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Xu C, Cheong JY, Mo X, Jérôme V, Freitag R, Agarwal S, Gharibi R, Greiner A. Thoroughly Hydrophilized Electrospun Poly(L-Lactide)/ Poly(ε-Caprolactone) Sponges for Tissue Engineering Application. Macromol Biosci 2023; 23:e2300143. [PMID: 37357761 DOI: 10.1002/mabi.202300143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/19/2023] [Indexed: 06/27/2023]
Abstract
Biodegradable electrospun sponges are of interest for various applications including tissue engineering, drug release, dental therapy, plant protection, and plant fertilization. Biodegradable electrospun poly(l-lactide)/poly(ε-caprolactone) (PLLA/PCL) blend fiber-based sponge with hierarchical pore structure is inherently hydrophobic, which is disadvantageous for application in tissue engineering, fertilization, and drug delivery. Contact angles and model studies for staining with a hydrophilic dye for untreated, plasma-treated, and surfactant-treated PLLA/PCL sponges are reported. Thorough hydrophilization of PLLA/PCL sponges is found only with surfactant-treated sponges. The MTT assay on the leachates from the sponges does not indicate any cell incompatibility. Furthermore, the cell proliferation and penetration of the hydrophilized sponges are verified by in vitro cell culture studies using MG63 and human fibroblast cells.
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Affiliation(s)
- Chengzhang Xu
- Macromolecular Chemistry and Bavarian Polymer Institute, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
| | - Jun Young Cheong
- Bavarian Center for Battery Technology (BayBatt) and Department of Chemistry, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
| | - Xiumei Mo
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Biological Science and Medical Engineering, Donghua University, Shanghai, 201620, P. R. China
| | - Valérie Jérôme
- Chair for Process Biotechnology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
| | - Ruth Freitag
- Chair for Process Biotechnology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
| | - Seema Agarwal
- Macromolecular Chemistry and Bavarian Polymer Institute, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
| | - Reza Gharibi
- Department of Organic Chemistry and Polymer, Faculty of Chemistry, Kharazmi University, Tehran, 15719-14911, Iran
| | - Andreas Greiner
- Macromolecular Chemistry and Bavarian Polymer Institute, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany
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Mohajeri S, Amsden BG. In Vivo Degradation Mechanism and Biocompatibility of a Biodegradable Aliphatic Polycarbonate: Poly(Trimethylene Carbonate- co-5-Hydroxy Trimethylene Carbonate). ACS APPLIED BIO MATERIALS 2021; 4:3686-3696. [PMID: 35014453 DOI: 10.1021/acsabm.1c00160] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A recently developed viscous liquid aliphatic polycarbonate, poly(trimethylene carbonate-co-5-hydroxy trimethylene carbonate), has advantageous properties for the delivery of acid-sensitive drugs such as proteins and peptides. This copolymer degrades in vitro via an alkaline-catalyzed intramolecular cyclization reaction yielding oligo (trimethylene carbonate), glycerol, and carbon dioxide, but its in vivo degradation mechanisms are presently unknown. The in vivo degradation mechanism and tissue response to this copolymer were investigated following subcutaneous implantation in Wistar rats. The molecular weight and composition of the copolymer varied in the same manner following subcutaneous implantation as observed in vitro. These findings suggest that the copolymer also degraded in vivo principally via intramolecular cyclization. The tissue response in terms of the inflammatory zone cell density, fibrous capsule thickness, and macrophage response was intermediate to that of two clinically used biodegradable sutures, Vicryl and Monocryl, indicating that the copolymer can be considered biotolerable. Collectively, the data show that further development of this copolymer as a drug delivery material is warranted.
