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The aim of this research was to investigate the technique for preparation of coated valproic acid and sodium valproate sustained-release matrix tablets. Different diluents were tested and selected as the effective absorbent for oily valproic acid. Effect of the amount of absorbent and hydroxypropylmethylcellulose on drug release from valproic acid-sodium valproate matrix tablets prepared with wet granulation technique was evaluated in pH change system. Colloidal silicon dioxide effectively adsorbed liquid valproic acid during wet granulation and granule preparation. The amounts of colloidal silicon dioxide and hydroxypropylmethylcellulose employed in tablet formulations affected drug release from the tablets. The drug release was prominently sustained for over 12 h using hydroxypropylmethylcellulose-based hydrophilic matrix system. The mechanism of drug release through the matrix polymer was a diffusion control. The drug release profile of the developed matrix tablet was similar to Depakine Chrono®, providing the values of similarity factor (f2) and difference factor (f1) of 85.56 and 2.37, respectively. Eudragit® L 30 D-55 was used as effective subcoating material for core matrix tablets before over coating with hydroxypropylmethylcellulose film with organic base solvent. Drug release profile of coated matrix tablet was almost similar to that of Depakine Chrono®.

Poly(L-lactic acid) (PLA) is a biodegradable and bioabsorbable polymer which has many potential uses. However, PLA shows the poor toughness, slow degradation rate and relatively hydrophobic.Poly(ethylene glycol) (PEG) is widely used as a plasticizer and of great interest because it presents outstanding properties, e.g. solubility in water and also in some organic solvents, lack of toxicity and absence of antigenicity and immunogenicity, which are essential for biomedical applications. The aim of this study was to investigate the ability of high amount PEG 400 to improve the characteristics of PLA matrix film. PLA matrix films were prepared using a solvent casting method and their various properties were investigated. Mechanical properties were determined with texture analyzer. Contact angle and surface free energy were measured using the goniometer. From the mechanical properties evaluated (tensile strength (TS) and elongation at break (E)), all plasticized PLA films exhibited the softer behavior and the plasticized PLA films with150 % PEG 400 indicated the higher % elongation at break than pure PLA, significantly. The contact angle and surface free energy values indicated that PEG 400 could improve the wettability of solventsand also increase % water sorption and % weight loss with as dose dependent.Surprisingly, SEM photographs revealed more porous structure as the higher amount PEG 400 was incorporated in PLA film. This porous structure and density of developed plasticized PLA film could be modified with temperature change technique. Parameters affecting the 3-D porous plasticized PLA matrix were revealed in this study. The optimum condition for producing the continuous 3-D porous plasticized PLA matrix was obtained. This porous topography in PLA matrix film will be applied further as material in tissue engineering and drug delivery systems.