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Kali G, Özkahraman B, Laffleur F, Knoll P, Wibel R, Zöller K, Bernkop-Schnürch A. Thiolated Cellulose: A Dual-Acting Mucoadhesive and Permeation-Enhancing Polymer. Biomacromolecules 2023; 24:4880-4889. [PMID: 37796043 PMCID: PMC10646989 DOI: 10.1021/acs.biomac.3c00577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/25/2023] [Indexed: 10/06/2023]
Abstract
This study aims to design an anionic, thiolated cellulose derivative and to evaluate its mucoadhesive and permeation-enhancing properties utilizing enoxaparin as a model drug. 2-Mercaptosuccinic acid-modified cellulose (cellulose-mercaptosuccinate) was synthesized by the reaction of cellulose with S-acetylmercaptosuccinic anhydride. The chemical structure of the target compound was confirmed by FTIR and 1H NMR spectroscopy. The thiol content was determined by Ellman's test. The conjugate exhibited 215.5 ± 25 μmol/g of thiol groups and 84 ± 16 μmol/g of disulfide bonds. Because of thiolation, mucoadhesion on porcine intestinal mucosa was 9.6-fold enhanced. The apparent permeability (Papp) of the model dye Lucifer yellow was up to 2.2-fold improved by 0.5% cellulose-mercaptosuccinate on a Caco-2 cell monolayer. Enoxaparin permeation through rat intestinal mucosa increased 2.4-fold in the presence of 0.5% cellulose-mercaptosuccinate compared with the drug in buffer only. In vivo studies in rats showed an oral bioavailability of 8.98% using cellulose-mercaptosuccinate, which was 12.5-fold higher than that of the aqueous solution of the drug. Results of this study show that the modification of cellulose with 2-mercaptosuccinic acid provides mucoadhesive and permeation-enhancing properties, making this thiolated polymer an attractive excipient for oral drug delivery.
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Affiliation(s)
- Gergely Kali
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Bengi Özkahraman
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
- Department of Polymer Materials, Faculty of Engineering, Hitit University, 19030 Corum, Turkey
| | - Flavia Laffleur
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Patrick Knoll
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Richard Wibel
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Katrin Zöller
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Andreas Bernkop-Schnürch
- Center for Chemistry
and Biomedicine, Department of Pharmaceutical Technology, Institute
of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
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Torlopov MA, Martakov IS, Mikhaylov VI, Cherednichenko KA, Sitnikov PА. Synthesis and properties of thiol-modified CNC via surface tosylation. Carbohydr Polym 2023; 319:121169. [PMID: 37567709 DOI: 10.1016/j.carbpol.2023.121169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/08/2023] [Accepted: 06/29/2023] [Indexed: 08/13/2023]
Abstract
SH-containing polymers and nanoparticles are a significant direction in the creation of novel materials. The aim of this work is the synthesis of cellulose nanocrystals (CNC) with a surface modified by tosyl functions (CNC-Ts) and their further modification into SH-containing nanocrystals (CNC-SH). CNC-Ts were synthesized in an aqueous-organic emulsion from never-dried particles, while maintaining the size and supramolecular structure of CNC; the content of Ts-functions is up to 2.5 mmol·g-1. Structure of the derivatives was analyzed by TEM, XRD, CP/MAS 13C NMR and FTIR spectroscopies. Nucleophilic substitution and hydrolysis of the obtained thioisouronium salts leads to the production of CNC-SH. To quantify SH-groups we used elemental analysis, potentiometric titration and Folin-Ciocalteu and Ellman's reagents. It is shown that SH-groups on the surface are partially oxidized and are involved in a dense network of hydrogen bonds. Rheological properties of CNC-SH hydrosols are close to those of CNC, addition of H2O2 at acidic pH leads to an increase in viscosity of the system; H2O2 added at neutral pH causes opposite effect - viscosity decreases. CNC-SH have a high capacity for sorption of Cr(VI) in acidic environments and exhibit photoreductive properties under UV irradiation.
