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Agrahari V, Anderson SM, Peet MM, Wong AP, Singh ON, Doncel GF, Clark MR. Long-acting HIV Pre-exposure Prophylaxis (PrEP) approaches: Recent advances, emerging technologies and development challenges. Expert Opin Drug Deliv 2022; 19:1365-1380. [PMID: 36252277 PMCID: PMC9639748 DOI: 10.1080/17425247.2022.2135699] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Introduction: Poor or inconsistent adherence to daily oral pre-exposure prophylaxis (PrEP) has emerged as a key barrier to effective HIV prevention. The advent of potent long-acting (LA) antiretrovirals (ARVs) in conjunction with advances in controlled release technologies has enabled LA ARV drug delivery systems (DDS) capable of providing extended dosing intervals and overcome the challenge of suboptimal drug adherence with daily oral dosing. Areas covered: This review discusses the current state of the LA PrEP field, recent advances, and emerging technologies, including ARV prodrug modifications and new DDS. Technological challenges, knowledge gaps, preclinical testing considerations, and future directions important in the context of clinical translation and implementation of LA HIV PrEP are discussed. Expert opinion: The HIV prevention field is evolving faster than ever and the bar for developing next-generation LA HIV prevention options continues to rise. The requirements for viable LA PrEP products to be implemented in resource-limited settings are challenging, necessitating proactive consideration and product modifications during the design and testing of promising new candidates. If successfully translated, next-generation LA PrEP that are safe, affordable, highly effective, and accepted by both end-users and key stakeholders will offer significant potential to curb the HIV pandemic.
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Affiliation(s)
- Vivek Agrahari
- CONRAD, Eastern Virginia Medical School, Norfolk, VA, USA
| | | | | | - Andrew P. Wong
- CONRAD, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Onkar N. Singh
- CONRAD, Eastern Virginia Medical School, Norfolk, VA, USA
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2
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Jacobs GP. Irradiation of pharmaceuticals: A literature review. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2021.109795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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3
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Park K, Otte A, Sharifi F, Garner J, Skidmore S, Park H, Jhon YK, Qin B, Wang Y. Potential Roles of the Glass Transition Temperature of PLGA Microparticles in Drug Release Kinetics. Mol Pharm 2020; 18:18-32. [PMID: 33331774 DOI: 10.1021/acs.molpharmaceut.0c01089] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Poly(lactic-co-glycolic acid) (PLGA) has been used for long-acting injectable drug delivery systems for more than 30 years. The factors affecting the properties of PLGA formulations are still not clearly understood. The drug release kinetics of PLGA microparticles are influenced by many parameters associated with the formulation composition, manufacturing process, and post-treatments. Since the drug release kinetics have not been explainable using the measurable properties, formulating PLGA microparticles with desired drug release kinetics has been extremely difficult. Of the various properties, the glass transition temperature, Tg, of PLGA formulations is able to explain various aspects of drug release kinetics. This allows examination of parameters that affect the Tg of PLGA formulations, and thus, affecting the drug release kinetics. The impacts of the terminal sterilization on the Tg and drug release kinetics were also examined. The analysis of drug release kinetics in relation to the Tg of PLGA formulations provides a basis for further understanding of the factors controlling drug release.
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Affiliation(s)
- Kinam Park
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States.,College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States.,Akina, Inc., West Lafayette, Indiana 47906, United States
| | - Andrew Otte
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Farrokh Sharifi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - John Garner
- Akina, Inc., West Lafayette, Indiana 47906, United States
| | - Sarah Skidmore
- Akina, Inc., West Lafayette, Indiana 47906, United States
| | - Haesun Park
- Akina, Inc., West Lafayette, Indiana 47906, United States
| | - Young Kuk Jhon
- Office of Pharmaceutical Quality, Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland 20993, United States
| | - Bin Qin
- Office of Generic Drugs, Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland 20993, United States
| | - Yan Wang
- Office of Generic Drugs, Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland 20993, United States
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Nkanga CI, Fisch A, Rad-Malekshahi M, Romic MD, Kittel B, Ullrich T, Wang J, Krause RWM, Adler S, Lammers T, Hennink WE, Ramazani F. Clinically established biodegradable long acting injectables: An industry perspective. Adv Drug Deliv Rev 2020; 167:19-46. [PMID: 33202261 DOI: 10.1016/j.addr.2020.11.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 12/11/2022]
Abstract
Long acting injectable formulations have been developed to sustain the action of drugs in the body over desired periods of time. These delivery platforms have been utilized for both systemic and local drug delivery applications. This review gives an overview of long acting injectable systems that are currently in clinical use. These products are categorized in three different groups: biodegradable polymeric systems, including microparticles and implants; micro and nanocrystal suspensions and oil-based formulations. Furthermore, the applications of these drug delivery platforms for the management of various chronic diseases are summarized. Finally, this review addresses industrial challenges regarding the development of long acting injectable formulations.
