Effect of various poloxamer coatings on in vitro adhesion of isohexylcyanoacrylate nanospheres to rat ileal segments under liquid flow

Influence of Poloxamer 188 on Anti-Inflammatory and Analgesic Effects of Diclofenac-Loaded Nanoemulsion: Formulation, Optimization and in Vitro/in Vivo Evaluation

In this study, a polymer-stabilized nanoemulsion (PNE) was developed to improve the inflammatory and analgesic activities of diclofenac (DA). DA-PNEs were prepared from sesame oil and poloxamer 188 (P188), polysorbate 80, and span 80 as emulsifiers and optimized by a systematic multi-objective optimization method. The developed DA-PNEs exhibited thermodynamical stability with low viscosity. The mean diameter, PDI, surface charge, and entrapment efficiency of DA-PNEs were 122.49±3.42 nm, 0.226±0.08, -47.3 ± 3.6 mV, and 93.57±3.4 %, respectively. The cumulative in vitro release profile of DA-PNEs was significantly higher than the neat drug in simulated gastrointestinal fluids. The anti-inflammatory activities of DA-PNEs were evaluated in the λ-carrageenan-induced paw edema model. To investigate the effect of P188 on analgesic and anti-inflammatory activities, a formulation without P188 was also prepared and named DA-NEs. Following oral administration, DA-PNEs showed a significantly higher (p<0.05) effect in reducing pain and inflammation symptoms as compared to free diclofenac and DA-NEs. Moreover, histopathological examination confirmed that DA-PNEs meaningfully reduced the extent of paw edema, comparable to that of DA. Taken together, the findings of the in vitro and in vivo studies suggest that diclofenac-loaded P188-stabilized nanoemulsion can be considered a potential drug delivery system for treating and controlling inflammatory disorders and alleviating pains.

Advanced materials for drug delivery across mucosal barriers

Mucus is a viscoelastic gel that traps pathogens and other foreign particles to limit their penetration into the underlying epithelium. Dosage forms containing particle-based drug delivery systems are trapped in mucosal layers and will be removed by mucus turnover. Mucoadhesion avoids premature wash-off and prolongs the residence time of drugs on mucus. Moreover, mucus penetration is essential for molecules to access the underlying epithelial tissues. Various strategies have been investigated to achieve mucoadhesion and mucus penetration of drug carriers. Innovations in materials used for the construction of drug-carrier systems allowed the development of different mucoadhesion and mucus penetration delivery systems. Over the last decade, advances in the field of materials chemistry, with a focus on biocompatibility, have led to the expansion of the pool of materials available for drug delivery applications. The choice of materials in mucosal delivery is generally dependent on the intended therapeutic target and nature of the mucosa at the site of absorption. This review presents an up-to-date account of materials including synthesis, physical and chemical modifications of mucoadhesive materials, nanocarriers, viral mimics used for the construction of mucosal drug delivery systems.

Optimization, characterization and evaluation of chitosan-tailored cubic nanoparticles of clotrimazole

The present study deals with improvement of the mucoadhesive properties of monoolein based cubic nanoparticles by incorporating chitosan. Chitosan-tailored cubic nanoparticles were prepared by thin film hydration followed by ultrasonication employing clotrimazole as model drug. The effect of Pluronic F127 fraction and concentration of chitosan on particle size and % mucin binding of the formulations was studied using 2-factor, 3-level, central composite experimental design. The concentration of chitosan was found to influence particle size and % mucin binding of cubic nanoparticles while Pluronic F127 fraction influenced only the % mucin binding. Studies indicated 8.33(%w/w) fraction of Pluronic F127 and 0.17 (%w/v) concentration of chitosan as optimum concentration. Finally, the optimized batch was characterized by polarized light microscopy, small-angle X-ray scattering (SAXS) and transmission electron microscopy. The results unveiled incorporation of chitosan did not disrupt the inner cubic structure of nanoparticles. Peak indexing of SAXS data revealed the coexistence of P-type and D-type cubic phases in nanoparticles. Further, comparative evaluation studies showed significantly higher anti-fungal activity of clotrimazole-loaded chitosan-tailored cubic nanoparticles than conventional suspension of clotrimazole against Candida albicans.