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Affiliation(s)
- Mikhail A Torlopov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
| | - Ilia S Martakov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation.
| | - Vasily I Mikhaylov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
| | | | - Petr А Sitnikov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
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Buang F, Chatzifragkou A, Amin MCIM, Khutoryanskiy VV. Synthesis of Methacryloylated Hydroxyethylcellulose and Development of Mucoadhesive Wafers for Buccal Drug Delivery. Polymers (Basel) 2022; 15:polym15010093. [PMID: 36616443 PMCID: PMC9823848 DOI: 10.3390/polym15010093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/14/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
Non-ionic hydroxyethylcellulose (HEC) has limited mucoadhesive properties for application in transmucosal drug delivery. In this study, HEC was chemically modified by reaction with glycidyl methacrylate. This allowed introducing the methacryloyl groups to HEC structure to make it capable of forming covalent bonds with the sulfhydryl groups present in the mucin glycoprotein to achieve enhanced mucoadhesive properties. The results showed a successful modification of HEC as confirmed by 1H NMR and FTIR spectroscopies. The quantification of methacryloyl moieties was conducted using HPLC. The toxicity studies using in vivo planaria acute toxicity assay, in vivo planaria fluorescent test, and in vitro MTT assay with Caco-2 cell line confirmed that the chemical modification of HEC does not result in any toxicological effects. Mucoadhesive wafers were developed based on parent and modified HEC as a model dosage form for buccal delivery. The mucoadhesive properties of modified HEC assessed using a tensile test were found to be significantly better compared to unmodified HEC.
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Affiliation(s)
- Fhataheya Buang
- Reading School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, UK
- Centre for Drug Delivery Technology, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | - Afroditi Chatzifragkou
- Department of Food and Nutritional Sciences, University of Reading, Whiteknights, Reading RG6 6AD, UK
| | - Mohd Cairul Iqbal Mohd Amin
- Centre for Drug Delivery Technology, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | - Vitaliy V. Khutoryanskiy
- Reading School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, UK
- Correspondence:
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Entirely S-protected thiolated hydroxyethylcellulose: Design of a dual cross-linking approach for hydrogels. Eur J Pharm Biopharm 2022; 181:292-299. [PMID: 36427674 DOI: 10.1016/j.ejpb.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 11/25/2022]
Abstract
AIM The aim of this study was the synthesis and evaluation of entirely S-protected thiolated hydroxyethylcellulose (HEC) with low and high viscosity, as well as thiolated poly-L-lysine (poly-L-Lys) used as dual-acting ionic as well as thiol-disulfide exchange mediated cross-linking hydrogel. METHODS Bis(mercaptosuccinic acid) was covalently attached to low and high viscous HECs via Fisher esterification, obtaining S-protected polymers. Poly-L-Lys-cysteine was synthesized via amidation of poly-L-Lys-HBr with cysteine (Cys). Thiolated polymers were examined in terms of cytotoxicity and rheological behavior of hydrogels containing these thiomers was evaluated with a cone-plate rheometer. RESULTS Thiomers showed less cytotoxicity compared to the corresponding unmodified polymers. Rheological studies showed that cross-linking occurred between the two polymers via thiol-disulfide exchange reactions facilitated by the complementary charges. Employing poly-L-Lys-Cys in a concentration of either 0.5 or 5% (m/v) resulted in a 34.5-fold or 17.3-fold as well as a 53.6-fold or 29.6-fold improvement in dynamic viscosity within 5 min at 37 °C on S-protected thiolated low and high viscous HEC, compared to the corresponding unmodified HECs, respectively. CONCLUSION By the combination of anionic S-protected thiolated polymers with a cationic thiolated polymer, dual-acting hydrogels exhibiting a time dependent increase in viscosity can be designed.
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Cui J, Cueto C, Bien C, Preda D, Gamliel D, Emrick T. Robust polymer foams from 2-hydroxyethyl cellulose: Fabrication, stability, and chemical functionalization. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Okra-Thioglycolic Acid Conjugate—Synthesis, Characterization, and Evaluation as a Mucoadhesive Polymer. Processes (Basel) 2020. [DOI: 10.3390/pr8030316] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The success of mucoadhesive drug delivery systems relies on the type of polymer used, which becomes adhesive naturally upon hydration. Intended polymers should be able to maintain prolonged contact with biological membranes, and to protect or cater the drug to a prolonged period. Most of the hydro polymers form weak non-covalent bonds, that hinder localization of dosage forms at specific sites resulting in therapeutic inefficiency. This can be overcome by the thiol functionalization of natural polymers. In the present study, natural okra gum (OG) was extracted, followed by thiolation (TOG) and evaluated for mucoadhesion property and its role in enhancing the efficacy of repaglinide as a model drug (short-acting Type II antidiabetic drug). The thiol functionalization of OG (TOG) was confirmed by a Fourier-transform infrared spectroscopy (FTIR) study that showed a polyhedral to a spherical shape that had a rougher surface. Differential scanning calorimetry (DSC) and X-Ray Diffraction (XRD) studies of TOG indicated a decline in endothermic transition temperature and high crystallinity, respectively, in comparison to OG. CSFR (Crushing Strength: Friability Ratio), weight and thickness variations of repaglinidetablets formulated using TOG were >80% and <2.5% respectively. The highest swelling index (107.89 ± 1.99%) and strong mucoadhesion due to high disulfide bonds were observed for repaglinide TOG tablets in comparison to RG OG tablets. In-vitro release studies indicated a controlled drug release from thiolated formulations proportional to the concentration of thiomers that have a good correlation with in-vivo studies. Pharmacokinetic studies indicated higher AUC (area under the curve), longer t1/2 with thiomers. and Level A IVIV (in vitro in vivo) correlation was established from the bioavailability and dissolution data. Consequently, all the obtained results suggest that thiomers based formulations can be promising drug delivery systems, even in targeting onerous mucosal surfaces like nasal, ocular or vaginal.
