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Yamashita S, Katsumi H, Sakane T, Yamamoto A. Phosphorylated Serine-Modified Polyamidoamine Dendrimer as an Osteoid Surface-Targeting Drug Carrier. Mol Pharm 2022; 19:2573-2582. [PMID: 35666687 DOI: 10.1021/acs.molpharmaceut.2c00271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of this study was to develop a polyethylene glycol (PEG)-conjugated third-generation polyamidoamine dendrimer (PAMAM) with phosphorylated serine as an osteoid surface-targeting drug carrier for the treatment of bone diseases. We conjugated PAMAM backbones to l-serine and obtained Ser-PAMAM. Then, phosphoric acid and PEG were covalently bound to the Ser-PAMAM to generate PEGylated phosphorylated Ser-PAMAM (PEG-phosSer-PAMAM). Using osteoblast-like cells (MC3T3-E1 cells) cultured in 3D collagen gels, we showed that phosSer-PAMAM adsorbed both the hydroxyapatite and type I collagen components of the bone matrix. Fourier transform infrared spectroscopy analysis indicated that the phosphoryl side chains of phosSer-PAMAM formed electrostatic interactions and hydrogen bonds with the anionic amino acid residues of type I collagen. Mice were intravenously injected with the foregoing molecules, and a tissue distribution study disclosed that the lower limb bone took up about twice as much 111In-labeled PEG-phosSer-PAMAM as 111In-labeled nonphosphorylated PEG-Ser-PAMAM or unmodified PAMAM. An intrabone distribution experiment showed that fluorescein isothiocyanate (FITC)-labeled PEG-phosSer-PAMAM accumulated on the osteoid surfaces, which is associated with bone pathogenesis such as skeletal dysplasias and osteoporosis to a far greater extent than nonphosphorylated PEG-Ser-PAMAM. Our findings indicated that PEG-phosSer-PAMAM is a promising carrier for efficient drug targeting to osteoid surfaces.
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Affiliation(s)
- Shugo Yamashita
- Department of Biopharmaceutics, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan.,Department of Pharmaceutical Technology, Kobe Pharmaceutical University, Higashinada-ku, Kobe 658-8558, Japan
| | - Hidemasa Katsumi
- Department of Biopharmaceutics, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Toshiyasu Sakane
- Department of Pharmaceutical Technology, Kobe Pharmaceutical University, Higashinada-ku, Kobe 658-8558, Japan
| | - Akira Yamamoto
- Department of Biopharmaceutics, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
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Beig A, Ackermann R, Wang Y, Schutzman R, Schwendeman SP. Minimizing the initial burst of octreotide acetate based long-acting microspheres by the solvent evaporation method. Int J Pharm 2022; 624:121842. [DOI: 10.1016/j.ijpharm.2022.121842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 11/24/2022]
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Keum T, Noh G, Seo JE, Bashyal S, Sohn DH, Lee S. Examination of Effective Buccal Absorption of Salmon Calcitonin Using Cell-Penetrating Peptide-Conjugated Liposomal Drug Delivery System. Int J Nanomedicine 2022; 17:697-710. [PMID: 35210769 PMCID: PMC8857984 DOI: 10.2147/ijn.s335774] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/27/2022] [Indexed: 11/23/2022] Open
Abstract
Introduction The buccal route has been considered an attractive alternative delivery route for injectable formulations. Cell-penetrating peptides (CPPs) are gaining increased attention for their cellular uptake and tissue permeation effects. This study was aimed to evaluate the in vitro and ex vivo permeation-enhancing effect of penetratin-conjugated liposomes for salmon calcitonin (sCT) in TR146 human buccal cells and porcine buccal tissues. Methods Penetratin was conjugated to phospholipids through a maleimide-thiol reaction. Liposomes were prepared and sCT was encapsulated using a thin-film hydration method. Physical properties such as particle size, zeta potential, encapsulation efficiency, and morphological images via transmission electron microscopy were obtained. Cellular uptake studies were conducted using flow cytometry (FACS) and confocal laser scanning microscopy (CLSM). A cell permeation study was performed using a Transwell® assay, and permeation through porcine buccal tissue was evaluated. The amount of sCT permeated was quantified using an ELISA kit and was optically observed using CLSM. Results The particle size of penetratin-conjugated liposomes was approximately 123.0 nm, their zeta potential was +29.6 mV, and their calcitonin encapsulation efficiency was 18.0%. In the cellular uptake study using FACS and CLSM, stronger fluorescence was observed in penetratin-conjugated liposomes compared with the solution containing free sCT and control liposomes. Likewise, the amount of sCT permeated from penetratin-conjugated liposomes was higher than that from the free sCT solution and control liposomes by 5.8-fold across TR146 cells and 91.5-fold across porcine buccal tissues. Conclusion Penetratin-conjugated liposomes are considered a good drug delivery strategy for sCT via the buccal route.
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Affiliation(s)
- Taekwang Keum
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
- Center for Forensic Pharmaceutical Science, Daegu, Republic of Korea
| | - Gyubin Noh
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
- Center for Forensic Pharmaceutical Science, Daegu, Republic of Korea
| | - Jo-Eun Seo
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
| | - Santosh Bashyal
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
- Center for Forensic Pharmaceutical Science, Daegu, Republic of Korea
| | - Dong Hwan Sohn
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
| | - Sangkil Lee
- College of Pharmacy, Keimyung University, Daegu, Republic of Korea
- Center for Forensic Pharmaceutical Science, Daegu, Republic of Korea
- Correspondence: Sangkil Lee, College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 42601, Republic of Korea, Tel +82-53-580-6655, Fax +82-53-580-5164, Email
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Park H, Ha DH, Ha ES, Kim JS, Kim MS, Hwang SJ. Effect of Stabilizers on Encapsulation Efficiency and Release Behavior of Exenatide-Loaded PLGA Microsphere Prepared by the W/O/W Solvent Evaporation Method. Pharmaceutics 2019; 11:E627. [PMID: 31771254 PMCID: PMC6955873 DOI: 10.3390/pharmaceutics11120627] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to investigate the effects of various stabilizers on the encapsulation efficiency and release of exenatide-loaded PLGA (poly(lactic-co-glycolic acid)) microspheres prepared by the water-in-oil-in-water (W/O/W) solvent evaporation (SE) method. It was shown that the stabilizers affected exenatide stability in aqueous solutions, at water/dichloromethane interfaces, on PLGA surfaces, or during freeze-thawing and freeze-drying procedures. Sucrose predominantly reduces instability generated during freeze-thawing and freeze-drying. Phenylalanine prevents the destabilization at the water-dichloromethane (DCM) interface through decreased adsorption. Poloxamer 188 enhances stability in aqueous solutions and prevents adsorption to PLGA. Proline and lysine decrease adsorption on PLGA surfaces. Fourier transform infra-red spectroscopy (FT-IR) was used to find the molecular interaction of additives with exenatide or PLGA. Additives used in stability assessments were then added stepwise into the inner or outer water phase of the W/O/W double emulsion, and exenatide-loaded microspheres were prepared using the solvent evaporation method. The effect of each stabilizer on the encapsulation efficiency and release behavior of microspheres correlated well with the stability assessment results, except for the negative effect of poloxamer 188. Particle size analysis using laser diffractometry, scanning electron microscopy (SEM), water vapor sorption analysis, differential scanning calorimetry (DSC), and circular dichroism (CD) spectroscopy were also employed to characterize the prepared exenatide-loaded PLGA microsphere. This study demonstrated that an adequate formulation can be obtained by the study about the effect of stabilizers on peptide stability at the preformulation step. In addition, it can help to overcome various problems that can cause the destabilization of a peptide during the microsphere-manufacturing process and sustained drug release.
