Sustained release of 5-fluorouracil from polymeric nanoparticles

Therapeutic targeting of siRNA/anti-cancer drug delivery system for non-melanoma skin cancer. Part I: Development and gene silencing of JAK1siRNA/5-FU loaded liposome nanocomplexes

Non-melanoma skin cancer (NMSC) is one of the most prevalent cancers, leading to significant mortality rates due to limited treatment options and a lack of effective therapeutics. Janus kinase (JAK1), a non-receptor tyrosine kinase family member, is involved in various cellular processes, including differentiation, cell proliferation and survival, playing a crucial role in cancer progression. This study aims to provide a more effective treatment for NMSC by concurrently silencing the JAK1 gene and administering 5-Fluorouracil (5-FU) using liposome nanocomplexes as delivery vehicles. Utilizing RNA interference (RNAi) technology, liposome nanocomplexes modified with polyethylene imine (PEI) were conjugated with siRNA molecule targeting JAK1 and loaded with 5-FU. The prepared formulations (NL-PEI) were characterized in terms of their physicochemical properties, morphology, encapsulation efficiency, in vitro drug release, and stability. Cell cytotoxicity, cell uptake and knockdown efficiency were evaluated in human-derived non-melanoma epidermoid carcinoma cells (A-431). High contrast transmission electron microscopy (CTEM) images and dynamic light scattering (DLS) measurements revealed that the nanocomplexes formed spherical morphology with uniform sizes ranging from 80-120 nm. The cationic NL-PEI nanocomplexes successfully internalized within the cytoplasm of A-431, delivering siRNA for specific sequence binding and JAK1 gene silencing. The encapsulation of 5-FU in the nanocomplexes was achieved at 0.2 drug/lipid ratio. Post-treatment with NL-PEI for 24, 48 and 72 h showed cell viability above 80 % at concentrations up to 8.5 × 101 µg/mL. Notably, 5-FU delivery via nanoliposome formulations significantly reduced cell viability at 5-FU concentration of 5 µM and above (p < 0.05) after 24 h of incubation. The NL-PEI nanocomplexes effectively silenced the JAK1 gene in vitro, reducing its expression by 50 %. Correspondingly, JAK1 protein level decreased after transfection with JAK1 siRNA-conjugated liposome nanocomplexes, leading to a 37 % reduction in pERK (phosphor extracellular signal-regulated kinase) protein expression. These findings suggest that the combined delivery of JAK1 siRNA and 5-FU via liposomal formulations offers a promising and novel treatment strategy for targeting genes and other identified targets in NMSC therapy.

Swelling kinetics of mixtures of soybean phosphatidylcholine and glycerol dioleate

Lipid-based drug delivery systems offer the potential to enhance bioavailability, reduce dosing frequency, and improve patient adherence. In aqueous environment, initially dry lipid depots take up water and form liquid crystalline phases. Variation of lipid composition, depot size and hydration-induced phase transitions will plausibly affect the diffusion in and out of the depot. Lipid depots of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) mixtures were hydrated for varying time durations in a phosphate-buffered saline (PBS) buffer and then analyzed with Karl Fischer titration, magnetic resonance imaging (MRI) and gravimetrically. Mathematical modeling of the swelling process using diffusion equations, was used to estimate the parameters of diffusion. Both composition of lipid mixture and depot size affect swelling kinetics… The diffusion parameters obtained in Karl Fischer titration and MRI (with temporal and spatial resolution respectively) are in good agreement. Remarkably, the MRI results show a gradient of water content within the depot even after the end of diffusion process. Apparently contradicting the first Fick's law in its classical form, these results find an explanation using the generalized Fick's law that considers the gradient of chemical potential rather than concentration as the driving force of diffusion.

Nanostructures for site-specific delivery of oxaliplatin cancer therapy: Versatile nanoplatforms in synergistic cancer therapy