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Affiliation(s)
- Christian Isalomboto Nkanga
- Center for Chemico- and Bio-Medicinal Research (CCBR), Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa; Faculty of Pharmaceutical Sciences, University of Kinshasa, B.P. 212, Kinshasa, XI, Democratic Republic of the Congo; Technical Research and Development, Novartis Pharma AG, Basel 4002, Switzerland
| | - Andreas Fisch
- Technical Research and Development, Novartis Pharma AG, Basel 4002, Switzerland
| | - Mazda Rad-Malekshahi
- Department of Pharmaceutical Biomaterials and Medical Biomaterials Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Birgit Kittel
- Novartis Institute for Biomedical Research, Novartis Pharma AG, Basel 4002, Switzerland
| | - Thomas Ullrich
- Novartis Institute for Biomedical Research, Novartis Pharma AG, Basel 4002, Switzerland
| | - Jing Wang
- Technical Research and Development, Novartis Pharma AG, Basel 4002, Switzerland
| | - Rui Werner Maçedo Krause
- Center for Chemico- and Bio-Medicinal Research (CCBR), Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
| | - Sabine Adler
- Technical Research and Development, Novartis Pharma AG, Basel 4002, Switzerland
| | - Twan Lammers
- Department of Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Wim E Hennink
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, the Netherlands
| | - Farshad Ramazani
- Technical Research and Development, Novartis Pharma AG, Basel 4002, Switzerland.
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Domańska IM, Oledzka E, Sobczak M. Sterilization process of polyester based anticancer-drug delivery systems. Int J Pharm 2020; 587:119663. [PMID: 32702451 DOI: 10.1016/j.ijpharm.2020.119663] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/02/2020] [Accepted: 07/14/2020] [Indexed: 01/07/2023]
Abstract
Recently, growing interest in biodegradable polyesters as drug carriers in the development of innovative anticancer drug delivery systems (DDSs) has been observed. These compounds are thermally unstable, and are therefore, particularly demanding due to the limited number of available sterilization techniques. Furthermore, the DDSs sterilization process is often limited to aseptic filtration. Ensuring aseptic production is very demanding and costly, and it is therefore necessary to work on the application of new sterilization methods. In view of this, this review presents the current state of knowledge regarding the radiation sterilization process of some anticancer drugs as well biodegradable polyester carriers (such as polylactide, polyglycolide, poly(ε-caprolactone), poly(trimethylene carbonate) and co- or terpolymers of lactide, glycolide, ε-caprolactone and trimethylene carbonate). The structural changes in anticancer DDSs under the influence of ionizing radiation and the potential degradation mechanisms of both, polyester carriers and cytostatics during the sterilization process of ionizing radiation as well as their effects on the microstructure and properties of DDSs have been discussed in this paper.
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Affiliation(s)
- Izabela M Domańska
- Department of Biomaterials Chemistry, Chair of Analytical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, 1 Banacha St., Warsaw 02-097, Poland.
| | - Ewa Oledzka
- Department of Biomaterials Chemistry, Chair of Analytical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, 1 Banacha St., Warsaw 02-097, Poland.
| | - Marcin Sobczak
- Department of Biomaterials Chemistry, Chair of Analytical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, 1 Banacha St., Warsaw 02-097, Poland.
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Leelakanok N, Geary S, Salem A. Fabrication and Use of Poly(d,l-lactide-co-glycolide)-Based Formulations Designed for Modified Release of 5-Fluorouracil. J Pharm Sci 2017; 107:513-528. [PMID: 29045885 DOI: 10.1016/j.xphs.2017.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 10/03/2017] [Accepted: 10/06/2017] [Indexed: 12/14/2022]
Abstract
5-fluorouracil (5-FU) is a chemotherapeutic agent that has been used for the treatment of a variety of malignancies since its initial introduction to the clinic in 1957. Owing to its short biological half-life, multiple dosings are generally required to maintain effective 5-FU plasma concentrations throughout the therapeutic period. Clinical studies have shown that continuous 5-FU administration is generally superior to bolus injection as exhibited by lower toxicities and increased therapeutic efficacy. Optimal therapeutic efficacy, however, is often compromised by the limiting therapeutic index. Whilst oral formulations are also used, these suffer from the drawbacks of variable bioavailability and first-pass metabolism. As a result, sustained release formulations of 5-FU have been investigated in an effort to mimic the kinetics of continuous infusion particularly for situations where local delivery is considered appropriate. The biocompatible, biodegradable, and highly tunable synthetic polymer, poly(d,l-lactide-co-glycolide) (PLGA), is widely used as a vector for sustained drug delivery, however, issues such as insufficient loading and inappropriate burst release kinetics have dogged progress into the clinic for small hydrophilic drugs such as 5-FU. This review provides introductory information about the mechanism of action, pharmacokinetic and physicochemical properties, and clinical use of 5-FU that have contributed to the development of PLGA-based 5-FU release platforms. In addition, this review provides information on fabrication methods used for a range of 5-FU-loaded PLGA formulations and discusses factors affecting the release kinetics of 5-FU as well as the in vitro and in vivo antitumor or antiproliferative efficacy of these platforms.
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Affiliation(s)
- Nattawut Leelakanok
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242
| | - Sean Geary
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242
| | - Aliasger Salem
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, Iowa City, Iowa 52242.
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7
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Li Y, Chu Z, Li X, Ding X, Guo M, Zhao H, Yao J, Wang L, Cai Q, Fan Y. The effect of mechanical loads on the degradation of aliphatic biodegradable polyesters. Regen Biomater 2017; 4:179-190. [PMID: 28596915 PMCID: PMC5458542 DOI: 10.1093/rb/rbx009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/01/2017] [Accepted: 03/06/2017] [Indexed: 12/11/2022] Open
Abstract
Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices. The performances during biodegradation process play crucial roles for final realization of their functions. Because physiological and biochemical environment in vivo significantly affects biodegradation process, large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades. In this review article, we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process. Other physiological and biochemical factors related to mechanical loads were also discussed. The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer. Besides, the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers. This indicated that investigations into effects of mechanical loads on the degradation should be indispensable. More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately. Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.
