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Tao W, Xie P, Huang C, Wang Y, Huang Y, Yin Z. Construction of PLGA nanoparticles modified with RWrNM and DLPC and their application in acute rhinosinusitis. Drug Deliv Transl Res 2024; 14:1063-1076. [PMID: 37966678 DOI: 10.1007/s13346-023-01450-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2023] [Indexed: 11/16/2023]
Abstract
In an effort to overcome the nasal mucus barrier and epithelial barrier, as well as reduce entry into the bloodstream, we designed RWrNM and DLPC-modified PLGA nanoparticles (PDR-NPs). These nanoparticles were further encapsulated with dexamethasone acetate (Dexac) to form Dexac/PDR-NPs. Transmission electron microscopy (TEM) analysis revealed their spherical shape with an outer lipid layer. Dynamic light scattering (DLS) determined their particle size to be 125.77 ± 2.01 nm, with a polydispersity index (PDI) of 0.139 ± 0.029. The experimental results demonstrate that DLPC-modified PLGA nanoparticles can effectively reduce interactions with mucin at different concentrations, decrease aggregation, and facilitate their crossing of the mucus barrier. Additionally, results from the cellular uptake assay revealed a significantly greater uptake of PDR-NPs by inflammatory RAW 264.7 cells (2.99-fold higher than that of free C6, p < 0.0001) and inflammatory HUVECs (7.20-fold higher than that of free C6, p < 0.0001). Furthermore, Dexac/PDR-NPs effectively reduced the levels of inflammatory factors nitric oxide (NO) (p < 0.001) and interleukin-6 (IL-6) (p < 0.05) in the supernatant of inflammatory RAW 264.7 cells. Intravital imaging of rats revealed that PDR-NPs had a longer residence time in inflamed nasal tissue compared to PD-NPs. Furthermore, in vivo pharmacodynamic experiments showed that Dexac/PDR-NPs effectively reduced the symptoms of nasal inflammation, lowered the pH of nasal secretions, decreased serum inflammatory factor levels (TNF-α and IL-6), and reduced nasal mucosal inflammatory factor levels (IL-1β), while also reducing the degree of inflammation in the nasal mucosa. Both cytotoxicity assays and in vivo results indicate that PDR-NPs have a good safety profile. PDR-NPs not only overcome the nasal mucus barrier but also reduce the systemic toxicities associated with drug entry into the circulation by enhancing the targeting of inflammatory macrophages and inflammatory vascular endothelial cells. PDR-NPs allow for an "open sources and cut costs" treatment strategy to increase drug retention in the inflamed nasal tissues, reducing toxicity and increasing efficacy. In conclusion, PDR-NPs can be a promising drug delivery system for the local treatment of acute rhinosinusitis.
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Affiliation(s)
- Wanjun Tao
- Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17, Block 3 Southern Renmin Road, Chengdu, 610041, China
| | - Pei Xie
- Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17, Block 3 Southern Renmin Road, Chengdu, 610041, China
| | - Chengyuan Huang
- Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17, Block 3 Southern Renmin Road, Chengdu, 610041, China
| | - Ying Wang
- Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17, Block 3 Southern Renmin Road, Chengdu, 610041, China
| | - Yu Huang
- Haisco Pharmaceutical Group Co., Ltd, Chengdu, China
| | - Zongning Yin
- Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17, Block 3 Southern Renmin Road, Chengdu, 610041, China.