As a clinically approved treatment strategy, chemotherapy-mediated tumor suppression has been compromised, and in spite of introducing various kinds of anticancer drugs, cancer eradication with chemotherapy is still impossible. Chemotherapy drugs have been beneficial in improving the prognosis of cancer patients, but after resistance emerged, their potential disappeared. Oxaliplatin (OXA) efficacy in tumor suppression has been compromised by resistance. Due to the dysregulation of pathways and mechanisms in OXA resistance, it is suggested to develop novel strategies for overcoming drug resistance. The targeted delivery of OXA by nanostructures is described here. The targeted delivery of OXA in cancer can be mediated by polymeric, metal, lipid and carbon nanostructures. The advantageous of these nanocarriers is that they enhance the accumulation of OXA in tumor and promote its cytotoxicity. Moreover, (nano)platforms mediate the co-delivery of OXA with drugs and genes in synergistic cancer therapy, overcoming OXA resistance and improving insights in cancer patient treatment in the future. Moreover, smart nanostructures, including pH-, redox-, light-, and thermo-sensitive nanostructures, have been designed for OXA delivery and cancer therapy. The application of nanoparticle-mediated phototherapy can increase OXA's potential in cancer suppression. All of these subjects and their clinical implications are discussed in the current review.

pH-Sensitive nanoparticles containing 5-fluorouracil and leucovorin as an improved anti-cancer option for colon cancer

Background: Parenteral administration of chemotherapeutic drugs, 5-fluorouracil (5-FU) and leucovorin (LV), is commonly used to treat large bowel carcinomas such as colon cancer (CC) and colorectal carcinoma (CRC). Aim: Our study aims to design a novel nanoparticulate drug-delivery vehicle for oral use capable of colon-specific release. Methods: A modified double-emulsion solvent evaporation method was used in the preparation of pH-responsive Eudargit^® S100 polymeric nanoparticles, loaded with 5-FU/LV combination (5-FU/LV-loaded Eudargit S100 NPs). Results: Our optimized drug-loaded NP showed a pH-responsive drug release and exhibited significantly more cytotoxic actions in cancer-cell lines than free drugs. Conclusion: These findings open the way for conducting clinical trials for colon malignancies treated with nanoparticles.

Electrospun Fibres of Chitosan/PVP for the Effective Chemotherapeutic Drug Delivery of 5-Fluorouracil

Electrospun nanofibrous mats consisting of chitosan (CS) and polyvinylpyrrolidone (PVP) were constructed. Tuning of solution and process parameters was performed and resulted in an electrospun system containing a 6:4 ratio of PVP:CS. This is a significant increase in the proportion of spun CS on the previously reported highest ratio PVP:CS blend. SEM analysis showed that the nanofibrous mats with 4 wt% CS/6 wt% PVP (sample E) comprised homogenous, uniform fibres with an average diameter of 0.569 μm. XPS analysis showed that the surface of the samples consisted of PVP. Raman and FTIR analysis revealed intermolecular interactions (via H-bonding) between PVP and CS. In FTIR spectra, the contribution of chitosan to CS/PVP complexes was shown by the downshift of the C=O band and by the linear increase in intensity of C-O stretching in CS. XPS analysis showed a smaller shift at the binding energy 531 eV, which relates to the amide of the acetylated functional groups. The obtained results demonstrate a sensitivity of Raman and FTIR tests to the presence of chitosan in PVP:CS blend. The chemotherapy drug 5-Fu was incorporated into the constructs and cell viability studies were performed. WST-8 viability assay showed that exposure of A549 human alveolar basal epithelial cells to 10 mg/mL 5-Fu loaded fibres was most effective at killing cells over 24 h. On the other hand, the constructs with loading of 1 mg/mL of drug were not efficient at killing A549 human alveolar basal epithelial cells. This study showed that CS/PVP/5-Fu constructs have potential in chemotherapeutic drug delivery systems.

Preparation and evaluation of inhalable dry powder containing glucosamine-conjugated gefitinib SLNs for lung cancer therapy

Gefitinib as an epidermal growth factor receptor tyrosine kinase inhibitor has strong potential in lung cancer therapy. However, a major challenge of using gefitinib is its toxicities. In the present study, we developed a dry powder inhaler dosage form containing gefitinib loaded glucosamine targeted solid lipid nanopaticles (Gef-G-SLNs) to locally transfer anticancer agent to the lung tumor. The Gef-G-SLNs were prepared by emulsion-solvent diffusion and evaporation method and optimized with irregular factorial design. The optimized nanoformulation was tested for action against A549 cells. Mannitol or lactose based dry powders were obtained from Gef-G-SLNs after spray drying and characterized using Anderson Cascade Impactor. The optimized formulation had drug loading of 33.29%, encapsulation efficiency of 97.31 ± 0.23%, zeta potential of -15.53 ± 0.47 mV, particle size of 187.23 ± 14.08 nm, polydispersity index of 0.28 ± 0.02 and release efficiency of 35.46 ± 2.25%. The Gef-G-SLNs showed superior anticancer effect compared to free gefitinib. The increased cellular uptake of G-SLNs in A549 cells was demonstrated compared with non-targeted SLNs using flow cytometry and fluorescence microscopy. The produced mannitol based microparticles showed suitable aerodynamic properties with an acceptable mass median aerodynamic diameter of 4.48 µm and fine particle fraction of 44.41%. Therefore, it can be concluded that this formulation represents promising drug delivery to treatment of lung cancer.

