101
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Barakat NS, Radwan MA. In Vitro Performance of Carbamazepine Loaded to Various Molecular Weights of Poly (D, L-Lactide-Co-Glycolide). Drug Deliv 2008; 13:9-18. [PMID: 16401588 DOI: 10.1080/10717540500308992] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The purpose of this study was to develop and assess the in vitro characteristics of carbamazepine-loaded microspheres. A solvent evaporation method was used to incorporate carbamazepine (CBZ) into poly (D,L-lactide-co-glycolide) (PLGA) with different molecular weights. The optimum conditions for CBZ-PLGA microspheres preparation were considered and the in vitro release of CBZ of PLGA microspheres were followed up to 24 hr in USP dissolution medium. The effect of using different ratios of PLGA microspheres, prepared with different molecular weights, for optimizing CBZ release also was investigated. CBZ encapsulation efficiency was 68 to 82% for all prepared formulations. Thermograms of CBZ-PLGA microspheres suggest that CBZ was totally entrapped with the PLGA polymer. The presence of Pluronic F-68 has improved the encapsulation of CBZ, resulted in better and smoother microspheres surfaces and enhanced its release pattern. CBZ release profiles were biphasic patterns; after an initial burst, a constant CBZ release rate was observed up to 24 hr. The release from these PLGA-based spherical matrices was consistent with the diffusion mechanism. CBZ dissolution T(50%) was significantly affected (> 3-fold) by increasing the lactide percent from 33.3 to 66.6% from different microspheres mixtures. The present study provides evidence that the encapsulation of CBZ to PLGA microspheres, either as a single polymer or mixture of two, was a successful attempt to control the release of CBZ.
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Affiliation(s)
- Nahla S Barakat
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
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102
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Park HY, Oh KS, Koo HM, Cho SH, Chung SJ, Lim YT, Kim D, Yuk SH. Heparin-immobilized pluronic/PVA composite microparticles for the sustained delivery of ionic drug. J Microencapsul 2008; 25:106-10. [DOI: 10.1080/02652040701800917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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103
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Budhian A, Siegel SJ, Winey KI. Production of haloperidol-loaded PLGA nanoparticles for extended controlled drug release of haloperidol. J Microencapsul 2008; 22:773-85. [PMID: 16421087 DOI: 10.1080/02652040500273753] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study developed an emulsion-solvent evaporation method for producing haloperidol-loaded PLGA nanoparticles with up to 2% (wt/wt. of polymer) drug content, in vitro release duration of over 13 days and less than 20% burst release. The free haloperidol is removed from the nanoparticle suspension using a novel solid phase extraction technique. This leads to a more accurate determination of drug incorporation efficiency than the typical washing methods. It was discovered that PLGA end groups have a strong influence on haloperidol incorporation efficiency and its release from PLGA nanoparticles. The hydroxyl-terminated PLGA (uncapped) nanoparticles have a drug incorporation efficiency of more than 30% as compared to only 10% with methyl-terminated PLGA (capped) nanoparticles. The in vitro release profile of nanoparticles with uncapped PLGA has a longer release period and a lower initial burst as compared to capped PLGA. By varying other processing and materials parameters, the size, haloperidol incorporation and haloperidol release of the haloperidol-loaded PLGA nanoparticles were controlled.
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Affiliation(s)
- Avinash Budhian
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272, USA
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104
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Ricci-Júnior E, Marchetti JM. Preparation, characterization, photocytotoxicity assay of PLGA nanoparticles containing zinc (II) phthalocyanine for photodynamic therapy use. J Microencapsul 2008; 23:523-38. [PMID: 16980274 DOI: 10.1080/02652040600775525] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Nanoparticles containing Zinc (II) Phthalocyanine (ZnPc) were prepared by a spontaneous emulsification diffusion method utilizing poly-(D,L lactic-co-glycolic acid) (PLGA), characterized and available in cellular culture. The process yield and encapsulation efficiency were 60% and 80%, respectively. The nanoparticles have a mean diameter of 200 nm, a narrow size distribution with polydispersive index of 0.15, smooth surface and spherical shape. ZnPc loaded nanoparticles maintain their photophysical behaviour after the encapsulation process. Photosensitizer released from nanoparticles was sustained with a burst effect of 10% for 3 days. The photocytotoxicity was evaluated on P388-D1 cells. They were incubated with ZnPc loaded Np by 6 h and exposed to light (675 nm) for 120 s, and light dose of 30 J cm-2. After 24 h of incubation, the cellular viability was determined, obtaining 60% of cellular death. All the physical-chemical and photobiological measurements performed allowed one conclude that ZnPc loaded PLGA nanoparticles are a promising drug delivery system for PDT.
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Affiliation(s)
- Eduardo Ricci-Júnior
- Faculty of Pharmaceutical Sciences, Laboratory of Pharmaceutical Technology, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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105
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D'Souza R, Mutalik S, Udupa N. In VitroandIn VivoPreparation Evaluations of Bleomycin Implants and Microspheres Prepared with DL-Poly (Lactide-Co-Glycolide). Drug Dev Ind Pharm 2008; 32:175-84. [PMID: 16537198 DOI: 10.1080/03639040500466064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In this investigation, poly(lactide-co-glycolide) (PLGA) gel implants and microspheric depot systems of bleomycin (BLM) were formulated and evaluated in vivo in mice bearing transplantable solid tumor (fibrosarcoma). The pharmacodynamic studies showed that both the formulations retarded tumor growth significantly (p<0.05) when compared to the control animals (without any drug treatment). Preliminary pharmacokinetic studies illustrated controlled release of the drug into the systemic circulation to elicit the anti-neoplastic action. The gel implants showed better release characteristics and greater pharmacodynamic action when compared to the microspheres, thus demonstrating the feasibility of employing biodegradable depot polymer gel matrix for chronic cancer therapy.
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Affiliation(s)
- R D'Souza
- Manipal College of Pharmaceutical Sciences, Manipal, 576 104, Karnataka, India.
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106
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Samdancioglu S, Calis S, Sumnu M, Atilla Hincal A. Formulation and In Vitro Evaluation of Bisphosphonate Loaded Microspheres for Implantation in Osteolysis. Drug Dev Ind Pharm 2008; 32:473-81. [PMID: 16638686 DOI: 10.1080/03639040500528871] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Chitosan and poly(lactide-co-glycolide) acid (PLGA) microspheres loaded with alendronate sodium (AS) were prepared for orthopedic as well as dental applications. In orthopedics the aim was to make the total joint prostheses stay in the body for a long time without causing bone tissue loss, while in dentistry it was aimed to treat the alveolar bone resorption caused by periodontitis and also to make the dental treatment using implants easier by reducing the bone loss in patients with osteoporosis. Solvent evaporation method was used to prepare AS loaded PLGA microspheres and emulsion polimerization method was used to prepare AS loaded chitosan microspheres. Particle size, loading efficacy, surface characteristics, and in vitro release characteristics were examined on prepared formulations. After the examination of the scanning electron microscopy photographs of microspheres, chitosan microspheres were observed to have spherical structure and smooth surface characteristics while PLGA microspheres were observed to have spherical porous surface structure. Loading efficacy was found to be 3.30% for chitosan microspheres and 7.70% for PLGA microspheres. It was observed that 85% of AS had been released at the end of the third day from chitosan microspheres whereas 58% was released at the end of the fifth day from PLGA microspheres. It was found that chitosan microspheres gave first order release while PLGA microspheres gave zero order release.