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Affiliation(s)
- Ying Li
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Zhaowei Chu
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Xiaoming Li
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Xili Ding
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Meng Guo
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Haoran Zhao
- Department of Biomedical Engineer, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Jie Yao
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Lizhen Wang
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
| | - Qiang Cai
- Key Laboratory of Advanced Materials of Ministry of Education of China, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Yubo Fan
- School of Biological Science and Medical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, International Research Center for Implantable and Interventional Medical Devices, Beihang University, Beijing 100191, People’s Republic of China
- National Research Center for Rehabilitation Technical Aids, Beijing 100176, People’s Republic of China
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8
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Chitosan-N-acetyl cysteine microspheres for ocular delivery of acyclovir: Synthesis and in vitro/in vivo evaluation. J Drug Deliv Sci Technol 2016. [DOI: 10.1016/j.jddst.2016.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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9
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Xu Y, Kim CS, Saylor DM, Koo D. Polymer degradation and drug delivery in PLGA-based drug-polymer applications: A review of experiments and theories. J Biomed Mater Res B Appl Biomater 2016; 105:1692-1716. [PMID: 27098357 DOI: 10.1002/jbm.b.33648] [Citation(s) in RCA: 223] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/25/2016] [Accepted: 02/12/2016] [Indexed: 01/03/2023]
Abstract
Poly (lactic-co-glycolic acid) (PLGA) copolymers have been broadly used in controlled drug release applications. Because these polymers are biodegradable, they provide an attractive option for drug delivery vehicles. There are a variety of material, processing, and physiological factors that impact the degradation rates of PLGA polymers and concurrent drug release kinetics. This work is intended to provide a comprehensive and collective review of the physicochemical and physiological factors that dictate the degradation behavior of PLGA polymers and drug release from contemporary PLGA-based drug-polymer products. In conjunction with the existing experimental results, analytical and numerical theories developed to predict drug release from PLGA-based polymers are summarized and correlated with the experimental observations. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1692-1716, 2017.
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Affiliation(s)
- Yihan Xu
- Materials Science and Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53211
| | - Chang-Soo Kim
- Materials Science and Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53211
| | - David M Saylor
- Division of Biology, Chemistry, and Materials Science, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993
| | - Donghun Koo
- Materials Science R&D, MilliporeSigma, Milwaukee, Wisconsin, 53209
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10
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Abuhanoğlu G, Ozer AY. Radiation sterilization of new drug delivery systems. Interv Med Appl Sci 2014; 6:51-60. [PMID: 24936306 PMCID: PMC4047505 DOI: 10.1556/imas.6.2014.2.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/17/2014] [Accepted: 02/14/2014] [Indexed: 11/19/2022] Open
Abstract
Radiation sterilization has now become a commonly used method for sterilization of several active ingredients in drugs or drug delivery systems containing these substances. In this context, many applications have been performed on the human products that are required to be sterile, as well as on pharmaceutical products prepared to be developed. The new drug delivery systems designed to deliver the medication to the target tissue or organ, such as microspheres, nanospheres, microemulsion, and liposomal systems, have been sterilized by gamma (γ) and beta (β) rays, and more recently, by e-beam sterilization. In this review, the sterilization of new drug delivery systems was discussed other than conventional drug delivery systems by γ irradiation.
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Affiliation(s)
- Gürhan Abuhanoğlu
- Department of Radiopharmacy, Faculty of Pharmacy, Hacettepe University Sıhhiye, Ankara Turkey
| | - A Yekta Ozer
- Department of Radiopharmacy, Faculty of Pharmacy, Hacettepe University Sıhhiye, Ankara Turkey
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Xie X, Li Z, Zhang L, Chi Q, Yang Y, Zhang H, Yang Y, Mei X. A novel acceleratedin vitrorelease method to evaluate the release of thymopentin from PLGA microspheres. Pharm Dev Technol 2014; 20:633-40. [DOI: 10.3109/10837450.2014.892131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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12
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Tuin SA, Pourdeyhimi B, Loboa EG. Interconnected, microporous hollow fibers for tissue engineering: Commercially relevant, industry standard scale-up manufacturing. J Biomed Mater Res A 2013. [DOI: 10.1002/jbm.a.35002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Stephen A. Tuin
- Joint Department of Biomedical Engineering; at the University of North Carolina at Chapel Hill and North Carolina State University; 4208B EBIII, CB 7115, 911 Oval Raleigh, NC 27695
| | - Behnam Pourdeyhimi
- Nonwovens Cooperative Research Center, The Nonwovens Institute, North Carolina State University; 1000 Main Campus Drive Raleigh North Carolina 27695