Design of an amphiphilic hyperbranched core/shell-type polymeric nanocarrier platform for drug delivery

An amphiphilic core/shell-type polymer-based drug carrier system (HPAE- PCL-b -MPEG), composed of hyperbranched poly(aminoester)-based polymer (HPAE) as the core building block and poly(ethylene glycol)-b - poly(ε-caprolactone) diblock polymers (MPEG-b -PCL) as the shell building block, was designed. The synthesized polymers were characterized with FTIR, 1 H NMR, 13 C NMR, and GPC analysis. Monodisperse HPAE-PCL-b - MPEG nanoparticles with dimensions of < 200 nm and polydispersity index of < 0.5 were prepared by nanoprecipitation method and characterized with SEM, particle size, and zeta potential analysis. 5-Fluorouracil was encapsulated within HPAE-PCL-b -MPEG nanoparticles. In vitro drug release profiles and cytotoxicity of blank and 5-fluorouracil-loaded nanoparticles were examined against the human colon cancer HCT116 cell line. All results suggest that HPAE-PCL-b - MPEG nanoparticles offer an alternative and effective drug nanocarrier system for drug delivery applications.

Carboxymethyl cellulose-based wafer enriched with resveratrol-loaded nanoparticles for enhanced wound healing

The present study aimed to prepare and investigate the wound healing potential of carboxymethyl cellulose (CMC)-based wafers incorporated with resveratrol (RSV)-loaded cellulose acetate butyrate (CAB) NPs. Accordingly, RSV-CAB NPs were prepared using the solvent evaporation method. The effect of different formulation parameters (polymer content, surfactant concentration, and the volume ratio of aqueous phase to organic phase) on the properties of NPs was investigated using the Box-Behnken design. Then, the optimized NPs were incorporated in wafers comprising CMC combined with hydroxyl propyl methyl cellulose (HPMC) or chitosan. Hydration capacity, porosity, adhesive strength, and hardness of the prepared nanocomposite wafers were examined. Optimized formulation was spherical, showing the particle size, polydispersity index, zeta potential, encapsulation efficiency %, drug loading %, and release efficiency % of 248.5 nm, 0.38, - 1.59, 87.58, 25.94, and 67.10, respectively. The CMC-HPMC wafers exhibited higher porosity, hydration capacity, and adhesive performance, as compared with the CMC wafers alone and CMC-chitosan wafers. Wound healing test and histological evaluation in the excisional wounds of the rats showed that the RSV-NPs-wafers were more effective as a healing accelerator, in comparison to wafers without drug or those containing the free RSV. These results demonstrated the potential of the RSV-NPs-wafer in wound healing drug delivery applications. Graphical abstract.

Preparation and in vitro evaluation of 5-fluorouracil-loaded PCL nanoparticles for colon cancer treatment

Nanoparticles loaded with 5-fluorouracil (5-FU) for colon cancer therapies were prepared using the solvent evaporation technique, which involved lyophilization by freeze-drying. Formulations produced a substantially high encapsulation efficiency of approximately 93%. A positive correlation was seen when increasing polycaprolactone (PCL) and/or PVA concentrations and the size of nanoparticles produced. Increasing PCL concentration had a considerable influence on PDI while increasing PVA concentration had a lesser effect. All nanoparticles possessed a negative zeta potential, particularly in formulations with low polymer and polymer emulsifier concentrations. The formulation with the lowest PCL and PVA concentration was characterized by the most optimal properties; which accounts for the desirable delayed release profile of the active drug in dissolution testing indicating an improved targeting capability and enhanced bioavailability at the action site. Cytotoxicity studies showed that 5-FU loaded PCL nanoparticles had higher antiproliferative effect than free 5-FU on Caco-2 cell line (p < 0.05). The encouraging results obtained offer reasons for optimism regarding the future of 5-FU nanoparticles as a promising drug delivery system which could be further improved by including either enteric coating or encapsulating the nanoparticles onto microparticles to overcome unanticipated degradation.

