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1.
Glioblastoma multiforme (GBM) is a highly advanced and invasive brain tumor due to which current treatments cannot completely treat GBM or prevent recurrence. Therefore, adjunctive treatments are required. As part of the invasive and angiogenic nature of GBM, it has been well established that matrix metalloprotease-2 (MMP-2) and MMP-9 are overactive. To better treat GBM using chemotherapy, we have designed a hydrogel-based delivery system that can control the release of drugs based on the activity of MMPs. A model chemotherapeutic agent, cisplatin (CDDP), complexed to an MMP substrate (peptide-linker) was incorporated into poly(ethylene glycol) diacrylate hydrogel wafers having different poly(ethylene glycol) chain lengths (M(n) approximately 574 and 4000). Hydrogel wafers were studied for physical characteristics and drug release in the presence and absence of MMPs. There was a substantial increase in CDDP release for the poly(ethylene glycol) 4000 hydrogel indicating that this chain length provides a mesh size that is sufficient to permit MMP activity within the hydrogel. CDDP bioactivity increased when the cell media was spiked with MMPs (0% cell survival) in case of the longer chain length as compared to in the absence of MMPs (approximately 50% cell survival). The results suggest that this system can be used for selective, local delivery of drugs where higher amounts of the drug are released in response to metastasis, angiogenesis, and invasion-promoting proteases. This strategy may prove to be a novel and effective method to overcome inadequacies in current controlled drug release systems.  相似文献   

2.
Systemically injected nanoparticle (NPs) targeting tumor vasculature offer a venue for anti-angiogenic therapies as well as cancer detection and imaging. Clinical application has been limited, however, due to the challenge of elucidating the complex interplay of nanotechnology, drug, and tumor parameters. A critical factor representing the likelihood of endothelial adhesion is the NP vascular affinity, a function of vascular receptor expression and NP size and surface-bound ligand density. We propose a theoretical framework to simulate the tumor response to vasculature-bound drug-loaded NPs and examine the interplay between NP distribution and accumulation as a function of NP vascular affinity, size, and drug loading and release characteristics. The results show that uniform spatial distribution coupled with high vascular affinity is achievable for smaller NPs but not for larger sizes. Consequently, small (100 nm) NPs with high vascular affinity are predicted to be more effective than larger (1000 nm) NPs with similar affinity, even though small NPs have lower drug loading and local drug release compared to the larger NPs. Medium vascular affinity coupled with medium or larger sized NPs is also effective due to a more uniform distribution with higher drug loading and release. Low vascular affinity hampered treatment efficacy regardless of NP size, with larger NPs additionally impeded by heterogeneous distribution and drug release. The results further show that increased drug diffusivity mainly benefits heterogeneously distributed NPs, and would negatively affect efficacy otherwise due to increased wash-out. This model system enables evaluation of efficacy for vascular-targeted drug-loaded NPs as a function of critical NP, drug, and tumor parameters.  相似文献   

3.
The aim of the present study was to design a novel/conceptual delivery system using ibuprofen, anticipated for chronotherapy in arthritis with porous material to overcome the formulation limits (multiple steps, polymers, excipients) and to optimize drug loading for a desired release profile suitable for in vitro investigations. The objective of this delivery system lies in the availability of maximum drug amount for absorption in the wee hours as recommended. Drug loading using 32 factorial design on porous carrier, synthesized by high internal phase emulsion technique using styrene and divinylbenzene, was done via solvent evaporation using methanol and dichloromethane. The system was evaluated in vitro for drug loading, encapsulation efficiency, and surface characterization by scanning electron, atomic force microscopy, and customized drug release study. This study examined critical parameters such as solvent volume, drug amount, and solvent polarity on investigations related to drug adsorption and release mostly favoring low-polarity solvent dichloromethane. Overall release in all batches ranged 0.98–52% in acidic medium and 71–94% in basic medium. These results exhibit uniqueness in achieving the least drug release of 0.98%, an ideal one, without using any release modifiers, making it distinct from other approaches/technologies for time and controlled release and for chronotherapy.  相似文献   