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Affiliation(s)
- Sibel Samdancioglu
- Hacettepe University, Department of Pharmaceutical Technology, Faculty of Pharmacy, Sihhiye 06100, Ankara, Turkey
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107
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Sun Y, Wang J, Zhang X, Zhang Z, Zheng Y, Chen D, Zhang Q. Synchronic release of two hormonal contraceptives for about one month from the PLGA microspheres: In vitro and in vivo studies. J Control Release 2008; 129:192-9. [DOI: 10.1016/j.jconrel.2008.04.022] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 04/18/2008] [Accepted: 04/25/2008] [Indexed: 10/22/2022]
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108
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Jain RA, Brito L, Straub JA, Tessier T, Bernstein H. Effect of powder processing on performance of fenofibrate formulations. Eur J Pharm Biopharm 2008; 69:727-34. [DOI: 10.1016/j.ejpb.2007.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 11/19/2007] [Accepted: 12/06/2007] [Indexed: 10/22/2022]
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109
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Wischke C, Schwendeman SP. Principles of encapsulating hydrophobic drugs in PLA/PLGA microparticles. Int J Pharm 2008; 364:298-327. [PMID: 18621492 DOI: 10.1016/j.ijpharm.2008.04.042] [Citation(s) in RCA: 546] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 04/29/2008] [Accepted: 04/29/2008] [Indexed: 10/22/2022]
Abstract
Injectable biodegradable and biocompatible copolymers of lactic and glycolic acid (PLGA) are an important advanced delivery system for week-to-month controlled release of hydrophobic drugs (e.g., from biopharmaceutical classification system class IV), which often display poor oral bioavailability. The basic principles and considerations to develop such microparticle formulations is reviewed here based on a comprehensive study of papers and patents from the beginnings of hydrophobic drug encapsulation in polylactic acid and PLGA up through the very recent literature. Challenges with the diversity of drug properties, microencapsulation methods, and organic solvents are evaluated in light of the precedence of commercialized formulations and with a focus on decreasing the time to lab-scale encapsulation of water-insoluble drug candidates in the early stage of drug development. The influence of key formulation variables on final microparticle characteristics, and how best to avoid undesired microparticle properties, is analyzed mechanistically. Finally, concepts are developed to manage the common issues of maintaining sink conditions for in vitro drug release assays of hydrophobic compounds. Overall, against the backdrop of an increasing number of new, poorly orally available drug entities entering development, microparticle delivery systems may be a viable strategy to rescue an otherwise undeliverable substance.
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Affiliation(s)
- Christian Wischke
- Department of Pharmaceutical Sciences, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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110
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Legrand P, Lesieur S, Bochot A, Gref R, Raatjes W, Barratt G, Vauthier C. Influence of polymer behaviour in organic solution on the production of polylactide nanoparticles by nanoprecipitation. Int J Pharm 2007; 344:33-43. [PMID: 17616282 DOI: 10.1016/j.ijpharm.2007.05.054] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 05/20/2007] [Accepted: 05/23/2007] [Indexed: 10/23/2022]
Abstract
The aim of this study was to define the parameters determining an optimized yield of monodisperse, nanosized particles after nanoprecipitation of a biodegradable polymer, with a view to industrial scale-up the process. Poly(d,l)-lactides (PLAs) from a homologous series of different molar masses were nanoprecipitated at different initial polymer concentrations from two organic solvents, acetone and tetrahydrofuran (THF), into water without surfactant according to a standardized procedure. Quasi-elastic light scattering and gel permeation chromatography with universal detection were used respectively to size the particles and to determine the molar mass distribution of the polymeric chains forming both nanoparticles and bulk aggregates. The intrinsic viscosity of the polymers as a function of molar mass and solvent were determined by kinematic viscosity measurements in organic solutions. High yields of small nanoparticles were obtained with polymers of lower molar mass (22600 and 32100 g/mol). For a given polymer concentration in organic solution, the particle diameter was always lower from acetone than from THF. For initial molar masses higher than 32100 g/mol, only dilute organic solutions gave significant yields of nanoparticles. Furthermore, polymer mass fractionation occurred with increasing initial molar mass and/or concentration: the nanoparticles were formed by polymeric chains of molar masses significantly lower than the average initial one. In general, nanoparticle production was satisfactory when the initial organic solution of polymer was in the dilute rather than the semi-dilute regime. Moreover, acetone, which acted as a theta solvent for PLA, always led to smaller particles and better yields than THF.
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Affiliation(s)
- Philippe Legrand
- University Paris Sud, UMR CNRS 8612, IFR 141, Châtenay Malabry, F-92296, France
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111
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Aou K, Hsu SL, Kleiner LW, Tang FW. Roles of Conformational and Configurational Defects on the Physical Aging of Amorphous Poly(lactic acid). J Phys Chem B 2007. [DOI: 10.1021/jp074509t] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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112
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Degradable Polymer Microspheres for Controlled Drug Delivery. ADVANCES IN POLYMER SCIENCE 2007. [DOI: 10.1007/3-540-45734-8_3] [Citation(s) in RCA: 278] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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113
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Abstract
The rapid prototyping (RP) technology has advanced in various fields such as verification
of design, and functional test. Recently, researchers have studied bio-materials to fabricate
functional bio-RP parts. In this research, a nano composite deposition system (NCDS) was
developed to fabricate three-dimensional functional parts for bio-applications. In the hybrid process,
the material removal process by mechanical micro machining and/or the deposition process are
combined. NCDS uses biocompatible or biodegradable polymer resin as matrix and various bioceramics
to form bio-composite materials. To test drug release rate in vivo environment, two
different types of drug delivery system (DDS) were fabricated using the bio-composite materials. 1)
Container type DDS used poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil as the drug
composite while polycaprolactone(PCL) served as the container of the drug. 2) Scaffold type DDS
formed porous microstructure with poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil
composite. The effect of geometry of the DDS on release rate of drug is under investigation.
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114
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Mahoney CM, Yu J, Gardella JA. Depth profiling of poly(L-lactic acid)/triblock copolymer blends with time-of-flight secondary ion mass spectrometry. Anal Chem 2007; 77:3570-8. [PMID: 15924391 DOI: 10.1021/ac048274i] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Time-of-flight secondary ion mass spectrometry employing an SF5+ polyatomic primary ion source was utilized to obtain a series of in-depth profiles from PLLA/Pluronic-P104 (poly(ethylene oxide-co-propylene oxide) triblock copolymer) blends in attempts to quantify the in-depth surface segregated Pluronic region. The resultant in-depth profiles were consistent with theoretical models describing the surface segregated region in polymeric blends and copolymer systems, with a surface enriched Pluronic-P104 region, followed by a P104 depletion layer, and finally a constant composition bulk region. These results were consistent over a range of concentrations (1-25%). The depth profiles obtained using cluster SIMS were compared to information obtained using X-ray photoelectron spectroscopy. The results demonstrate that, with cluster primary ion bombardment, we are for the first time able to quantify the polymeric composition as a function of depth within certain multicomponent polymer blends. This success can be attributed to the sputter characteristics of polyatomic primary ion bombardment (SF5+) as compared to monatomic primary ion beams.
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Affiliation(s)
- Christine M Mahoney
- Chemical Science and Technology Laboratory, Surface and Microanalysis Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, Maryland 20899, USA.
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115
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Liu YF, Huang KL, Peng DM, Liu SQ, Wu H. Synthesis and properties of novel aliphatic polycarbonate from carbon dioxide with 1,2-butylene oxide and ɛ-caprolactone. CHINESE CHEM LETT 2007. [DOI: 10.1016/j.cclet.2006.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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116
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Maver U, Godec A, Bele M, Planinsek O, Gaberscek M, Srcic S, Jamnik J. Novel hybrid silica xerogels for stabilization and controlled release of drug. Int J Pharm 2007; 330:164-74. [PMID: 17055199 DOI: 10.1016/j.ijpharm.2006.09.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 09/08/2006] [Accepted: 09/09/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE The goal was to show that incorporation of a model drug into a porous solid matrix with small enough pores should lead to composites in which the drug would be in the amorphous rather than in the crystalline state. Due to spatial constraints, the amorphous state was expected to be temporally highly stable. METHODS As a porous solid matrix silica was selected, while nifedipine served as a model drug. The silica-drug composites were prepared using a sol-gel procedure at conditions which yielded pores in the range 2-3 nm. To tune the properties of composites, two silica precursors were combined: tetraethoxysilane (TEOS) and bis-1,2-(triethoxysilyl)ethane (BTSE). RESULTS In all composites the amorphous state of nifedipine was proven using several analytical methods. The amorphicity was preserved for at least several months. Drug incorporation into purely TEOS-based silica decreased significantly the release rate. Loosening the structure by addition of BTSE, while preserving the amorphicity, increased the drug dissolution rate. The dissolution behaviour was explained using a combination of the Noyes-Whitney and power law model. CONCLUSION The observed release patterns could be interesting for therapies requiring a high initial drug concentration in blood plasma, followed by a slower release rate of the remaining drug.