Development of gatifloxacin-loaded cationic polymeric nanoparticles for ocular drug delivery

The present investigation aimed at improving the ocular bioavailability of gatifloxacin by prolonging its residence time in the eye and reducing problems associated with the drug re-crystallization after application through incorporation into cationic polymeric nanoparticles. Gatifloxacin-loaded nanoparticles were prepared via the nanoprecipitation and double emulsion techniques. A 50:50 Eudragit® RL and RS mixture was used as cationic polymer with other formulation parameters varied. Prepared nanoparticles were evaluated for size, zeta potential, and drug loading. An optimized formulation was selected and further characterized for in vitro drug release, cytotoxicity, and antimicrobial activity. The double emulsion method produced larger nanoparticles than the nanoprecipitation method (410 nm and 68 nm, respectively). Surfactant choice also affected particle size and zeta potential with Tween 80 producing smaller-sized particles with higher zeta potential than PVA. However, the zeta potential was positive at all experimental conditions investigated. The optimal formulation produced by double emulsion technique and has achieved 46% drug loading. This formulation had optimal physicochemical properties with acceptable cytotoxicity results, and very prolonged release rate. The particles antimicrobial activities of the selected formulation have been tested against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and showed prolonged antimicrobial effect for gatifloxacin.

Nanoparticles of biodegradable polymers for new-concept chemotherapy

The current regimen of chemotherapy is far from satisfactory--its efficiency is limited and patients suffer from serious side effects. Various drug delivery devices have been under intensive investigation in the past few decades in attempts to develop controlled and targeted methods of chemotherapy administration. This article reviews the latest developments in nanoparticles of biodegradable polymers for chemotherapy of cancer and other diseases such as cardiovascular restenosis. The preliminary results obtained in the author's laboratory are used to demonstrate the concept. This review is written with the belief that engineering, in particular, chemical engineering principles, can be applied and further developed to solve the problems in the current practice of chemotherapy and promote a new concept of chemotherapy - chemotherapy at home.

Development and evaluation of 5-fluorouracil loaded chitin nanogels for treatment of skin cancer

This study focuses on development and evaluation of 5-fluorouracil (5-FU) loaded chitin nanogels (FCNGs). It formed good, stable aqueous dispersion with spherical particles in 120-140 nm size range and showed pH responsive swelling and drug release. The FCNGs showed toxicity on melanoma (A375) in a concentration range of 0.4-2.0mg/mL, but less toxicity toward human dermal fibroblast (HDF) cells by MTT assay. Confocal analysis revealed uptake of FCNGs by both cells. From skin permeation experiments, FCNGs showed almost same steady state flux as that of control 5-FU but the retention in the deeper layers of skin was found to be 4-5 times more from FCNGs. Histopathological evaluation revealed loosening of the horny layer of epidermis by interaction of cationically charged chitin, with no observed signs of inflammation and so FCNGs can be a good option for treatment of skin cancers.

Bacterial exopolysaccharide based nanoparticles for sustained drug delivery, cancer chemotherapy and bioimaging

Introduction of a novel biocompatible, stable, biomaterial for drug delivery application remains always challenging. In the present study, we report the synthesis of an extremophilic bacterial sulfated polysaccharide based nanoparticle as a stable biocompatible material for drug delivery, evaluation of anticancer efficacy and bioimaging. Mauran (MR), the sulfated exopolysaccharide extracted from a moderately halophilic bacterium, Halomonas maura was used for the synthesis of nanoparticles along with chitosan (CH). MR/CH nanoparticles were synthesized by simple polyelectrolyte complexation of anionic MR and cationic CH. The MR/CH hybrid nanoparticles formed were ranging between 30 and 200 nm in diameter with an overall positive zeta potential of 27.5±5 mV and was found to be stable under storage in solution for at least 8 weeks. In vitro drug release studies showed a sustained and prolonged delivery of 5-fluorouracil (5FU) for 10-12 days from MR/CH nanoparticles under three different pHs of 4.5, 6.9 and 7.4 respectively. Cytotoxicity assay revealed that MR/CH nanoparticles were non-cytotoxic towards normal cells and toxic to cancer cells. Also, 5FU loaded MR/CH nanoparticles were found more effective than free 5FU in its sustained and controlled manner of killing breast adenocarcinoma cells. Fluorescein isothiocyanate (FITC) labeled MR/CH nanoparticles were used for cell binding and uptake studies; thereby demonstrating the application of dye tagged MR/CH nanoparticles for safe and nontoxic mode of live cellular imaging. We report the introduction of an extremophilic bacterial polysaccharide, MR, for the first time as a novel biocompatible and stable biomaterial to the world of nanotechnology, pharmaceutics and biomedical technology.

