Formulation and Evaluation of Floating Natural Polymer-Based Microspheres of Doxycycline Hyclate Using Alginate-Xanthan Gum Binary System

Abstract

Doxycycline hyclate floating microspheres were developed using a sodium alginate–xanthan gum binary matrix to provide gastroretentive sustained drug release. Nine formulations (F1–F9) were prepared by ionotropic gelation with sodium bicarbonate as the buoyancy-generating agent and calcium chloride as the cross-linker. The microspheres were evaluated for practical yield, particle size, entrapment efficiency, buoyancy, drug content, Fourier-transform infrared compatibility, and in vitro drug release. Increasing polymer concentration generally increased particle size, entrapment, and buoyancy while slowing drug release. F8 showed the most suitable overall performance, with a practical yield of 88.26 ± 6.74%, particle size of 604.52 ± 46.38 µm, entrapment efficiency of 86.28 ± 6.32%, buoyancy of 88.64 ± 6.46%, and drug content of 98.52 ± 1.12%. The formulation released 91.64% of doxycycline at 12 h. Its release behaviour was best described by the Korsmeyer–Peppas model and was reported as non-Fickian. F8 also retained acceptable characteristics during 60 days of accelerated storage. The study demonstrated the formulation feasibility of alginate–xanthan gum floating microspheres for sustained doxycycline delivery.