Formulation and in Vitro Characterization of Floating Tablets of Doxofylline

Abstract

Doxofylline is a novel methylxanthine derivative widely used in the management of bronchial asthma and chronic obstructive pulmonary disease (COPD); however, its short biological half-life necessitates frequent dosing, which may compromise patient compliance. The present study aimed to develop and evaluate gastro-retentive floating tablets of doxofylline to prolong gastric residence time and achieve sustained drug release. Floating tablets were prepared by the direct compression method using hydrophilic polymers such as hydroxypropyl methylcellulose (HPMC K4M) and xanthan gum in varying concentrations, along with sodium bicarbonate and citric acid as gas-generating agents. A total of nine formulations (DXFT1–DXFT9) were developed and evaluated for pre-compression parameters, post-compression characteristics, in vitro buoyancy, swelling behavior, drug content, and in vitro dissolution studies. All formulations exhibited acceptable flow properties and complied with pharmacopeial limits for weight variation, hardness, friability, and drug content. In vitro dissolution studies demonstrated sustained drug release over 12 hours, with formulation DXFT7 showing the most desirable performance, releasing 99.12% of doxofylline at 12 hours along with the shortest floating lag time (8 seconds) and the highest swelling index (90.12%). Drug release kinetics revealed that most formulations followed zero-order release with diffusion-controlled mechanisms, as confirmed by Higuchi and Korsmeyer–Peppas models. Stability studies of the optimized formulation (DXFT7) indicated no significant changes in drug content or buoyancy parameters over three months. Overall, the study concludes that gastro-retentive floating tablets of doxofylline can be successfully formulated to provide prolonged gastric retention and sustained drug release, thereby improving therapeutic efficacy and patient compliance