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Krzyzanowski N, Porcar L, Perez-Salas U. A Small-Angle Neutron Scattering, Calorimetry and Densitometry Study to Detect Phase Boundaries and Nanoscale Domain Structure in a Binary Lipid Mixture. Membranes (Basel) 2023; 13:323. [PMID: 36984710 PMCID: PMC10051979 DOI: 10.3390/membranes13030323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Techniques that can probe nanometer length scales, such as small-angle neutron scattering (SANS), have become increasingly popular to detect phase separation in membranes. But to extract the phase composition and domain structure from the SANS traces, complementary information is needed. Here, we present a SANS, calorimetry and densitometry study of a mixture of two saturated lipids that exhibits solidus-liquidus phase coexistence: 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (dDPPC, tail-deuterated DPPC) and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). With calorimetry, we investigated the phase diagram for this system and found that the boundary traces for both multilamellar vesicles (MLVs) as well as 50 nm unilamellar vesicles overlap. Because the solidus boundary was mostly inaccessible by calorimetry, we investigated it by both SANS and molecular volume measurements for a 1:1 dDPPC:DLPC lipid mixture. From the temperature behavior of the molecular volume for the 1:1 dDPPC:DLPC mixture, as well as the individual molecular volume of each lipid species, we inferred that the liquidus phase consists of only fluid-state lipids while the solidus phase consists of lipids that are in gel-like states. Using this solidus-liquidus phase model, the SANS data were analyzed with an unrestricted shape model analysis software: MONSA. The resulting fits show irregular domains with dendrite-like features as those previously observed on giant unilamellar vesicles (GUVs). The surface pair correlation function describes a characteristic domain size for the minority phase that decreases with temperature, a behavior found to be consistent with a concomitant decrease in membrane mismatch between the liquidus and solidus phases.
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Affiliation(s)
- Natalie Krzyzanowski
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
| | - Lionel Porcar
- Large Scale Structures Group, Institut Laue-Langevin, CEDEX 9, 38042 Grenoble, France
| | - Ursula Perez-Salas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
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Kamble S, Patil S, Appala VRM. Nano-mechanical characterization of asymmetric DLPC/DSPC supported lipid bilayers. Chem Phys Lipids 2020; 234:105007. [PMID: 33160952 DOI: 10.1016/j.chemphyslip.2020.105007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 10/13/2020] [Accepted: 11/02/2020] [Indexed: 11/25/2022]
Abstract
Asymmetric distribution of lipid molecules in the inner and outer leaflets of the plasma membrane is a common occurrence in the membrane formation. Such asymmetric arrangement is a crucial parameter to manipulate the properties of the cell membrane. It controls signal transduction, endocytosis, exocytosis in the cells. The artificial membrane is often used to study the lateral and transverse arrangement of the lipid molecules in place of the cell membrane. Nano-mechanical characterization of the model membrane helps to understand the mechanical stability of the lipid bilayer. The stability is sensitive to the variations in the lipid composition and their local organization. In this article, we present both topographical and nano-mechanical properties of lipid bilayer characterized by atomic force microscopy (AFM). The results show that the asymmetric lipid bilayer formation is an intrinsic character. We have selected a bi-component fluid-gel phase 1,2-dilauroyl-sn-glycero-3-phosphocholine:1,2-disteroyl-sn-glycero-3-phosphocholine (DLPC: DSPC) system for our studies. We have observed domain formation and phase separation in the bilayer by increasing the composition of the gel phase DSPC. In force spectroscopy studies, we determine the mechanical strength of the bilayer for unique mixtures of DLPC: DSPC by measuring the breakthrough force. These results also show the effect of asymmetry in the lipid bilayer. Besides AFM studies, we have implemented a coarse-grained (CG) molecular dynamics (MD) simulation using the gromacs package at room temperature and 1 bar pressure. The results from the simulation study have been compared with AFM study. It was found that the simulation studies corroborated the findings from AFM such as an increase in the bilayer thickness, change in the phase state, asymmetric and symmetric domain formation in the lipid bilayer.