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Affiliation(s)
- Uros Maver
- Faculty of Pharmacy, University of Ljubljana, Askerceva 7m, 1000 Ljubljana, Slovenia
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117
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De Jong WH, Dormans JAMA, Van Steenbergen MJ, Verharen HW, Hennink WE. Tissue response in the rat and the mouse to degradable dextran hydrogels. J Biomed Mater Res A 2007; 83:538-45. [PMID: 17530632 DOI: 10.1002/jbm.a.31302] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Two types of hydroxyethyl-methacrylated dextran (dex-HEMA) hydrogels differing in crosslink density were compared for local tissue responses and degradation characteristics in mice and rats. Implants (1 mm thick, rat: 10 mm diameter, mouse: 6 mm diameter) varying in degree of HEMA substitution (DS5 and DS13, meaning 5 or 13 HEMA groups per 100 glucose units of dextran) were subcutaneously implanted and tissue responses were evaluated at week 2, 6, and 13 after implantation. In the rat after 2 weeks a slight fibrous capsule was formed composed of macrophages and fibroblasts sometimes accompanied by a minimal infiltrate. Small fragments, surrounded by macrophages and giant cells indicated hydrogel degradation. After 13 weeks DS5 implants were resorbed while parts of the DS13 implants were still present. In the mouse a moderate to strong capsule formation was present at 2 weeks accompanied by inflammatory cells (macrophages and polymorphonuclear granulocytes) and debris. Draining lymph node activation was observed. Skin ulceration was present irrespective of the type of implant. Clear differences in the tissue responses between the rat and mouse were noted, as well as between implants of different degree of substitution. Mice showed a more pronounced early inflammatory response compared with rats, whereas the degradation was more complete in rats than in mice. The differences in histology between the hydrogels disappeared over time at 13 weeks after implantation and similar responses were noted for both types of hydrogels. Both in mice and rats the DS5 hydrogels showed a faster degradation rate than the DS13 hydrogels.
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Affiliation(s)
- Wim H De Jong
- Laboratory for Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
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118
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Taluja A, Youn YS, Bae YH. Novel approaches in microparticulate PLGA delivery systems encapsulating proteins. ACTA ACUST UNITED AC 2007. [DOI: 10.1039/b706939a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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119
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Mei N, Zhou P, Pan LF, Chen G, Wu CG, Chen X, Shao ZZ, Chen GQ. Biocompatibility of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) modified by silk fibroin. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2006; 17:749-58. [PMID: 16897168 DOI: 10.1007/s10856-006-9686-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 10/24/2005] [Indexed: 05/11/2023]
Affiliation(s)
- Na Mei
- The Key Laboratory of Molecular Engineering of Polymers, Ministry of Education, Macromolecular Science Department, Fudan University, Shanghai, 200433, China
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120
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Puisieux F, Seiller M, Devissaguet JP. Les systèmes de délivrance des médicaments : un réel progress pour la thérapeutique*. ANNALES PHARMACEUTIQUES FRANÇAISES 2006; 64:219-59. [PMID: 16902389 DOI: 10.1016/s0003-4509(06)75318-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Established at the request of the Research Committee of the French National Academy of Pharmacy, this report on drug delivery systems (DDS) is a summary of information gathered by interviewing leaders in the pharmaceutical community and from the international literature. This report includes: a rapid recall of pharmaceutical formulations and changes over the last decades; a definition of DDS, indications on their evolution and a discussion on their contribution to drug administration; information on firms specialized in the elaboration of DDS, their interactions with the drug industry and the current and future market for DDS; a presentation of the potential offered by DDS for the drug industry; a discussion on technical, regulatory, and economic issues which could obstruct drug administration using a DDS; a description of certain DDS selected for their therapeutic contributions and a brief presentation of perspectives; a presentation of certain recommendations for organizations concerned with DDS.
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121
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Aukunuru JV, Ayalasomayajula SP, Kompella UB. Nanoparticle formulation enhances the delivery and activity of a vascular endothelial growth factor antisense oligonucleotide in human retinal pigment epithelial cells. J Pharm Pharmacol 2006; 55:1199-206. [PMID: 14604462 DOI: 10.1211/0022357021701] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The objective of this study was to investigate the delivery and activity of a vascular endothelial growth factor (VEGF) antisense oligonucleotide in a human retinal pigment epithelial cell line (ARPE-19) using a biodegradable nanoparticulate delivery system. A 19-mer antisense phosphorothioate oligonucleotide (PS-ODN) complementary to bases 6-24 relative to the translational start site of the VEGF mRNA, a sense PS-ODN and a mismatch PS-ODN were examined for the inhibition of secretion and mRNA expression of VEGF using an enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively. Nanoparticles of the antisense oligonucleotides were formulated using a poly(lactide-co-glycolide) (50:50) copolymer using a double emulsion solvent evaporation method. After preparing nanoparticles, drug loading, encapsulation efficiency and particle size were determined. The cells were exposed to either plain solution of oligonucleotide or nanoparticles of oligonucleotide from Day 3 through Day 6. Alternatively, the cells were incubated with PS-ODNs and lipofectin for 4 h on Day 4. In all studies, VEGF secretion and mRNA expression were determined on Day 6. The particle size, drug loading and encapsulation efficiency were 252 nm, 5.5% and 16.5%, respectively. The antisense PS-ODN inhibited VEGF mRNA and protein secretion when delivered using nanoparticles or lipofectin but not in its free form. This was consistent with the ability of nanoparticles and lipofectin to elevate the cellular uptake of the oligonucleotide by 4-fold and 13-fold, respectively. Neither mismatch nor sense oligonucleotides inhibited VEGF secretion. In conclusion, biodegradable nanoparticles enhance cellular delivery of a VEGF antisense oligonucleotide and inhibit VEGF secretion and mRNA expression in a human retinal pigment epithelial cell line.
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Affiliation(s)
- Jithan V Aukunuru
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, 68198-6025, USA
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122
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Gao P, Ding P, Xu H, Yuan Z, Chen D, Wei J, Chen D. In vitro and in vivo characterization of huperzine a loaded microspheres made from end-group uncapped poly(d,l-lactide acid) and poly(d,l-lactide-co-glycolide acid). Chem Pharm Bull (Tokyo) 2006; 54:89-93. [PMID: 16394556 DOI: 10.1248/cpb.54.89] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this work was to develop biodegradable microspheres for long term delivery of a potent acetyl cholinesterase inhibitor, huperzine A (Hup-A), which is of interest in the palliative treatment of Alzheimer's disease. Microspheres were successfully prepared with specifically end-group uncapped poly(d,l-lactide acid) and poly(d,l-lactide-co-glycolide acid) using a simple o/w solvent evaporation method. The morphology, particle size and size distribution, drug loading capacity, drug entrapment efficiency (EE) and in vitro drug release were studied in detail. It was found that the terminal group and the inherent viscosity (IV) of the polymers played key role in the drug encapsulation: higher EE was achieved with end-group uncapped and low IV polymers. In vitro drug release from microspheres made from the selected three kinds of polymers revealed sustained release of Hup-A without significant burst release. Preliminary pharmacokinetic study following subcutaneous injection of Hup-A loaded microspheres illustrated the sustained release of the drug over 6-8 weeks at clinically relevant doses in vivo. The studies demonstrated the feasibility of long term delivery of Hup-A using biodegradable microspheres.