Adsorption, desorption, and removal of polymeric nanomedicine on and from cellulose surfaces: effect of size

The increased production and commercial use of nanoparticulate drug delivery systems combined with a lack of regulation to govern their disposal may result in their introduction to soils and ultimately into groundwater systems. To better understand how such particles interact with environmentally significant interfaces, we study the adsorption, desorption, and removal behavior of poly(ethylene glycol)-based nanoparticulate drug delivery systems on and from cellulose, which is the most common organic compound on Earth. It is shown that such an adsorption process is only partially reversible, and most of the adsorbate particles do not desorb from the cellulose surface even upon rinsing with a large amount of water. The rate constant of adsorption decreases with increasing particle size. Furthermore, hydrodynamic forces acting parallel to the surfaces are found to be of great importance in the context of particle dynamics near the cellulose surface, and ultimately responsible for the removal of some fraction of particles via rolling or sliding. As the particle size increases, the removal rates of the particles increase for a given hydrodynamical condition.

Chitosan nanoparticles as a new delivery system for the chemotherapy agent tegafur

BACKGROUND

Despite the very efficient antitumor activity of conventional chemotherapy, generally high doses of anticancer molecules must be administered to obtain the required therapeutic action, simultaneously leading to severe side effects. This is frequently a consequence of the development of multidrug resistance by cancer cells and of the poor pharmacokinetic profile of these agents.

OBJECTIVE

In Order to improve the antitumor effect of tegafur and overcome their important drawbacks, we have investigated its incorporation into a drug nanoplatform based on the biodegradable polymer chitosan.

MATERIALS AND METHODS

Two tegafur loading methods were studied: (i) absorption into the polymeric network (entrapment procedure); and (ii) surface deposition (adsorption procedure) in already formed chitosan nanoparticles.

RESULTS

Tegafur entrapment into the polymeric matrix has yielded higher drug loading values and a slower drug release profile, compared to single surface adsorption. The main factores determining the drug loading to chitosan were identified.

DISCUSSION AND CONCLUSION

Such polymeric colloid present very interesting properties for efficient tegafur delivery to cancer.

5-Fluorouracil-loaded BSA nanoparticles: formulation optimization and in vitro release study

Over the past few decades, there has been considerable interest in developing protein nanoparticles as drug delivery devices. The underlying rationale is their exceptional characteristics, namely biodegradability and nonantigenicity. Herein, phase separation method was used to prepare 5-fluorouracil-loaded bovine serum albumin (BSA) nanoparticles. Drug release was tracked by continuous flow dialysis technique. Effect of process variables on loading efficiency of 5-fluorouracil was investigated and optimized through Taguchi's M16 design with the amount of entrapped drug as response. Optimum condition was found to be 2 mg/mL of 5-fluorouracil, 3.7 mL of added ethanol, 176 microL of glutaraldehyde, drug-protein incubation time of 30 min, and pH of 8.4 for 200 mg of BSA in 2 mL drug solution. pH had the most noticeable effect on the amount of entrapped drug, but glutaraldehyde had the least. Mean diameter and zeta potential of fabricated nanoparticles under these conditions were 210 nm and -31.7 mV, respectively. Drug-loaded BSA nanoparticles suspension maintained constant release of drug for 20 h under experimental conditions, so this colloidal drug carrier is capable of releasing drug in a sustained manner.

Celecoxib-loaded poly(D,L-lactide-co-glycolide) nanoparticles prepared using a novel and controllable combination of diffusion and emulsification steps as part of the salting-out procedure