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Zheng F, Li R, He Q, Koral K, Tao J, Fan L, Xiang R, Ma J, Wang N, Yin Y, Huang Z, Xu P, Xu H. The electrostimulation and scar inhibition effect of chitosan/oxidized hydroxyethyl cellulose/reduced graphene oxide/asiaticoside liposome based hydrogel on peripheral nerve regeneration in vitro. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 109:110560. [PMID: 32228996 DOI: 10.1016/j.msec.2019.110560] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/22/2019] [Accepted: 12/14/2019] [Indexed: 10/25/2022]
Abstract
The application of hollow nerve conduits in the repair of peripheral nerve defects is effected by inferior recovery, and nerve extension is hampered by the scar tissue generated during the repair process. In this study, the filler in hollow nerve conduit, chitosan/oxidized hydroxyethyl cellulose (CS/OHEC) hydrogel loaded asiaticoside liposome and the conductive reduced graphene oxide (rGO) were developed and used to reform the microenvironment for peripheral nerve regeneration. The physiochemical properties of CS/OHEC/rGO/asiaticoside liposome hydrogel were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and compressive modulus, porosity, swelling ratio, degradation and conductivity. In addition, the asiaticoside release profiles in vitro were investigated. The hydrogel had a continuous porous network structure with pore size distribution in the range of 50-250 μm. The majority of the hydrogels had porosities above 70%, and a compressive modulus of 0.45 MPa. The weight loss rate of hydrogel reached 76.14 ± 4.45% within 8 weeks. The conductivity of the hydrogel was 5.27 ± 0.42 × 10-4 S/cm. The hydrogel was non-toxic and suitable for adhesion and proliferation of nerve cells in vitro. In addition, the application of electrical stimulation after the addition of rGO can promote the differentiation and proliferation of nerve cells, accelerating nerve regeneration. The asiaticoside released from the hydrogel had a significant inhibitory effect on the growth and collagen secretion of fibroblasts, eliminating scars for regenerative nerves, which can promote the function recovery of defected peripheral nerve. Together, these positive results indicate that the hydrogel would be a promising candidate for peripheral nerve regeneration.
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Affiliation(s)
- Furong Zheng
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Rui Li
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Qundi He
- Wuhan Mafangshan Middle School, Wuhan 430070, China
| | - Kelly Koral
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Junyan Tao
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lihong Fan
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Runzhi Xiang
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Jingyao Ma
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Na Wang
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Yixia Yin
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhijun Huang
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Peihu Xu
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China.
| | - Haixing Xu
- Department of Pharmaceutical Engineering, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China; Wuhan Kanghua Century Pharmaceutical Limited Company, Wuhan 430070, China.
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Leichner C, Jelkmann M, Bernkop-Schnürch A. Thiolated polymers: Bioinspired polymers utilizing one of the most important bridging structures in nature. Adv Drug Deliv Rev 2019; 151-152:191-221. [PMID: 31028759 DOI: 10.1016/j.addr.2019.04.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 12/13/2022]
Abstract
Thiolated polymers designated "thiomers" are obtained by covalent attachment of thiol functionalities on the polymeric backbone of polymers. In 1998 these polymers were first described as mucoadhesive and in situ gelling compounds forming disulfide bonds with cysteine-rich substructures of mucus glycoproteins and crosslinking through inter- and intrachain disulfide bond formation. In the following, it was shown that thiomers are able to form disulfides with keratins and membrane-associated proteins exhibiting also cysteine-rich substructures. Furthermore, permeation enhancing, enzyme inhibiting and efflux pump inhibiting properties were demonstrated. Because of these capabilities thiomers are promising tools for drug delivery guaranteeing a strongly prolonged residence time as well as sustained release on mucosal membranes. Apart from that, thiomers are used as drugs per se. In particular, for treatment of dry eye syndrome various thiolated polymers are in development and a first product has already reached the market. Within this review an overview about the thiomer-technology and its potential for different applications is provided discussing especially the outcome of studies in non-rodent animal models and that of numerous clinical trials. Moreover, an overview on product developments is given.