Mucoadhesive nanoparticles made of thiolated quaternary chitosan crosslinked with hyaluronan

Mucoadhesive polymeric nanoparticles intended for drug transport across the gastrointestinal mucosa were prepared from quaternary ammonium-chitosan conjugates synthesised from reduced-MW chitosan (32 kDa). Conjugates contained pendant moieties of 2-4 adjacent diethyl-dimethylene-ammonium groups substituted on repeating units (26-55%). Conjugates were thiolated via amide bonds with thioglycolic acid to yield products with thiol content in the 35-87 μmol/g range. Nanoparticles with mean size in the 270-370 nm range and positive zeta-potential (+3.7 to +12.5 mV) resulted from ionotropic gelation of the thiolated conjugates with de-polymerised hyaluronic acid (470 kDa). The nanoparticles were fairly stable in size and thiol content and showed a significant mucoadhesivity, matching and even exceeding that of the constituent polymers. Nanoparticles were internalised by endothelial progenitor cells in direct relation to their surface charge intensity. Nanoparticle uptake significantly improved cell viability and resistance to oxidation. The lyophilised nanoparticles were re-dispersible and could make a manageable formulation for oral use.

Comparison of different absorption enhancers on the intranasal absorption of isosorbide dinitrate in rats

The objective of this work was to study the influence of different absorption enhancers on the intranasal absorption of isosorbide dinitrate (ISDN). First of all, an in situ nasal perfusion technique in rats was used to investigate the effect of pH, concentration of drug solution and different absorption enhancers on the intranasal absorption of ISDN. The absorption enhancers investigated include hydroxypropyl-beta-cyclodextrin (HP-beta-CD), chitosans (CS) of different molecular weight, and poloxamer 188. All of them enhanced the intranasal absorption of ISDN remarkably. It was found that poloxamer 188 had better permeation enhancing effect than that of HP-beta-CD and CS of the same concentration. Thereafter, in vivo behaviors of the selected formulations were studied in rats and the pharmacokinetic parameters were calculated and compared with that of intravenous injection. Both in situ and in vivo studies demonstrated that poloxamer 188 played a key role in promoting intranasal absorption of ISDN. In nasal ciliotoxicity test, all the absorption enhancers investigated showed good safety profiles. Taking both enhancing effect and safety into account, we suggest poloxamer 188 is the most promising as an intranasal absorption enhancer.

Design aspects of poly(alkylcyanoacrylate) nanoparticles for drug delivery

Poly(alkylcyanoacrylate) (PACA) nanoparticles were first developed 25 years ago taking advantage of the in vivo degradation potential of the polymer and of its good acceptance by living tissues. Since then, various PACA nanoparticles were designed including nanospheres, oil-containing and water-containing nanocapsules. This made possible the in vivo delivery of many types of drugs including those presenting serious challenging delivery problems. PACA nanoparticles were proven to improve treatments of severe diseases like cancer, infections and metabolic disease. For instance, they can transport drugs across barriers allowing delivery of therapeutic doses in difficult tissues to reach including in the brain or in multidrug resistant cells. This review gives an update on the more recent developments and achievements on design aspects of PACA nanoparticles as delivery systems for various drugs to be administered in vivo by different routes of administration.

Investigation of pluronic and PEG-PE micelles as carriers of meso-tetraphenyl porphine for oral administration

Meso-tetraphenyl porphine (mTPP) is a highly lipophilic, fluorescent porphyrin derivate and it is used as photosensitizer on the treatment of malign neoplasms. The aim of this study was to prepare mTPP loaded pluronic F127 and polyethylene glycol-distearoyl phosphatidylethanolamine (PEG(2000)-DSPE) micelles to evaluate polymeric micelles potential for the transport of drugs through intestinal mucosa. Transport and bioadhesion behaviors of polymeric micelles was investigated using Caco-2 cell monolayer and everted rat intestine models. In order to show that Caco-2 cells can be used as a transport model cytotoxicity of formulations was tested. Cell viability was more than 80%, showing that Caco-2 cells will keep their viability during the transport studies demonstrating that prepared formulations can be securely used as oral drug carrier systems. Plain micelles were labeled with a fluorescent agent rhodamine-phosphatidylethanolamine (Rh-PE) and their transport through Caco-2 cells was investigated beside mTPP loaded micelles. At the end of 4h transport study through Caco-2 cells, cumulative transport (%) of fluorescent agents were around 14% and 1% in Rh-PE labeled and mTPP loaded micelles This difference was attributed to the different placement of mTPP and Rh-PE in the micellar core. Drug transport was not estimated in everted rat intestine model but the bioadhesion was 79% and 70% for mTPP loaded pluronic F127 and PEG(2000)-DSPE micelles. These good bioadhesion rates are promising for oral drug delivery.