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Affiliation(s)
- Ping Gao
- Department of Pharmaceutics, School of Pharmaceutical Science, Shenyang Pharmaceutical University, China
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123
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Ricci-Júnior E, Marchetti JM. Zinc(II) phthalocyanine loaded PLGA nanoparticles for photodynamic therapy use. Int J Pharm 2006; 310:187-95. [PMID: 16442755 DOI: 10.1016/j.ijpharm.2005.10.048] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 09/28/2005] [Accepted: 10/10/2005] [Indexed: 11/25/2022]
Abstract
Sophisticated delivery systems, such as nanoparticles, represent a growing area in biomedical research. Nanoparticles (Np) were prepared using a solvent emulsion evaporation method (SEEM) to load zinc(II) phthalocyanine (ZnPc). Np were obtained using poly (D,L latic-co-glycolic acid) (PLGA). ZnPc is a second generation of photoactive agents used in photodynamic therapy. ZnPc loaded PLGA nanoparticles were prepared by SEEM, characterized and available in cellular culture. The process yield and encapsulation efficiency were 80 and 70%, respectively. The nanoparticles have a mean diameter of 285 nm, a narrow size distribution with polydispersive index of 0.12, smooth surface and spherical shape. ZnPc loaded nanoparticles maintains its photophysical behavior after encapsulation. Photosensitizer release from nanoparticles was sustained with a moderate and burst effect of 15% for 3 days. The photocytotoxicity of ZnPc loaded PLGA Np was evaluated on P388-D1 cells what were incubated with ZnPc loaded Np (5 microM) by 6h and exposed to red light (675 nm) for 120 s, and light dose of 30 J/cm(2). After 24h of incubation, the cellular viability was determined, obtaining 61% of cellular death. All the physical-chemical, photophysical and photobiological measurements performed allow us conclude that ZnPc loaded PLGA nanoparticles is a promising drug delivery system for photodynamic therapy.
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Affiliation(s)
- Eduardo Ricci-Júnior
- Laboratory of Pharmaceutical Technology, Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, University of São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil
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124
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Santoveña A, García JT, Oliva A, Llabrés M, Fariña JB. A mathematical model for interpreting in vitro rhGH release from laminar implants. Int J Pharm 2006; 309:38-43. [PMID: 16376037 DOI: 10.1016/j.ijpharm.2005.10.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 10/06/2005] [Accepted: 10/26/2005] [Indexed: 11/27/2022]
Abstract
Recombinant human growth hormone (rhGH), used mainly for the treatment of growth hormone deficiency in children, requires daily subcutaneous injections. The use of controlled release formulations with appropriate rhGH release kinetics reduces the frequency of medication, improving patient compliance and quality of life. Biodegradable implants are a valid alternative, offering the feasibility of a regular release rate after administering a single dose, though it exists the slight disadvantage of a very minor surgical operation. Three laminar implant formulations (F(1), F(2) and F(3)) were produced by different manufacture procedures using solvent-casting techniques with the same copoly(D,L-lactic) glycolic acid (PLGA) polymer (Mw=48 kDa). A correlation in vitro between polymer matrix degradation and drug release rate from these formulations was found and a mathematical model was developed to interpret this. This model was applied to each formulation. The obtained results where explained in terms of manufacture parameters with the aim of elucidate whether drug release only occurs by diffusion or erosion, or by a combination of both mechanisms. Controlling the manufacture method and the resultant changes in polymer structure facilitates a suitable rhGH release profile for different rhGH deficiency treatments.
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Affiliation(s)
- A Santoveña
- Departamento de Ingeniería Química y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain.
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125
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Dhanaraju MD, Gopinath D, Ahmed MR, Jayakumar R, Vamsadhara C. Characterization of polymeric poly(ε-caprolactone) injectable implant delivery system for the controlled delivery of contraceptive steroids. J Biomed Mater Res A 2006; 76:63-72. [PMID: 16108044 DOI: 10.1002/jbm.a.30458] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Contraceptive steroids levonorgestrel (LNG) and ethinyl estradiol (EE) have been encapsulated with poly(epsilon-caprolactone) (PCL) microspheres using a w / o /w double emulsion method. The microspheres prepared were smooth and spherical, with a mean size from 8-25 microm. In vitro release profiles of microspheres showed a trend of increasing initially at the first week, and thereafter the release was sustained. At the end of the seventh week LNG/EE from 1:5 and 1:10 PCL microspheres were 60 and 48%, 52 and 46%, respectively. An in vitro degradation study shows that at the 20th week the microspheres maintained the surface integrity. The PCL microspheres showed a triphasic in vivo release profile with an initial burst effect due to the release of the steroid adsorbed on the microsphere surface, a second sustained release phase due to the steroid diffusion through the pores or channels formed in the polymer matrix, and third phase due to polymer bioerodible. Histological examination of PCL microspheres injected intramuscularly into thigh muscle of a rat showed a minimal inflammatory reaction demonstrating that contraceptive steroid-loaded microspheres were biocompatible. The level of inflammatory cytokines determined by immunostaining for IL-1alpha, the tissue response to formulations at the first week was considered mild, whereas at the end of the 20th week the inflammatory response ceased. Thus, this study helped us to evaluate the feasibility of using these microspheres as a long-acting biodegradable drug delivery system for contraceptive steroids.
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126
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Liu TY, Lin WC, Yang MC, Chen SY. Miscibility, thermal characterization and crystallization of poly(l-lactide) and poly(tetramethylene adipate-co-terephthalate) blend membranes. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.10.100] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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127
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Ha CS, Gardella JA. Surface Chemistry of Biodegradable Polymers for Drug Delivery Systems. Chem Rev 2005; 105:4205-32. [PMID: 16277374 DOI: 10.1021/cr040419y] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chang-Sik Ha
- Department of Polymer Science and Engineering, Pusan National University, Pusan 609-735, Korea
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128
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Kim MS, Seo KS, Hyun H, Kim SK, Khang G, Lee HB. Sustained release of bovine serum albumin using implantable wafers prepared by MPEG-PLGA diblock copolymers. Int J Pharm 2005; 304:165-77. [PMID: 16198075 DOI: 10.1016/j.ijpharm.2005.08.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 08/14/2005] [Accepted: 08/16/2005] [Indexed: 10/25/2022]
Abstract
MPEG-PLGA diblock copolymers, consisting of methoxy polyethylene glycol (MPEG) and poly(L-lactic-co-glycolic acid) (PLGA), were synthesized by ring-opening polymerization of L-lactide and glycolide in the presence of MPEG as an initiator. Implantable wafers, using diblock copolymers as a drug carrier, were fabricated by direct compression method after freeze milling of the diblock copolymers and bovine serum albumin-fluorescein isothiocyanate (BSA-FITC) as a model protein drug. The wafers prepared with MPEG-PLGA diblock copolymers exhibited initial burst in the release of BSA. The BSA release profiles from the wafers depended on MPEG-PLGA diblock copolymer compositions. The in vitro release of the BSA also correlated with the degradation rate of the PLGA part in the diblock polymers. The wafers prepared from diblock copolymers with an increased MPEG segment showed the more structural metamorphosis of crack form due to higher water absorption of MPEG inside the wafer, and induced faster BSA release. The wafers prepared by using MPEG-PLGA diblock copolymers in the presence of small intestinal submucosa (SIS) as a drug carrier additive exhibited controlled BSA release profiles, although the wafers exhibited release patterns with a lag time at the initial stage as the MPEG segment in diblock copolymer compositions increased. Thus, we confirmed that the MPEG-PLGA diblock copolymers could be used as a protein delivery carrier in implantable wafer form.
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Affiliation(s)
- Moon Suk Kim
- Nanobiomaterials Laboratory, Korea Research Institute of Chemical Technology, P.O. Box 107, 100 Jang-dong, Yuseong-gu, Daejeon 305-600, Republic of Korea.
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129
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Teixeira M, Cerqueira F, Barbosa CM, Nascimento MSJ, Pinto M. Improvement of the inhibitory effect of xanthones on NO production by encapsulation in PLGA nanocapsules. J Drug Target 2005; 13:129-35. [PMID: 15823964 DOI: 10.1080/10611860400027717] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
For the first time the inhibitory effect of xanthone and 3-methoxyxanthone on nitric oxide (NO) production by IFN-gamma/LPS activated J774 macrophage cell line is reported. A remarkable improvement of this effect promoted by encapsulation of these compounds in nanocapsules of poly (DL-lactide-co-glycolide) (PLGA) is also demonstrated. A weak inhibitory effect of 3.6% on NO production by activated macrophages was observed for xanthone at the highest studied concentration (100 microM). This effect was slightly higher for 3-methoxyxanthone at the same concentration, producing a reduction of 16.5% on NO production. In contrast, equivalent concentrations of xanthone and 3-methoxyxanthone incorporated in nanocapsules produced a significant decrease on NO production of 91.8 and 80.0%, respectively. Empty nanocapsules also exhibited a slight NO inhibitory activity, which may be due to the presence of soybean lecithin in the composition of the nanosystems. The viability of the macrophages was not affected either by free or nanoencapsulated xanthones. Fluorescence microscopy analysis confirmed that a phagocytic process was involved in the macrophage uptake of xanthone- and 3-methoxyxanthone-loaded PLGA nanocapsules. Phagocytosis might be the main mechanism responsible for the enhancement of the intracellular delivery of both compounds and consequently for the improvement of their biological effect.