A novel procedure for the manufacture of celecoxib-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles is described that is based upon combining salting out and emulsion-evaporation steps. An entrapment efficiency, a measure of the actual to theoretical drug content, of 97.3% was achieved, being superior to that achieved when these popular techniques were used separately (emulsion evaporation, 40.1%; salting out, 10.0%). The ratio of a water miscible solvent (acetone) to a non water-miscible solvent (dichloromethane) was shown to be the primary determinants of size and drug loading. Once optimized, using an organic phase of 3 : 1 acetone : dichloromethane vol : vol ratio, further control on particle parameters could be exerted using modification of acetone diffusion by alterations in MgCl2 x 6H2O concentration. This step was shown to have a small effect on both the mean nanoparticle size and entrapment efficiency, but found to reduce the polydispersity considerably. Diffusion control using a 45% w/v MgCl2 x 6H2O solution produced nanoparticles with a mean size of 151.4 nm, a polydispersity index of 0.023 and 98.1% entrapment efficiency. Electron microscopy showed the particles to be smooth and spherical. Sheer homogenization during the emulsification step was shown to be not as effective as sonication, with the latter technique able to produce nanoparticles after 1 min of application. Drug release studies across a semi-permeable membrane demonstrated a reduction in the burst effect as the ratio of acetone in the organic phase was increased. Calorimetry studies suggested that celecoxib existed in the nanoparticle as a molecular dispersion, with additional evidence for a strong interaction between the PLGA and the absorbed poly(vinyl alcohol) stabilizer. Formation of a strong interaction between celecoxib and PLGA, together with the formation of a radial drug gradient give a release profile that does not possess the prevalent burst effect seen with other nanoparticulate drug-loaded systems.

Novel strategies to improve the anticancer action of 5-fluorouracil by using drug delivery systems

Because of the fundamental importance of new therapeutic routes for cancer treatment, a number of systems based on colloidal particles as vehicles for the delivery of the anticancer drug 5-fluorouracil have been devised. The target is always to provide the proper dose of the antitumor agent only at the desired locus of action, thus reducing the unwanted side effects. In this review, the main strategies and the more significant results in the development of 5-fluorouracil carriers for cancer treatment are discussed.

Polymer-surfactant nanoparticles for sustained release of water-soluble drugs

Poor drug encapsulation efficiency and rapid release of the encapsulated drug limit the use of nanoparticles in biomedical applications involving water-soluble drugs. We have developed a novel polymer-surfactant nanoparticle formulation, using the anionic surfactant Aerosol OT (AOT) and polysaccharide polymer alginate, for sustained release of water-soluble drugs. Particle size of nanoparticles, as determined by atomic force microscopy and transmission electron microscopy, was in the range of 40-70 nm. Weakly basic molecules like methylene blue, doxorubicin, rhodamine, verapamil, and clonidine could be encapsulated efficiently in AOT-alginate nanoparticles. In vitro release studies with basic drug molecules indicate that nanoparticles released 60-70% of the encapsulated drug over 4 weeks, with near zero-order release during the first 15 days. Studies with anionic drug molecules demonstrate poorer drug encapsulation efficiency and more rapid drug release than those observed with basic drugs. Further studies investigating the effect of sodium concentration in the release medium and the charge of the drug suggest that calcium-sodium exchange between nanoparticle matrix and release medium and electrostatic interaction between drug and nanoparticle matrix are important determinants of drug release. In conclusion, we have formulated a novel surfactant-polymer drug delivery carrier demonstrating sustained release of water-soluble drugs.

Study of carbonyl iron/poly(butylcyanoacrylate) (core/shell) particles as anticancer drug delivery systems Loading and release properties

The aim of this study is to develop a detailed investigation of the capabilities of carbonyl iron/poly(butylcyanoacrylate) (core/shell) particles for the loading and release of 5-Fluorouracil and Ftorafur. The anionic polymerization procedure, used to obtain poly(alkylcyanoacrylate) nanoparticles for drug delivery, was followed in the synthesis of the composite particles, except that the polymerization medium was a carbonyl iron suspension. The influence of the two mechanisms of drug incorporation (entrapment in the polymeric network and surface adsorption) on the drug loading and release profiles were investigated by means of spectrophotometric and electrophoretic measurements. The optimum loading conditions were ascertained and used to perform drug release evaluations. Among the factors affecting drug loading, both pH and drug concentration were found to be the main determining ones. For both drugs, the release profile was found to be biphasic, since the drug adsorbed on the surface was released rather rapidly (close to 100% in 1h), whereas the drug incorporated in the polymer matrix required between 10 and 20h to be fully released. The kinetics of the drug release from the core/shell particles was mainly controlled by the pH of the release medium, the type of drug incorporation, and the amount of drug loaded.