| | - Elizabeth G. Loboa
- Joint Department of Biomedical Engineering; at the University of North Carolina at Chapel Hill and North Carolina State University; 4208B EBIII, CB 7115, 911 Oval Raleigh, NC 27695
- Materials Science Engineering; North Carolina State University; EB1 911 Partners Way Raleigh North Carolina 27695
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Gamma irradiation of active self-healing PLGA microspheres for efficient aqueous encapsulation of vaccine antigens. Pharm Res 2013; 30:1768-78. [PMID: 23515830 DOI: 10.1007/s11095-013-1019-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/01/2013] [Indexed: 01/20/2023]
Abstract
PURPOSE To investigate the effect of γ-irradiation of poly(lactic-co-glycolic acid) (PLGA)/Al(OH)₃/0 or 5 wt% diethyl phthalate (DEP) microspheres for active self-healing encapsulation of vaccine antigens. METHODS Microspheres were irradiated with ⁶⁰Co at 2.5 and 1.8 MRad and 0.37 and 0.20 MRad/h. Encapsulation of tetanus toxoid (TT) was achieved by mixing Al(OH)₃-PLGA microspheres with TT solution at 10-38°C. Electron paramagnetic resonance (EPR) spectroscopy was used to examine free radical formation. Glass transition temperature (T(g)) and molecular weight of PLGA was measured by differential scanning calorimetry and gel permeation chromatography, respectively. Loading and release of TT were examined by modified Bradford, amino acid analysis, and ELISA assays. RESULTS EPR spectroscopy results indicated absence of free radicals in PLGA microspheres after γ-irradiation. Antigen-sorbing capacity, encapsulation efficiency, and T(g) of the polymer were also not adversely affected. When DEP-loaded microspheres were irradiated at 0.2 MRad/h, some PLGA pores healed during irradiation and PLGA healing during encapsulation was suppressed. The molecular weight of PLGA was slightly reduced when DEP-loaded microspheres were irradiated at the same dose rate. At the 0.37 MRad/h dose rate, these trends were not observed and the full immunoreactivity of TT was preserved during encapsulation and 1-month release. Gamma irradiation slightly increased TT initial burst release. The small increase in total irradiation dose from 1.8 to 2.5 MRad had insignificant effect on the polymer and microspheres properties analyzed. CONCLUSIONS Gamma irradiation is a plausible approach to provide a terminally sterilized, self-healing encapsulation PLGA excipient for vaccine delivery.
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14
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Barrett C, Cameron R, Best S. Bioceramic and Biopolymer Nanocomposite Materials for Use in Orthopedic Applications. Tissue Eng Regen Med 2012. [DOI: 10.1201/b13049-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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15
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Simón-yarza T, Garbayo E, Tamayo E, Prósper F, Blanco-prieto* MJ. Drug Delivery in Tissue Engineering: General Concepts. NANOSTRUCTURED BIOMATERIALS FOR OVERCOMING BIOLOGICAL BARRIERS 2012. [DOI: 10.1039/9781849735292-00501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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16
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Checa-Casalengua P, Jiang C, Bravo-Osuna I, Tucker BA, Molina-Martínez IT, Young MJ, Herrero-Vanrell R. Preservation of biological activity of glial cell line-derived neurotrophic factor (GDNF) after microencapsulation and sterilization by gamma irradiation. Int J Pharm 2012; 436:545-54. [PMID: 22828071 DOI: 10.1016/j.ijpharm.2012.07.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 07/10/2012] [Accepted: 07/12/2012] [Indexed: 11/25/2022]
Abstract
A main issue in controlled delivery of biotechnological products from injectable biodegradable microspheres is to preserve their integrity and functional activity after the microencapsulation process and final sterilization. The present experimental work tested different technological approaches to maintain the biological activity of an encapsulated biotechnological product within PLGA [poly (lactic-co-glycolic acid)] microspheres (MS) after their sterilization by gamma irradiation. GDNF (glial cell line-derived neurotrophic factor), useful in the treatment of several neurodegenerative diseases, was chosen as a labile model protein. In the particular case of optic nerve degeneration, GDNF has been demonstrated to improve the damaged retinal ganglion cells (RGC) survival. GDNF was encapsulated in its molecular state by the water-in-oil-in-water (W/O/W) technique or as solid according to the solid-in-oil-in-water (S/O/W) method. Based on the S/O/W technique, GDNF was included in the PLGA microspheres alone (S/O/W 1) or in combination with an antioxidant (vitamin E, Vit E) (S/O/W 2). Microspheres were sterilized by gamma-irradiation (dose of 25 kGy) at room and low (-78 °C) temperatures. Functional activity of GDNF released from the different microspheres was evaluated both before and after sterilization in their potential target cells (retinal cells). Although none of the systems proposed achieved with the goal of totally retain the structural stability of the GDNF-dimer, the protein released from the S/O/W 2 microspheres was clearly the most biologically active, showing significantly less retinal cell death than that released from either W/O/W or S/O/W 1 particles, even in low amounts of the neurotrophic factor. According to the results presented in this work, the biological activity of biotechnological products after microencapsulation and sterilization can be further preserved by the inclusion of the active molecule in its solid state in combination with antioxidants and using low temperature (-78 °C) during gamma irradiation exposure.