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Affiliation(s)
- Heejun Park
- College of Pharmacy, Pusan National University, 63 Busandaehak-ro, Geumjeong-gu, Busan 46241, Korea; (H.P.); (D.-H.H.); (E.-S.H.)
| | - Dong-Hyun Ha
- College of Pharmacy, Pusan National University, 63 Busandaehak-ro, Geumjeong-gu, Busan 46241, Korea; (H.P.); (D.-H.H.); (E.-S.H.)
| | - Eun-Sol Ha
- College of Pharmacy, Pusan National University, 63 Busandaehak-ro, Geumjeong-gu, Busan 46241, Korea; (H.P.); (D.-H.H.); (E.-S.H.)
| | - Jeong-Soo Kim
- Dong-A ST Co., Ltd., Giheung-gu, Yongin, Gyeonggi 446-905, Korea;
| | - Min-Soo Kim
- College of Pharmacy, Pusan National University, 63 Busandaehak-ro, Geumjeong-gu, Busan 46241, Korea; (H.P.); (D.-H.H.); (E.-S.H.)
| | - Sung-Joo Hwang
- College of Pharmacy and Yonsei Institute of Pharmaceutical Sciences, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Korea
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Kaur L, Sharma A, Yadav AK, Mishra N. Recent advances on biodegradable polymeric carrier-based mucosal immunization: an overview. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2017; 46:452-464. [PMID: 28685588 DOI: 10.1080/21691401.2017.1345927] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mucosal administration of vaccine is most prevalent way to induce desired immunity against various types of antigen and microbial in central and in addition, the peripheral blood in most external mucosal surface. Mucosal delivery of vaccine provides both humoral and cellular responses against mucosal infection. Mucosa, which are exposed to heavy loads of commensal and pathogenic microorganism, are one of the main region where infections are built up, also, thus have frontline status in immunity, making mucosa perfect site for vaccines application. The nasal route is favoured over parenteral route due to ease of administration, protection of antigen from degradation and induces sIgA which is not produced by systemic immunity. Natural and synthetic polymers are utilized to get nanoparticles carrier systems for development of nasal mucosal antibodies. The present review summarized the recent development in the field of vaccine delivery by means of mucoadhesive polymeric carriers. This review also describes the recent patent conceded for mucosal immunization utilizing these polymeric carriers.
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Affiliation(s)
- Lovedeep Kaur
- a Department of Pharmaceutics , ISF College of Pharmacy , Moga , Punjab , India
| | - Ankush Sharma
- a Department of Pharmaceutics , ISF College of Pharmacy , Moga , Punjab , India
| | - Awesh Kumar Yadav
- b Department of Pharmaceutics , Bhagyoday Tirth Pharmacy, College , Sagar , Madhya Pradesh , India
| | - Neeraj Mishra
- a Department of Pharmaceutics , ISF College of Pharmacy , Moga , Punjab , India
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Gaspar DP, Serra C, Lino PR, Gonçalves L, Taboada P, Remuñán-López C, Almeida AJ. Microencapsulated SLN: An innovative strategy for pulmonary protein delivery. Int J Pharm 2017; 516:231-246. [DOI: 10.1016/j.ijpharm.2016.11.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 10/20/2022]
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Umerska A, Matougui N, Groo AC, Saulnier P. Understanding the adsorption of salmon calcitonin, antimicrobial peptide AP114 and polymyxin B onto lipid nanocapsules. Int J Pharm 2016; 506:191-200. [DOI: 10.1016/j.ijpharm.2016.04.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 04/08/2016] [Accepted: 04/13/2016] [Indexed: 11/25/2022]
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Allahyari M, Mohit E. Peptide/protein vaccine delivery system based on PLGA particles. Hum Vaccin Immunother 2016; 12:806-28. [PMID: 26513024 PMCID: PMC4964737 DOI: 10.1080/21645515.2015.1102804] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 09/15/2015] [Accepted: 09/27/2015] [Indexed: 12/19/2022] Open
Abstract
Due to the excellent safety profile of poly (D,L-lactide-co-glycolide) (PLGA) particles in human, and their biodegradability, many studies have focused on the application of PLGA particles as a controlled-release vaccine delivery system. Antigenic proteins/peptides can be encapsulated into or adsorbed to the surface of PLGA particles. The gradual release of loaded antigens from PLGA particles is necessary for the induction of efficient immunity. Various factors can influence protein release rates from PLGA particles, which can be defined intrinsic features of the polymer, particle characteristics as well as protein and environmental related factors. The use of PLGA particles encapsulating antigens of different diseases such as hepatitis B, tuberculosis, chlamydia, malaria, leishmania, toxoplasma and allergy antigens will be described herein. The co-delivery of antigens and immunostimulants (IS) with PLGA particles can prevent the systemic adverse effects of immunopotentiators and activate both dendritic cells (DCs) and natural killer (NKs) cells, consequently enhancing the therapeutic efficacy of antigen-loaded PLGA particles. We will review co-delivery of different TLR ligands with antigens in various models, highlighting the specific strengths and weaknesses of the system. Strategies to enhance the immunotherapeutic effect of DC-based vaccine using PLGA particles can be designed to target DCs by functionalized PLGA particle encapsulating siRNAs of suppressive gene, and disease specific antigens. Finally, specific examples of cellular targeting where decorating the surface of PLGA particles target orally administrated vaccine to M-cells will be highlighted.
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Affiliation(s)
- Mojgan Allahyari
- Department of Recombinant Protein Production, Research & Production Complex, Pasteur Institute of Iran, Tehran, Iran
| | - Elham Mohit
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Jain D, Athawale R, Bajaj A, Shrikhande S, Goel PN, Gude RP. Studies on stabilization mechanism and stealth effect of poloxamer 188 onto PLGA nanoparticles. Colloids Surf B Biointerfaces 2013; 109:59-67. [PMID: 23608470 DOI: 10.1016/j.colsurfb.2013.03.027] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 03/17/2013] [Accepted: 03/18/2013] [Indexed: 01/20/2023]
Abstract
In nanoparticulate engineering for drug delivery systems, poloxamers tri block copolymers are employed as adsorbing molecules to modify the aggregation state and impart stability to products. The aim was to prepare nanoparticles using poloxamer188 as stabiliser and investigate the mechanism of stabilisation of the prepared particles. Nanoparticles were prepared by solvent diffusion method with poloxamer 188 as stabiliser. Hydrodynamic thickness and zeta potential of the prepared nanoparticles were determined by photon correlation spectroscopy. To study the extent of adsorption of poloxamer onto the prepared nanoparticles, adsorption isotherms were constructed. The adsorbed amount of poloxamer 188 onto the particles was determined by depletion method. Macrophageal uptake study was performed to assess the uptake of the prepared nanoparticles using RAW 264.7 cell lines. Nanoparticles were prepared with slight increase in particle size and in absolute value of zeta potential compared to uncoated particles suggesting that this effect was due to adsorption of poloxamer 188. TEM studies and surface area analysis supported the results obtained from particle size analysis indicating preparation of particles with a thin layer of adsorbed poloxamer 188. Adsorption kinetics modeling suggested that at low concentrations (0.001-0.010 g/L), Langmuir monolayer equation fits quite well and at higher concentrations (above 0.010 g/L) multilayer adsorption of poloxamer 188 onto the prepared particles occurred. Thus the nanoparticles had multilayer of poloxamer 188 adsorbed onto the non uniform surface of PLGA. Results of macrophageal uptake and liver cell study exhibits adsorbed concentration dependent bypass of RES uptake of nanoparticles. Hence, results substantiate the application of adsorption isotherms for designing nanoparticles possessing potential to exhibit prolonged circulation when administered in vivo.
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Affiliation(s)
- Darshana Jain
- CU Shah College of Pharmacy, SNDT Women's University, Santacruz (West), Mumbai, India
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Miladi K, Sfar S, Fessi H, Elaissari A. Drug carriers in osteoporosis: preparation, drug encapsulation and applications. Int J Pharm 2013; 445:181-95. [PMID: 23376227 DOI: 10.1016/j.ijpharm.2013.01.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 12/10/2012] [Accepted: 01/16/2013] [Indexed: 01/23/2023]
Abstract
Carriers are largely used to enhance therapy efficiency via the encapsulation of active molecules. The encapsulation enhances the stability of drug molecules, improves the targeting properties and prolongs pharmacological activity via continuous local release of active molecules. The aim of this review is to report the carrier systems used in osteoporosis therapy. This state of the art research has mainly focused on describing all types of carriers used in this area, their elaboration and properties, the drug characteristics used in such specific application, and drug release and efficiency. In this field, various processes have been used in order to obtain well-defined capsules, spheres and more complex carriers. In this exhaustive review, each process is described, illustrated and discussed.
