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      Development and Characterization of PLGA Nanoparticle-Laden Hydrogels for Sustained Ocular Delivery of Norfloxacin in the Treatment of Pseudomonas Keratitis: An Experimental Study


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          Norfloxacin (NFX) has low ocular bioavailability. The current work aimed to develop NFX-loaded nanoparticle (NP)-laden hydrogels to improve the ocular potential of NFX, minimize the need for frequent instillations and lower undesirable side effects.


          NFX-loaded NPs were developed via the double-emulsion/solvent evaporation technique, according to 2 1.4 1 full factorial design, using two types of polylactic-co-glycolic acid (PLGA) polymer and four (drug: polymer) ratios. NPs were evaluated for particle size (PS), polydispersity index (PDI), zeta potential (ZP), drug entrapment efficiency percentage (EE%), drug percentage released after 30 min (Q 30min) and 12 hours (Q 12h), drug percentage permeated through goat corneas after 30 min (P 30min) and 12 hours (P 12h) and morphology. Two formulae were statistically selected and incorporated into hydroxypropyl methylcellulose (HPMC)-based hydrogels; G1 – G4. The latter systems were evaluated for appearance, clarity, pH, spreadability, rheology, drug percentages released, drug percentages permeated, antimicrobial activity against Pseudomonas aeruginosa, and histopathological changes.


          The selected NPs (NP2 and NP6) were spherical in shape and possessed suitable PS (392.02 nm and 190.51 nm) and PDI (0.17 and 0.18), high magnitude of ZP (−30.43 mV and −33.62 mV), high EE% (79.24% and 91.72%), low Q 30min (10.96% and 16.65%) and P 30min (17.39% and 21.05%) and promising Q 12h (58.23% and 71.20%) and P 12h (53.31% and 65.01%), respectively. Clear, spreadable, tolerable, pseudoplastic, and thixotropic HPMC-based hydrogels were developed. They showed more prolonged drug release and drug permeation profiles. NP2- and NP6-laden hydrogels (G3 and G4 systems, respectively) had promising antibacterial activity, and reasonable histopathological safety.


          G3 and G4 are potential ocular delivery systems for NFX.

          Most cited references72

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          Nano/micro technologies for delivering macromolecular therapeutics using poly(D,L-lactide-co-glycolide) and its derivatives.

          Biodegradable nano/microparticles of poly(D,L-lactide-co-glycolide) (PLGA) and PLGA-based polymers are widely explored as carriers for controlled delivery of macromolecular therapeutics such as proteins, peptides, vaccines, genes, antigens, growth factors, etc. These devices are mainly produced by emulsion or double-emulsion technique followed by solvent evaporation or spray drying. Drug encapsulation, particle size, additives added during formulation, molecular weight, ratio of lactide to glycolide moieties in PLGA and surface morphology could influence the release characteristics. Encapsulation efficiency and release rates through nano/microparticle-mediated drug delivery devices can be optimized to improve their therapeutic efficacy. In this review, important findings of the past decade on the encapsulation and release profiles of macromolecular therapeutics from PLGA and PLGA-based nano/microparticles are discussed critically in relation to nature and type of bioactive molecule, carrier polymer and experimental variables that influence the delivery of macromolecular therapeutics. Even though extensive research on biodegradable microparticles containing macromolecular drugs has greatly advanced to the level of production know-how, the effects of critical parameters influencing drug encapsulation are not sufficiently investigated for nano-scaled carriers. The present review attempts to address some important data on nano/microparticle-based delivery systems of PLGA and PLGA-derived polymers with reference to macromolecular drugs.
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            Biodegradable nanoparticles for drug and gene delivery to cells and tissue.

            Biodegradable nanoparticles formulated from poly (D,L-lactide-co-glycolide) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents including plasmid DNA, proteins and peptides and low molecular weight compounds. Research about the mechanism of intracellular uptake of nanoparticles, their trafficking and sorting into different intracellular compartments, and the mechanism of enhanced therapeutic efficacy of nanoparticle-encapsulated agent at cellular level is more recent and is the primary focus of the review. Recent studies in our laboratory demonstrated rapid escape of PLGA nanoparticles from the endo-lysosomal compartment into cytosol following their uptake. Based on the above mechanism, various potential applications of nanoparticles for delivery of therapeutic agents to the cells and tissue are discussed.
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              Beware of R(2): Simple, Unambiguous Assessment of the Prediction Accuracy of QSAR and QSPR Models.

              The statistical metrics used to characterize the external predictivity of a model, i.e., how well it predicts the properties of an independent test set, have proliferated over the past decade. This paper clarifies some apparent confusion over the use of the coefficient of determination, R(2), as a measure of model fit and predictive power in QSAR and QSPR modeling. R(2) (or r(2)) has been used in various contexts in the literature in conjunction with training and test data for both ordinary linear regression and regression through the origin as well as with linear and nonlinear regression models. We analyze the widely adopted model fit criteria suggested by Golbraikh and Tropsha ( J. Mol. Graphics Modell. 2002 , 20 , 269 - 276 ) in a strict statistical manner. Shortcomings in these criteria are identified, and a clearer and simpler alternative method to characterize model predictivity is provided. The intent is not to repeat the well-documented arguments for model validation using test data but rather to guide the application of R(2) as a model fit statistic. Examples are used to illustrate both correct and incorrect uses of R(2). Reporting the root-mean-square error or equivalent measures of dispersion, which are typically of more practical importance than R(2), is also encouraged, and important challenges in addressing the needs of different categories of users such as computational chemists, experimental scientists, and regulatory decision support specialists are outlined.

                Author and article information

                Drug Des Devel Ther
                Drug Des Devel Ther
                Drug Design, Development and Therapy
                05 February 2021
                : 15
                : 399-418
                [1 ]Department of Pharmaceutics, College of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology , Giza, Egypt
                [2 ]Department of Ophthalmology, Faculty of Medicine, Cairo University , Cairo, Egypt
                [3 ]Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University , Cairo, Egypt
                [4 ]Department of Pharmaceutics, Faculty of Pharmacy and Drug Technology, Egyptian Chinese University , Cairo, Egypt
                Author notes
                Correspondence: Mina I Tadros Tel +20 1223620458Fax +20 223628246 Email mina.tadros@pharma.cu.edu.eg
                Author information
                © 2021 Gebreel et al.

                This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms ( https://www.dovepress.com/terms.php).

                : 23 November 2020
                : 19 January 2021
                Page count
                Figures: 7, Tables: 10, References: 72, Pages: 20
                Original Research

                Pharmacology & Pharmaceutical medicine
                norfloxacin,nanoparticles,plga,ocular delivery,pseudomonas keratitis


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