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Affiliation(s)
- P Checa-Casalengua
- Dep. of Pharmacy and Pharmaceutical Technology, School of Pharmacy, Avd. Complutense s/n, Complutense University, Madrid 28040, Spain
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Choonara YE, Pillay V, Danckwerts MP, Carmichael TR, du Toit LC, Khan RA. Micromechanical and physical stability analysis of an irradiated poly (lactic-co-glycolic acid) donut-shaped minitablet device for intraocular implantation. Pharm Dev Technol 2012; 18:1186-203. [PMID: 22335771 DOI: 10.3109/10837450.2011.619541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This study pragmatically characterized the micromechanical and physical stability of a poly(lactic-co-glycolic acid) (PLGA)-based ganciclovir (GCV)-loaded donut-shaped minitablet (DSMT) device for intraocular implantation. Thermal and spectroscopic analysis was performed on various drug-polymer permutations. Porositometric profiles were quantitatively analyzed coupled with qualitatively SEM imaging. The tensile strength (TS) and fracture energy (FE) of the device was also determined pre- and post-γ-sterilization. Inimitably, chemometric and molecular modeling provided a supportive confirmatory tool for establishing fundamental correlative suppositions between the transitioned surface morphology and the micromechanical stability after γ-irradiation. Isotherm plot volumes ranged between -0.028 ± 0.022 and 0.110 ± 0.005 m(2)/g for pre- and post-sterilized devices, respectively, revealing a microporous alteration in porosity. Pre-sterilized devices had larger pores (BJHa=286.22 vs. 192.49 Å) and lower FE (151.301 ± 6.089 N/m) and TS (26.396 ± 1.062 N) values while sterilized devices had crystalline matrices that facilitated the superiorly controlled drug release kinetcs obtained. DSC thermograms displayed the characteristic disordered crystallization of GCV and hydration exotherms resulting from ionization during γ-irradiation. FTIR spectrograms showed fingerprint molecular imprints of GCV and axial stretching of hybridized carbons of PLGA with no subversive drug-polymer interactions after γ-irradiation. Integration of the results inveterately revealed that compression and subsequent γ-irradiation of the device affected desirable micromechanical and solid-state stability behavior.
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Affiliation(s)
- Yahya E Choonara
- University of the Witwatersrand, Faculty of Health Sciences, Department of Pharmacy and Pharmacology , 7 York Road, Parktown, 2193, Johannesburg, South Africa
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18
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Rothstein SN, Little SR. A “tool box” for rational design of degradable controlled release formulations. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm01668c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Srivastava P, Wagh RS, Naik DG. γ-irradiation: A simple route for isomerization of geraniol into nerol and linalool. RADIOCHEMISTRY 2010. [DOI: 10.1134/s1066362210050206] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Design and influence of γ-irradiation on the biopharmaceutical properties of nanoparticles containing an antigenic complex from Brucella ovis. Eur J Pharm Sci 2009; 37:563-72. [DOI: 10.1016/j.ejps.2009.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 04/03/2009] [Accepted: 05/03/2009] [Indexed: 11/24/2022]
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21
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Effects of ionizing radiation sterilization on microparticulate drug delivery systems based on poly-α-hydroxyacids: an overview. J Drug Deliv Sci Technol 2009. [DOI: 10.1016/s1773-2247(09)50017-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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Fernández-Carballido A, Herrero-Vanrell R, Molina-Martínez IT, Pastoriza P. Sterilized ibuprofen-loaded poly(D,L-lactide-co-glycolide) microspheres for intra-articular administration: effect ofγ-irradiation and storage. J Microencapsul 2008; 21:653-65. [PMID: 15762322 DOI: 10.1080/09687860400008437] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The aim of this study was to prepare and characterize a controlled-release system (microspheres) loaded with ibuprofen, for intra-articular administration, to extend its anti-inflammatory effect in the knee joint cavity. Among the bioresorbable polymers employed, poly(D,L-lactic-co-glycolic) acid (PLGA) (13137 Da) was chosen because of its high biocompatiblity. Microspheres were produced by the solvent evaporation process from an O/W emulsion. Labrafil M 1944 CS was included in the formulation as an additive in order to modulate the release rate of the non-steroidal anti-inflammatory drug (NSAID). Once prepared, the microspheres were sobre-sterilized by gamma-irradiation. The effect of the irradiation dose (25 kGy) exposure, at low temperature, on the formulation was evaluated. The sterilization procedure employed did not alter the physicochemical characteristics of the formulation. Dissolution profiles of formulations behaved similarly and overlapped (f2=87.23, f1=4.2) before and after sterilization. Size Exclusion Chromatography (SEC) revealed no significant changes in the polymer molecular weight. Additionally, a stability study of the sterilized formulation was carried out using microsphere storage conditions of 4 degrees C in a vacuum desiccator for 1 year. The results obtained after storing the sterilized microspheres show no significant alterations in the ibuprofen release rate (f2 = 85.06, f1 = 4.32) or in the molecular weight of the PLGA (12957 Da). The employment of low molecular weight PLGA polymers resulted as advantageous, due to the practical absence of degradation after gamma irradiation (25 kGy) exposure at low temperature.
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Affiliation(s)
- A Fernández-Carballido
- Departamento de Farmacia y Tecnologia Farmaceutica, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain.
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23
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Novel strategies to improve the anticancer action of 5-fluorouracil by using drug delivery systems. Molecules 2008; 13:2340-69. [PMID: 18830159 PMCID: PMC6245407 DOI: 10.3390/molecules13102340] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 09/16/2008] [Accepted: 09/16/2008] [Indexed: 12/12/2022] Open
Abstract
Because of the fundamental importance of new therapeutic routes for cancer treatment, a number of systems based on colloidal particles as vehicles for the delivery of the anticancer drug 5-fluorouracil have been devised. The target is always to provide the proper dose of the antitumor agent only at the desired locus of action, thus reducing the unwanted side effects. In this review, the main strategies and the more significant results in the development of 5-fluorouracil carriers for cancer treatment are discussed.