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Brannigan RP, Khutoryanskiy VV. Progress and Current Trends in the Synthesis of Novel Polymers with Enhanced Mucoadhesive Properties. Macromol Biosci 2019; 19:e1900194. [PMID: 31361091 DOI: 10.1002/mabi.201900194] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/07/2019] [Indexed: 01/28/2023]
Abstract
Mucoadhesion is defined as the adherence of a synthetic or natural polymer to a mucosal membrane via physical or chemical interactions. Mucoadhesive materials are widely used to develop dosage forms for transmucosal drug delivery via ocular, nasal, esophageal, oral, vaginal, rectal, and intravesical routes of administration. This review will discuss some of the most prominent and recent synthetic methodologies employed to modify polymeric materials in order to enhance their mucoadhesive properties. This includes chemical conjugation of polymers with molecules bearing thiol-, catechol-, boronate-, acrylate-, methacrylate-, maleimide-, and N-hydroxy(sulfo)succinimide ester- groups.
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Affiliation(s)
- Ruairí P Brannigan
- Department of Chemistry, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland
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Asim MH, Moghadam A, Ijaz M, Mahmood A, Götz RX, Matuszczak B, Bernkop-Schnürch A. S-protected thiolated cyclodextrins as mucoadhesive oligomers for drug delivery. J Colloid Interface Sci 2018; 531:261-268. [PMID: 30036850 DOI: 10.1016/j.jcis.2018.07.062] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/14/2018] [Accepted: 07/16/2018] [Indexed: 11/17/2022]
Abstract
AIM The purpose of this study was to develop a novel mucoadhesive thiolated and S-protected gamma cyclodextrin (γ-CD) with an intact ring backbone to assure a prolonged residence time at specific target sites. METHOD Thiolated γ-CD was generated through bromine substitution of its hydroxyl groups followed by replacement to thiol groups using thiourea. In the second step, thiol groups were protected by disulfide bond formation with 2-mercaptonicotinic acid (2-MNA). RESULT Thiolated γ-CD displayed 1385 ± 84 µmol thiol groups per gram of oligomer and the amount of MNA determined in the S-protected oligomer was 1153 ± 41 µmol per gram of oligomer. In-vitro screening of mucoadhesive properties of thiolated and S-protected γ-CD was done by two methods. Rheological investigation revealed the conjugates non-mucolytic with only a slight increase in viscosity of thiolated and S-protected γ-CD as compared to unmodified γ-CD, whereas mucoadhesive properties of the new thiolated and S-protected γ-CD performed on freshly excised porcine intestinal mucosa showed 44.4- and 50.9-fold improvement in mucoadhesion, respectively. The new conjugates did not show any cytotoxicity to Caco-2 cells even at a concentration of 1% (m/v) for 24 h. In addition, in-vitro studies of α-amylase degradation of γ-CD, γ-CD-SH and γ-CD-SS-MNA confirmed that all conjugates are biodegradable. CONCLUSION These outcomes predict that these new conjugates of γ-CD might provide a new favorable tool for drug delivery providing a prolonged residence time on mucosal surfaces.
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Affiliation(s)
- Mulazim Hussain Asim
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; Department of Pharmaceutics, Faculty of Pharmacy, University of Sargodha, 40100 Sargodha, Pakistan
| | - Ali Moghadam
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; Institute of Biotechnology, College of Agriculture, Shiraz University, Shiraz, Iran
| | - Muhammad Ijaz
- Department of Pharmacy, COMSATS University Islamabad, Lahore Campus, 54000 Lahore, Pakistan
| | - Arshad Mahmood
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, 22060 Abbottabad, Pakistan
| | - Roman Xaver Götz
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Barbara Matuszczak
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Andreas Bernkop-Schnürch
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
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Moghadam A, Ijaz M, Asim MH, Mahmood A, Jelkmann M, Matuszczak B, Bernkop-Schnürch A. Non-ionic thiolated cyclodextrins - the next generation. Int J Nanomedicine 2018; 13:4003-4013. [PMID: 30022823 PMCID: PMC6045911 DOI: 10.2147/ijn.s153226] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Introduction The current study was aimed at developing a novel mucoadhesive thiolated cyclodextrin (CD) without ionizable groups and an intact ring backbone for drug delivery. Materials and methods Thiolated beta CD (β-CD) was prepared through bromine substitution of its hydroxyl groups followed by replacement to thiol groups using thiourea. The thiolated β-CD was characterized in vitro via dissolution studies, cytotoxicity studies, mucoadhesion studies on freshly excised porcine intestinal mucosa, and inclusion complex formation with miconazole nitrate. Results Thiolated β-CDs namely β-CD-SH600 and β-CD-SH1200 displayed 558.66 ± 78 and 1,163.45 ± 96 µmol thiol groups per gram of polymer, respectively. Stability constant (Kc) of 190 M-1 confirmed the inclusion complex formation of miconazole nitrate with β-CD-SH. Inclusion complexes of β-CD-SH600 and β-CD-SH1200 resulted in 157- and 257-fold increased solubility of miconazole nitrate, respectively. In addition, more than 80% of thiol groups were stable even after 6 hours at pH 5. Both β-CD-SH compounds showed at least 1.3-fold improved solubility in water. In contrast to cationic thiolated CDs of the first generation, both thiomers showed no significant cytotoxicity. The mucoadhesive properties of the new thiolated CDs were 39.73- and 46.37-fold improved, respectively. Conclusion These results indicate that β-CD-SH might provide a new favorable tool for delivery of poorly soluble drugs providing a prolonged residence time on mucosal surfaces.
