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DEMİR, SERAP

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End date: 2008 ×

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    Preparation, characterization, and drug release properties of poly(2-hydroxyethyl methacrylate) hydrogels having beta-cyclodextrin functionality
    (JOHN WILEY & SONS INC, 2008) OGAN, AYŞE; Demir, Serap; Kahraman, M. Vezir; Bora, Nil; Apohan, Nilhan Kayaman; Ogan, Ayse
    A new beta-cyclodextrin urethane-methacrylate monomer was synthesized from the reaction of toluene-2,4-diisocyanate, 2-hydroxyethyl methacrylate (HEMA), and beta-cyclodextrin (beta-CD). Based on inclusion character of beta-CD, a series of hydrogels were prepared by irradiating the mixtures of beta-cyclodextrin urethane-methacrylate monomer (beta-CD-UM), poly(ethylene glycol) diacrylate (PEG-DA), HEMA, and the photoinitator. Gel percentages and equilibrium swelling ratios (%) of hydrogels were investigated. It was observed that the equilibrium-swelling ratio increased with increasing beta-CD-UM content in the hydrogel composition. SEM images demonstrated that beta-CD-UM based hydrogel have porous fractured surface. In this study four different drug molecules, salicylic acid, sulfathiazole, rifampicin, and methyl orange as model drug, which are capable of forming inclusion complexes with beta-CD were chosen. For sulfathiazole and rifampicin, the drug loadings are very low (0.04 and 0.008 mmol/g dry gel), whereas methyl orange and salicylic acid drug uptakes are found as 0.15 and 0.18 mmol/g dry gel, respectively. The incorporation of beta-CD-UM comonomer into the gel slightly reduces the methyl orange and salicylic acid releases. However, a significant enhancement was achieved in the case of sulfathiazole delivery. It can be concluded that the inclusion complex formation capability of beta-CD moiety increases the drug release by improving the aqueous solubility of hydrophobic drugs. On the other hand, in the case of hydrophilic drugs, the drug release retards by forming strong drug-beta-CD complex and reducing the drug diffusivity. (C) 2008 Wiley Periodicals, Inc.
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    Intrinsic factor and vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] microspheres: preparation, characterization and drug release
    (WILEY, 2008) OGAN, AYŞE; Demir, Serap; Ogan, Ayse; Kayaman-Apohan, Nilhan
    BACKGROUND: Vitamin B12 is an essential vitamin required by all mammals. Absorption of vitamin B12 is facilitated by binding of intrinsic factor-vitamin B12 complex to specific receptors in the ileum. In humans a deficiency of this vitamin or a lack of intrinsic factor leads to pernicious anaemia. The major objective of the present study was to prepare intrinsic factor-vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] (PLGA)-based microparticles and to investigate their release kinetics. RESULTS: PLGA copolymer was synthesized by the ring-opening polymerization method and characterized using gel permeation chromatography, Fourier transform infrared spectroscopy and H-1 NMR. The glass transition temperature measurement showed a single T-g at 40 degrees C. The intrinsic factor-vitamin B12 complex-loaded PLGA microspheres were prepared by a water-in-oil-in-water double emulsion solvent extraction/evaporation technique. An environmental scanning electron microscopy investigation demonstrated that the PLGA particles had a mean particle diameter of 38 gm. Interestingly, different drug release patterns (bi- and triphasic ones) were observed for vitamin B12-loaded and intrinsic factor-vitamin B12 complex-loaded microspheres. In contrast to the rapid release of vitamin B12 by itself, in vitro release tests showed that intrinsic factor and vitamin B12 in the complex were released from PLGA microspheres in a sustained manner over 15 days. CONCLUSION: PLGA microspheres can be an effective carrier for the intrinsic factor-vitamin B12 complex. (C) 2007 Society of Chemical Industry.