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24
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Faiman L. Observation of the degradation due to irradiation of CR 39 polymer by long-term monitoring of mass loss. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2007.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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25
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Ražem D, Katušin-Ražem B. The effects of irradiation on controlled drug delivery/controlled drug release systems. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2007.06.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Arifin DY, Lee LY, Wang CH. Mathematical modeling and simulation of drug release from microspheres: Implications to drug delivery systems. Adv Drug Deliv Rev 2006; 58:1274-325. [PMID: 17097189 DOI: 10.1016/j.addr.2006.09.007] [Citation(s) in RCA: 392] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 09/04/2006] [Indexed: 11/21/2022]
Abstract
This article aims to provide a comprehensive review of existing mathematical models and simulations of drug release from polymeric microspheres and of drug transport in adjacent tissues. In drug delivery systems, mathematical modeling plays an important role in elucidating the important drug release mechanisms, thus facilitating the development of new pharmaceutical products by a systematic, rather than trial-and-error, approach. The mathematical models correspond to the known release mechanisms, which are classified as diffusion-, swelling-, and erosion-controlled systems. Various practical applications of these models which explain experimental data are illustrated. The effect of gamma-irradiation sterilization on drug release mechanism from erosion-controlled systems will be discussed. The application of existing models to nanoscale drug delivery systems specifically for hydrophobic and hydrophilic molecules is evaluated. The current development of drug transport modeling in tissues utilizing computational fluid dynamics (CFD) will also be described.
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Affiliation(s)
- Davis Yohanes Arifin
- Molecular Engineering of Biological and Chemical Systems Program, Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore 117576, Singapore
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Abstract
Gamma (gamma)-irradiation is finding increasing use in the sterilization of pharmaceutical products. However, irradiation also might affect the performance of drug delivery systems. In this study, the influence of gamma-irradiation on the characteristics of chitosan microparticles was investigated. The diclofenac sodium was incorporated into chitosan microparticles by spray-drying method. The chitosan microparticles (placebo and drug-loaded) were irradiated at doses of 5, 15, and 25 kGy using a (60)Co source. Later, the microparticles were characterized by Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and atomic force microscopy. In addition, microparticles also were evaluated for their sizes, drug content, swelling, and drug release behavior. Encapsulation efficiency of irradiated and nonirradiated microparticles was essentially the same. Notably, surface roughness (rms) of placebo microparticles decreased significantly after gamma-irradiation when compared with nonirradiated placebo microparticles. FTIR spectroscopy revealed that gamma-irradiation of chitosan microparticles induced neither cross-linking nor formation of new group in the chitosan matrix. EPR spectroscopy results showed that the gamma rays induced only one kind of free radical in the chitosan matrix. Size, crystallinity, and thermal properties of the chitosan microparticles did not change much after gamma-irradiation. gamma-irradiated microparticles, exhibited a slightly higher drug release rate and low swelling capacity than the nonirradiated microparticles.
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28
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Memisoglu-Bilensoy E, Hincal AA. Sterile, injectable cyclodextrin nanoparticles: effects of gamma irradiation and autoclaving. Int J Pharm 2006; 311:203-8. [PMID: 16413708 DOI: 10.1016/j.ijpharm.2005.12.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 11/30/2005] [Accepted: 12/05/2005] [Indexed: 10/25/2022]
Abstract
Sterility is required as stated by compendial requirements and registration authorities worldwide for an injectable drug carrier system. In this study, injectable nanospheres and nanocapsules prepared from amphiphilic beta-cyclodextrin, beta-CDC6, were assessed for their in vitro properties such as particle size distribution, zeta potential, nanoparticle yield (%), drug entrapment efficiency and in vitro drug release profiles. Different sterilization techniques such as gamma irradiation and autoclaving were evaluated for their feasibility regarding the maintenance of the above mentioned nanoparticle properties after sterilization. It was found that amount these techniques, sterilization with gamma irradiation seemed to be the most appropriate technique with no effect on particle size, drug loading and drug release properties. Gamma irradiation causes some chemical changes on beta-CDC6 observed as changes in zeta potential but this does not lead to any significant changes for nanoparticle properties. Autoclaving caused massive aggregation for the nanoparticles followed by precipitation, which led to the conclusion that excessive heat disrupted nanoparticle integrity. Sterile filtration was not feasible since nanoparticle sizes were larger than the filter pore size and the yield after sterilization was very low. Thus, it can be concluded that blank and drug loaded beta-CDC6 nanospheres and nanocapsules are capable of being sterilized by gamma irradiation.
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Affiliation(s)
- Erem Memisoglu-Bilensoy
- Hacettepe University Faculty of Pharmacy, Department of Pharmaceutical Technology, 06100 Ankara, Turkey.