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Affiliation(s)
- Sara Mohajeri
- Department of Chemical Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada.,Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada
| | - Brian G Amsden
- Department of Chemical Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada.,Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada
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Mohajeri S, Burke-Kleinman J, Maurice DH, Amsden BG. Formulation parameters governing sustained protein delivery from degradable viscous liquid aliphatic polycarbonates. Int J Pharm 2020; 590:119965. [PMID: 33045320 DOI: 10.1016/j.ijpharm.2020.119965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/28/2020] [Accepted: 10/06/2020] [Indexed: 11/18/2022]
Abstract
Viscous liquid degradable polymers have advantages as drug depots for sustained protein delivery. We have created a new aliphatic polycarbonate for this purpose, poly(trimethylene carbonate-co-5-hydroxy trimethylene carbonate), which upon degradation retains a near neutral micro-environmental pH. As such, this copolymer is highly suited to the delivery of acid sensitive proteins. We show that the mechanism of protein release from this liquid copolymer is consistent with the formation of super-hydrated regions as a result of the osmotic activity of the solution formed upon distributed protein particle dissolution. Protein release can be manipulated by controlling polymer hydrophobicity which can be adjusted by molecular weight and choice of initiator. Moreover, protein release is highly dependent on protein solubility which impacts the osmotic activity of the solution formed upon dissolution of the protein particles while protein molecular size and isoelectric point are not as influential. As demonstrated by the release of highly bioactive vascular endothelial growth factor, formulations of this copolymer are suitable for prolonged delivery of protein therapeutics.
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Affiliation(s)
- Sara Mohajeri
- Department of Chemical Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada; Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada
| | - Jonah Burke-Kleinman
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston K7L 3N6, Canada
| | - Donald H Maurice
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston K7L 3N6, Canada
| | - Brian G Amsden
- Department of Chemical Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada; Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada.
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Louka DA, Holwell N, Thomas BH, Chen F, Amsden BG. Highly Bioactive SDF-1α Delivery from Low-Melting-Point, Biodegradable Polymer Microspheres. ACS Biomater Sci Eng 2017; 4:3747-3758. [DOI: 10.1021/acsbiomaterials.7b00403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dimitra A. Louka
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Nathan Holwell
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Brandon H. Thomas
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Fei Chen
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Brian G. Amsden
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
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López A, Persson C, Hilborn J, Rojas R. Comparative characterization of oligomeric precursors intended for injectable implants. POLYM ADVAN TECHNOL 2013. [DOI: 10.1002/pat.3042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Alejandro López
- Department of Engineering Sciences, Division of Applied Materials Science, The Ångström Laboratory; Uppsala University; Uppsala Sweden
| | - Cecilia Persson
- Department of Engineering Sciences, Division of Applied Materials Science, The Ångström Laboratory; Uppsala University; Uppsala Sweden
| | - Jöns Hilborn
- Department of Materials Chemistry, Division of Polymer Chemistry, The Ångström Laboratory; Uppsala University; Uppsala Sweden
| | - Ramiro Rojas
- Department of Materials Chemistry, Division of Polymer Chemistry, The Ångström Laboratory; Uppsala University; Uppsala Sweden
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Levy-Nissenbaum E, Khan W, Pawar RP, Tabakman R, Naftali E, Winkler I, Kaufman O, Klapper L, Domb AJ. Pharmacokinetic and efficacy study of cisplatin and paclitaxel formulated in a new injectable poly(sebacic-co-ricinoleic acid) polymer. Eur J Pharm Biopharm 2012; 82:85-93. [DOI: 10.1016/j.ejpb.2012.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 05/30/2012] [Accepted: 06/04/2012] [Indexed: 10/28/2022]
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Mikhail A, Sharifpoor S, Amsden B. Initiator structure influence on thermal and rheological properties of oligo(ε-caprolactone). JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 17:291-301. [PMID: 16689016 DOI: 10.1163/156856206775997278] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Biodegradable thermoplastic oligomers have potential as biomaterials for tissue augmentation and drug-delivery applications. One means of obtaining such a biomaterial is through the ring-opening polymerization of epsilon-caprolactone using an alcohol initiator. In this paper we continue to examine the influence of the structure of the initiator used on the thermal and rheological properties of oligo(epsilon-caprolactone). Specifically, primary and secondary pentanol, and cis- and trans-pentenol were studied as initiators in the preparation of oligomers of constant molecular weight. In agreement with previous work, the secondary conformer yielded higher melt viscosities, lower degrees of crystallinity and lower glass transition temperatures. The cis conformer produced the lowest melt viscosity; however, the activation energy for flow was higher than obtained previously with oleyl alcohol. This result was attributed to the alkane chain lengths on either side of the cis double bond in the initiator. The order of melt viscosity increased with initiator conformer as follows: cis, trans, primary and secondary. The results were explained in terms of oligomer chain flexibility in the melt.
