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    Design of ocular drug delivery platforms and in vitro - in vivo evaluation of riboflavin to the cornea by non-interventional (epi-on) technique for keratoconus treatment
    (Elsevier, 2020) Aytekin, Eren; Ozturk, Naile; Vurla, Imran; Polat, H. Kerem; Cakmak, Hasan Basri; Calis, Sema; Pehlivan, Sibel Bozdag
    Aim: Keratoconus is a common and progressive eye disease characterized by thinning and tapering of the cornea. This degenerative eye disease is currently treated in the clinic with an interventional technique (epi-off) that can cause serious side effects as a result of the surgical procedure. The aim of this project is to design innovative formulations for the development of a riboflavin-containing medicinal product to develop a non-invasive (epi-on) keratoconus treatment as an alternative to current treatment modalities. Methods: Nanostructured lipid carriers (NLCs) were successfully loaded with either riboflavin base of riboflavin-5-phosphate sodium and designed with either Stearylamine (positive charge) or Trancutol P (permeation enhancer). In vitro characterization studies, cytotoxicity and permeability studies were performed. Selected formulations and commercial preparations were applied and compared in ex-vivo corneal drug accumulation and transition studies. Furthermore, in vivo studies were performed to assess drug accumulation in the rat cornea and the corneal stability after NLC treatment was investigated via a biomechanical study on isolated rabbit corneas. Results: Both in vitro and ex-vivo as well as in vivo data showed that from the prepared NLC formulations, the most effective formulation was riboflavin-5-phosphate sodium containing NLC with Transcutol P as permeation enhancer. It possessed the highest drug loading content, low accumulation in the cornea but high permeability through the cornea as well as the highest functional performance in corneal crosslinking. Conclusion: Topical application of riboflavin-5-phosphate sodium loaded NLC systems designed with permeation enhancer Transcutol P may act as a potential alternative for non-invasive keratoconus treatments.
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    Öğe
    Effect of precipitation inhibitors on supersaturation and solubility of furosemide
    (Marmara Univ, 2021) Gulsun, Tugba; Ozturk, Naile; Kara, Asli; Sahin, Selma; Vural, Imran
    Furosemide is a widely used diuretic drug for the treatment of edema associated with heart, liver cirrhosis, renal diseases and hypertension. It is a Class IV drug with low aqueous solubility and low permeability according to Biopharmaceutics Classification System (BCS). Furosemide was chosen as a model drug to examine the effect of polymeric precipitation inhibitors (PPIs) on the supersaturation and solubility. Solubility and concentration change of furosemide as a function of time at pH 1.2 and 6.8 were determined to show the effects of PPIs on furosemide solubility. The 24 h equilibrium solubility of furosemide was 0.017 +/- 0.004 and 3.62 +/- 0.201 mg/mL at pH 1.2 and pH 6.8 buffer solutions, respectively. PPI type and concentration (0.05%, 0.25%) did not increase furosemide solubility at pH 1.2. However, both hydroxypropylmethylcellulose (HPMC) and polyvinylpyrrolidoneK17 (PVPK17) at two concentrations increased furosemide solubility at pH 1.2 and 6.8. In addition, viscosity of solutions was in the range of 2.2-3.7 centipoise, and it was not influenced by PPIs concentrations. Our results showed that designing supersaturated formulations using PPIs can be useful and promising to enhance solubility of furosemide.
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    Öğe
    Exploiting ionisable nature of PEtOx-co-PEI to prepare pH sensitive, doxorubicin-loaded micelles
    (Taylor & Francis Ltd, 2020) Ozturk, Naile; Kara, Asli; Gulyuz, Sevgi; Ozkose, Umut Ugur; Tasdelen, Mehmet Atilla; Bozkir, Asuman; Vural, Imran
    Aims This study was conducted to evaluate block copolymers containing two different poly(ethyleneimine) (PEI) amounts, as new pH-sensitive micellar delivery systems for doxorubicin. Methods Micelles were prepared with block copolymers consisting of poly(2-ethyl-2-oxazoline)-co-poly(ethyleneimine) (PEtOx-co-PEI) and poly(epsilon-caprolactone) (PCL) as hydrophilic and hydrophobic blocks, respectively. Doxorubicin loading, micelle size, pH-dependent drug release, and in vitro cytotoxicity on MCF-7 cells were investigated. Results The average size of drug-loaded micelles was under 100 nm and drug loading was between 10.7% and 48.3% (w/w). pH-sensitive drug release was more pronounced (84.7% and 68.9% (w/w) of drug was released at pH 5.0 and pH 7.4, respectively) for the micelles of the copolymer with the lowest PEI amount. The cell viability of doxorubicin-loaded micelles which were prepared by the copolymer with the lowest PEI amount was 28-33% at 72 h. Conclusions PEtOx-co-PEI-b-PCL micelles of this copolymer were found to be stable and effective pH-sensitive nano-sized carriers for doxorubicin delivery.