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Affiliation(s)
- Ali Moghadam
- Institute of Biotechnology, College of Agriculture, Shiraz University, Shiraz, Iran.,Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria,
| | - Muhammad Ijaz
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria, .,Department of Pharmacy, COMSATS Institute of Information and Technology, Lahore, Pakistan
| | - Mulazim Hussain Asim
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria, .,Department of Pharmaceutics, Faculty of Pharmacy, University of Sargodha, Sargodha, Pakistan
| | - Arshad Mahmood
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria, .,Department of Pharmacy, COMSATS Institute of Information Technology Abbottabad, Pakistan
| | - Max Jelkmann
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria,
| | - Barbara Matuszczak
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Andreas Bernkop-Schnürch
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria,
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Szilágyi BÁ, Gyarmati B, Horvát G, Laki Á, Budai-Szűcs M, Csányi E, Sandri G, Bonferoni MC, Szilágyi A. The effect of thiol content on the gelation and mucoadhesion of thiolated poly(aspartic acid). POLYM INT 2017. [DOI: 10.1002/pi.5411] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Barnabás Áron Szilágyi
- Soft Matters Group, Department of Physical Chemistry and Materials Science; Budapest University of Technology and Economics; Budapest Hungary
| | - Benjámin Gyarmati
- Soft Matters Group, Department of Physical Chemistry and Materials Science; Budapest University of Technology and Economics; Budapest Hungary
| | - Gabriella Horvát
- Institute of Pharmaceutical Technology and Regulatory Affairs; University of Szeged; Szeged Hungary
| | - Ádám Laki
- Soft Matters Group, Department of Physical Chemistry and Materials Science; Budapest University of Technology and Economics; Budapest Hungary
| | - Mária Budai-Szűcs
- Institute of Pharmaceutical Technology and Regulatory Affairs; University of Szeged; Szeged Hungary
| | - Erzsébet Csányi
- Institute of Pharmaceutical Technology and Regulatory Affairs; University of Szeged; Szeged Hungary
| | | | | | - András Szilágyi
- Soft Matters Group, Department of Physical Chemistry and Materials Science; Budapest University of Technology and Economics; Budapest Hungary
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Leonaviciute G, Suchaoin W, Matuszczak B, Lam HT, Mahmood A, Bernkop-Schnürch A. Preactivated thiolated pullulan as a versatile excipient for mucosal drug targeting. Carbohydr Polym 2016; 151:743-751. [DOI: 10.1016/j.carbpol.2016.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/01/2016] [Accepted: 06/01/2016] [Indexed: 10/21/2022]
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Shah KU, Shah SU, Dilawar N, Khan GM, Gibaud S. Thiomers and their potential applications in drug delivery. Expert Opin Drug Deliv 2016; 14:601-610. [PMID: 27548003 DOI: 10.1080/17425247.2016.1227787] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Thiomers are the product of the immobilization of sulfhydryl-bearing ligands onto the polymer backbone of a conventional polymer, which results in a significant improvement in mucoadhesion; in situ gelation and efflux inhibition compare with unchanged polymers. Because of thiol groups, thiomers have more reactivity and enhanced protection against oxidation. Since the late 1990s, extensive work has been conducted on these promising polymeric excipients in the pharmaceutical field. Areas covered: This review covers thiomers, their classification and their different properties. Various techniques for the synthesis, purification and characterization of thiomers are described in detail. This review also encompasses their various properties such as mucoadhesion, permeation enhancement, in situ gelation and efflux inhibition, as well as different formulations based on thiomers. In addition to the use of thiomers as multifunctional excipients, this review also encompasses their use as drugs. Expert opinion: The synthesis is realized by linkage of sulfhydryl-bearing ligands but reported methods give low yields. Higher degrees of modification are not necessary and would probably lead to extreme changes in properties. Nevertheless, an accurate characterization of the final product is important. The scale-up procedure for industrial manufacturing has been adapted to produce GMP materials; Lacrimera® eye drops have already entered the European market.