Nanoparticles as potential oral delivery systems of proteins and vaccines: a mechanistic approach

Peptides and proteins remain poorly bioavailable upon oral administration. One of the most promising strategies to improve their oral delivery relies on their association with colloidal carriers, e.g. polymeric nanoparticles, stable in gastrointestinal tract, protective for encapsulated substances and able to modulate physicochemical characteristics, drug release and biological behavior. The mechanisms of transport of these nanoparticles across intestinal mucosa are reviewed. In particular, the influence of size and surface properties on their non-specific uptake or their targeted uptake by enterocytes and/or M cells is discussed. Enhancement of their uptake by appropriate cells, i.e. M cells by (i) modeling surface properties to optimize access to and transport by M cells (ii) identifying surface markers specific to human M cell allowing targeting to M cells and nanoparticles transcytosis is illustrated. Encouraging results upon in vivo testing are reported but low bioavailability and lack of control on absorbed dose slow down products development. Vaccines are certainly the most promising applications for orally delivered nanoparticles.

Effectiveness of submicron-sized, chitosan-coated liposomes in oral administration of peptide drugs

The mucoadhesive behavior of chitosan-coated liposomes in the intestinal tract of the rat was examined to elucidate their particle size effects on the absorption of an entrapped drug, calcitonin. The intestine was removed from rats after oral administration of liposomes containing a fluorescent dye, and its various parts were observed with confocal laser scanning microscopy. Penetration of submicron-sized liposomes (ssLip) or chitosan-coated ssLip (ssCS-Lip) into the mucosa was observed, while such behavior was not observed for the multilamellar liposomes, even when coated with chitosan (CS-Lip). The retentive property of ssCS-Lip was confirmed by measuring the amount of dye in each part of the intestine. The pharmacologic effects of calcitonin-loaded liposomes of different particle size were measured after oral administration in rats. The pharmacologic effect of oral administration of ssLip coated with chitosan was detected up to 120 h after administration. The extensive pharmacologic effect of ssCS-Lip was attributed to their prolonged retention in the intestinal mucosa, partly owing to their penetrative property into the intestinal mucosa. The chitosan-coated ssLip, with their higher retentive property in the intestinal tract, are much more effective than ssLip and CS-Lip in improving the enteral absorption of peptide drugs.

Poly(alkylcyanoacrylates) as biodegradable materials for biomedical applications

This review considers the use of poly(alkylcyanoacrylates) (PACAs) as biomedical materials. We first present the different aspects of the polymerization of alkylcyanoacrylate monomers and briefly discuss their applications as skin adhesives, surgical glues and embolitic materials. An extensive review of the developments and applications of PACAs as nanoparticles for the delivery of drugs is then given. The methods of preparation of the nanoparticles are presented and considerations concerning the degradation, in vivo distribution, toxicity and cytotoxicity of the nanoparticles are discussed. The different therapeutic applications are presented according to the route of administration of the nanoparticles and include the most recent developments in the field.

Mucoadhesive properties of carbopol or chitosan-coated liposomes and their effectiveness in the oral administration of calcitonin to rats

Mucoadhesive liposomes were prepared by coating multilamellar liposomes with Carbopol (CP) in a similar manner to that used in the preparation of chitosan-coated liposomes (CS-Lip) previously reported [Takeuchi et al., Chem. Pharm. Bull. 42 (1994) 1954-1956; Pharm. Res. 13 (1996) 896-901]. The positively charged liposomes containing dipalmitoylphosphatidylcholine (DPPC) and stearylamine at an optimum formulation ratio (40:1) could be coated with CP without aggregation of the liposomal particles during the coating process. The mucoadhesive properties of both the resultant polymer-coated liposomes (CP-Lip and CS-Lip) and the positively or negatively charged noncoated liposomes (Non-Lip) were evaluated using the rat intestine. The order was CS-Lip> or = CP-Lip>positively charged Non-Lip>negatively charged Non-Lip. The adhesive property of CP-Lip decreased on increasing pH of the dispersing medium from pH 5.0 to 7.4, probably owing to the electric repulsion between CP-Lip and the mucus layer. The effectiveness of the liposomal formulations in oral administration of calcitonin was evaluated by measuring the change in the blood calcium concentration of rats. Administration of CP-Lip and CS-Lip containing calcitonin showed an enhanced and prolonged reduction in blood calcium concentration. The overall pharmacological effect of CP- and CS-Lips evaluated by means of the area under the plasma calcium concentration curve was 2.4 and 2.8 times higher than that of negatively and positively charged Non-Lips, respectively.