Drug incorporation and release of water soluble drugs from novel functionalized poly(glycerol adipate) nanoparticles

We have previously demonstrated the ability of poly(glycerol adipate) backbone (PGA) and PGA polymer backbone substituted with varying amounts of pendant C(18) chain length acyl groups to yield Dexamethasone phosphate DXMP loaded nanoparticles. The aim of this study was to obtain a deeper understanding of the underlying principles responsible for good drug incorporation and controlled release of drugs from poly (glycerol adipate) (PGA) nanoparticles. We compared the incorporation of the water soluble drugs DXMP and Cytosine arabinoside (CYT-ARA) in both unmodified and substituted PGA polymers. We investigated the effect of change in acyl group chain length and the degree of substitution on the physicochemical properties, drug loading and release of DXMP and CYT-ARA. Nanoparticles were prepared by the interfacial deposition technique and the simultaneous emulsification method. Amongst the nanoparticles prepared using acylated polymers with varying chain lengths (C(2) to C(10)) for DXMP incorporation, polymers with acyl group chain lengths containing 8 carbon atoms (C(8)) showed maximum drug incorporation. Amongst the C(8) series, polymers with 100% acylation provided both good drug incorporation and a controlled release for DXMP while for CYT-ARA it was the unsubstituted polymer backbone that had maximum drug loading and slower release. A number of inter-related factors are responsible for producing particles with particular size, zeta potential, drug loading and release characteristics. Drug loading and release from nanoparticles are primarily influenced by the nature of interactions between the drug and polymers which in turn depend upon the type of drug used and the physical chemistry of the polymer.

Ftorafur loading and controlled release from poly(ethyl-2-cyanoacrylate) and poly(butylcyanoacrylate) nanospheres

In the present work, a method is described to prepare polymeric colloidal nanospheres, consisting of poly(ethyl-2-cyanoacrylate) (PE-2-CA) or poly(butylcyanoacrylate) (PBCA), loaded with the anticancer drug ftorafur. The method is based on the anionic polymerization procedure, often used in the synthesis of poly(alkylcyanoacrylate) nanospheres for drug delivery. A detailed investigation of the capabilities of both polymeric nanoparticles to load this drug is shown. The effect of synthesis residuals and degradation products on the absorbance of supernatants was considered in the loading and release measurement methodologies, because of their potential perturbing influence on the determination of ftorafur concentration in solution. We found the existence of two mechanisms of drug incorporation: absorption or entrapment in the polymeric network, and surface adsorption, detectable by means of zeta potential and spectrophotometric measurements. Among the factors affecting the drug incorporation to the polymer network, the type of polymer, the pH and the drug concentration are the main determining ones. Moreover, the acidity of the medium needs to be controlled in order to avoid the formation of macroaggregates of solids. The optimum loading conditions were used to perform ftorafur release evaluations from polymeric particles, and the influence of the mechanism of drug incorporation, the amount of drug loaded, and the type of polymer on the drug release were studied.

Synthesis, characterization, andin vitro 5-Fu release behavior of poly(2,2-dimethyltrimethylene carbonate)-poly(ethylene glycol)-poly(2,2-dimethyltrimethylene carbonate) nanoparticles

Novel ABA-type amphiphilic triblock copolymers composed of poly (ethylene glycol) (PEG) as hydrophilic segment and poly (2,2-dimethyltrimethylene carbonate) (PDTC) as hydrophobic segment were synthesized by ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by dihydroxyl PEG. The influence of introducing PEG block on crystalline behavior of PDTC segment was investigated by DSC. Polymeric micelles in aqueous medium were characterized by fluorescence spectroscopy and dynamic light scattering. The critical micelle concentration of these copolymers was in the range of 5.1-50.5 mg/L. Particle size was 80-280 nm. Core-shell-type nanoparticles were prepared by the dialysis technique. Zeta potential was measured by laser Doppler anemometry, and all nanoparticles had negative zeta potential. Transmission electron microscopy images demonstrated that these nanoparticles were spherical in shape. Anticancer drug 5-fluorouracil (5-Fu) as a model drug was loaded in the polymeric nanoparticles. X-ray powder diffraction demonstrated that 5-Fu was encapsulated into polymeric nanoparticles as molecular dispersion. In vitro cytotoxicity of nanoparticles was evaluated by MTT assay. In vitro release behavior of 5-Fu was investigated, and sustained drug release was achieved.