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Affiliation(s)
- K Miladi
- University of Lyon, F-69622, Lyon, France
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Abstract
Proteins constitute an increasing proportion of the drugs in development. The barriers to their entry into the blood stream and rapid clearance means that they often have to be injected several times a day, affecting patient compliance. This paper reviews the major technologies enabling the development of injectable sustained-release products and formulation strategies to maintain protein integrity and modify release rates. Whilst many injectable sustained-release products are on the market, these are all delivering small molecular weight drugs and peptides. This is due to the manufacturing processes that denature and degrade the proteins upon encapsulation and release into the body. Formulation strategies are discussed and a number of new technologies reviewed that are able to overcome the issues with conventional manufacturing processes. The reliance of many processes on organic solvents has prevented their application to the development of injectable sustained release protein products. The development of entirely solvent free and aqueous methods of manufacture of these products has meant that numerous sustained-release protein products are close to reaching the market.
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Yang M, Yamamoto H, Kurashima H, Takeuchi H, Yokoyama T, Tsujimoto H, Kawashima Y. Design and evaluation of poly(dl-lactic-co-glycolic acid) nanocomposite particles containing salmon calcitonin for inhalation. Eur J Pharm Sci 2012; 46:374-80. [DOI: 10.1016/j.ejps.2012.02.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 01/19/2012] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
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Yang M, Yamamoto H, Kurashima H, Takeuchi H, Yokoyama T, Tsujimoto H, Kawashima Y. Design and evaluation of inhalable chitosan-modified poly (dl-lactic-co-glycolic acid) nanocomposite particles. Eur J Pharm Sci 2012; 47:235-43. [DOI: 10.1016/j.ejps.2012.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 05/26/2012] [Accepted: 05/29/2012] [Indexed: 01/01/2023]
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Zhang Y, Schwendeman SP. Minimizing acylation of peptides in PLGA microspheres. J Control Release 2012; 162:119-26. [PMID: 22546683 DOI: 10.1016/j.jconrel.2012.04.022] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 04/04/2012] [Accepted: 04/14/2012] [Indexed: 11/16/2022]
Abstract
The main objective of this study was to characterize and find mechanisms to prevent acylation of therapeutic peptides encapsulated in glucose-star poly(d,l-lactic-co-glycolic acid) (PLGA) microspheres. The effect of addition of divalent cation salts CaCl(2), MnCl(2) as well as carboxymethyl chitosan (CMCS) on inhibition of acylation of octreotide (Oct), salmon calcitonin (sCT), and human parathyroid hormone (hPTH) was evaluated. Peptide content and integrity inside the degrading microspheres was monitored by reversed-phase high performance liquid chromatography (HPLC) and mass spectrometry during release incubation under physiological conditions. The extent of peptide acylation was strongly inhibited in the formulations containing divalent cations and/or CMCS as excipients, although specific effects were dependent on the specific peptide and excipient combinations. Both inorganic cations improved stability of Oct and hPTH but not sCT. Addition of CMCS alone was ineffective. Combining inorganic cations with CMCS improved stability of Oct and sCT but it had no effect on hPTH stability. The operative stabilization mechanisms are consistent with blocking peptide-PLGA interactions by a) directly competing for PLGA interactions with dications and/or b) increasing peptide affinity in the stabilizer phase within PLGA pores. Hence, inorganic multivalent cations are general stabilizers against peptide acylation, the effect of which may be augmented in certain instances with addition of CMCS.
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Affiliation(s)
- Ying Zhang
- Department of Pharmaceutical Sciences, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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Rapid probing of biological surfaces with a sparse-matrix peptide library. PLoS One 2011; 6:e23551. [PMID: 21858167 PMCID: PMC3156232 DOI: 10.1371/journal.pone.0023551] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 07/20/2011] [Indexed: 02/02/2023] Open
Abstract
Finding unique peptides to target specific biological surfaces is crucial to basic research and technology development, though methods based on biological arrays or large libraries limit the speed and ease with which these necessary compounds can be found. We reasoned that because biological surfaces, such as cell surfaces, mineralized tissues, and various extracellular matrices have unique molecular compositions, they present unique physicochemical signatures to the surrounding medium which could be probed by peptides with appropriately corresponding physicochemical properties. To test this hypothesis, a naïve pilot library of 36 peptides, varying in their hydrophobicity and charge, was arranged in a two-dimensional matrix and screened against various biological surfaces. While the number of peptides in the matrix library was very small, we obtained “hits” against all biological surfaces probed. Sequence refinement of the “hits” led to peptides with markedly higher specificity and binding activity against screened biological surfaces. Genetic studies revealed that peptide binding to bacteria was mediated, at least in some cases, by specific cell-surface molecules, while examination of human tooth sections showed that this method can be used to derive peptides with highly specific binding to human tissue.
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Ghassemi AH, van Steenbergen MJ, Barendregt A, Talsma H, Kok RJ, van Nostrum CF, Crommelin DJA, Hennink WE. Controlled release of octreotide and assessment of peptide acylation from poly(D,L-lactide-co-hydroxymethyl glycolide) compared to PLGA microspheres. Pharm Res 2011; 29:110-20. [PMID: 21744173 PMCID: PMC3246586 DOI: 10.1007/s11095-011-0517-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/15/2011] [Indexed: 11/24/2022]
Abstract
Purpose To investigate the in vitro release of octreotide acetate, a somatostatin agonist, from microspheres based on a hydrophilic polyester, poly(D,L-lactide-co-hydroxymethyl glycolide) (PLHMGA). Methods Spherical and non-porous octreotide-loaded PLHMGA microspheres (12 to 16 μm) and loading efficiency of 60–70% were prepared by a solvent evaporation. Octreotide release profiles were compared with commercial PLGA formulation (Sandostatin LAR®); possible peptide modification with lactic, glycolic and hydroxymethyl glycolic acid units was monitored. Results PLHMGA microspheres showed burst release (~20%) followed by sustained release for 20–60 days, depending on the hydrophilicity of the polymer. Percentage of released loaded peptide was high (70–90%); > 60% of released peptide was native octreotide. PLGA microspheres did not show peptide release for the first 10 days, after which it was released in a sustained manner over the next 90 days; > 75% of released peptides were acylated adducts. Conclusions PLHMGA microspheres are promising controlled systems for peptides with excellent control over release kinetics. Moreover, substantially less peptide modification occurred in PLHMGA than in PLGA microspheres. Electronic Supplementary Material The online version of this article (doi:10.1007/s11095-011-0517-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Amir H Ghassemi
- Department of Pharmaceutics Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
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Ralla K, Sohling U, Suck K, Sander F, Kasper C, Ruf F, Scheper T. Adsorption and separation of proteins by a synthetic hydrotalcite. Colloids Surf B Biointerfaces 2011; 87:217-25. [PMID: 21684727 DOI: 10.1016/j.colsurfb.2011.05.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 11/27/2022]
Abstract
In this study, the potential use of a synthetic Mg/Al hydrotalcite (layered double hydroxide) as a novel chromatography material for protein purification was investigated. The hydrotalcite is present in its carbonate form and is characterized by an Al/Mg-ratio of 1.85. Zetapotential measurements confirm a positive surface potential up to pH 10 suggesting applicability as anion exchanger. The binding of model proteins covering a broad range of isoelectric points and molecular weights was performed at different pH-values under batch conditions to evaluate the binding behaviour of the hydrotalcite. Furthermore, static binding capacities were exemplarily determined for hemoglobin and human serum albumin. Additionally, the adsorption and elution of hemoglobin was studied under dynamic conditions. The binding behaviour of the hydrotalcite was compared to commercially available anion exchangers and was found to be a function of pH, depending on the model protein. Variant adsorption behaviour is explained by further interactions like hydrogen bonds and by an unequal charge distribution over the protein surfaces. The hydrotalcite reveals high adsorption capacities under static (260 mg/g) as well as under dynamic conditions (88 mg/g at 34 cm/h; 61 mg/g at 340 cm/h). With appropriate buffers like 500 mM carbonate (pH 10) the adsorbed proteins can be nearly completely desorbed making regeneration possible. Due to the binding and elution properties it is concluded, that the hydrotalcite can serve anion exchange material for chromatographic protein separations.
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Affiliation(s)
- Kathrin Ralla
- Institut für Biotechnologie, FG Bioverfahrenstechnik, Technische Universität Berlin, Berlin, Germany.