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Affiliation(s)
- Kifayat Ullah Shah
- a Department of Pharmacy , Quaid-e-Azam University , Islamabad , Pakistan
| | - Shefaat Ullah Shah
- b Department of Pharmaceutics, Faculty of Pharmacy , Gomal University , D.I.Khan , Pakistan.,c EA3452/CITHEFOR, Faculté de Pharmacie , Université de Lorraine , Nancy , France
| | - Naz Dilawar
- a Department of Pharmacy , Quaid-e-Azam University , Islamabad , Pakistan
| | - Gul Majid Khan
- a Department of Pharmacy , Quaid-e-Azam University , Islamabad , Pakistan
| | - Stéphane Gibaud
- c EA3452/CITHEFOR, Faculté de Pharmacie , Université de Lorraine , Nancy , France
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Pereira de Sousa I, Buttenhauser K, Suchaoin W, Partenhauser A, Perrone M, Matuszczak B, Bernkop-Schnürch A. Thiolated graphene oxide as promising mucoadhesive carrier for hydrophobic drugs. Int J Pharm 2016; 509:360-367. [DOI: 10.1016/j.ijpharm.2016.05.059] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/25/2016] [Accepted: 05/27/2016] [Indexed: 01/12/2023]
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Abstract
Aim: It was the aim of this study to synthesize pectin (PEC) with sulfhydryl groups and evaluate its suitability in buccal application. Materials & methods: Native PEC was chemically modified by covalent attachment of sulfhydryl-bearing cysteine (CYS). Stability assays in form of water uptake behavior and erosion study were performed. Additionally, mucoadhesive study on buccal mucosa was performed. Results: Pectin–cysteine (PECCYS) was successfully synthesized as proved by IR and Ellman's assay exhibiting 436.59 ± 127.87 µmol thiol groups per gram polymer. Stability assay showed that PECCYS revealed a 2.27-fold improved water uptake and mucoadhesiveness augmented 3.75-fold in comparison to unmodified PEC. Conclusion: PECCYS might be a future suitable excipient for buccal adhesive application.
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Mucoadhesive polymers: Synthesis and in vitro characterization of thiolated poly(vinyl alcohol). Int J Pharm 2016; 503:141-9. [DOI: 10.1016/j.ijpharm.2016.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/04/2016] [Accepted: 03/05/2016] [Indexed: 11/18/2022]
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Novel bioadhesive polymers as intra-articular agents: Chondroitin sulfate-cysteine conjugates. Eur J Pharm Biopharm 2016; 101:25-32. [DOI: 10.1016/j.ejpb.2016.01.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 01/04/2016] [Accepted: 01/08/2016] [Indexed: 11/17/2022]
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S-protected thiolated hydroxyethyl cellulose (HEC): Novel mucoadhesive excipient with improved stability. Carbohydr Polym 2016; 144:514-21. [PMID: 27083843 DOI: 10.1016/j.carbpol.2016.02.075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/23/2016] [Accepted: 02/26/2016] [Indexed: 11/21/2022]
Abstract
The aim of this study was the design of novel S-protected thiolated hydroxyethyl cellulose (HEC) and the assessment of its mucoadhesive properties and biodegradability compared to the corresponding unmodified polymer. Thiolated HEC was S-protected via disulfide bond formation between 6-mercaptonicotinamide (6-MNA) and the thiol substructures of the polymer. In vitro screening of mucoadhesive properties was accomplished using two different methods: rotating cylinder studies and viscosity measurements. Moreover, biodegradability of these polymers by cellulase, xylanase and lysozyme was evaluated. MTT and LDH assays were performed on Caco-2 cells to determine the cytotoxicity of S-protected thiolated HEC. Thiolated HEC displayed 280.09±1.70μmol of free thiol groups per gram polymer. S-protected thiolated HEC exhibiting 270.8±21.11μmol immobilized 6-MNA ligands per gram of polymer was shown being 2.4-fold more mucoadhesive compared to thiolated HEC. No mucoadhesion was observed in case of unmodified HEC. Results were in a good agreement with rheological studies. The presence of free thiol moieties likely caused lower degree of hydrolysis by xylanase, whereas the degradation by both enzymes cellulase and xylanase was more hampered when 6-MNA was introduced as ligand for thiol group's protection. Findings in cell viability revealed that all three conjugates were non-toxic. S-protection of thiolated hydroxyethyl cellulose improved mucoadhesive properties and provided pronounced stability towards enzymatic attack, that makes this excipient superior for non-invasive drug administration over thiolated and unmodified forms.
