In order to enhance the delivery of drugs with limited absorption due to poor solubility/dissolution, approaches are being developed to improve the dissolution rates and solubility of drug molecules. These approaches include identification of water-soluble salts of parent drugs, preparation of stable amorphous drug formulations, inclusion of solubility-enhancing agents in the dosage form, and particle size reduction. Technologies to reduce drug particle size to sub-micrometer range are being applied to product development more frequently. Electrospinning is being considered as one of the technologies which can produce nanosized drugs incorporated in polymeric nanofibers. In vitro and in vivo studies have demonstrated that the release rates of drugs from these nanofiber formulations are enhanced compared to those from original drug substance. This technology has the potential to be used for enhancing the oral delivery of poorly soluble drugs.

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A series of novel thermotropic block copolyesters based on poly(tetramethy1ene 4,4'-(terephthaloy1dioxy)dibenzoates) (Triad-4) and poly(buty1ene terephthalate) (PBT) were synthesized by high-temperature polycondensation in solution to minimize sequence randomization by transesterification. Three different schemes were examined in order to facilitate the systematic variation of block length and block content. All reaction schemes predict the formation of tetramethylene 4-(terephthaloy1oxy)benzoate (Diad-4) moieties in the block copolymers. Diad-4 homopolymer and ita block copolymer with PBT were synthesized and characterized and were compared to Triad-4-co-PBT block copolymers. The compositions of all block copolymers were determined from IH NMR spectroscopy. The DSC thermogram of a typical block copolymer revealed the presence of two major melting transitions, corresponding to the separate melting of PBT and Triad4 domains. During the cooling cycle separate and distinct crystallization exotherms were also observed. Polarizing optical microscopy showed that all block copolymers were liquid crystalline and exhibited a nematic texture.

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