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Jain S, Malyala P, Pallaoro M, Giuliani M, Petersen H, O'hagan DT, Singh M. A Two-Stage Strategy for Sterilization of Poly(lactide-co-glycolide) Particles by γ-Irradiation Does Not Impair Their Potency for Vaccine Delivery. J Pharm Sci 2011; 100:646-54. [DOI: 10.1002/jps.22306] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ghassemi AH, van Steenbergen MJ, Talsma H, van Nostrum CF, Crommelin DJA, Hennink WE. Hydrophilic polyester microspheres: effect of molecular weight and copolymer composition on release of BSA. Pharm Res 2010; 27:2008-17. [PMID: 20602152 PMCID: PMC2916118 DOI: 10.1007/s11095-010-0205-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 06/23/2010] [Indexed: 11/24/2022]
Abstract
Purpose To study the release of a model protein, bovine serum albumin (BSA), from microspheres of an hydroxylated aliphatic polyester, poly(lactic-co-hydroxymethyl glycolic acid) (PLHMGA). Methods BSA-loaded microspheres were prepared by a double emulsion solvent evaporation method. The effect of copolymer composition and the molecular weight of the copolymer on in vitro release and degradation were studied. The integrity of the released BSA was studied by fluorescence spectroscopy and size exclusion chromatography (SEC). Results Microspheres prepared from PLHMGA with 50% hydroxymethyl glycolic acid (HMG) showed a burst release followed by a sustained release in 5–10 days. PLHMGA microspheres prepared from a copolymer with 35% and 25% HMG showed a sustained release of BSA up to 80% for 30 and 60 days, respectively. The release of BSA was hardly affected by the molecular weight of the polymer. Fluorescence spectroscopy and SEC showed that the released BSA preserved its structural integrity. Microspheres were fully degradable, and the degradation time increased from ~20 days to 60 days when the HMG content decreased from 50% to 25%. Conclusions Taking the degradation and release data together, it can be concluded that the release of BSA from PLHMGA microspheres is governed by degradation of the microspheres.
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Affiliation(s)
- Amir H Ghassemi
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, P.O. Box 80082, Sorbonnelaan 16, 3508 TB, Utrecht, The Netherlands
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20
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Ralla K, Sohling U, Riechers D, Kasper C, Ruf F, Scheper T. Adsorption and separation of proteins by a smectitic clay mineral. Bioprocess Biosyst Eng 2010; 33:847-61. [DOI: 10.1007/s00449-010-0408-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
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21
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Yarbrough DK, Hagerman E, Eckert R, He J, Choi H, Cao N, Le K, Hedger J, Qi F, Anderson M, Rutherford B, Wu B, Tetradis S, Shi W. Specific binding and mineralization of calcified surfaces by small peptides. Calcif Tissue Int 2010; 86:58-66. [PMID: 19949943 PMCID: PMC2798077 DOI: 10.1007/s00223-009-9312-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 10/16/2009] [Indexed: 11/28/2022]
Abstract
Several small (<25aa) peptides have been designed based on the sequence of the dentin phosphoprotein, one of the major noncollagenous proteins thought to be involved in the mineralization of the dentin extracellular matrix during tooth development. These peptides, consisting of multiple repeats of the tripeptide aspartate-serine-serine (DSS), bind with high affinity to calcium phosphate compounds and, when immobilized, can recruit calcium phosphate to peptide-derivatized polystyrene beads or to demineralized human dentin surfaces. The affinity of binding to hydroxyapatite surfaces increases with the number of (DSS)(n) repeats, and though similar repeated sequences-(NTT)(n), (DTT)(n), (ETT)(n), (NSS)(n), (ESS)(n), (DAA)(n), (ASS)(n), and (NAA)(n)-also showed HA binding activity, it was generally not at the same level as the natural sequence. Binding of the (DSS)(n) peptides to sectioned human teeth was shown to be tissue-specific, with high levels of binding to the mantle dentin, lower levels of binding to the circumpulpal dentin, and little or no binding to healthy enamel. Phosphorylation of the serines of these peptides was found to affect the avidity, but not the affinity, of binding. The potential utility of these peptides in the detection of carious lesions, the delivery of therapeutic compounds to mineralized tissues, and the modulation of remineralization is discussed.
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Affiliation(s)
- Daniel K. Yarbrough
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
- Present Address: C3-Jian, Inc, Inglewood, CA 90301 USA
| | - Elizabeth Hagerman
- Department of Bioengineering, University of California, Los Angeles, CA 90095 USA
| | - Randal Eckert
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095 USA
- Present Address: C3-Jian, Inc, Inglewood, CA 90301 USA
| | - Jian He
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
- Present Address: C3-Jian, Inc, Inglewood, CA 90301 USA
| | - Hyewon Choi
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
| | - Nga Cao
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
| | - Karen Le
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
| | | | - Fengxia Qi
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
- Present Address: College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034 USA
| | | | - Bruce Rutherford
- Department of Oral Biology, University of Washington, Seattle, WA 98195 USA
| | - Ben Wu
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
- Department of Bioengineering, University of California, Los Angeles, CA 90095 USA
- Department of Materials Science, University of California, Los Angeles, CA 90095 USA
| | - Sotiris Tetradis
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
| | - Wenyuan Shi
- School of Dentistry, University of California, Los Angeles, CA 90095-1668 USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095 USA
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22
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Zhang Y, Sophocleous AM, Schwendeman SP. Inhibition of peptide acylation in PLGA microspheres with water-soluble divalent cationic salts. Pharm Res 2009; 26:1986-94. [PMID: 19533307 DOI: 10.1007/s11095-009-9914-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 05/20/2009] [Indexed: 11/26/2022]
Abstract
PURPOSE To test the potential of water-soluble divalent cationic salts to inhibit acylation of octreotide encapsulated in poly(D,L-lactic-co-glycolic acid)-star (PLGA) microspheres. METHODS The divalent cationic salts, calcium chloride and manganese chloride, previously shown to disrupt peptide sorption, were introduced in PLGA microspheres prepared by the double emulsion-solvent evaporation method. Peptide stability was monitored by reversed-phase high performance liquid chromatography (RP-HPLC) and identified by liquid chromatography coupled with mass spectrometry (LC-MS) during microsphere degradation under physiological conditions for 4 weeks. Microsphere morphology and salt content were examined by scanning electron microscopy (SEM) and inductively coupled plasma-optical emission spectroscopy (ICP-OES), respectively. RESULTS Addition of divalent cationic salts solely to the organic phase did not provide acylation inhibition. However, addition of the salt inhibitors to both the primary emulsion and the outer water phase resulted in improved drug and salt encapsulation efficiency as well as significantly decreased salt leaching and octreotide acylation. After 28 days, the extent of acylation inhibition afforded by divalent cations was > 58% relative to 13% for the NaCl control group. CONCLUSIONS Water-soluble divalent cationic salts represent a suitable class of stabilizer of peptide acylation in PLGA microspheres and this study provides an important formulation approach to maximize stabilizer potency.
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Affiliation(s)
- Ying Zhang
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
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23
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van der Walle CF, Sharma G, Ravi Kumar MNV. Current approaches to stabilising and analysing proteins during microencapsulation in PLGA. Expert Opin Drug Deliv 2009; 6:177-86. [DOI: 10.1517/17425240802680169] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Literature Alerts. J Microencapsul 2008. [DOI: 10.3109/02652049609006807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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25
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Literature Alerts. J Microencapsul 2008. [DOI: 10.3109/02652049609026046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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26
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Saini P, Greenspan P, Lu DR. Adsorption of Brain Proteins on the Surface of Poly (D,L-lactide-co-glycolide) (PLGA) Microspheres. Drug Deliv 2008. [DOI: 10.3109/10717549709051884] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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27
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Drogoz A, Munier S, Verrier B, David L, Domard A, Delair T. Towards Biocompatible Vaccine Delivery Systems: Interactions of Colloidal PECs Based on Polysaccharides with HIV-1 p24 Antigen. Biomacromolecules 2008; 9:583-91. [DOI: 10.1021/bm701154h] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexandre Drogoz
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
| | - Séverine Munier
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
| | - Bernard Verrier
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
| | - Laurent David
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
| | - Alain Domard
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
| | - Thierry Delair
- Unité Mixte CNRS-BioMérieux, UMR 2714, ENS Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS, 7 Passage du Vercors, 69967 Lyon Cedex 07, France, and Laboratoire des Matériaux Polymères et des Biomatériaux, UMR CNRS 5223 Ingénierie des Matériaux Polymères, Université de Lyon, Université Lyon 1, Domaine Scientifique de la Doua, Bât. ISTIL, 15 Bd. A. Latarjet, 69622 Villeurbanne Cedex, France
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Yang DJ, Zhang LF, Xu L, Xiong CD, Ding J, Wang YZ. Fabrication and characterization of hydrophilic electrospun membranes made from the block copolymer of poly(ethylene glycol-co-lactide). J Biomed Mater Res A 2007; 82:680-8. [PMID: 17323320 DOI: 10.1002/jbm.a.31099] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To improve the hydrophilicity, pliability, and egradability of some biodegradable polymers such as polylactide (PLA), a triblock copolymer, and poly(ethylene glycol-co-lactide) (PELA) has been electrospun into fibrous membranes in the fiber sizes of 7.5 microm to 250 nm. The relationship between electrospinning parameters (such as voltage, concentration, and feeding rate) and the fiber diameters has been investigated. The characterizations for the structure and morphology of electrospun membranes were carried out using differential scanning calorimetry (DSC), (1)H NMR, and scanning electron microscopy (SEM). The hydrophilicity of the membrane was determined by contact angle measurements in bi-distilled water, and it was shown that the hydrophilicity of the copolymer could be adjusted by the content of the poly (ethylene glycol) (PEG) segment in the copolymer. The results of in vitro degradation study showed that the submicrostructure of the fibrous membrane and the incorporation of hydrophilic PEG into PLA block could accelerate the degradation of the membrane in regards to the changes of inherent viscosity, tensile strength, and weight loss.