4.
For improving effectiveness of conventional chemotherapy of subcutaneous tumor, we selected 2-methoxyestradiol (2-ME) as a model drug, local injectable PLGA-PEG-PLGA copolymer thermosensitive hydrogel loading 2-ME liposomes instead of free 2-ME as a novel two-phase drug delivery system was developed, which avoid rapid clearance of liposomes follwing systemic administration. This new transport system was characterized in vitro and in vivo including rheological behavior, thermo-sensitiveness, stability, released character and intratumoral delivery. The PLGA-PEG-PLGA copolymer solution exhibited still reversible thermosensitive property and better syringeability after incorporated 2-ME liposomes. The 2-ME liposomes were demonstrated stable in the hydrogel by five methods such as scanning electron microscopy (SEM), fluorescent labeling, opalescence, particle size and ultrafiltration methods. Results showed that intact liposomes could be released from the hydrogel and following zero-order model, and sustained release one–two months in vitro and in vivo. In vivo release data demonstrating that 2-ME liposomes could be transported to tumor site, improved therapeutic efficacy and bioavailability of 2-ME liposomes in subcutaneous tumor chemotherapy.  相似文献   

5.
Malignant gliomas are aggressive forms of primary brain tumors characterized by a poor prognosis. The most successful treatment so far is the local implantation of polymer carriers (Gliadel® wafers) for the sustained release of carmustine. To improve the effectiveness of local drug treatment, new polymer carriers and pharmacological agents are currently being investigated. Of particular interest is a set of novel thermo‐gelling polymers for the controlled release of hydrophobic drugs such as paclitaxel (e.g., OncoGel?). Herein, we use computational mass transport simulations to investigate the effectiveness of paclitaxel delivery from hydrogel‐forming polymer carriers. We found similar (within 1–2 mm) therapeutic penetration distances of paclitaxel when released from these hydrogels as compared with carmustine released from Gliadel® wafers. Effective therapeutic concentrations were maintained for >30 days for paclitaxel when released from the hydrogel as compared with 4 days for carmustine released from Gliadel® wafers. Convection in brain tissue prevented the formation of a uniform drug concentration gradient around the implant. In addition, the surface area to volume ratio of the gel is an important factor that should be considered to maintain a controlled release of paclitaxel within the degradation lifetime of the polymer matrix. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011  相似文献   

6.
In this article, modified κ-carrageenan hydrogel nanocomposites were synthesized to increase the release ability of carrageenan hydrogels under gastrointestinal conditions. The effect of MgO nanoparticle loading in a model drug (methylene blue) release is investigated. Characterization of hydrogels were carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Differential Scanning Calorimetry (DSC). Genipin was used to increase the delivery performance in gastrointestinal tract delivery by decreasing release in simulated stomach conditions and increasing release in simulated intestine conditions. It is shown that the amount of methylene blue released from genipin-cross-linked nanocomposites can be 67.5% higher in intestine medium and 56% lower in the stomach compared to κ-carrageenan hydrogel. It was found that by changing the nanoparticle loading and genipin concentration in the composite, the amount of drug released can be monitored. Therefore, applying nanoparticles appears to be a potential strategy to develop controlled drug delivery especially in gastrointestinal tract studies.  相似文献   

7.
ABSTRACT: BACKGROUND: Nanoparticle based delivery of anticancer drugs have been widely investigated. However, a very important process for Research & Development in any pharmaceutical industry is scaling nanoparticle formulation techniques so as to produce large batches for preclinical and clinical trials. This process is not only critical but also difficult as it involves various formulation parameters to be modulated all in the same process. METHODS: In our present study, we formulated curcumin loaded poly (lactic acid-co-glycolic acid) nanoparticles (PLGA-CURC). This improved the bioavailability of curcumin, a potent natural anticancer drug, making it suitable for cancer therapy. Post formulation, we optimized our process by Reponse Surface Methodology (RSM) using Central Composite Design (CCD) and scaled up the formulation process in four stages with final scale-up process yielding 5 g of curcumin loaded nanoparticles within the laboratory setup. The nanoparticles formed after scale-up process were characterized for particle size, drug loading and encapsulation efficiency, surface morphology, in vitro release kinetics and pharmacokinetics. Stability analysis and gamma sterilization were also carried out. RESULTS: Results revealed that that process scale-up is being mastered for elaboration to 5 g level. The mean nanoparticle size of the scaled up batch was found to be 158.5 [PLUS-MINUS SIGN] 9.8 nm and the drug loading was determined to be 10.32 [PLUS-MINUS SIGN] 1.4 %. The in vitro release study illustrated a slow sustained release corresponding to 75 % drug over a period of 10 days. The pharmacokinetic profile of PLGA-CURC in rats following i.v. administration showed two compartmental model with the area under the curve (AUC0-[INFINITY]) being 6.139 mg/L h. Gamma sterilization showed no significant change in the particle size or drug loading of the nanoparticles. Stability analysis revealed long term physiochemical stability of the PLGA-CURC formulation. CONCLUSIONS: A successful effort towards formulating, optimizing and scaling up PLGA-CURC by using Solid-Oil/Water emulsion technique was demonstrated. The process used CCD-RSM for optimization and further scaled up to produce 5 g of PLGA-CURC with almost similar physicochemical characteristics as that of the primary formulated batch.  相似文献   