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Affiliation(s)
- Andrew Mikhail
- Department of Chemical Engineering, Queen's University, Kingston, Ontario, Canada
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Tomkins A, Kontopoulou M, Amsden B. Preparation and characterization of blends of star-poly(ε-caprolactone-co-D,L-lactide) and oligo(ε-caprolactone). JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 16:1009-21. [PMID: 16128234 DOI: 10.1163/1568562054414694] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Polymer blending provides a relatively facile means of combining the separate desirable properties of different polymers into a single material. In this paper blends of a low-molecular-weight star co-polymer of epsilon-caprolactone and D,L-lactide with a linear oligo(epsilon-caprolactone) are prepared and characterized as a possible biodegradable injectable drug-delivery vehicle. The melting characteristics, melt viscosity and degree of crystallinity of the blends were measured, and an in vitro degradation study was performed over a period of 12 weeks. The blends all had a single glass transition temperature and an onset of melting point near body temperature, with the melting point range decreasing as the star co-polymer content increased. The melt viscosity of the blends increased as the star co-polymer content increased, in a manner consistent with miscible blend behavior. The star co-polymer degraded fastest, with a more than 60% mass decrease over the 12-week period. As the oligo(epsilon-caprolactone) content increased, the degradation rate decreased, with the oligo(epsilon-caprolactone) exhibiting a mass loss of only 12% over the 12-week period.
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Affiliation(s)
- A Tomkins
- Department of Chemical Engineering, Dupuis Hall, Queen's University, Kingston, ON, Canada K7L 3N6
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Sukarto A, Amsden BG. Low melting point amphiphilic microspheres for delivery of bone morphogenetic protein-6 and transforming growth factor-β3 in a hydrogel matrix. J Control Release 2012; 158:53-62. [DOI: 10.1016/j.jconrel.2011.10.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 09/30/2011] [Accepted: 10/14/2011] [Indexed: 11/25/2022]
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Babasola OI, Amsden BG. Surface Eroding, Liquid Injectable Polymers Based on 5-Ethylene Ketal ε-Caprolactone. Biomacromolecules 2011; 12:3423-31. [DOI: 10.1021/bm200980a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oladunni Iyabo Babasola
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
- Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada
| | - Brian G. Amsden
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
- Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada
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11
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Amsden BG. Liquid, Injectable, Hydrophobic and Biodegradable Polymers as Drug Delivery Vehicles. Macromol Biosci 2010; 10:825-35. [DOI: 10.1002/mabi.200900465] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Timbart L, Tse MY, Pang SC, Babasola O, Amsden BG. Low Viscosity Poly(trimethylene carbonate) for Localized Drug Delivery: Rheological Properties andin vivoDegradation. Macromol Biosci 2009; 9:786-94. [DOI: 10.1002/mabi.200800318] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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13
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Shikanov A, Vaisman B, Shikanov S, Domb AJ. Efficacy of poly(sebacic acid-co-ricinoleic acid) biodegradable delivery system for intratumoral delivery of paclitaxel. J Biomed Mater Res A 2009; 92:1283-91. [DOI: 10.1002/jbm.a.32429] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Wu F, Jin T. Polymer-based sustained-release dosage forms for protein drugs, challenges, and recent advances. AAPS PharmSciTech 2008; 9:1218-29. [PMID: 19085110 DOI: 10.1208/s12249-008-9148-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 09/04/2008] [Indexed: 11/30/2022] Open
Abstract