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Affiliation(s)
- De-Juan Yang
- Center for Degradable and Flame-Retardant Polymeric Materials, College of Chemistry, Sichuan University, Chengdu 610064, China
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29
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Houchin M, Neuenswander S, Topp E. Effect of excipients on PLGA film degradation and the stability of an incorporated peptide. J Control Release 2006; 117:413-20. [PMID: 17207882 PMCID: PMC1864950 DOI: 10.1016/j.jconrel.2006.11.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 11/22/2006] [Accepted: 11/27/2006] [Indexed: 11/24/2022]
Abstract
The effect of pH modifying excipients on the chemical stability of a model peptide (VYPNGA) and the degradation of poly(dl-lactide-co-glycolide)(PLGA) was studied in PLGA films under accelerated storage conditions. pH modifiers included a basic amine (proton sponge), a basic salt (magnesium hydroxide) and two pH buffers (ammonium acetate and magnesium acetate). Changes in film pH were monitored using (13)C NMR, peptide degradation products were quantified by LC/MS/MS and PLGA degradation was analyzed by TGA, DSC and SEC. Inclusion of pH modifiers had little impact on PLGA degradation. The proton sponge affected an initial decrease in pH but reduced peptide deamidation and chain cleavage relative to an unbuffered control. Magnesium hydroxide produced an initial increase in pH but also showed increased peptide deamidation. Ammonium acetate decreased pH and increased peptide chain cleavage, presumably due to increased PLGA hydrolysis. Magnesium acetate buffer increased the initial pH but resulted in increased peptide loss. The extent of peptide acylation increased in all formulations, most notably in the proton sponge modified films. The effectiveness of pH modifiers in PLGA formulations under storage conditions is dependant on both the mechanism of pH alteration and the peptide degradation reaction of interest.
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Affiliation(s)
- M.L. Houchin
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS
| | | | - E.M. Topp
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS
- *To whom correspondence should be addressed: Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Ave. Lawrence, KS 66047, Phone: 785-864-4820, e-mail:
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30
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Houchin ML, Heppert K, Topp EM. Deamidation, acylation and proteolysis of a model peptide in PLGA films. J Control Release 2006; 112:111-9. [PMID: 16529840 DOI: 10.1016/j.jconrel.2006.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 01/25/2006] [Accepted: 01/30/2006] [Indexed: 11/30/2022]
Abstract
The relative rates of deamidation, acylation and proteolysis (i.e. amide bond cleavage) were determined for a model peptide (VYPNGA) in poly (dl-lactide-co-glycolide) films. Films were stored at 70 degrees C and either 95%, 75%, 60%, 45%, 28%, or approximately 0% relative humidity and at 37 degrees C and 95% relative humidity. Peptide degradation products were identified by ESI+MS/MS and quantitated by LC/MS/MS. Extensive overlap of degradation mechanisms occurred, producing a complex mixture of products. Acylation was the dominant peptide degradation reaction (10-20% of total peptide) at early stages of PLGA hydrolysis and at intermediate relative humidity (60-45% RH). Deamidation and proteolysis were dominant (25-50% and 20-40% of total peptide, respectively) at later stages and at high relative humidity (95-75% RH). Understanding the relative rates of each peptide degradation reaction will allow for improved design of PLGA formulations that preserve the stability of peptide and protein drugs.
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Affiliation(s)
- M L Houchin
- Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, USA
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31
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Ibrahim MA, Ismail A, Fetouh MI, Göpferich A. Stability of insulin during the erosion of poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres. J Control Release 2005; 106:241-52. [PMID: 15970349 DOI: 10.1016/j.jconrel.2005.02.025] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 02/20/2005] [Indexed: 11/15/2022]
Abstract
In recent years, the acylation of peptides during the erosion of poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres has been described in the literature. To investigate whether insulin is prone to the covalent attachment of lactic or glycolic acid, insulin-loaded PLA and PLGA microspheres containing 5% bovine insulin were manufactured using a w/o/w multiple emulsion-solvent evaporation technique. Microspheres were characterized for their insulin encapsulation efficiency and release characteristics in phosphate-buffered saline (PBS) at pH 7.4 and 37 degrees C. Moreover, the stability of the peptide during 18 days of release was evaluated using HPLC and HPLC-MS techniques. The results showed that the insulin loading efficiencies of PLA and PLGA microspheres were 75.18% and 79.63%, respectively. The microspheres were spherical with relatively porous surfaces with an average diameter of 40 and 53 mum, respectively. Insulin release from the microspheres was characterized by an initial burst, which was attributed to the amount of protein located on or close to the microsphere surface. The total ion chromatogram (TIC) of insulin samples extracted after 18 days of erosion in phosphate buffer pH 7.4 at 37 degrees C revealed that deamidation was the major mechanism of instability. Surprisingly, no acylation products were found. Control experiments in concentrated lactic acid solutions confirmed a minimal reactivity of the peptide under these conditions.
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Bilati U, Allémann E, Doelker E. Strategic approaches for overcoming peptide and protein instability within biodegradable nano- and microparticles. Eur J Pharm Biopharm 2005; 59:375-88. [PMID: 15760718 DOI: 10.1016/j.ejpb.2004.10.006] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2004] [Accepted: 10/29/2004] [Indexed: 11/17/2022]
Abstract
This paper reviews the major factors that are closely involved in peptide and protein degradation during the preparation of biodegradable nano- and microparticles. The various means usually employed for overcoming these obstacles are described, in order to bring to the fore the strategies for protein stabilization. Both processing and formulation parameters can be modified and are distinctly considered from a strategic point of view. We describe how partial or full protein stability retention within the carriers and during drug release might be achieved by individual or combined optimized strategies. Additionally, problems commonly encountered during protein quantification, stability determination and release are briefly reviewed. Artefacts that might occur during sampling and analytical procedures and which might hinder critical interpretation of results are discussed.
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Affiliation(s)
- Ugo Bilati
- School of Pharmacy, University of Geneva, Geneva, Switzerland
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Na DH, DeLuca PP, Lee KC. Direct determination of the peptide content in microspheres by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Anal Chem 2005; 76:2669-73. [PMID: 15117214 DOI: 10.1021/ac035477i] [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: 11/29/2022]
Abstract
A quantitative determination of peptides incorporated into poly(d,l-lactide-co-glycolide) microspheres by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was accomplished in a single step without pretreatment for extracting the peptide from the microsphere. The conventional extraction methods often underestimate the actual amount of peptide because of incomplete extraction from the microspheres or loss during the procedures. In this study, the microspheres dissolved in acetonitrile containing 0.1% trifluoroacetic acid were mixed with matrix solution containing the internal standard, and the peptide content was directly determined by MALDI-TOF MS. The drug content values determined by MALDI-TOF MS in both the leuprolide- and salmon calcitonin-incorporated microspheres were closer to the theoretical contents than those determined by the conventional extraction method. This method using MALDI-TOF MS could be a good alternative to time-consuming and less-accurate conventional methods.