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Bahulkar SS, Munot NM, Surwase SS. Synthesis, characterization of thiolated karaya gum and evaluation of effect of pH on its mucoadhesive and sustained release properties. Carbohydr Polym 2015; 130:183-90. [DOI: 10.1016/j.carbpol.2015.04.064] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 03/15/2015] [Accepted: 04/27/2015] [Indexed: 10/23/2022]
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Fenugreek gum derivatives with improved bioadhesion and controlled drug release: In vitro and in vivo characterization. J Drug Deliv Sci Technol 2015. [DOI: 10.1016/j.jddst.2015.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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22
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Suchaoin W, Bonengel S, Hussain S, Huck CW, Ma BN, Bernkop-Schnürch A. Synthesis and In Vitro Evaluation of Thiolated Carrageenan. J Pharm Sci 2015; 104:2523-30. [DOI: 10.1002/jps.24514] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/06/2015] [Accepted: 05/06/2015] [Indexed: 01/10/2023]
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Abstract
INTRODUCTION Since thiolated polymers - known as thiomers - have entered the pharmaceutical arena in the late 1990 s, more and more academic and industrial research groups have started to work with these promising polymeric excipients. Meanwhile, various thiomers are the subject of clinical trials and the first product based on thiolated chitosan will reach the market in 2015. Due to the formation of disulfide bonds with mercaptopyridine substructures, thiol groups of thiomers are on the one hand more reactive and on the other hand are protected toward oxidation. These so-called preactivated thiomers representing the second generation of thiomers are subject of this review. AREAS COVERED Within this review, preactivated thiomers are classified and their mode of action is described. Furthermore, different synthetic pathways, purification and chemical characterization methods of preactivated thiomers are explained. Their properties including mucoadhesive, permeation-enhancing, efflux pump inhibitory and in situ gelling properties are described. In addition, various formulations based on preactivated thiomers are introduced. EXPERT OPINION The first-generation thiomers have already shown great potential resulting in various product developments. Preactivated thiomers - representing the second generation of thiomers - offer the additional advantage of even comparatively more reactive sulfhydryl ligands and of stability toward oxidation. According to this, they are promising novel polymeric excipients for various applications.
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Affiliation(s)
- Muhammad Ijaz
- University of Innsbruck, Institute of Pharmacy, Center for Chemistry and Biomedicine, Center for Molecular Bioscience (CMBI), Department of Pharmaceutical Technology , Innrain 80/82, 6020 Innsbruck , Austria +43 512 507 58601 ; +43 512 507 58699 ;
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Mucoadhesive polymers in the design of nano-drug delivery systems for administration by non-parenteral routes: A review. Prog Polym Sci 2014. [DOI: 10.1016/j.progpolymsci.2014.07.010] [Citation(s) in RCA: 333] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Bonengel S, Bernkop-Schnürch A. Thiomers--from bench to market. J Control Release 2014; 195:120-9. [PMID: 24993428 DOI: 10.1016/j.jconrel.2014.06.047] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/16/2014] [Accepted: 06/24/2014] [Indexed: 01/22/2023]
Abstract
Thiolated polymers or designated thiomers are obtained by immobilization of sulhydryl bearing ligands on the polymeric backbone of well-established polymers such as poly(acrylates) or chitosans. This functionalization leads to significantly improved mucoadhesive properties compared to the corresponding unmodified polymers, as disulfide bonds between thiol groups of thiomers and cysteine-rich glycoproteins of the mucus gel layer are formed. Furthermore, enzyme- and efflux-pump inhibiting as well as improved permeation-enhancing properties are advantages of thiolization. By the covalent attachment of mercaptonicotinamide substructures via disulfide bonds to thiolated polymers these properties are even substantially further improved and stability towards oxidation even in aqueous media can be provided. Meanwhile, more than 50 research groups worldwide are working on thiolated polymers. For certain thiomers the scale up process for industrial production has already been done and GMP material is available. Furthermore, safety of thiolated poly(acrylic acid), thiolated chitosan and thiolated hyaluronic acid could be demonstrated via orientating studies in human volunteers and via various clinical trials. The first product (Lacrimera® eye drops, Croma-Pharma) containing a chitosan-N-acetylcysteine conjugate for treatment of dry eye syndrome will enter the European market this year. It is the only product providing a sustained protective effect on the ocular surface due to its comparatively much more prolonged residence time worldwide. Various further products utilizing, for instance, thiolated hyaluronic acid in ocular surgery are in the pipeline.
