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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®.

12Spray-dried formulations offer an attractive delivery system for administration of drug 13 encapsulated into liposomes to the lung, but can suffer from low encapsulation efficiency 14 and poor aerodynamic properties. In this paper the effect of the concentration of the 15 anti-adherent l-leucine was investigated in tandem with the protectants sucrose and 16 trehalose. Two manufacturing methods were compared in terms of their ability to offer small 17 liposomal size, low polydispersity and high encapsulation of the drug indometacin. 18Unexpectedly sucrose offered the best protection to the liposomes during the spray drying 19 process, although formulations containing trehalose formed products with the best powder 20 characteristics for pulmonary delivery; high glass transition (Tg) values, fine powder fraction 21 (FPF) and yield. It was also found that L-leucine contributed positively to the characteristics 22 of the powders, but that it should be used with care as above the optimum concentration of 23 0.5% (w/w) the size and polydispersity index increased significantly for both disaccharide 24formulations. Relating to the method of manufacture it was found that while both the 25 sucrose and trehalose conferred protection on the liposomes produced using either method 26 the ethanol-based proliposome method offered improved drug incorporation and did not 27 suffer from loss of drug caused by dilution effects. 28