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Affiliation(s)
- Dong Hee Na
- College of Pharmacy, SungKyunKwan University, Suwon City 440-746, Korea
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Kim TH, Park TG. Critical effect of freezing/freeze-drying on sustained release of FITC-dextran encapsulated within PLGA microspheres. Int J Pharm 2004; 271:207-14. [PMID: 15129987 DOI: 10.1016/j.ijpharm.2003.11.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The cause of initial burst release of hydrophilic macromolecular drugs from biodegradable polymeric microspheres was identified. Poly(D,L-lactic-co-glycolic acid) microspheres encapsulating fluorescein isothiocyanate (FITC)-labled dextran was prepared by a double emulsion solvent evaporation method. The extent of initial burst release was examined by varying the formulation process conditions such as solvent evaporation, washing, freezing, and freeze-drying. Confocal microscopy was employed to analyze the underlying mechanism of burst release. The extent of burst release was gradually reduced after the repeated washing of embryonic microspheres before freeze-drying, indicating that FITC-dextran molecules entrapped within unhardened microspheres were slowly diffused out. However, freezing and subsequent drying processes of the embryonic microspheres resulted in much increased extent of burst release, suggesting that the initial burst release was primarily caused by the rapid diffusion of FITC-dextran through the microporous channels. Confocal microscopic analysis revealed that the freeze-drying process generated water-escaping micro-channels, through which the encapsulated molecules were presumably dumped out. Vacuum-drying was a good alternative choice in reducing the initial burst, compared to freeze-drying.
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Affiliation(s)
- Tae Hyoung Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
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Raghuvanshi RS, Katare YK, Lalwani K, Ali MM, Singh O, Panda AK. Improved immune response from biodegradable polymer particles entrapping tetanus toxoid by use of different immunization protocol and adjuvants. Int J Pharm 2002; 245:109-21. [PMID: 12270248 DOI: 10.1016/s0378-5173(02)00342-3] [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: 11/29/2022]
Abstract
Poly lactide-co-glycolide (PLGA) and polylactide (PLA) particles entrapping immunoreactive tetanus toxoid (TT) were prepared using the solvent evaporation method. The effect of different formulation parameters such as polymer hydrophobicity, particle size and use of additional adjuvants on the generation of immune responses in experimental animals was evaluated. Immune responses from hydrophobic polymer particles were better than those from hydrophilic polymer. Immunization with physical mixtures of different size particles resulted in further improvement in anti-TT antibody titers in Wistar rats. Physical mixture of nano and microparticles resulted in early as well as high antibody titers in experimental animals. Immunization with polymer particles encapsulating stabilized TT elicited anti-TT antibody titers, which persisted for more than 5 months and were higher than those obtained with saline TT. However, antibody responses generated by single point immunization of either particles or physical mixture of particles were lower than the conventional two doses of alum-adsorbed TT. Immunization with nanoparticles along with alum resulted in very high and early immune response: high anti-TT antibody titers were detected as early as 15 days post-immunization. Use of a squalene emulsion along with the particles during immunization enhanced the level of anti-TT antibody titers considerably. Single point immunization with admixtures of PLA microparticles and alum resulted in antibody response very close to that achieved by two injections of alum-adsorbed TT; the antibody titers were more than 50 microg/ml over a period of 6 months. These results indicated that the judicious choice of polymer and particles size, protecting the immunoreactivity of the entrapped antigen and the appropriate design of immunization protocol along with suitable adjuvant can lead to the generation of long lasting immune response from single dose vaccine formulation using polymer particles.
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Affiliation(s)
- Rajeev S Raghuvanshi
- Product Development Cell, National Institute of Immunology, Aruna Asaf Ali Marg, 110 067, New Delhi, India
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Lucke A, Fustella E, Tessmar J, Gazzaniga A, Göpferich A. The effect of poly(ethylene glycol)-poly(D,L-lactic acid) diblock copolymers on peptide acylation. J Control Release 2002; 80:157-68. [PMID: 11943395 DOI: 10.1016/s0168-3659(02)00020-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The combination of poly(ethylene glycol) (PEG) with a biodegradable poly(ester), such as poly(D,L-lactic acid) (PLA), is an approach that has been successfully used for the stabilization of proteins and peptides in several biodegradable delivery devices. The acylation of peptides inside degrading PLA microspheres has been described only recently as another instability mechanism related to the accumulation of polymer degradation products inside eroding PLA. We investigated whether the block copolymerization of PLA with PEG reduces peptide acylation inside degrading microspheres. Diblock copolymers consisting of poly(D,L-lactic acid) covalently bound to poly(ethylene glycol)-monomethyl ether (Me.PEG-PLA) were used for these investigations. Human atrial natriuretic peptide (ANP) was incorporated into microspheres manufactured from Me.PEG5-PLA45, a diblock copolymer with an overall PEG content of 10%. Peptide integrity inside the microspheres was monitored by HPLC-MS analysis during 4 weeks of microsphere degradation in isotonic phosphate buffer (pH 7.4) at 37 degrees C. Inside the degrading Me.PEG5-PLA45 microspheres, acylation products as well as an oxidation product of ANP were formed. The results demonstrate that the combination of PEG with PLA does not necessarily display a favorable effect concerning peptide acylation inside degrading polymer microspheres. However, they also suggested that the acylation reaction is mainly driven by the formation and accumulation of polymer degradation products inside the degrading microspheres.
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Affiliation(s)
- Andrea Lucke
- Department of Pharmaceutical Technology, University of Regensburg, 93040 Regensburg, Germany
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37
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Abstract
PURPOSE Poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) microspheres were investigated concerning the possible acylation of incorporated peptides. METHODS Atrial natriuretic peptide (ANP) and salmon calcitonin (sCT) were encapsulated into PLA and PLGA microspheres. Peptide integrity was monitored by HPLC-MS analysis during microsphere degradation for four weeks. sCT fragmentation with endoproteinase Glu-C was used for identifying modified amino acids. Peptide stability in lactic acid solutions was investigated to elucidate possible mechanisms for preventing peptide acylation. RESULTS Both peptides were acylated by lactic and glycolic acid units inside degrading microspheres in a time-dependent manner. After 21 days, 60% ANP and 7% sCT inside PLA microspheres were acylated. Fragmentation of sCT with endoproteinase Glu-C revealed that besides the N-terminal amine group, lysine, tyrosine or serine are further possible targets to acylation. Stability studies of the peptides in lactic acid solutions suggest that oligomers are the major acylation source and that lower oligomer concentration and higher pH substantially decreased the reaction velocity. CONCLUSIONS The use of PLA and PLGA for drug delivery needs substantially more circumspection. As, according to FDA standards. the potential hazards of peptide acylation products need to be assessed, our findings may have significant implications for products already on the market. Techniques to minimize the acylation reaction are suggested.
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Affiliation(s)
- Andrea Lucke
- Department of Pharmaceutical Technology, University of Regensburg, Germany
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Jamie Tsung M, Burgess DJ. Preparation and characterization of gelatin surface modified PLGA microspheres. AAPS PHARMSCI 2001; 3:E11. [PMID: 11741261 PMCID: PMC2779555 DOI: 10.1208/ps030211] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This study optimized conditions for preparing and characterizing gelatin surface modified poly (lactic-co-glycolic acid) (PLGA) copolymer microspheres and determined this system's interaction with fibronectin. Some gelatin microspheres have an affinity for fibronectin-bearing surfaces; these microspheres exploit the interaction between gelatin and fibronectin. PLGA copolymer microspheres were selected because they have reproducible and slow-release characteristics in vivo. The PLGA microspheres were surface modified with gelatin to impart fibronectin recognition. Dexamethasone was incorporated into these microspheres because dexamethasone is beneficial in chronic human diseases associated with extra fibronectin expression (eg, cardiovascular disease, inflammatory disorders, rheumatoid arthritis). The gelatin surface modified PLGA microspheres (prepared by adsorption, conjugation, and spray coating) were investigated and characterized by encapsulation efficiency, particle size, in vitro release, and affinity for fibronectin. The gelatin-coated PLGA microspheres had higher interaction with fibronectin compared with the other gelatin surface modified PLGA microspheres (adsorption and conjugation). Dexamethasone was released slowly (over 21 days) from gelatin surface modified PLGA microspheres.