8.
Conventional drug delivery systems of docetaxel (DTX) are challenged with low drug loading efficiency and potential carriers-induced toxicity. In this work, a docetaxel prodrug self-assembled nanosystem was designed and synthesized by conjugating docetaxel with oleic acid (OA) exploring a thioether as the linker, which is redox-sensitive to the redox environment within tumor cells. Notably, the carrier-free nanomedicine which does not need any carrier has obviously high drug loading that reaches 58%. Moreover, the cytotoxicity of DTX-S-OA maintains an equal level with DTX. The novel prodrug conjugate therefore has a promising perspective as carrier-free nanomedicine for cancer therapy due to its high drug loading property, redox-sensitive release and long circulation mechanism.  相似文献   

9.
Coating of liposomes with polyethylene-glycol (PEG) by incorporation in the liposome bilayer of PEG-derivatized lipids results in inhibition of liposome uptake by the reticulo-endothelial system and significant prolongation of liposome residence time in the blood stream. Parallel developments in drug loading technology have improved the efficiency and stability of drug entrapment in liposomes, particularly with regard to cationic amphiphiles such as anthracyclines. An example of this new generation of liposomes is a formulation of pegylated liposomal doxorubicin known as Doxil® or Caelyx®, whose clinical pharmacokinetic profile is characterized by slow plasma clearance and small volume of distribution. A hallmark of these long-circulating liposomal drug carriers is their enhanced accumulation in tumors. The mechanism underlying this passive targeting effect is the phenomenon known as enhanced permeability and retention (EPR) which has been described in a broad variety of experimental tumor types. Further to the passive targeting effect, the liposome drug delivery platform offers the possibility of grafting tumor-specific ligands on the liposome membrane for active targeting to tumor cells, and potentially intracellular drug delivery. The pros and cons of the liposome platform in cancer targeting are discussed vis-à-vis nontargeted drugs, using as an example a liposome drug delivery system targeted to the folate receptor.  相似文献   

10.
Liposomes and polymers are widely used drug carriers for controlled release since they offer many advantages like increased treatment effectiveness, reduced toxicity and are of biodegradable nature. In this work, anticancer drug‐loaded PLGA‐lecithin‐PEG nanoparticles (NPs) were synthesized and were functionalized with AS1411 anti‐nucleolin aptamers for site‐specific targeting against tumor cells which over expresses nucleolin receptors. The particles were characterized by transmission electron microscope (TEM) and X‐ray photoelectron spectroscopy (XPS). The drug‐loading efficiency, encapsulation efficiency and in vitro drug release studies were conducted using UV spectroscopy. Cytotoxicity studies were carried out in two different cancer cell lines, MCF‐7 and GI‐1 cells and two different normal cells, L929 cells and HMEC cells. Confocal microscopy and flowcytometry confirmed the cellular uptake of particles and targeted drug delivery. The morphology analysis of the NPs proved that the particles were smooth and spherical in shape with a size ranging from 60 to 110 nm. Drug‐loading studies indicated that under the same drug loading, the aptamer‐targeted NPs show enhanced cancer killing effect compared to the corresponding non‐targeted NPs. In addition, the PLGA‐lecithin‐PEG NPs exhibited high encapsulation efficiency and superior sustained drug release than the drug loaded in plain PLGA NPs. The results confirmed that AS1411 aptamer‐PLGA‐lecithin‐PEG NPs are potential carrier candidates for differential targeted drug delivery. Biotechnol. Bioeng. 2012; 109: 2920–2931. © 2012 Wiley Periodicals, Inc.  相似文献   