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Affiliation(s)
- Maribel Teixeira
- CEQOFFUP--Centro de Estudos de Química Orgânica, Fitoquímica e Farmacologia da Universidade do Porto, Faculdade de Farmácia, Universidade do Porto, R. Aníbal Cunha, 164, 4050-047 Porto, Portugal
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130
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Teixeira M, Alonso MJ, Pinto MMM, Barbosa CM. Development and characterization of PLGA nanospheres and nanocapsules containing xanthone and 3-methoxyxanthone. Eur J Pharm Biopharm 2005; 59:491-500. [PMID: 15760730 DOI: 10.1016/j.ejpb.2004.09.002] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Revised: 09/01/2004] [Accepted: 09/03/2004] [Indexed: 11/29/2022]
Abstract
The aim of the present work was to develop and characterize two different nanosystems, nanospheres and nanocapsules, containing either xanthone (XAN) or 3-methoxyxanthone (3-MeOXAN), with the final goal of improving the delivery of these poorly water-soluble compounds. The xanthones-loaded nanospheres (nanomatrix systems) and nanocapsules (nanoreservoir systems), made of poly(DL-lactide-co-glycolide) (PLGA), were prepared by the solvent displacement technique. The following characteristics of nanoparticle formulations were determined: particle size and morphology, zeta potential, incorporation efficiency, thermal behaviour, in vitro release profiles and physical stability at 4 degrees C. The nanospheres had a mean diameter <170 nm, a narrow size distribution (polydispersity index <0.1), and a negative surface charge (zeta potential <-36 mV). Their incorporation efficiencies were 33% for XAN and 42% for 3-MeOXAN. The presence of the xanthones did not affect the nanospheres size and zeta potential. DSC studies indicated that XAN and 3-MeOXAN were dispersed at a molecular level within the polymeric nanomatrix. Nanocapsules were also nanometric (mean size <300 nm) and exhibited a negative charge (zeta potential <-36 mV). Their incorporation efficiency values (>77%) were higher than those corresponding to nanospheres for both xanthones. The release of 3-MeOXAN from nanocapsules was similar to that observed for the correspondent nanoemulsion, indicating that drug release is mainly governed by its partition between the oil core and the external aqueous medium. In contrast, the release of XAN from nanocapsules was significantly slower than from the nanoemulsion, a behaviour that suggests an interaction of the drug with the polymer. Nanocapsule formulations exhibited good physical stability at 4 degrees C during a 4-month period for XAN and during a 3-month period for 3-MeOXAN.
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Affiliation(s)
- Maribel Teixeira
- Centro de Estudos de Química Orgânica, Fitoquímica e Farmacologia da Universidade do Porto-Faculdade de Farmácia do Porto, Porto, Portugal
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131
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Dittrich M, Pokorová D, Kladnícková I, Hampl J. Some basic parameters of microspheres fabricated from a branched oligoester by a rapid procedure. J Microencapsul 2005; 21:593-606. [PMID: 15762317 DOI: 10.1080/02652040400000470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Microspheres were prepared from a branched copolymer of DL-lactic acid with mannitol containing native albumin and albumin labelled with fluorescein isothiocyanate, using a rapid method of distribution of methylformate as the solvent of the copolymer from the intermediate phase of the multiple w/o/w emulsion. The primary w/o emulsion was prepared by the method of homogenization with a turbine or, alternatively, by the method of dispersion with ultrasound in modified vessels. Different additives in the external aqueous phase, such as polyvinyl alcohol or the gelatin hydrolyzate as emulsifiers were tested. Ammonium sulphate, methylformate or ethyl acetate were used as moderators of solidification of microspheres. The effect of these selected formulation parameters on the size, encapsulation efficiency, yield of microspheres and on the course of the BSA and FITC-BSA release in vitro conditions were examined.
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Affiliation(s)
- M Dittrich
- Faculty of Pharmacy, Charles University, Heyrovského 1203, CZ 500 05, Hradec Králové, Czech Republic.
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132
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Dailey LA, Kissel T. New poly(lactic-co-glycolic acid) derivatives: Modular polymers with tailored properties. DRUG DISCOVERY TODAY. TECHNOLOGIES 2005; 2:7-13. [PMID: 24981749 DOI: 10.1016/j.ddtec.2005.05.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Poly(lactic-co-glycolic acid) (PLGA) is one of the most widely used polymers in drug delivery, despite several well-characterized shortcomings. Polymer modification is one approach to improve PLGA-based formulation properties, such as drug stability, drug release profiles, mechanism of polymer degradation and the possibility of drug targeting. A brief summary of recent reports on PLGA modifications is provided and a new class of branched polyester derivatives is introduced. In vitro and in vivo applications of the new branched polyesters as protein carriers, gene delivery vehicles, vaccine adjuvants and pulmonary drug delivery vehicles are described.:
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Affiliation(s)
- Lea Ann Dailey
- Nektar Therapeutics, 150 Industrial Rd, San Carlos, CA 94070, USA.
| | - Thomas Kissel
- Department of Pharmaceutics and Biopharmacy, Philipps University, Ketzerbach 63, 35037 Marburg, Germany
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133
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Sarazin P, Roy X, Favis BD. Controlled preparation and properties of porous poly(l-lactide) obtained from a co-continuous blend of two biodegradable polymers. Biomaterials 2004; 25:5965-78. [PMID: 15183611 DOI: 10.1016/j.biomaterials.2004.01.065] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2003] [Accepted: 01/26/2004] [Indexed: 11/19/2022]
Abstract
This study prepares porous PLLA from a blend of two biodegradable polymers. This approach is based on a detailed and quantitative morphology control of the blends. Co-continuous blends comprised of poly(L-lactide)/poly(epsilon-caprolactone) PLLA/PCL, were prepared via melt processing. Through a judicious combination of concentration control and a subsequent annealing step it is possible to generate a wide range of sizes for the co-continuous phases. Subsequent extraction of the PCL porogen phase generates a fully interconnected porous PLLA material with a void volume between 50% and 60%. The volume average pore diameter is controlled from 1.5 to 88 microm as measured by mercury intrusion porosimetry. Through static annealing it is also possible to generate porous structures well beyond that upper limit of pore size. The upper limit of pore size reported above is in the range required for scaffolds for tissue engineering. Micrographs of porous polyglycolide and PCL derived from co-continuous blends of PLLA/polyglycolide and PCL/poly(ethylene oxide) are also shown and demonstrate the versatility and wide applicability of this preparation protocol. The porous structures produced from PLLA/PCL blends possess a high level of mechanical integrity and a degree of crystallinity between 25% and 38%. High values of both compressive modulus and strength at 10%-strain are obtained, greater than 190 and 11 MPa, respectively. The compressive modulus is found to be from 10% to 20% of that of the pure PLLA material. A series of loading studies were also carried out and it was shown that under a pressure of 40 atm applied for 1 h, the pores of a 1.5 microm porous PLLA structure were filled to approximately 80% by water. In addition, the loading of an aqueous solution of a model drug compound, bovine serum albumin (BSA), was carried out at 40 atm and the results indicate that large quantities of BSA (up to 25% of the weight of the original porous capsule) can be driven into the pores. These results indicate that the internal porous structure is accessible to aqueous solution and that this material also has potential as a substrate for controlled release applications.