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Affiliation(s)
- Sonja Bonengel
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Andreas Bernkop-Schnürch
- Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
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Biodegradable human serum albumin nanoparticles as contrast agents for the detection of hepatocellular carcinoma by magnetic resonance imaging. Eur J Pharm Biopharm 2014; 87:132-41. [DOI: 10.1016/j.ejpb.2013.12.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 12/12/2013] [Indexed: 11/23/2022]
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AL-Kahtani AA, Sherigara B. Controlled release of diclofenac sodium through acrylamide grafted hydroxyethyl cellulose and sodium alginate. Carbohydr Polym 2014; 104:151-7. [DOI: 10.1016/j.carbpol.2014.01.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 11/30/2013] [Accepted: 01/05/2014] [Indexed: 11/26/2022]
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Sosnik A. Reversal of multidrug resistance by the inhibition of ATP-binding cassette pumps employing "Generally Recognized As Safe" (GRAS) nanopharmaceuticals: A review. Adv Drug Deliv Rev 2013; 65:1828-51. [PMID: 24055628 DOI: 10.1016/j.addr.2013.09.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 09/06/2013] [Accepted: 09/10/2013] [Indexed: 12/17/2022]
Abstract
Pumps of the ATP-binding cassette superfamily (ABCs) regulate the access of drugs to the intracellular space. In this context, the overexpression of ABCs is a well-known mechanism of multidrug resistance (MDR) in cancer and infectious diseases (e.g., viral hepatitis and the human immunodeficiency virus) and is associated with therapeutic failure. Since their discovery, ABCs have emerged as attractive therapeutic targets and the search of compounds that inhibit their genetic expression and/or their functional activity has gained growing interest. Different generations of pharmacological ABC inhibitors have been explored over the last four decades to address resistance in cancer, though clinical results have been somehow disappointing. "Generally Recognized As Safe" (GRAS) is a U.S. Food and Drug Administration designation for substances that are accepted as safe for addition in food. Far from being "inert", some amphiphilic excipients used in the production of pharmaceutical products have been shown to inhibit the activity of ABCs in MDR tumors, emerging as a clinically translatable approach to overcome resistance. The present article initially overviews the classification, structure and function of the different ABCs, with emphasis on those pumps related to drug resistance. Then, the different attempts to capitalize on the activity of GRAS nanopharmaceuticals as ABC inhibitors are discussed.
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Affiliation(s)
- Alejandro Sosnik
- The Group of Biomaterials and Nanotechnology for Improved Medicines (BIONIMED), Department of Pharmaceutical Technology, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Argentina; National Science Research Council (CONICET), Argentina; Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel.
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Yandrapu SK, Kanujia P, Chalasani KB, Mangamoori L, Kolapalli RV, Chauhan A. Development and optimization of thiolated dendrimer as a viable mucoadhesive excipient for the controlled drug delivery: An acyclovir model formulation. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2013; 9:514-22. [DOI: 10.1016/j.nano.2012.10.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 09/27/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
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32
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Singh I, Rana V. Enhancement of Mucoadhesive Property of Polymers for Drug Delivery Applications. ACTA ACUST UNITED AC 2013. [DOI: 10.7569/raa.2013.097307] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Development and in vivo evaluation of an oral vitamin B12 delivery system. Eur J Pharm Biopharm 2012; 84:132-7. [PMID: 23262165 DOI: 10.1016/j.ejpb.2012.11.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 08/27/2012] [Accepted: 11/16/2012] [Indexed: 11/23/2022]
Abstract
Recently, poly(acrylic acid)-cysteine (PAA-cys) based formulations have shown to modulate vitamin B12 absorption across Caco-2 cells monolayers and rat intestinal mucosa. The aim of the present study was to provide a proof-of-principle for a delivery system based on PAA-cys in vivo by administering vitamin B12 to Sprague Dawley rats. In vitro, the permeation enhancing effect of unmodified and thiolated PAA was evaluated using rat intestinal mucosa mounted on Ussing type chambers and was compared to that of verapamil and reduced glutathione (GSH). Vitamin B12 transport in the presence of 0.5% (m/v) PAA-cys was 3.96-fold improved compared to buffer, while 91.5% and 56.5% increased compared to verapamil and GSH, respectively. In vivo, the oral administration of minitablets based on 0.5mg vitamin B12 with 4.5mg PAA or PAA-cys resulted in a significant improvement of vitamin B12 absolute bioavailability. The area under the serum concentration-time curve (AUC₀₋₈) of vitamin B12 after administration of PAA and PAA-cys minitablets was 1.74-fold and 2.92-fold higher in comparison with oral solution, respectively. Thiolated formulations provided an absolute bioavailability of 0.89%. According to the achieved results, PAA-cys can be considered a valuable tool for improving the oral bioavailability of vitamin B12.
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