11.
Coating of liposomes with polyethylene-glycol (PEG) by incorporation in the liposome bilayer of PEG-derivatized lipids results in inhibition of liposome uptake by the reticulo-endothelial system and significant prolongation of liposome residence time in the blood stream. Parallel developments in drug loading technology have improved the efficiency and stability of drug entrapment in liposomes, particularly with regard to cationic amphiphiles such as anthracyclines. An example of this new generation of liposomes is a formulation of pegylated liposomal doxorubicin known as Doxil or Caelyx, whose clinical pharmacokinetic profile is characterized by slow plasma clearance and small volume of distribution. A hallmark of these long-circulating liposomal drug carriers is their enhanced accumulation in tumors. The mechanism underlying this passive targeting effect is the phenomenon known as enhanced permeability and retention (EPR) which has been described in a broad variety of experimental tumor types. Further to the passive targeting effect, the liposome drug delivery platform offers the possibility of grafting tumor-specific ligands on the liposome membrane for active targeting to tumor cells, and potentially intracellular drug delivery. The pros and cons of the liposome platform in cancer targeting are discussed vis-à-vis nontargeted drugs, using as an example a liposome drug delivery system targeted to the folate receptor.  相似文献   

12.
The purpose of this study is to explore and develop a novel biocompatibility drug delivery carrier for controllingontrolled drug release. The a-eleostearic acid grafted hydroxyapatite (a-ESA-g-HA) composite was synthesized by using silane coupling agent and characterized by Fourier Transformation Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscope (SEM), respectively. The in vitro drug loading and controlled release behaviors of a-ESA-g-HA composite were investigated using ciprofloxacin as the model drug. The amount of ciprofloxacin loading and released was cal- culated by absorbance value which was determined by UV-Vis spectrophotometry at wavelength of 277 nm. The biocompatibility of a-ESA-g-HA composite was assessed by 3-(4,5)-dimethylthiahiazo(-z-yl)-3,5-di-phenytetrazoliumromide(MTT) assay, nuclear morphology and platelet adhesion. The results showed that the a-ESA-g-HA had nontoxic and good biocompatibility. According to the results mentioned above, the a-ESA-g-HA is an effective drug delivery carrier, which could increase drug loading capacity and control drug release, so further studies are necessary to evaluate clinical application and human health care.  相似文献   

13.
A new approach to engineer a local drug delivery system with delayed release using nanostructured surface with nanotube arrays is presented. TNT arrays electrochemically generated on a titanium surface are used as a model substrate. Polymer micelles as drug carriers encapsulated with drug are loaded at the bottom of the TNT structure and their delayed release is obtained by loading blank micelles (without drug) on the top. The delayed and time-controlled drug release is successfully demonstrated by controlling the ratio of blank and drug loaded-micelles. The concept is verified using four different polymer micelles (regular and inverted) loaded with water-insoluble (indomethacin) and water-soluble drugs (gentamicin).  相似文献   

14.
A molecular dynamics simulation study is reported to investigate the loading and release of ibuprofen (IBU) in amphiphilic peptide (AF)6H5K15 (FA32) and its derivatives (F12H5K15 and F16H5K15). The peptides are represented by the MARTINI coarse-grained model, and a similar model is developed here for IBU. Upon the loading of IBU in FA32, quasi-spherical core/shell structured micelles are formed. IBU is predominantly located in the hydrophobic core and covered by Phe and Ala residues, while Lys is in the hydrophilic shell. With increasing concentration of IBU, the micelles become larger due to increased hydrophobic interactions. In FA32 derivatives, the loading of IBU leads to different morphologies; particularly, a well-structured nanofibre is formed in F16H5K15. Upon pH change, the release of IBU from FA32 micelles is found to be slower than from F16H5K15 nanofibre, suggesting the former is better in controlled release. The simulation study reveals that IBU-loaded morphology can be altered by changing the type of peptide and has a significant effect on IBU release profile. This bottom-up insight might be useful in the rational design of carriers for efficient drug loading and release.  相似文献   

15.
Research efforts have been devoted to demonstrating that the pH-sensitive characteristics of poly NIPAAm/chitosan nanoparticles can be applied to targeting tumors. A copolymer of (NIPAAm) and chitosan (4:1, m/m) was synthesized, and its drug release characteristics investigated. The results revealed that drug-loaded nanoparticles which encapsulation and loading efficiencies were 85.7% and 9.6%, respectively, exhibited pH-sensitive responses to tumor pH. The cumulative release rate was significantly enhanced below pH 6.8 and decreased rapidly above pH 6.9 at 36.5 ± 0.5 °C. MTT assay and fluorescence microscopic study showed that drug release was drastically promoted in tumor surroundings while exerting less effect in normal conditions. For mice treated with nanoparticles, the decrease in body weight was limited, and significant tumor regression was observed with complete regression in more than 50% of the mice. The life span of tumor-bearing mice was significantly increased when they were treated with nanoparticles. Thereby, the super pH-sensitive poly NIPAAm/chitosan nanoparticles may provide outstanding advantages for anti-cancer drug delivery.  相似文献   