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Affiliation(s)
- Sagar Kamble
- Department of Applied Physics, Defence Institute of Advanced Technology (DIAT) DU., Girinagar, Pune, India
| | - Snehal Patil
- Department of Applied Physics, Defence Institute of Advanced Technology (DIAT) DU., Girinagar, Pune, India
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Park J, Jung TW, Chung YH, Park ES, Jeong JH. 1,2-Dilinoleoyl-sn-glycero-3-phosphocholine increases insulin sensitivity in palmitate-treated myotubes and induces lipolysis in adipocytes. Biochem Biophys Res Commun 2020; 533:162-167. [PMID: 32943187 DOI: 10.1016/j.bbrc.2020.09.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 10/23/2022]
Abstract
Obesity causes the development of insulin resistance and type 2 diabetes. Phosphatidylcholine (PPC) has been reported to increase hepatic insulin sensitivity and lipolysis in adipose tissue to resolve local obesity. In this study, we proposed 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC), the main active species of PPC, as an effective substance for the treatment of obesity-mediated disorders such as impaired fat metabolism and insulin resistance. Therefore, we investigated the potential lipolytic effects of DLPC on adipocytes and insulin signaling in muscle cells. In this study, DLPC-treated 3T3-L1 adipocytes showed enhanced tumor necrosis factor α (TNF-α) release. Suppression of TNF-α by short interfering RNA (siRNA) mitigated DLPC-induced lipolysis and apoptosis. DLPC treatment increased peroxisome proliferator-activated receptor α (PPARα) expression levels in C2C12 myocytes. siRNA-mediated suppression of PPARα abrogated the suppressive effects of DLPC on palmitate-induced inflammation and insulin resistance. In conclusion, DLPC enhanced lipolysis and apoptosis via a TNFα-dependent pathway in adipocytes and attenuated palmitate-induced insulin resistance through PPARα-mediated suppression of inflammation in myocytes.
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Affiliation(s)
- Jinwoo Park
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Tae Woo Jung
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Yoon Hee Chung
- Department of Anatomy, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Eon Sub Park
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea; Department of Global Innovative Drug, the Graduate School of Chung-Ang University, Seoul, Republic of Korea; Department of Pathology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea.
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea; Department of Global Innovative Drug, the Graduate School of Chung-Ang University, Seoul, Republic of Korea.
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Gerván P, Soltész P, Filep O, Berencsi A, Kovács I. Posterior-Anterior Brain Maturation Reflected in Perceptual, Motor and Cognitive Performance. Front Psychol 2017; 8:674. [PMID: 28512442 PMCID: PMC5411422 DOI: 10.3389/fpsyg.2017.00674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/13/2017] [Indexed: 11/13/2022] Open
Abstract
Based on several postmortem morphometric and in vivo imaging studies it has been postulated that brain maturation roughly follows a caudal to rostral direction. In this study, we linked this maturational pattern to psychological function employing a series of well-established behavioral tasks. We addressed three distinct functions and brain regions with a perceptual (contour integration, CI), motor (finger tapping, FT), and executive control (Navon global–local) task. Our purpose was to investigate basic visual integration functions relying on primary visual cortex (V1) in CI; motor coordination function related to primary motor cortex (M1) in FT, and the executive control component, switching, related to the dorsolateral prefrontal region of the brain in the Navon task. 122 volunteer subjects were recruited to participate in this study between the ages of 10 and 20 (females n = 63, males n = 59). Employing conventional statistical methods, we found that 10 and 12 year olds are performing significantly weaker than 20 year olds in all three tasks. In the CI and Navon global–local tasks, even 14 years old perform poorer than adults. We have also investigated the developmental trajectories by fitting sigmoid curves on our data streams. The analysis of the developmental trajectories of the three tasks showed a posterior to anterior pattern in the emergence of the developmental functions with the earliest development in the visual CI task (V1), followed by motor development in the FT task (M1), and cognitive development as measured in the Navon global–local task (DLPC) being the slowest. Gender difference was also present in FT task showing an earlier maturation for girls in the motor domain.
