The applicability of the solid dispersion technique as a method for enhancing the GI absorption of a drug has been explored in order to achieve better dissolution characteristics and better bioavailability for poorly soluble drugs. Fexofenadine hydrochloride is an anti-histaminic agent used in the treatment of rashes and other allergic reactions. The objective of the present work is to improve the oral bioavailability of the poorly permeable Fexofenadine hydrochloride by solid dispersions using spray drying technique. Three formulations (F1, F2, F3) were prepared using Pluronics (Poloxamer188, Poloxamer407 and Cremophor RH 40) as solubilizers, HPMC 5CPS and ethanol as a co-solvent. The prepared formulations were evaluated for compatibility studies by X-ray diffraction, Differential Scanning Calorimetry and Polarized light microscopy. They were then evaluated for drug content, in vitro dissolution studies and in vivo studies were conducted to evaluate the relative bio availability of the drug. XRD studies showed no incompatibility, DSC and PLM studies confirmed the conversion of the drug from crystalline to amorphous form. From the above formulations F1 showed the drug content of 102.4% which complied with the assay limits and a percentage cumulative drug release of 99% which was found the best from all the formulations. In vivo studies revealed that F1 showed 6 fold increases in the relative bioavailability when compared with the pure drug and hence it was considered as the optimized formulation.