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Affiliation(s)
- Pierre Sarazin
- Department of Chemical Engineering Ecole Polytechnique, Centre de Recherche Appliquée Sur les Polymères, P.O. Box 6079, Station Centre-Ville, Montréal, Que., Canada H3C 3A7
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134
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Wang L, Chaw CS, Yang YY, Moochhala SM, Zhao B, Ng S, Heller J. Preparation, characterization, and in vitro evaluation of physostigmine-loaded poly(ortho ester) and poly(ortho ester)/poly(D,L-lactide-co-glycolide) blend microspheres fabricated by spray drying. Biomaterials 2004; 25:3275-82. [PMID: 14980422 DOI: 10.1016/j.biomaterials.2003.09.099] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2003] [Accepted: 09/22/2003] [Indexed: 11/29/2022]
Abstract
The physostigmine-loaded poly(ortho ester) (POE), poly(dl-lactide-co-glycolide) (PLGA) and POE/PLGA blend microspheres were fabricated by a spray drying technique. The in vitro degradation of, and physostigmine release from, the microspheres were investigated. SEM analysis showed that the POE and POE/PLGA blend particles were spherical. They were better dispersed when compared to the pure PLGA microspheres. Two glass transition temperature ( Tg ) values of the POE/PLGA blend microspheres were observed due to the phase separation of POE and PLGA in the blend system. XPS analysis proved that POE dominated the surfaces of POE/PLGA blend microspheres, indicating that the blend microspheres were coated with POE. The encapsulation efficiencies of all the microspheres were more than 95%. The incorporation of physostigmine reduced the Tg value of microspheres. The Tg value of the degrading microspheres increased with the release of physostigmine. For instance, POE blank microspheres and physostigmine-loaded POE microspheres had a Tg value of 67 degrees C and 48 degrees C, respectively. After 19 days in vitro incubation, Tg of the degrading POE microspheres increased to 55 degrees C. Weight loss studies showed that the degradation of the blend microspheres was accelerated with the presence of PLGA because its degradation products catalyzed the degradation of both POE and PLGA. The release rate of physostigmine increased with increase of PLGA content in the blend microspheres. The initial burst release of physostigmine was effectively suppressed by introducing POE to the blend microspheres. However, there was an optimized weight ratio of POE to PLGA (85:15 in weight), below which a high initial burst was induced. The POE/PLGA blend microspheres may make a good drug delivery system.
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Affiliation(s)
- Ling Wang
- Institute of Materials Research and Engineering, National University of Singapore, No. 3 Research Link, Singapore 117602, Singapore
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135
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Paciotti GF, Myer L, Weinreich D, Goia D, Pavel N, McLaughlin RE, Tamarkin L. Colloidal gold: a novel nanoparticle vector for tumor directed drug delivery. Drug Deliv 2004; 11:169-83. [PMID: 15204636 DOI: 10.1080/10717540490433895] [Citation(s) in RCA: 673] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Colloidal gold, a sol comprised of nanoparticles of Au(0), has been used as a therapeutic for the treatment of cancer as well as an indicator for immunodiagnostics. However, the use of these gold nanoparticles for in vivo drug delivery has never been described. This communication outlines the development of a colloidal gold (cAu) nanoparticle vector that targets the delivery of tumor necrosis factor (TNF) to a solid tumor growing in mice. The optimal vector, designated PT-cAu-TNF, consists of molecules of thiol-derivatized PEG (PT) and recombinant human TNF that are directly bound onto the surface of the gold nanoparticles. Following intravenous administration, PT-cAu-TNF rapidly accumulates in MC-38 colon carcinoma tumors and shows little to no accumulation in the livers, spleens (i.e., the RES) or other healthy organs of the animals. The tumor accumulation was evidenced by a marked change in the color of the tumor as it acquired the bright red/purple color of the colloidal gold sol and was coincident with the active and tumor-specific sequestration of TNF. Finally, PT-cAu-TNF was less toxic and more effective in reducing tumor burden than native TNF since maximal antitumor responses were achieved at lower doses of drug.
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136
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Schwach G, Oudry N, Delhomme S, Lück M, Lindner H, Gurny R. Biodegradable microparticles for sustained release of a new GnRH antagonist – part I: screening commercial PLGA and formulation technologies. Eur J Pharm Biopharm 2003; 56:327-36. [PMID: 14602174 DOI: 10.1016/s0939-6411(03)00096-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The formulation of a new GnRH antagonist (degarelix) in biodegradable poly(DL-lactide-co-glycolide) (PLGA) microparticles was investigated for the development of a 3-month sustained release formulation to treat prostate cancer. The aim was to screen formulation technologies and distinct copolymers to produce microparticles (MP) of different types with good entrapment efficiency (>85%) and peptide purity (>95%) after gamma sterilization. Basically, three types of degarelix-loaded MP (4, 8 and 16% w/w nominal content) were produced with solvent and non-solvent technologies, namely double-emulsion solvent evaporation, spray-drying and two extrusion methods. Besides composition, commercial copolymers differing in residual monomer content and functional group at the carboxylic terminus (acid or ester) were characterized and employed. Peptide loading capacity and purity, as well as shape, size characteristics, and porosity of the produced microparticles were discussed in relation to technology and copolymer choice. Spray-drying and micro-extrusion were the two preferred formulation technologies because of higher entrapment efficiency and better preservation of peptide purity during production and gamma-sterilization. The impact of formulation technologies on the MP characteristics overwhelmed the impact of copolymer selection. Nevertheless, one particular polymer was discarded since it was more susceptible towards radiolytic degradation. The resulting degarelix-MP will be tested in a biological assay for selection of the formulation based on performance.
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Affiliation(s)
- Grégoire Schwach
- Interuniversity Center of Geneva and Lyon, Pharmapeptides, Archamps, France
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137
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Mallardé D, Boutignon F, Moine F, Barré E, David S, Touchet H, Ferruti P, Deghenghi R. PLGA-PEG microspheres of teverelix: influence of polymer type on microsphere characteristics and on teverelix in vitro release. Int J Pharm 2003; 261:69-80. [PMID: 12878396 DOI: 10.1016/s0378-5173(03)00272-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Teverelix microspheres were produced by coacervation using a new type of poly(ester-carbonates) made of block copolymers of poly(lactic-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). Five different PLGA-PEG copolymers and one PLGA were used. The 'stability window' has been determined for all polymers. It varied depending on the molecular weight and the weight percentage of PEG. With increasing core loading (from 9.4 to 34.2%), the microparticle size increased from 10-50 to 5-1000 micrometer. The core loading did not have any influence on encapsulation yield, which remained above 80%. The influence of polymer type on microsphere characteristics was studied at two different core loadings: 9.4 and 28%. At a low core loading, the nature of the polymer had no influence on microsphere characteristics whereas at 28%, only PLGA-PEG copolymers gave acceptable microparticles in term of particle size. At 28%, the glass transition temperature (T(g)) of loaded particles was 1-8 degrees C higher than the T(g) of the corresponding polymer. Increasing the core loading increased teverelix release whereas polymer degradation was decreased. All microparticles made of PLGA-PEG copolymers showed a faster release of teverelix than PLGA-based microspheres, whatever the core loading. One PLGA-PEG was selected on the basis of in vitro release rate for further in vivo investigations.
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138
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Sun LF, Zhuo RX, Liu ZL. Synthesis and enzymatic degradation of 2-methylene-1,3-dioxepane and methyl acrylate copolymers. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/pola.10868] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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139
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Perugini P, Genta I, Conti B, Modena T, Cocchi D, Zaffe D, Pavanetto F. PLGA microspheres for oral osteopenia treatment: preliminary "in vitro"/"in vivo" evaluation. Int J Pharm 2003; 256:153-60. [PMID: 12695021 DOI: 10.1016/s0378-5173(03)00072-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this work was to prepare and to evaluate "in vitro"/"in vivo" microspheres based on poly(D,L-lactide-co-glycolide) copolymers containing ipriflavone, for the local treatment of oral bone loss. The first objective was the preparation and "in vitro" characterization of ipriflavone loaded microspheres, by emulsion/solvent evaporation method. Process parameters such as drug:polymer weight ratio, and molecular weight of copolymers, were also investigated. The second objective was to elaborate a suitable animal model of mandibular osteoporosis, to evaluate the efficacy of these microparticulate drug delivery systems. "In vivo" experiments were carried out on female rats, in which oral osteopenia was induced by gonadectomy and molar avulsion. Morphometric analysis of mandibular segment were carried out to quantify the development of oral osteopenia and the efficacy of drug loaded microspheres. Results showed that ipriflavone loaded PLGA microspheres can be successfully obtained with good "in vitro" characteristics, utilizing the emulsification/solvent evaporation method. "In vivo" experiments revealed that local administration of microspheres produced only mild inflammation on the injection site. Morphometric analyses showed, at the level of the third molar, a slight increase in spongy and total bone mass on rat jaw treated with microspheres with respect to control. Control animals exhibited a scarce degree of osteopenia demonstrating that this animal model is not suitable for this purpose.
