TY - JOUR AU - Okunlola, Adenike AU - Owojori, Temitope PY - 2016 TI - Impact of degree of substitution of acetylated Ofada rice starch polymer on the release properties of nimesulide microspheres JF - Journal of Excipients and Food Chemicals; Vol 7 No 1 (2016) KW - Acetylation; Degree of substitution; factorial design; Nimesulide; Ofada rice starch N2 - Nimesulide microspheres were prepared by the quasi-emulsion solvent diffusion method, using acetylated starches of the indigenous Ofada rice ( Oryza glaberrima Steud) with degrees of substitution (DS) 1.42 and 2.62. Full 2 3 factorial experimental design was performed using DS ( X 1 ), drug: polymer ratio ( X 2 ) and polymer concentration ( X 3 ) as independent factors; size, entrapment, swelling and time taken for 80% drug release (t 80 ) were the dependent variables.Contour plots were generated and data from in vitro release studies were fitted to various kinetic models. Nimesulide microspheres were near -spherical, with size 50.91±16.22 to 74.24 ± 24.73 µm for microspheres containing starch DS 1.42 and 21.05±4.25 to 46.10±3.85 µm for starch DS 2.62. Drug entrapment was 56.75±0.45 to 98.28±2.30 %. DS had the most influence on size, swelling and dissolution time (p = 0.01) and this was confirmed from the contour plots. The interaction between factors DS and drug: polymer ratio (X 1 X 2 ) had the highest influence on microsphere properties (p = 0.04). Drug release fitted into first order, Higuchi and Korsmeyer models.  Acetylated starch of Ofada rice DS 2.62 was found more suitable for the formulation of microspheres with reduced size, and swelling, higher entrapment and prolonged drug release.  UR - https://ojs.abo.fi/ojs/index.php/jefc/article/view/1392