Gel-based application of siRNA to human epithelial cancer cells induces RNAi-dependent apoptosis

Gene silencing by RNA interference (RNAi) operates at the level of mRNA that is targeted for destruction with exquisite sequence specificity. In principle, any disease-related mRNA sequence is a putative target for RNAi-based therapeutics. To develop this therapeutic potential, it is necessary to develop ways of inducing RNAi by clinically acceptable delivery procedures. Here, we ask if inducers of RNAi can be delivered to human cells via a gel-based medium. RNAi was induced using synthetic small interfering RNAs (siRNAs), which bypass the need for expression vectors and carry the added bonus of high potency and immediate efficacy. Established cultures of human cells of normal and tumor origin were overlaid with an agarose/liposome/siRNA gel formulation without adverse effects on cell viability or proliferation. Epithelial cancer cells (but not normal human fibroblasts) proved vulnerable to specific siRNAs delivered via the agarose/liposome/siRNA formulation. Moreover, proapoptotic siRNAs induced apoptosis of cervical carcinoma cells (treated with human papillomavirus [HPV] E7 siRNA) and of colorectal carcinoma cells (treated with Bcl-2 siRNA). Thus, we demonstrate successful topical gel-based delivery of inducers of RNAi to human epithelial cancer cells. Topical induction of RNAi opens an important new therapeutic approach for treatment of human diseases, including cervical cancer and other accessible disorders.

Comparative study of morphine diffusion from sustained release polymeric suspensions

In recent years, great efforts have been devoted to the design of drug delivery systems. Many polymeric excipients have been studied in order to make drug release fit the desired profiles. The aim of this work was to design a morphine oral suspension, as sustained release pharmaceutical formulations. To this end, two different ethylcellulose suspensions were prepared: one with the drug incorporated during synthesis (suspension A) so that the drug was inside the polymeric microparticles. In the second group of suspensions the drug was incorporated after synthesis (suspension B), thus resulting in the drug being adsorbed on the surface. The analytical technique used, spectrophotometry, showed that suspensions A were able to spontaneously encapsulate approximately 92% of the drug, whereas suspensions B adsorbed only 15% dose on the particle surface. Moreover, the diffusion results obtained with Franz-cells showed that suspensions A offered the possibility of easy control of the release rate of the active substance. This system transfers morphine hydrocloride during 24 h in accordance with a Weibull kinetic model. This dosage form presents the clinical advantage of less frequent dosing, with increased quality of life for patients. This report documents the suitability of our ethylcellulose polymeric suspension for encapsulated morphine with a controlled release rate.

A density-functional model for controlled release

Polymer diffusion based on density-functional theory is applied to controlled release systems. These models explicitly treat the multiphase characteristics of biomolecule-polymer composites typical of drug delivery devices. Polymer diffusion was modeled using the modified Cahn-Hilliard equation with periodic boundary conditions in one dimension and near-zero concentration boundaries in the second dimension. The diffusional driving forces are differences in chemical potential based in part on the Flory-Huggins free energy of mixing in polymer systems rather than concentration gradients. Release rates from this model were compared to exponential models typically used in the drug delivery literature. Simulations based on this model showed that the diffusional exponent is 1/2; this exponent is consistent with Fickian models at early times. Particle growth, which also occurs in diffusing, dispersed systems, was observed. The particle growth exponent in these systems was 2/3, twice the value typical in bulk ripening systems. The increased growth rate was caused by the elimination of small particles due to diffusion out of the system, which removed the low particle size region of the distribution faster than ripening alone.

Potential applications of PLGA film-implants in modulating in vitro drugs release

In this work we evaluate poly(lactic/glycolic) acid (PLGA) film-implants as potential biodegradable devices for controlled release of two different drugs: 5-Fluorouridine (5-FUR), a conventional low molecular weight water-soluble compound and SPf66 malaria vaccine, a therapeutic synthetic polypeptide. Three types of devices were prepared by solvent-casting techniques alone or combined with compression method: simple monolithic discs (SMD), multilayer discs with a central monolithic layer (MLDM), and multilayer discs with a central drug-reservoir (MLDR). For the highly water-soluble drug, 5-FUR, in vitro release from SMD showed an initial burst (24% in 2 h) followed by prolonged release over 20 days. In contrast, from a MLDM (two drug-free PLGA discs were added to the SMD) showed an initial lag-time of 12 days followed by a very fast second release phase. Finally, when the load of this system was increased from 3 to 9%, an extended release over 20 days with a low burst effect was obtained. For SPf66, the central reservoir containing the synthetic polypeptide MLDR reduces the possibility of degradation due to peptide contact with polymer solution. When four layers were added, 10 days sustained-release was obtained without any burst effect. With six layers a moderate pulse was obtained, 18-22 days from the beginning of the release. The results show the suitability of the proposed devices to control release and avoid the burst effect with highly water-soluble drugs; as well as modulate in vitro peptide release.