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29
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D'Souza SS, DeLuca PP. Methods to assess in vitro drug release from injectable polymeric particulate systems. Pharm Res 2006; 23:460-74. [PMID: 16400516 DOI: 10.1007/s11095-005-9397-8] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Accepted: 11/03/2005] [Indexed: 10/25/2022]
Abstract
This review provides a compilation of the methods used to study real-time (37 degrees C) drug release from parenteral microparticulate drug delivery systems administered via the subcutaneous or intramuscular route. Current methods fall into three broad categories, viz., sample and separate, flow-through cell, and dialysis techniques. The principle of the specific method employed along with the advantages and disadvantages are described. With the "sample and separate" technique, drug-loaded microparticles are introduced into a vessel, and release is monitored over time by analysis of supernatant or drug remaining in the microspheres. In the "flow-through cell" technique, media is continuously circulated through a column containing drug-loaded microparticles followed by analysis of the eluent. The "dialysis" method achieves a physical separation of the drug-loaded microparticles from the release media by use of a membrane, which allows for sampling without interference of the microspheres. With all these methods, the setup and sampling techniques seem to influence in vitro release; the results are discussed in detail, and criteria to aid in selection of a method are stated. Attempts to establish in vitro-in vivo correlation for these injectable dosage forms are also discussed. It would be prudent to have an in vitro test method for microparticles that satisfies compendial and regulatory requirements, is user friendly, robust, and reproducible, and can be used for quality-control purposes at real-time and elevated temperatures.
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Affiliation(s)
- Susan S D'Souza
- University of Kentucky College of Pharmacy, Lexington, Kentucky, 40536, USA
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30
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Menei P, Montero-Menei C, Venier MC, Benoit JP. Drug delivery into the brain using poly(lactide-co-glycolide) microspheres. Expert Opin Drug Deliv 2005; 2:363-76. [PMID: 16296760 DOI: 10.1517/17425247.2.2.363] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Among the strategies developed for drug delivery into the CNS, locally controlled drug release by the way of an implantable polymeric device has been developed in recent years. The first polymeric devices developed were macroscopic implants needing open surgery for implantation. Over the last few years, poly(lactide-co-glycolide) microspheres have been shown to be safe and promising for drug delivery into the brain. Poly(lactide-co-glycolide) is biodegradable and biocompatible with brain tissue. Due to their size, these microspheres can be easily implanted by stereotaxy in discrete, precise and functional areas of the brain without causing damage to the surrounding -tissue. Brain tumour treatments have been developed using this approach and clinical trials have been performed. Potential applications in neurodegenerative diseases have also been explored, particularly neurotrophic factor delivery and cell therapy.
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Affiliation(s)
- Philippe Menei
- Centre Hospitalo-Universitaire, Departement de Neurochirurgie, Angers, France.
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31
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Martínez-Sancho C, Herrero-Vanrell R, Negro S. Study of gamma-irradiation effects on aciclovir poly(D,L-lactic-co-glycolic) acid microspheres for intravitreal administration. J Control Release 2005; 99:41-52. [PMID: 15342179 DOI: 10.1016/j.jconrel.2004.06.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Accepted: 06/08/2004] [Indexed: 11/26/2022]
Abstract
Gamma-irradiation effects on aciclovir poly(D,L-lactic-co-glycolic) acid (PLGA) microspheres, with gelatin as additive, were studied. Microspheres with a 2:2:10 aciclovir:gelatin:polymer ratio were prepared by the solvent evaporation method and sterilised by gamma-irradiation at a dose of 25 kGy. Loading efficiency, morphology (particle size analysis, scanning electron microscopy (SEM)), physical chemistry (infrared (IR) absorption spectrophotometry, differential scanning calorimetry (DSC), X-ray diffraction and gel permeation chromatography (GPC)) and in vitro release assays for 73 days were performed to evaluate the sterilisation effect on microsphere characteristics. After gamma-irradiation, no surface changes were observed by SEM. Microparticle mean diameter and aciclovir loading efficiency were not affected by gamma-ray exposition. IR spectroscopy, DSC and X-ray diffraction showed no modification of the bulk properties of the microspheres or their components. The controlled release profiles of aciclovir-loaded microspheres for 73 days were not altered upon exposure to gamma-irradiation. GPC measurements showed a decrease in molecular weight of the polymer. The sterilisation method is adequate because microspheres underwent no change after exposition to gamma-irradiation. These favourable properties of the aciclovir-loaded microspheres make them a suitable system for the intravitreal treatment of herpes virus infections, in an animal model.
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Affiliation(s)
- Concepción Martínez-Sancho
- Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Plaza Ramon y Cajal sn, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Siepmann J, Faisant N, Akiki J, Richard J, Benoit JP. Effect of the size of biodegradable microparticles on drug release: experiment and theory. J Control Release 2004; 96:123-34. [PMID: 15063035 DOI: 10.1016/j.jconrel.2004.01.011] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Accepted: 01/15/2004] [Indexed: 11/29/2022]
Abstract
The aim of this study was to investigate the effect of the size of biodegradable microparticles (monolithic dispersions) on the release rate of an incorporated drug in a quantitative way. 5-Fluorouracil-loaded, poly(lactic-co-glycolic acid)-based microparticles were prepared with a solid-in-oil-in-water solvent extraction technique. In vitro drug release from different-sized particle fractions was measured in phosphate buffer pH 7.4. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and size exclusion chromatography (SEC) were used to monitor the degradation behavior of the polymer and morphological changes of the microparticles upon exposure to the release medium. Based on these experimental results, an appropriate mathematical theory was identified and used to get further insight into the underlying physical and chemical processes, which are involved in the control of drug release. Interestingly, the relative as well as the absolute release rate of the drug increased with increasing microparticle radius, despite of the increasing diffusion pathways. SEC, DSC and SEM analysis revealed that the degradation behavior of the matrix forming polymer was not significantly affected by the size of the devices and that autocatalytic effects do not seem to play a major role. Importantly, the initial drug loading significantly increased with increasing radius of the drug delivery system. Thus, large microparticles became more porous during drug release than small microparticles, leading to higher apparent diffusivities and drug transport rates. This effect overcompensated the effect of the increasing diffusion pathways with increasing microparticle radius, resulting in increased drug release rates with increasing device dimension. The applied mathematical model, considering drug diffusion with non-constant diffusivities (to account for polymer degradation) was able to quantitatively describe the observed drug release patterns. Importantly, an exponential relationship could be established between the diffusion coefficient and the initial loading of the drug. Based on this dependency, it was possible to predict the resulting drug release kinetics for arbitrary microparticle sizes in a quantitative way.