While the concept of using polymer-based sustained-release delivery systems to maintain therapeutic concentration of protein drugs for extended periods of time has been well accepted for decades, there has not been a single product in this category successfully commercialized to date despite clinical and market demands. To achieve successful systems, technical difficulties ranging from protein denaturing during formulation process and the course of prolonged in vivo release, burst release, and incomplete release, to low encapsulation efficiency and formulation complexity have to be simultaneously resolved. Based on this updated understanding, formulation strategies attempting to address these aspects comprehensively were reported in recent years. This review article (with 134 citations) aims to summarize recent studies addressing the issues above, especially those targeting practical industrial solutions. Formulation strategies representative of three areas, microsphere technology using degradable hydrophobic polymers, microspheres made of water soluble polymers, and hydrophilic in vivo gelling systems will be selected and introduced. To better understand the observations and conclusions from different studies for different systems and proteins, physicochemical basis of the technical challenges and the pros and cons of the corresponding formulation methods will be discussed.
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Sharifpoor S, Amsden B. In vitro release of a water-soluble agent from low viscosity biodegradable, injectable oligomers. Eur J Pharm Biopharm 2007; 65:336-45. [PMID: 17084069 DOI: 10.1016/j.ejpb.2006.09.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 09/14/2006] [Accepted: 09/20/2006] [Indexed: 11/24/2022]
Abstract
Low-molecular-weight poly(epsilon-caprolactone-co-1,3-trimethylene carbonate) and poly(1,3-trimethylene carbonate) are potential vehicles for the regio-specific delivery of water-soluble agents. In this paper, the characteristics and the mechanism governing the in vitro release of a model water-soluble drug, vitamin B12, from these polymer vehicles were determined. The loading of vitamin B12 was kept to 1 w/w%. The oligomers examined ranged from amorphous, high viscosity to crystalline but low viscosity. The oligomers did not degrade appreciably in vitro. The total fraction of vitamin B12 released increased as the crystallinity of the oligomers decreased, reaching nearly total release only for the completely amorphous oligomers. The rate of release was fastest for the amorphous oligomers and dependent on their viscosity. Inclusion of a more osmotically active agent, trehalose, into the vitamin B12 particles through co-lyophilization resulted in enhanced total fraction released and a faster release rate. The results are consistent with an osmotically driven release mechanism.
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Affiliation(s)
- Soroor Sharifpoor
- Department of Chemical Engineering, Queen's University, Kingston, Canada
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Trimaille T, Gurny R, Möller M. Poly(hexyl-substituted lactides): Novel injectable hydrophobic drug delivery systems. J Biomed Mater Res A 2007; 80:55-65. [PMID: 16958050 DOI: 10.1002/jbm.a.30888] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Poly(hexyl-substituted lactides) (PHLA) as new hydrophobic polyesters with controlled molecular weights and narrow distributions were synthesized by ring-opening polymerization (ROP) using tin(II) 2-ethylhexanoate (Sn(Oct)(2)) and benzyl alcohol as catalyst and initiator. Glass transition temperatures (T(g)) and zero shear viscosities (eta(0)) at 25 degrees C could be modulated from T(g)= -42 degrees C to -10 degrees C and 40 to 4850 Pa s, respectively, by varying the polymer molecular weight and the number of hexyl groups along the polymer chain. Degradation studies were performed in terms of both mass and molecular weight loss in the course of time. The degradation mechanism is shown to be of the "bulk erosion" type, and comparable to standard poly(D,L-lactide) (PLA). Despite the increased steric hindrance in the poly(monohexyl-substituted lactide) (PmHLA) due to the hexyl side groups, its degradation rate at pH 7.4 and 37 degrees C was found to be slightly higher than observed for the analogue standard PLA. This could be attributed to the flexible rubbery state of the hexyl-substituted polymer (T(g) approximately -15 degrees C) at the physiological temperature, which is favoring the degradation in comparison to the rigid and glassy standard PLA (T(g) approximately 40 degrees C). In contrast, degradation studies performed at 60 degrees C, where both polymers are above their glass transition temperature, confirmed that the degradation rate is lower for the sterically more hindered PmHLA. The degradation products were analyzed by ESI-MS. Hydrolysis lead first to the corresponding oligo-ester fragments and finally to the nontoxic 2-hydroxyoctanoic acid and lactic acid. Tetracycline was tested as a model drug for release studies. This drug was found to be released faster and in higher amounts in its active form from the PHLA matrix than from standard PLA. The results presented in this work demonstrate the potential of these hydrophobic polylactide-based semisolid materials as an alternative to conventional PLA/PLGA for injectable drug delivery systems.
