^® RS100 coated ATH@IER (ATH@MC) to establish a biphasic release system. ATH orally disintegrating tablets (ATH ODT) were manufactured using a composition of ATH@IER and ATH@MC (40:60, w/w), along with other excipients. Pharmacokinetic studies demonstrated that a single dose of ATH ODT produced a bimodal plasma concentration, resulting in a two-fold decrease in peak concentration (C_max) while maintaining an unchanged area under the drug concentration-time curve (AUC_0-t) compared to the commercial ATH oral solution administered once. Notably, the plasma drug concentration of ATH ODT remained steadier than that of the commercial product when administered twice. In conclusion, ATH ODT represents a promising formulation that effectively masks bitter taste and provides biphasic release for the treatment of ADHD.