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Affiliation(s)
- Patrícia Gerván
- Department of General Psychology, Institute of Psychology, Pázmány Péter Catholic UniversityBudapest, Hungary.,Laboratory for Psychological Research, Pázmány Péter Catholic UniversityBudapest, Hungary
| | - Péter Soltész
- Laboratory for Psychological Research, Pázmány Péter Catholic UniversityBudapest, Hungary
| | - Orsolya Filep
- Laboratory for Psychological Research, Pázmány Péter Catholic UniversityBudapest, Hungary
| | - Andrea Berencsi
- Laboratory for Psychological Research, Pázmány Péter Catholic UniversityBudapest, Hungary.,Bárczi Gusztáv Faculty of Special Education, Institute for Methodology of Special Education and Rehabilitation, Eötvös Loránd UniversityBudapest, Hungary
| | - Ilona Kovács
- Department of General Psychology, Institute of Psychology, Pázmány Péter Catholic UniversityBudapest, Hungary.,Laboratory for Psychological Research, Pázmány Péter Catholic UniversityBudapest, Hungary
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Payton NM, Wempe MF, Xu Y, Anchordoquy TJ. Long-term storage of lyophilized liposomal formulations. J Pharm Sci 2014; 103:3869-3878. [PMID: 25308534 DOI: 10.1002/jps.24171] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/20/2014] [Accepted: 08/26/2014] [Indexed: 01/18/2023]
Abstract
Because aqueous liposomal formulations containing multiply unsaturated lipids are susceptible to chemical degradation, these formulations are often lyophilized. Despite their limited chemical stability, interest in the use of multiply unsaturated lipids to promote intracellular delivery has increased considerably in recent years. The goal of the current study was to examine the long-term storage stability of lyophilized formulations containing lipids with increasing levels of unsaturation, and various strategies that can be employed to improve stability. Aqueous lipid-trehalose formulations containing 1,2-dilinolenoyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLinPC), or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were lyophilized and stored at temperatures ranging from 4°C to 60°C. We observed that the lipid degradation rate increased as the storage temperature and unsaturation level were increased. Even the cleanest sugars, which are available commercially, contain iron contaminants, and it was observed that the chelation of these iron contaminants significantly improved the stability of DLPC during storage. However, the glass transition temperature of the sugar that was included in the formulation, the reduction of the oxygen in the aqueous sample prior to lyophilization, the inclusion of helper lipids (i.e., cholesterol), and the rate of freezing did not significantly improve stability.
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Affiliation(s)
- Nicole M Payton
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Michael F Wempe
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Yemin Xu
- Center for Pharmaceutical Biotechnology, Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Thomas J Anchordoquy
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado.
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Konyakhina TM, Wu J, Mastroianni JD, Heberle FA, Feigenson GW. Phase diagram of a 4-component lipid mixture: DSPC/DOPC/POPC/chol. Biochim Biophys Acta 2013; 1828:2204-14. [PMID: 23747294 DOI: 10.1016/j.bbamem.2013.05.020] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 05/20/2013] [Accepted: 05/22/2013] [Indexed: 11/15/2022]
Abstract
We report the first 4-component phase diagram for the lipid bilayer mixture, DSPC/DOPC/POPC/chol (distearoylphosphatidylcholine/dioleoylphosphatidylcholine/1-palmitoyl, 2-oleoylphosphatidylcholine/cholesterol). This phase diagram, which has macroscopic Ld+Lo phase domains, clearly shows that all phase boundaries determined for the 3-component mixture containing DOPC transition smoothly into the boundaries for the 3-component mixture containing POPC, which has nanoscopic phase domains of Ld+Lo. Our studies start from two published ternary phase diagrams, and show how these can be combined into a quaternary phase diagram by study of a few hundred samples of intermediate compositions.
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Key Words
- 1,1′-didodecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate
- 1,1′-dieicosanyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate
- 1,2-Dilauroyl-sn-glycero-3-phosphocholine
- 1,2-Dioleoyl-sn-glycero-3-phosphocholine
- 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine
- 1,2-Distearoyl-sn-glycero-3-phosphocholine
- 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- 1-Stearoyl-2-oleoyl-sn-glycero-3-phosphocholine
- 2-(4,4-Difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine
- 3-Dye method
- 4-Component lipid phase diagram
- BoDIPY-PC
- C12:0-DiI
- C20:0-DiI
- Chol
- Cholesterol
- Competing interaction
- DHE
- DLPC
- DOPC
- DPPC
- DSPC
