"Development of Hollow Floating Microspheres for Enhanced Bioavailability of Drugs with Narrow Absorption Window"

ABSTRACTThe present study was aimed at developing gastroretentive floating microspheres ofPentoxifylline to enhance gastric residence time and provide sustained drug release. Floatingmicrospheres were prepared using Eudragit S100, Eudragit L100, Ethyl Cellulose 100 cps,and Ethyl Cellulose 22 cps as polymeric carriers. Drug–polymer compatibility studies wereperformed using Fourier Transform Infrared Spectroscopy (FTIR) and Differential ScanningCalorimetry (DSC). FTIR spectra confirmed the absence of significant drug–polymerinteractions, while DSC analysis demonstrated the thermal stability of Pentoxifylline withinthe formulated microspheres. Standard calibration curves of Pentoxifylline in 0.1 N HCl andphosphate buffer pH 6.8 exhibited excellent linearity with correlation coefficients (R2) of0.9997 and 0.998, respectively.The prepared microspheres were evaluated for particle size, flow properties, percentage yield,drug entrapment efficiency, buoyancy, surface morphology, and in vitro drug releasebehavior. The particle size of the optimized formulations ranged from 433.09 ± 18.35 to621.45 ± 1.12 μm. Drug entrapment efficiency varied between 55.85 ± 2.3% and 76.57 ±0.3%, while buoyancy values ranged from 80.66 ± 2.08% to 92.37 ± 4.91%, indicatingexcellent floating characteristics. Formulations F8 and F14 demonstrated superiorphysicochemical properties and were selected as optimized batches. Scanning ElectronMicroscopy (SEM) revealed spherical microspheres with smooth surfaces, porous structures,and hollow internal cavities responsible for their floating behavior.In vitro dissolution studies showed sustained drug release over 12 hours. Formulation F8exhibited controlled drug release with 92.75% cumulative drug release, whereas formulationF14 showed 98.91% cumulative drug release in phosphate buffer pH 6.8 after 12 hours.Stability studies conducted at refrigerated, room, and accelerated conditions for six weeksdemonstrated no significant changes in drug content, confirming the stability of the optimizedformulations.