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Affiliation(s)
- P Perugini
- Department of Pharmaceutical Chemistry, University of Pavia, V.le Taramelli 12, 27100, Pavia, Italy
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140
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Abstract
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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Affiliation(s)
- Jayanth Panyam
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
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141
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Corbin PS, Webb MP, McAlvin JE, Fraser CL. Biocompatible polyester macroligands: new subunits for the assembly of star-shaped polymers with luminescent and cleavable metal cores. Biomacromolecules 2002; 2:223-32. [PMID: 11749177 DOI: 10.1021/bm005621z] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of a series of star-shaped, biocompatible polyesters--polylactides (PLAs), polycaprolactones (PCLs), and various copolymer analogues--with either labile iron(II) tris-bipyridyl or luminescent ruthenium(II) tris-bipyridyl cores is described. These polymers were readily assembled by a convergent, metal-template-assisted approach that entailed the synthesis of bipyridine (bpy) ligands incorporating PLA- and PCL-containing arms and subsequent chelation of the "macroligands" to iron(II) or ruthenium(II). Specifically, the polyester macroligands bpyPLA(2) and bpyPCL(2) were prepared by a stannous octoate catalyzed ring-opening polymerization of DL- or L-lactide and epsilon-caprolactone, using bis(hydroxymethyl)-2,2'-bipyridine as the initiator. Copolymers bpy(PCL-PLA)(2) and bpy(PLA-PCL)(2) were generated in an analogous manner using bpyPLA(2) and bpyPCL(2) as macroinitiators. Polymers with narrow molecular weight distributions and with molecular weights close to values expected based upon monomer/initiator loading were produced. The macroligands were subsequently chelated to iron(II) to afford six-armed, iron-core star polymers, which were characterized by UV-vis and (1)H NMR spectroscopy. Estimated chelation efficiencies for formation of the star polymers (M(n) calcd: 20-240 kDa) were high, as determined by UV-vis spectral analysis. Within the molecular weight range investigated, differential scanning calorimetry and thermogravimetric analysis revealed that the small amounts of metal in the polyester stars and differences in polymer architecture had little effect on the thermal properties of the PLA/PCL materials. However, thin films of the red-violet colored iron-core stars exhibited reversible, thermochromic bleaching. Solutions and films of the polymers also responded (with color loss) to a variety of chemical stimuli (e.g., acid, base, peroxides, ammonia), thus revealing potential for use in diverse sensing applications. Likewise, the polyester macroligands were chelated to ruthenium(II) to produce both linear and star-shaped polymers, which were characterized by UV-vis and (1)H NMR spectral analysis. Molecular weights of the polymers were determined by gel permeation chromatography (M(n)(MALLS): 6-30 kDa) with in-line, UV-vis diode-array detection, confirming the presence of the [Ru(bpy)(3)](2+) core in the eluting polymer fractions. As was the case with the corresponding iron-core polyesters, estimated chelation efficiencies were high.
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Affiliation(s)
- P S Corbin
- Department of Chemistry, University of Virginia, McCormick Road, P.O. Box 400319, Charlottesville, Virginia 22904-4319, USA
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142
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Dorta MJ, Santoveña A, Llabrés M, Fariña JB. Potential applications of PLGA film-implants in modulating in vitro drugs release. Int J Pharm 2002; 248:149-56. [PMID: 12429469 DOI: 10.1016/s0378-5173(02)00431-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this work we evaluate poly(lactic/glycolic) acid (PLGA) film-implants as potential biodegradable devices for controlled release of two different drugs: 5-Fluorouridine (5-FUR), a conventional low molecular weight water-soluble compound and SPf66 malaria vaccine, a therapeutic synthetic polypeptide. Three types of devices were prepared by solvent-casting techniques alone or combined with compression method: simple monolithic discs (SMD), multilayer discs with a central monolithic layer (MLDM), and multilayer discs with a central drug-reservoir (MLDR). For the highly water-soluble drug, 5-FUR, in vitro release from SMD showed an initial burst (24% in 2 h) followed by prolonged release over 20 days. In contrast, from a MLDM (two drug-free PLGA discs were added to the SMD) showed an initial lag-time of 12 days followed by a very fast second release phase. Finally, when the load of this system was increased from 3 to 9%, an extended release over 20 days with a low burst effect was obtained. For SPf66, the central reservoir containing the synthetic polypeptide MLDR reduces the possibility of degradation due to peptide contact with polymer solution. When four layers were added, 10 days sustained-release was obtained without any burst effect. With six layers a moderate pulse was obtained, 18-22 days from the beginning of the release. The results show the suitability of the proposed devices to control release and avoid the burst effect with highly water-soluble drugs; as well as modulate in vitro peptide release.
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Affiliation(s)
- María Jesús Dorta
- Dpto. Ingeniería Química y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de La Laguna, 38200 Tenerife, Spain
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143
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Schaefer MJ, Singh J. Effect of tricaprin on the physical characteristics and in vitro release of etoposide from PLGA microspheres. Biomaterials 2002; 23:3465-71. [PMID: 12099290 DOI: 10.1016/s0142-9612(02)00053-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The purpose of this article is to examine the effects of tricaprin on the physical characteristics and in vitro release of etoposide from poly (lactic-co-glycolic acid) microspheres. The microspheres were synthesized through the use of a single-emulsion solvent-extraction procedure. Samples from each batch of microspheres were then analyzed for size distribution, drug loading efficiency, surface characteristics, in vitro release, and in vitro degradation of microspheres. Microsphere batches were synthesized using three different etoposide concentrations (15%, 10%, and 5% w/w) with tricaprin concentrations of 25% and 50%. The incorporation of 50% tricaprin significantly increased (p<0.05) the size of the microspheres for all three etoposide concentrations in comparison to microspheres prepared without tricaprin (control). The percentage of tricaprin used did not significantly affect the drug loading efficiency of the microspheres. The addition of tricaprin was shown to significantly increase (p<0.05) the in vitro release of etoposide from the microspheres prepared with all three concentrations of etoposide and the two different tricaprin percentages. Examination of the surface characteristics of the tricaprin loaded microspheres showed a dimpled surface with what appeared to be pockets of tricaprin dispersed throughout. In the in vitro degradation study, the tricaprin microspheres grew very porous as the degradation time increased, but they still retained a recognizable structure even after 30 days of degradation.
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Affiliation(s)
- Matthew J Schaefer
- Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo 58105, USA
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144
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Re: Bioabsorbable Ciprofloxacin-Containing and Plain Self-Reinforced Polylactide-Polyglycolide 80/20 Screws: Pullout Strength Properties in Human Cadaver Parietal Bones. Johanna Tiainen; Minna Veiranto; Esa Suokas; Pertti Törmälä, Timo Waris, Milomir Ninkovic, Nureddin Ashammakhi, J Craniofacial Surg 2002 May;13:427–433. J Craniofac Surg 2002. [DOI: 10.1097/00001665-200207000-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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145
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Dorta MJ, Oliva A, Munguía O, Llabrés M, Fariña JB. In-vitro release of fluoropyrimidines from PLGA film implants. J Pharm Pharmacol 2002; 54:757-63. [PMID: 12078991 DOI: 10.1211/0022357021779096] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The release of two low-molecular weight water-soluble fluoropyrimidines, 5-fluorouracil and 5-fluorouridine, from implants of PLGA films was modulated by varying the area (diameter) and number of layers of film per implant. The aim was to achieve continuous release without burst effect for at least a month. The film implants were prepared by the solvent evaporation technique. Except with 5-fluorouracil films, the in-vitro release profiles were in all cases triphasic, indicating that release proceeds by a combination of diffusion and polymer erosion. The experimental data fit the equation resulting from the sum of two exponentials, one direct and the other inverse. 5-fluorouridine release from simple films presented a relatively minor burst effect (24-28%). In contrast, the delivery of both compounds from sandwich-type implants occurred continuously without a burst effect, and lasted for 17-20 days. During the first phase, both 3- and 5-mm sandwiches released 55% of the dose of 5-fluorouridine, at rate constants of 0.037+/-0.021 h(-1) (n = 3) and 0.009+/-0.003 h(-1) (n=3), respectively. In the second phase, release was gradual from both simple films (k2 = 0.011-0.015 h(-1)) and sandwiches (k2 = 0.018-0.058 h(-1)). According to the analysis-of-variance results, neither the area nor type of implant influenced the rate constants significantly. The release profiles of 5-fluorouracil from simple films showed a severe burst effect (64-71%). Release of 5-fluorouracil was gradual only from sandwiches, 5 mm in diameter, showing a lag time unobserved in the 3-mm sandwiches. In the second phase, release was gradual (k2 = 0.014+/-0.003 h(-1)) from 3-mm implants. However, the high variability in results for 5-mm implants prevents conclusions being drawn about the model parameters. Therefore, the sandwich-type film implants showed their utility for releasing water-soluble drugs for a prolonged time, without burst effect.