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Affiliation(s)
- J Siepmann
- College of Pharmacy, Freie Universitaet Berlin, Kelchstrasse 31, 12169 Berlin, Germany.
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Alexis F. Factors affecting the degradation and drug-release mechanism of poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)]. POLYM INT 2004. [DOI: 10.1002/pi.1697] [Citation(s) in RCA: 315] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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Lee JS, Chae GS, Khang G, Kim MS, Cho SH, Lee HB. The effect of gamma irradiation on PLGA and release behavior of BCNU from PLGA wafer. Macromol Res 2003. [DOI: 10.1007/bf03218376] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Faisant N, Siepmann J, Richard J, Benoit JP. Mathematical modeling of drug release from bioerodible microparticles: effect of gamma-irradiation. Eur J Pharm Biopharm 2003; 56:271-9. [PMID: 12957642 DOI: 10.1016/s0939-6411(03)00104-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Bioerodible polymers used in controlled drug delivery systems, such as poly(lactic-co-glycolic acid) (PLGA) undergo radiolytic degradation during gamma-irradiation. In spite of the considerable practical importance, yet only little knowledge is available on the consequences of this sterilization method on the resulting drug release patterns in a quantitative way. The major objectives of the present study were: (i) to monitor the effects of different gamma-irradiation doses on the physicochemical properties of drug-free and drug-loaded, PLGA-based microparticles; (ii) to analyze the obtained experimental results using adequate mathematical models; (iii) to get further insight into the occurring physical and chemical phenomena; and (iv) to relate the applied gamma-irradiation dose in a quantitative way to the resulting drug release rate. 5-Fluorouracil-loaded, PLGA-based microparticles were prepared with an oil-in-water solvent extraction method and exposed to gamma-irradiation doses ranging from 0 to 33 kGy. Size exclusion chromatography, differential scanning calorimetry, scanning electron microscopy, particle size analysis, determination of the actual drug loading and in vitro drug release kinetics were used to study the effects of the gamma-irradiation dose on the physicochemical properties of the microparticles. Two mathematical models-a simplified and a more comprehensive one-were used to analyze the experimental results. The simplified model considers drug diffusion based on Fick's second law for spherical geometry and a Higuchi-like pseudo-steady-state approach. The complex model combines Monte Carlo simulations (describing polymer erosion) with partial differential equations quantifying drug diffusion with time-, position- and direction-dependent diffusivities. Interestingly, exponential relationships between the gamma-irradiation dose and the initial drug diffusivity within the microparticles could be established. Based on this knowledge both models were used to predict the resulting drug release kinetics as a function of the gamma-irradiation dose. Importantly, the theoretical predictions were confirmed by experimental results.
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Affiliation(s)
- N Faisant
- INSERM ERIT-M 0104, Université d'Angers, Angers, France
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36
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Siepmann J, Faisant N, Benoit JP. A new mathematical model quantifying drug release from bioerodible microparticles using Monte Carlo simulations. Pharm Res 2002; 19:1885-93. [PMID: 12523670 DOI: 10.1023/a:1021457911533] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The major objectives of this study were to 1) develop a new mathematical model describing all phases of drug release from bioerodible microparticles; 2) evaluate the validity of the theory with experimental data; and 3) use the model to elucidate the release mechanisms in poly(lactide-co-glycolide acid)-based microspheres. METHODS; 5-Fluorouracil-loaded microparticles were prepared with an oil-in-water solvent extraction technique and characterized in vitro. Monte Carlo simulations and sets of partial differential equations were used to describe the occurring chemical reactions and physical mass transport phenomena during drug release. RESULTS The new mathematical model considers drug dissolution, diffusion with nonconstant diffusivities and moving boundary conditions, polymer degradation/erosion, time-dependent system porosities, and the three-dimensional geometry of the devices. In contrast with previous theories, this model is able to describe the observed drug release kinetics accurately over the entire period of time, including 1) initial "burst" effects; 2) subsequent, approximately zero-order drug release phases; and 3) second rapid drug release phases. Important information, such as the evolution of the drug concentration profiles within the microparticles, can be calculated. CONCLUSIONS; A new, mechanistic mathematical model was developed that allows further insight into the release mechanisms in bioerodible microparticles.
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Affiliation(s)
- Juergen Siepmann
- College of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, 12169 Berlin, Germany.
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