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Affiliation(s)
| | - Diane J. Burgess
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, 372 Fairfield Road, Box U-2092, 06269-2092 Storrs, CT
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39
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Lucke A, Tessmar J, Schnell E, Schmeer G, Göpferich A. Biodegradable poly(D,L-lactic acid)-poly(ethylene glycol)-monomethyl ether diblock copolymers: structures and surface properties relevant to their use as biomaterials. Biomaterials 2000; 21:2361-70. [PMID: 11055283 DOI: 10.1016/s0142-9612(00)00103-4] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To obtain biodegradable polymers with variable surface properties for tissue culture applications, poly(ethylene glycol) blocks were attached to poly(lactic acid) blocks in a variety of combinations. The resulting poly(D,L-lactic acid)-poly(ethylene glycol)-monomethyl ether (Me.PEG-PLA) diblock copolymers were subject to comprehensive investigations concerning their bulk microstructure and surface properties to evaluate their suitability for drug delivery applications as well as for the manufacture of scaffolds in tissue engineering. Results obtained from 1H-NMR, gel permeation chromatography, wide angle X-ray diffraction and modulated differential scanning calorimetry revealed that the polymer bulk microstructure contains poly(ethylene glycol)-monomethyl ether (Me.PEG) domains segregated from poly(D,L-lactic acid) (PLA) domains varying with the composition of the diblock copolymers. Analysis of the surface of polymer films with atomic force microscopy and X-ray photoelectron spectroscopy indicated that there is a variable amount of Me.PEG chains present on the polymer surface, depending on the polymer composition. It could be shown that the presence of Me.PEG chains in the polymer surface had a suppressive effect on the adsorption of two model peptides (salmon calcitonin and human atrial natriuretic peptide). The possibility to modify polymer bulk microstructure as well as surface properties by variation of the copolymer composition is a prerequisite for their efficient use in the fields of drug delivery and tissue engineering.
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Affiliation(s)
- A Lucke
- Department of Pharmaceutical Technology, University of Regensburg, Germany
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40
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Dogru ST, Calis S, Oner F. Oral multiple w/o/w emulsion formulation of a peptide salmon calcitonin: in vitro-in vivo evaluation. J Clin Pharm Ther 2000; 25:435-43. [PMID: 11123497 DOI: 10.1046/j.1365-2710.2000.00306.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Salmon calcitonin (sCT) is a polypeptide hormone consisting of 32 amino acid residues (MW approx. 3400 Da), which can be used successfully for the treatment of osteoporosis, Paget's disease and hypercalcaemia. Only nasal and parenteral preparations of sCT are currently available, and as injections are poorly accepted by patients, nonparenteral preparations for oral, rectal and nasal administration are highly desirable. However, oral sCT is poorly bioavailable, being susceptible to enzymatic degradation in the gastrointestinal tract. OBJECTIVES To design a formulation of sCT suitable for oral use. METHOD A water/oil/water (w/o/w) type multiple emulsion formulation was designed for oral application of sCT. sCT was placed in the inner water phase, and a protease inhibitor, aprotinin, was included in the outer water phase of this system to investigate the influence of protease inhibitors in the presence of sCT. The effectiveness of the formulation was evaluated in vitro by placing emulsion samples in a dialysis medium and in vivo by using a rat model. RESULTS Incorporating sCT in the inner aqueous phase of a w/o/w emulsion appears to protect the peptide from enzymatic degradation. sCT was further protected by incorporating the protease inhibitor, aprotinin, in the outer aqueous phase. CONCLUSION w/o/w emulsion formulations appear to be promising carrier systems for peptide-protein drugs.
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Affiliation(s)
- S T Dogru
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Hacettepe University, 06100 Ankara, Turkey
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41
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Reddy KR. Controlled-release, pegylation, liposomal formulations: new mechanisms in the delivery of injectable drugs. Ann Pharmacother 2000; 34:915-23. [PMID: 10928404 DOI: 10.1345/aph.10054] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To review recent developments in novel injectable drug delivery mechanisms and outline the advantages and disadvantages of each. DATA SOURCES A MEDLINE (1995-January 2000) search using the terms polyethylene glycol, liposomes, polymers, polylactic acid, and controlled release was conducted. Additional references were identified by scanning bibliographies. STUDY SELECTION AND DATA EXTRACTION All articles were considered for inclusion. Abstracts were included only if they were judged to add critical information not otherwise available in the medical literature. DATA SYNTHESIS A number of systems that alter the delivery of injectable drugs have been developed in attempts to improve pharmacodynamic and pharmacokinetic properties of therapeutic agents. New drug delivery systems can be produced either through a change in formulation (e.g., continuous-release products, liposomes) or an addition to the drug molecule (e.g., pegylation). Potential advantages of new delivery mechanisms include an increased or prolonged duration of pharmacologic activity, a decrease in adverse effects, and increased patient compliance and quality of life. Injectable continuous-release systems deliver drugs in a controlled, predetermined fashion and are particularly appropriate when it is important to avoid large fluctuations in plasma drug concentrations. Encapsulating a drug within a liposome can produce a prolonged half-life and a shift of distribution toward tissues with increased capillary permeability (e.g., tumors, infected tissue). Pegylation provides a method for modification of therapeutic proteins to minimize many of the limitations (e.g., poor stability, short half-life, immunogenicity) associated with these agents. CONCLUSIONS Pegylation of therapeutic proteins is an established process with new applications. However, not all pegylated proteins are alike, and each requires optimization on a protein-by-protein basis to derive maximum clinical benefit. The language required to describe each pegylated therapeutic protein must be more precise to accurately distinguish each protein's differential pharmacologic properties.
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Affiliation(s)
- K R Reddy
- Department of Medicine, University of Miami School of Medicine, Center for Liver Diseases, FL 33136, USA.
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42
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Abstract
The commercial availability of peptides and proteins and their advantages as therapeutic agents have been the basis for tremendous efforts in designing delivery systems for such agents. The protection of these agents from biological fluids and physiological interactions is crucial for the treatment efficacy. One such agent is salmon calcitonin, a 32 amino-acid polypeptide hormone used in the treatment of bone diseases such as Paget's disease, hypercalcemia and osteoporosis. Researchers have studied different routes to deliver salmon calcitonin more effectively, including nasal, oral, vaginal and rectal delivery. These systems are designed to protect the polypeptide from the biological barriers that each delivery route imposes. Oil-based and polymer-based delivery systems are discussed.
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Affiliation(s)
- M Torres-Lugo
- Biomaterials and Drug Delivery Laboratories, School of Chemical Engineering, Purdue University, West Lafayette, IN 47906-1283, USA
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43
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Göpferich A, Peter SJ, Lucke A, Lu L, Mikos AG. Modulation of marrow stromal cell function using poly(D,L-lactic acid)-block-poly(ethylene glycol)-monomethyl ether surfaces. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1999; 46:390-8. [PMID: 10397997 DOI: 10.1002/(sici)1097-4636(19990905)46:3<390::aid-jbm12>3.0.co;2-n] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The adhesion of marrow stromal osteoblasts and the adsorption of fetal bovine serum (FBS) proteins to end-capped poly(D,L-lactic acid) 50:50 (PLA50) of molecular weight 17,000 (PLA5017), non-end-capped PLA50 of molecular weight 11,000 (PLA5011h), and a diblock copolymer made of poly(ethylene glycol)-monomethyl ether of molecular weight 5,000 and PLA50 of molecular weight 20,000 (Me. PEG5-PLA20) were investigated. Cell attachment and proliferation on both PLA50 polymers were equally good. The block copolymer did not allow the proliferation of cells. However, the attached cells were highly differentiated and metabolically active in contrast to the cells on PLA50. Moreover, surface analysis studies using electron spectroscopy revealed that FBS proteins adsorbed well from aqueous solutions to the PLA50 surfaces while they adsorbed substantially less to the block copolymer. These results suggest that Me.PEG-PLA block copolymers may be used to regulate protein adsorption and, therefore, cell adhesion by varying the block composition of the copolymer.
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Affiliation(s)
- A Göpferich
- Department of Pharmaceutical Technology, University of Regensburg, 93040 Regensburg, Germany.
