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Item Development of ibuprofen microspheres using acetylated plantain starches as polymer for sustained release(Springer Publications, 2018) Okunlola, A.; Ghomorai, T.Ibuprofen has a short half-life (1–3 h) and istypically administered 3–4 times daily with subsequent adverse side effects. A good approach to reduce these effects is the preparation of sustained-release formulations of ibuprofen. Acetylated starches form water-insoluble, acid-resistant films that can substantially retard drug release. Ibuprofen microspheres were prepared using acetylated plantain starch as sustained-release polymer. Starch obtained from unripe plantain (Musa Paradisiaca normalis) were acetylated using acetic anhydride with pyridine (degrees of substitution, DS 1.5 ± 0.05 and 2.20 ± 0.10). The starches were characterized using morphology, crystallinity, swelling, density and flow properties. Ibuprofen microspheres were prepared by quasi-emulsion solvent diffusion method, using acetylated plantain starches DS 1.5 and 2.20 in comparison to Eudragit S100. Full 32 factorial experimental design was performed with polymer type (X1), polymer: drug ratio (X2) as independent factors; microsphere size, entrapment, and quantity of drug released in 12 h (Q12) were dependent variables. The data from in vitro drug release were fitted to various kinetic models. Acetylation resulted in larger starch aggregates with disruption in crystalline order. Ibuprofen microspheres were spherical with size 5.50 ± 4.00–129.90 ± 12.97μm. Drug entrapment was 43.92 ± 4.00–79.91 ± 6.15%. Values of Q12 ranged from 20.10 ± 0.55 to 54.00 ± 5.71%. Interaction between variables X1 and X2 had positive effects on size and entrapment. Drug release fitted zero order, first order and Baker-Lonsdale kinetic models. Acetylated starch of plantain with DS 2.20 was suitable as a polymer at polymer:drug ratio 4:1 for the formulation of ibuprofen microspheres with prolonged drug release.Item Development of repaglinide microspheres using novel acetylatedstarches of bitter and Chinese yams as polymers(Elsevier B.V., 2016) Okunlola, A.; Adebayo, A. S.; Adeyeye, M. C.Tropical starches from Dioscorea dumetorum (bitter) and Dioscorea oppositifolia (Chinese) yams were acetylated with acetic anhydride in pyridine medium and utilized as polymers for the delivery of repaglinide in microsphere formulations in comparison to ethyl cellulose. Acetylated starches of bitter and Chinese yams with degrees of substitution of 2.56 and 2.70 respectively were obtained. Acetylation was confirmed by FTIR, 1 H NMR spectroscopy. A 32 factorial experimental design was performed using polymer type and drug-polymer ratio as independent variables. Particle size, swelling, entrapment and time for 50% drug release (t50) were dependent variables. Contour plots showed the relationship between the independent factors and the response variables. All variables except swelling increased with drug: polymer ratio. Entrapment efficiency was generally in the rank of Bitter yam > Ethyl cellulose > Chinese yam. Repaglinide microspheres had size 50 ± 4.00 to 350 ± 18.10μm, entrapment efficiency 75.30 ± 3.03 to 93.10 ± 2.75% and t50 3.20 ± 0.42 to 7.20 ± 0.55h. Bitter yam starch gave longer dissolution times than Chinese yam starch at all drug-polymer ratios. Drug release fitted Korsmeyer-Peppas and Hopfenberg models. Acety-lated bitter and Chinese yam starches were found suitable as polymers to prolong release of repaglinidein microsphere formulations.Item Impact of degree of substitution of acetylated ofada rice starch polymer on the release properties of nimesulide microspheres(IPEC-Americas Inc, 2016) Okunlola, A.; Owojori, T.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. A full 23 factorial experimental design was performed using DS (X1), drug:polymer ratio (X2) and polymer concentration (X3) as independent factors; size, entrapment, swelling and time taken for 80% drug release (t80) were the dependent variables. Contour plots were generated and data from the in vitro release studies were fitted to various kinetic models. Nimesulide microspheres were near spherical, sizes varying from 50.91±16.22 to 74.24±24.73μm for microspheres containing starch DS 1.42 and from 21.05±4.25 to 46.10±3.85μm for starch DS 2.62. Drug entrapment was 56.75±0.45 to 98.28±2.30%. DS had the greatest effect on the size, swelling and dissolution time (p = 0.01) which was confirmed by the contour plots. The interaction between factors DS and drug:polymer ratio (X1X2) had the greatest effect on the microsphere properties (p = 0.04). Drug release was fitted into the First Order, Higuchi and Korsmeyer models. Acetylated starch of Ofada rice DS 2.62 was found more suitable for the formulation of microspheres because of reduced size and swelling, higher entrapment and prolonged drug release.Item Acetylated starch of ofada rice as a sustained release polymer in microsphere formulations of repaglinide(Pharmaceutical Society of Nigeria, 2015) Okunlola, A.; Ogunkoya, T. O.Background: Acetylated starches with degrees of substitution (DS) of > 2 have been found suitable for sustained release applications because of their hydrophobic nature and thermoplasticity. The short half-life and high dosing frequency of repaglinide make it an ideal candidate for sustained release. Objectives: To formulate and evaluate repaglinide microspheres using acetylated starch of the indigenous rice species Oryza glaberrima Steud (Ofada) as polymer. Materials and Methods: Ofada rice starch was acetylated with acetic anhydride in pyridine (DS 2.68) and characterized for morphology (Scanning electron microscope, SEM), Crystallinity (Fourier Transform Infra-Red spectroscopy, FTIR, and X-ray diffraction crystallography, XRD), density and swelling. Microspheres of repaglinide were prepared by emulsification solvent-evaporation method, varying the drug-polymer ratio (1:2, 1:4, 1:8 and 1:10) and polymer type (ethyl cellulose as standard). Microspheres were characterized for particle size, wall thickness, swelling, entrapment efficiency, time taken for 80% drug release (t80) and permeability. Data obtained from in-vitro drug release studies were fitted to various kinetic models. Results: Repaglinide microspheres were near spherical, discrete and of size range 23.45 ± 4.25 to 44.55±3.85 μm. FTIR spectra revealed the absence of drug–polymer interaction and complete drug entrapment. Particle size, swelling, entrapment and wall thickness increased with drug: polymer ratio and were generally higher in microspheres containing acetylated Ofada rice starch while t80 (195±6.60 - 395± 24.75 min) was lower. Drug release fitted the Hixson-Crowell kinetic model. Conclusions: The acetylated starch of Ofada rice was found suitable as a polymer to sustain the release of repaglinide in microsphere formulations.