16.
Chitosan, a polysaccharide, having structural characteristics similar to glycosaminoglycans, seems to be nontoxic and bioabsorbable. This study highlights the use of chitosan matrix for controlled drug delivery systems. The steroid drugs, namely testosterone, progesterone and beta-oestradiol were mixed with chitosan and the films were prepared by evaporation technique. The in vitro release profile of these steroids from the film matrix was monitored, as a function of time, in phosphate buffered saline (PBS, pH 7.4) at 37 degree C using a U-V-spectrophotometer. The degradation, of these chitosan and drug loaded chitosan films, was also investigated by weight loss and tensile strength studies. The steroid release from chitosan films was compared with the release of these drugs from their microbeads. It appears, the films and the microbeads stayed intact during the dissolution study of 90 days and the possibility of using these systems in contraceptive applications and novel drug delivery systems are discussed.  相似文献   

17.
In order to understand the effect of antibiotics delivery to bone tissue, by biodegradable polymeric drug disc, for the treatment of osteomyelitis, a three-dimensional simulation model is developed. The simulation investigates the effect of pressure-induced convection on drug distribution, by taking into account the pressure gradient that exists between capillaries and interstitial space, and also as a result of the surgical opening. The clotting process at the surgical opening is incorporated into the simulation, and the effect of clotting duration is investigated. The clotting duration for the baseline simulation is 2 days and it is observed that increasing this duration depresses the mean drug concentration in the marrow and cortical bone. The effect of double burst release profile is also studied and it is observed that drug concentration drops too rapidly after the first burst to provide any therapeutic effect. However, it is shown that the drug concentration after the second burst stays above the minimum inhibitory concentration of the bacteria for a longer period of time, than would have been observed for a mono-burst release. Inserting non-biodegradable polymethylmethacrylate (PMMA) beads into bone seems to cause a higher average concentration of drug in the marrow. However, this could be brought about by the difference in the geometry between the disc and the bead, and the amount of drug packed in each bead. Further simulations on the management of dead space shows the ineffectiveness of having the void filled up with surgical gel as it becomes an additional barrier to drug delivery to the infected tissues.  相似文献   

18.
Conclusions  Results from the present study conclude that PR in combination with PVP and with incorporation of dibutyl phthalate (30% wt/wt) produces smooth flexible films with improved tensile strength and percentage elongation. The release rate of drug from films and permeation across skin increases with increase in drug and PVP loading but is independent of film thickness. Patches containing PR:PVP (7:3) show promise for pharmacokinetic and pharmacodynamic performance evaluation in a suitable animal model. In view of the overall results reported in the present study, it may be proposed that PR can be used in the design of a matrix type transdermal drug delivery system to prolong the drug release. Published: December 27, 2005  相似文献   

19.
United States Pharmacopeia dissolution apparatus II (paddle) and III (reciprocating cylinder) coupled with automatic sampling devices and software were used to develop a testing procedure for acquiring release profiles of colon-specific drug delivery system (CODES) drug formulations in multi-pH media using acetaminophen (APAP) as a model drug. System suitability was examined. Several important instrument parameters and formulation variables were evaluated. Release profiles in artificial gastric fluid (pH 1.2), intestinal fluid (pH 6.8), and pH 5.0 buffer were determined. As expected, the percent release of APAP from coated core tablets was highly pH dependent. A release profile exhibiting a negligible release in pH 1.2 and 6.8 buffers followed by a rapid release in pH 5.0 buffer was established. The drug release in pH 5.0 buffer increased significantly with the increase in the dip or paddle speed but was inversely related to the screen mesh observed at lower dip speeds. It was interesting to note that there was a close similarity (f 2=80.6) between the release profiles at dip speed 5 dpm and paddle speed 100 rpm. In addition, the release rate was reduced significantly with the increase in acid-soluble Eudragit E coating levels, but lactulose loading showed only a negligible effect. In conclusion, the established reciprocating cylinder method at lower agitation rates can give release profiles equivalent to those for the paddle procedure for CODES drug pH-gradient release testing. Apparatus III was demonstrated to be more convenient and efficient than apparatus II by providing various programmable options in sampling times, agitation rates, and medium changes, which suggested that the apparatus II approach has better potential for in vitro evaluation of colon-specific drug delivery systems.  相似文献   

20.
Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e., gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.  相似文献   

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