- Ergosta-5,7,9(11),22-tetraen-3β-ol
- FRET
- Förster resonance energy transfer
- GUV
- Giant unilamellar vesicle
- LHS
- Left hand side refers to left side of phase diagram, i.e. at lower χ(DSPC)
- Lipid raft
- Modulated phase
- PC
- POPC
- Phosphatidylcholine
- Quaternary phase diagram
- REE
- RHS
- RRE
- RSE
- Rapid solvent exchange
- Region of enhanced efficiency
- Region of reduced efficiency
- Right hand side, refers to right side of phase diagram, i.e.,, at higher χ(DSPC)
- SAE
- SM
- SOPC
- Sensitized acceptor emission
- Sphingomyelin
- T1–T6
- TLC
- TOE
- Thin-layer chromatography
- Trajectories 1–6. bSM, sphingomyelin derived from porcine brain
- Trp-Oleoyl Ester, N-oleoyl-dl-tryptophan ethyl ester
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Affiliation(s)
- Tatyana M Konyakhina
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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Ferrucci R, Priori A. Transcranial cerebellar direct current stimulation (tcDCS): motor control, cognition, learning and emotions. Neuroimage 2013; 85 Pt 3:918-23. [PMID: 23664951 DOI: 10.1016/j.neuroimage.2013.04.122] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/19/2013] [Accepted: 04/28/2013] [Indexed: 11/25/2022] Open
Abstract
The neurological manifestations of cerebellar diseases range from motor to cognitive or behavioral abnormalities. Experimental data in healthy subjects extend the cerebellar role to learning, emotional and mood control. The need for a non-invasive tool to influence cerebellar function in normal and pathological conditions led researchers to develop transcranial cerebellar direct current stimulation (tcDCS). tcDCS, like tDCS, depends on the principle that weak direct currents delivered at around 2mA for minutes over the cerebellum through surface electrodes induce prolonged changes in cerebellar function. tcDCS modulates several cerebellar skills in humans including motor control, learning and emotional processing. tcDCS also influences the cerebello-brain interactions induced by transcranial magnetic stimulation (TMS), walking adaptation, working memory and emotional recognition. Hence tcDCS is a simple physiological tool that can improve our physiological understanding of the human cerebellum, and should prove useful also in patients with cerebellar dysfunction or psychiatric disorders and those undergoing neurorehabilitation to enhance neuroplasticity.
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Affiliation(s)
- Roberta Ferrucci
- Centro Clinico per la Neurostimolazione, le Neurotecnologie ed i Disordini del Movimento, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122 Milano, Italy; Università degli Studi di Milano, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, via F. Sforza 35, 20122 Milano, Italy.
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Payton NM, Wempe MF, Betker JL, Randolph TW, Anchordoquy TJ. Lyophilization of a triply unsaturated phospholipid: effects of trace metal contaminants. Eur J Pharm Biopharm 2013; 85:306-13. [PMID: 23567484 DOI: 10.1016/j.ejpb.2013.03.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/20/2013] [Accepted: 03/23/2013] [Indexed: 11/30/2022]
Abstract
As liquid liposomal formulations are prone to chemical degradation and aggregation, these formulations often require freeze drying (e.g., lyophilization) to achieve sufficient shelf-life. However, liposomal formulations may undergo oxidation during lyophilization and/or during prolonged storage. The goal of the current study was to characterize the degradation of 1,2-dilinolenoyl-sn-glycero-3-phosphocholine (DLPC) during lyophilization and to also probe the influence of metal contaminants in promoting the observed degradation. Aqueous sugar formulations containing DLPC (0.01 mg/ml) were lyophilized, and DLPC degradation was monitored using HPLC/UV and GC/MS methods. The effect of ferrous ion and sucrose concentration, as well as lyophilization stage promoting lipid degradation, was investigated. DLPC degradation increased with higher levels of ferrous ion. After lyophilization, 103.1 ± 1.1%, 66.9 ± 0.8%, and 28.7 ± 0.7% DLPC remained in the sucrose samples spiked with 0.0 ppm, 0.2 ppm, and 1.0 ppm ferrous ion, respectively. Lipid degradation predominantly occurs during the freezing stage of lyophilization. Sugar concentration and buffer ionic strength also influence the extent of lipid degradation, and DLPC loss correlated with degradation product formation. We conclude that DLPC oxidation during the freezing stage of lyophilization dramatically compromises the stability of lipid-based formulations. In addition, we demonstrate that metal contaminants in sugars can become highly active when lyophilized in the presence of a reducing agent.
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Affiliation(s)
- N M Payton
- Department of Pharmaceutical Sciences, University of Colorado Denver, USA.
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