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44
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Diaz RV, Llabrés M, Evora C. One-month sustained release microspheres of 125I-bovine calcitonin. In vitro-in vivo studies. J Control Release 1999; 59:55-62. [PMID: 10210722 DOI: 10.1016/s0168-3659(98)00179-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To obtain a 1-month release formulation of 125I-bovine calcitonin, microspheres were prepared with three different PLA copolymers, PLGA I (mol. wt. [MW]=30000), polyethyleneglycol (PEG)-PLGA (MW=34000) and PLGA II (MW=12000) using the double emulsion method. The release of 125I-bovine calcitonin was assayed in vitro using dialysis bags at 37 degrees C in isotonic phosphate buffer (pH 7.4). The in vitro release results indicated a very slow release rate for an optimal 1-month sustained release formulation. 125I-bovine calcitonin microspheres were administered under the skin on the back of Wistar rats and the radioactivity at the injection site was subsequently measured over a 4-week period. The in vitro and in vivo profiles were affected by the weight average molecular weight of the copolymers. The 125I-bovine calcitonin release rate was faster from microspheres prepared with PLGA II (MW=12000) than from microspheres prepared with higher molecular weight copolymers (PLGA I and PEG-PLGA). Microspheres prepared with PLGA II (MW=12000) release 100% of the dose in 1 month, in vivo release profiles presented two phases, during the first 2 weeks approximately 70% of the 125I-bovine calcitonin injected was released, followed by a second slower phase.
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Affiliation(s)
- R V Diaz
- Departamento de Ingeniería Química y Tecnología Farmacéutica, Av. Astrofísico Francisco Sánchez s/n. Facultad de Farmacia, Universidad de La Laguna, 38200 La Laguna, Spain
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45
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Abstract
Surface adsorption of calcitonin on soda lime silica glass was investigated. An attempt was also made to examine the effect of additives on the inhibition of calcitonin adsorption. Results showed that the adsorption isotherms were of the Langmuir and Freundlich type, depending on pH. Less adsorption was found for calcitonin at pH 4.3. The addition of nonionic surfactants such as Pluronic F68 and Tween 80 to the calcitonin solutions demonstrated inhibition of absorption and reduction of adsorption rate. The addition of chlorobutanol also showed the effect of minimizing adsorption.
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Affiliation(s)
- S L Law
- Department of Medical Research, Veterans General Hospital, Taipei, Taiwan, Republic of China
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46
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Johansen P, Corradin G, Merkle HP, Gander B. Release of tetanus toxoid from adjuvants and PLGA microspheres: how experimental set-up and surface adsorption fool the pattern. J Control Release 1998; 56:209-17. [PMID: 9801444 DOI: 10.1016/s0168-3659(98)00084-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The classical adjuvants alum and Freund's Incomplete Adjuvant (IFA) are frequently used as references for the design of new adjuvants and antigen delivery systems, e.g., microspheres (MS). Poly(dl-lactic-co-glycolic acid) (PLGA) MS have been proposed for delivering antigen booster doses in vivo after a single injection. However, as antigen release kinetics from conventional adjuvants are generally unknown, it appears presumptuous to propose a desired antigen release pattern from PLGA MS. Therefore, we have studied the tetanus toxoid (Ttxd) in vitro release from alum, IFA formulations and MS in four different test systems. The results showed a stronger Ttxd association to alum than to IFA, and the release from both formulations lasted between 3-9 days. The total of ELISA-responsive antigen released was 60-85% of the actual dose. Both the total amount and the prolongation of release depended on the Ttxd dose. Furthermore, the incomplete in vitro release of Ttxd from the adjuvants and also from PLGA 50:50 MS was shown to be partly due to experimental conditions. Typically, Ttxd adsorbed on the glass vials used for the release test and also on the surface of the PLGA 50:50 MS, wherefrom it was released. In conclusion, the test system depending rate and quantity of release observed evidence the limitations of in vitro release data. Finally, for mimicking conventional vaccination schedules, i.e. injections typically at time points 0, 1, 3, and 12-24 months, PLGA MS should release antigen doses at the corresponding time points, and the release pulse should only last for a few days.
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Affiliation(s)
- P Johansen
- Department of Pharmacy, ETH-Zürich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland
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Labhasetwar V, Song C, Humphrey W, Shebuski R, Levy RJ. Arterial uptake of biodegradable nanoparticles: effect of surface modifications. J Pharm Sci 1998; 87:1229-34. [PMID: 9758682 DOI: 10.1021/js980021f] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Restenosis is the reobstruction of an artery following interventional procedures such as balloon angioplasty or stenting. Local pharmacotherapeutic approaches using controlled release systems are under investigation to inhibit the regional pathophysiologic process of restenosis. We have been investigating biodegradable nanoparticles (100 +/- 39 nm in diameter, mean +/- sd) for the local intra-arterial drug delivery. The purpose of this study was to investigate nanoparticle surface modifications (see Table 1) to enhance their arterial uptake. The PLGA (polylactic polyglycolic acid copolymer) nanoparticles were formulated by an oil-in-water emulsion solvent evaporation technique using a 2-aminochromone (U-86983, Upjohn and Pharmacia) (U-86) as a model antiproliferative agent. The various formulations of nanoparticles were evaluated for the arterial wall uptake by using an ex-vivo dog femoral artery model. The selected formulations were then tested in vivo in acute dog femoral artery and pig coronary artery models. The nanoparticles surface modified with a cationic compound, didodecyldimethylammonium bromide (DMAB), demonstrated 7-10-fold greater arterial U-86 levels compared to the unmodified nanoparticles in different ex-vivo and in-vivo studies. The mean U-86 levels were 10.7 +/- 1.7 microg/10 mg (dog) and 6.6 +/- 0.6 microg/10 mg (pig) in the artery segments ( approximately 2 cm) which were infused with the nanoparticles. The pig coronary studies further demonstrated that the infusion of nanoparticles with higher U-86 loading reduced the arterial U-86 levels, whereas increasing the nanoparticle concentration in the infusion solutions increased the arterial U-86 levels. The biodistribution studies in pigs following coronary arterial administration of nanoparticles demonstrated disposition of U-86 in the myocardium and distally in the liver and the lung. The mechanism of enhanced arterial uptake of the DMAB surface modified nanoparticles seems to be due to the alteration in the nanoparticle surface charge. The unmodified nanoparticles had a zeta potential of -27.8 +/- 0.5 mV (mean +/- sem, n = 5), whereas the DMAB modified nanoparticles demonstrated a zeta potential of +22.1 +/- 3.2 mV (mean +/- sem, n = 5). The adsorption of DMAB to the nanoparticle surface followed the Freundlich isotherm with binding capacity k = 28.1 microg/mg and affinity constant p = 2. 33. In conclusion, surface modified nanoparticles have potential applications for intra-arterial drug delivery to localize therapeutic agents in the arterial wall to inhibit restenosis.
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Affiliation(s)
- V Labhasetwar
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 600 South 42nd Street, Omaha, Nebraska 68198-6025, USA
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49
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Witschi C, Doelker E. Peptide degradation during preparation and in vitro release testing of poly(l-lactic acid) and poly(dl-lactic-co-glycolic acid) microparticles. Int J Pharm 1998. [DOI: 10.1016/s0378-5173(98)00155-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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50
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Jain R, Shah NH, Malick AW, Rhodes CT. Controlled drug delivery by biodegradable poly(ester) devices: different preparative approaches. Drug Dev Ind Pharm 1998; 24:703-27. [PMID: 9876519 DOI: 10.3109/03639049809082719] [Citation(s) in RCA: 191] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
There has been extensive research on drug delivery by biodegradable polymeric devices since bioresorbable surgical sutures entered the market two decades ago. Among the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) such as poly(lactide) (PLA), poly(glycolide) (PGA), and especially the copolymer of lactide and glycolide referred to as poly(lactide-co-glycolide) (PLGA) have generated tremendous interest because of their excellent biocompatibility, biodegradability, and mechanical strength. They are easy to formulate into various devices for carrying a variety of drug classes such as vaccines, peptides, proteins, and micromolecules. Most importantly, they have been approved by the United States Food and Drug Administration (FDA) for drug delivery. This review presents different preparation techniques of various drug-loaded PLGA devices, with special emphasis on preparing microparticles. Certain issues about other related biodegradable polyesters are discussed.
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Affiliation(s)
- R Jain
- Department of Applied Pharmaceutical Sciences, The University of Rhode Island, Kingston 02881, USA.
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