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Affiliation(s)
- Thomas Trimaille
- Department of Pharmaceutics and Biopharmaceutics, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, 30, Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
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Chitkara D, Shikanov A, Kumar N, Domb AJ. Biodegradable Injectable In Situ Depot-Forming Drug Delivery Systems. Macromol Biosci 2006; 6:977-90. [PMID: 17128422 DOI: 10.1002/mabi.200600129] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The scope of drug-delivery systems has expanded significantly in recent years providing new ways to deliver life saving therapeutics to patients. The development of new injectable drug-delivery systems has provided new vistas and opened up unexplored horizons in the field of science, particularly in controlled drug delivery since these systems possess unique advantages over traditional ones, which include ease of application, and localized and prolonged drug delivery. In the past few years, an increasing number of such systems has been reported in the literature for various biomedical applications, including drug delivery, cell encapsulation, and tissue repair. These are injectable fluids that can be introduced into the body in a minimally invasive manner prior to solidifying or gelling within the desired site. For this purpose both natural (chitosan, alginates) as well as synthetic polymers (PEGylated polyesters, ricinoleic acid-based polymers) have been utilized. These systems have been explored widely for the delivery of various therapeutic agents ranging for anti-neoplastic agents like paclitaxel to proteins and peptides such as insulin, almost covering every segment of the pharmaceutical field. This manuscript focuses on the recent advancements in the area of in situ forming biodegradable polymeric drug-delivery systems.
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Affiliation(s)
- Deepak Chitkara
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research, Sec. 67, SAS Nagar, Mohali 160062, India
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Hatefi A, Knight D, Amsden B. A biodegradable injectable thermoplastic for localized camptothecin delivery. J Pharm Sci 2004; 93:1195-204. [PMID: 15067696 DOI: 10.1002/jps.20045] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Camptothecin is an example of a potent drug with a short half-life that would benefit from a localized drug depot system that maintains its stability prior to being released. For this reason, a thermoplastic, biodegradable polymer drug depot was prepared and characterized, and the in vitro release of camptothecin examined. epsilon-Caprolactone oligomers were prepared by ring-opening polymerization initiated by various alcohols. The polymers were characterized via differential scanning calorimeter (DSC) for thermal transitions, and via a parallel plate rheometer for melt viscosity. Camptothecin was loaded into the oligomers and released into PBS buffer. The viscosity of the oligomers was alterable by the initiator used. The oligomers were semi-crystalline with melting points between 37 and 45 degrees C. Camptothecin was released from the oligomers in a diffusion-controlled manner, with the release rate increasing as the melt viscosity of the oligomer decreased. The unreleased camptothecin remained in its active lactone form for a period of up to 16 weeks.
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Affiliation(s)
- A Hatefi
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada K7L 3N6
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