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Affiliation(s)
- M Jesús Dorta
- Departamento de Ingeniería Química y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de La Laguna, Tenerife, Spain
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146
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Ambrosio AMA, Allcock HR, Katti DS, Laurencin CT. Degradable polyphosphazene/poly(alpha-hydroxyester) blends: degradation studies. Biomaterials 2002; 23:1667-72. [PMID: 11924588 DOI: 10.1016/s0142-9612(01)00293-9] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Biomaterials based on the polymers of lactic acid and glycolic acid and their copolymers are used or studied extensively as implantable devices for drug delivery, tissue engineering and other biomedical applications. Although these polymers have shown good biocompatibility, concerns have been raised regarding their acidic degradation products, which have important implications for long-term implantable systems. Therefore, we have designed a novel biodegradable polyphosphazene/poly(alpha-hydroxyester) blend whose degradation products are less acidic than those of the poly(alpha-hydroxyester) alone. In this study, the degradation characteristics of a blend of poly(lactide-co-glycolide) (50:50 PLAGA) and poly[(50% ethyl glycinato)(50% p-methylphenoxy) phosphazene] (PPHOS-EG50) were qualitatively and quantitatively determined with comparisons made to the parent polymers. Circular matrices (14mm diameter) of the PLAGA, PPHOS-EG50 and PLAGA-PPHOS-EG50 blend were degraded in non-buffered solutions (pH 7.4). The degraded polymers were characterized for percentage mass loss and molecular weight and the degradation medium was characterized for acid released in non-buffered solutions. The amounts of neutralizing base necessary to bring about neutral pH were measured for each polymer or polymer blend during degradation. The poly(phosphazene)/poly(lactide-co-glycolide) blend required significantly less neutralizing base in order to bring about neutral solution pH during the degradation period studied. The results indicated that the blend degraded at a rate intermediate to that of the parent polymers and that the degradation products of the polyphosphazene neutralized the acidic degradation products of PLAGA. Thus, results from these in vitro degradation studies suggest that the PLAGA-PPHOS-EG50 blend may provide a viable improvement to biomaterials based on acid-releasing organic polymers.
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Affiliation(s)
- Archel M A Ambrosio
- Department of Chemical Engineering, Center for Advanced Biomaterials and Tissue Engineering, Drexel University, Philadelphia, PA 19104, USA
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147
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Pérez C, Castellanos IJ, Costantino HR, Al-Azzam W, Griebenow K. Recent trends in stabilizing protein structure upon encapsulation and release from bioerodible polymers. J Pharm Pharmacol 2002; 54:301-13. [PMID: 11902796 DOI: 10.1211/0022357021778448] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Sustained release of pharmaceutical proteins from biocompatible polymers offers new opportunities in the treatment and prevention of disease. The manufacturing of such sustained-release dosage forms, and also the release from them, can impose substantial stresses on the chemical integrity and native, three-dimensional structure of proteins. Recently, novel strategies have been developed towards elucidation and amelioration of these stresses. Non-invasive technologies have been implemented to investigate the complex destabilization pathways that can occur. Such insights allow for rational approaches to protect proteins upon encapsulation and release from bioerodible systems. Stabilization of proteins when utilizing the most commonly employed procedure, the water-in-oil-in-water (w/o/w) double emulsion technique, requires approaches that are based mainly on either increasing the thermodynamic stability of the protein or preventing contact of the protein with the destabilizing agent (e.g. the water/oil interface) by use of various additives. However, protein stability is still often problematic when using the w/o/w technique, and thus alternative methods have become increasingly popular. These methods, such as the solid-in-oil-in-oil (s/o/o) and solid-in-oil-in-water (s/o/w) techniques, are based on the suspension of dry protein powders in an anhydrous organic solvent. It has become apparent that protein structure in the organic phase is stabilized because the protein is "rigidified" and therefore unfolding and large protein structural perturbations are kinetically prohibited. This review focuses on strategies leading to the stabilization of protein structure when employing these different encapsulation procedures.
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Affiliation(s)
- Caroline Pérez
- University of Puerto Rico, Department of Chemistry, San Juan 00931-3346, USA
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148
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Caliş S, Bozdag S, Kaş HS, Tunçay M, Hincal AA. Influence of irradiation sterilization on poly(lactide-co-glycolide) microspheres containing anti-inflammatory drugs. FARMACO (SOCIETA CHIMICA ITALIANA : 1989) 2002; 57:55-62. [PMID: 11902646 DOI: 10.1016/s0014-827x(01)01171-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gamma-irradiation is finding increasing use in the sterilization of pharmaceutical products. However, irradiation might also affect the performance of drug delivery systems. In this study, the influence of gamma-irradiation on the physicochemical properties of two commonly used non-steroidal anti-inflammatory drugs (NSAIDs) [naproxen sodium (NS) and diclofenac sodium (DS)] was investigated. The drugs were incorporated in poly(lactide-co-glycolide) (PLGA, 50:50; molecular weight 34000 or 88000 Da) microspheres. The biodegradable microspheres were irradiated at doses of 5, 15, 25 kGy using a 60Co source. Drug loading of irradiated and non-irradiated microspheres with both 34000 and 88000 Da polymers were essentially the same. A significant difference was noticed in the particle sizes of the irradiated as compared to the non-irradiated formulations. Notably, in release studies, the amount of active substance released from PLGA microspheres showed an increase with increasing irradiation dose. In DSC, the glass transition temperatures (Tg) of microspheres exhibited a slow increase with irradiation dose.
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Affiliation(s)
- Sema Caliş
- Department of Pharmaceutical Technology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey.
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149
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Abstract
Polymeric materials containing coordinative units have become a field of increasing interest. The combination of inorganic metal-containing units and macromolecules leads to supramolecular structures with new properties. One promising approach to such systems is the application of metallo-supramolecular initiators for living and controlled polymerization methods. The utilization of bi- and terpyridine units and complexes for this purpose will be discussed in this article.
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Affiliation(s)
- U S Schubert
- Laboratory of Macromolecular and Organic Chemistry SMO, Eindhoven University of Technology, The Netherlands.
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150
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Schaefer MJ, Singh J. Effect of additives on stability of etoposide in PLGA microspheres. Drug Dev Ind Pharm 2001; 27:345-50. [PMID: 11411902 DOI: 10.1081/ddc-100103734] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The purpose of this article was to determine the shelf life of etoposide in poly(lactic-co-glycolic acid) (PLGA) microspheres prepared with and without additives (i.e., tricaprin and isopropyl myristic acid ester [IPM]). The microspheres were prepared by a single-emulsion solvent extraction technique with and without 25% w/w additive. The batches of microspheres were subjected to an accelerated stability study at two elevated temperatures (70 degrees C and 80 degrees C or 80 degrees C and 90 degrees C). Samples were taken at 7, 14, 21, 28, and 35 days for estimation of drug content by high-performance liquid chromatography (HPLC). The drug stability in the microspheres was determined by plotting the log percentage drug remaining versus time to obtain the degradation rate constant k of etoposide at the measured temperature. This degradation rate constant was then used in the Arrhenius equation to obtain the activation energy of etoposide, which was utilized to determine the shelf life of the microspheres at room temperature. The results showed that all three microsphere formulations had good long-term stability at room temperature (6.62-8.86 years at 25 degrees C). The plain microspheres were shown to possess a shelf life of 6.62 years, and the IPM and tricaprin were the most stable with shelf lives of 8.25 and 8.86 years, respectively.
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Affiliation(s)
- M J Schaefer
- Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo 58105, USA
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