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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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    Development of besifloxacin HCl loaded nanofibrous ocular inserts for the treatment of bacterial keratitis: In vitro, ex vivo and in vivo evaluation
    (Elsevier, 2020) Polat, H. Kerem; Pehlivan, Sibel Bozdag; Ozkul, Ceren; Calamak, Semih; Ozturk, Naile; Aytekin, Eren; Firat, Aysegul
    Novel drug delivery systems have emerged to treat bacterial keratitis, an acute infection of the cornea. In this study, besifloxacin HCl loaded insert formulations were designed and investigated in vitro, ex vivo and in vivo for the treatment of bacterial keratitis. Besifloxacin HCl (BH) or BH-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) complex containing poly(caprolactone)/polyethylene glycol (PLC/PEG) fibrous inserts were prepared with an electrospinning method. These fibrous inserts were coated with mucoadhesive polymers such as sodium alginate (SA) or thiolated sodium alginate (TSA). Developed inserts compared to commercially available drug and it was found that coating of the insert surfaces with SA and TSA, increases bioadhesion of the formulations. Insert formulations showed a burst release in the first 2 days followed by a slow-release profile. Ex vivo transport studies showed that HP-beta-CD possessed a drug delivery level close to the commercial drug. Both TSA coated inserts as well as inserts containing HP-beta-CD-drug complex were effectively reducing bacterial keratitis in rabbit eyes upon single-dose application compared to multiple dosing with the commercial drug. Consequently, TSA coated inserts as well as the inserts containing HP-beta-CD-drug complex, may be potential alternatives to conventional market product by reducing the application frequency in the clinic leading to increased patient compliance.