Amoxicillin-loaded polyethylcyanoacrylate nanoparticles: influence of PEG coating on the particle size, drug release rate and phagocytic uptake

Polyethyleneglycol (PEG)-coated polyethylcyanoacrylate (PECA) nanoparticles loaded with amoxicillin were prepared and the influence of the PEG coating on the particle size, zeta potential, drug release rate and phagocytic uptake by murine macrophages was studied. Experimental results show that this colloidal drug delivery system could be useful for intravenous or oral administration. The profile of amoxicillin release from PECA nanoparticles system was studied under various conditions similar to those of some corporeal fluids. In all these experiments, amoxicillin release in the free form was studied by HPLC analysis. Experimental results showed that at pH 7.4 drug release rises when molecular weight of PEG added to polymerization medium increases; in human plasma on the contrary drug release is reduced as molecular weight of PEG rises. Phagocytosis was evaluated by incubating amoxicillin-loaded PECA nanoparticles with murine macrophages and determining the amount of phagocytized nanoparticles by dosing the amoxicillin present inside the macrophages. The results of this study showed significative differences between nanoparticles prepared in the presence or in the absence of PEG and demonstrated that the PEG coating reduces the macrophages uptake. These results suggest that nanoparticles prepared in the presence of PEG are stealth carriers, which could be an injectable colloidal system able to avoid MPS recognition after intravenous injection. Experimental data of drug release at pH 1.1 and in the presence of urease, taking into account the mucoadhesive properties of polyalkylcyanoacrylate nanoparticles and the activity of the amoxicillin versus Helicobacter pylori, suggest moreover that the colloidal drug delivery system obtained in our laboratory could be useful for the treatment of diseases caused by H. pylori by peroral administration.

Poloxamer 407 as a thermogelling and adhesive polymer for rectal administration of short-chain fatty acids

OBJECTIVES

The purpose of the study was to gel a rectal solution of short-chain fatty acids to decrease the loss of active materials in the colonic lumen and thereby optimize their absorption.

METHODS

Five thermogels were prepared with poloxamer 407 at concentrations ranging from 17% to 20%. Their viscosities were measured at room temperature and 37 degrees C, and their gelling temperatures were determined. The adhesive properties of each gel were assessed in vitro at 37 degrees C. Short-chain fatty acid release was studied using Guyot cells.

RESULTS

From the threshold concentration of 17.5%, the solutions, Newtonian at room temperature (50-80 mPa x s), gelled at 37 degrees C. The higher the concentration, the higher the viscosity (1750 to 49,000 mPa x s), the lower the gelling temperature (27.6 degrees C to 23.4 degrees C), and the stronger the work of adhesion (2.2 to 4.5 mJ). Short-chain fatty acid release from the 18% polymer gel was decreased by 60% compared to the rectal solution.

CONCLUSION

The 18% poloxamer 407 concentration provided a solution that was liquid at room temperature, that gelled at 37 degrees C, possessed adhesive properties, and controlled short-chain fatty acid release.

Design of nanoparticles composed of graft copolymers for oral peptide delivery

The development of a dosage form that improves the absorption of peptide and protein drugs via the gastrointestinal tract is one of the greatest challenges in the pharmaceutical field. Many researchers have taken up the challenge, using approaches including mucoadhesive drug delivery, colon delivery, particulate drug delivery such as nanoparticles, microcapsules, liposomes, emulsions, micelles, and so on. The objective of this article is to provide the reader with outlines of novel nanoparticle technologies for oral peptide delivery based on polymer chemistry. The physicochemical properties of nanoparticles and their behavior on exposure to physiological media are greatly dominated by their chemical structures and surface characteristics. We will especially focus on the design of nanoparticles composed of novel graft copolymers having a hydrophobic backbone and hydrophilic branches as drug carriers.

Mucoadhesive nanoparticulate systems for peptide drug delivery

This chapter describes the preparation of and methods for evaluating mucoadhesive nanoparticulate systems, including liposomes and polymeric nanoparticles. Mucoadhesive ability is conferred on the particulate systems by coating their surface with mucoadhesive polymers such as chitosan and Carbopol. The feasibility of this surface modification was confirmed by measuring the zeta potential. Several methods of evaluating the mucoadhesive properties of particulate systems have been reported in the literature. We have also developed some novel evaluation procedures including a particle counting method using a Coulter counter for polymer-coated liposomes. The mucoadhesive properties of the polymer-coated liposomes and polymeric nanoparticles were confirmed by means of these mucoadhesion tests. In applying these mucoadhesive nanoparticles to the oral and pulmonary administration of peptide drugs, more effective and prolonged action was observed in comparison with non-coated systems, thereby confirming the usefulness of mucoadhesive nanoparticulate systems for the delivery of peptide drugs.

Influence of the stabilizer coating layer on the purification and freeze-drying of poly(D,L-lactic acid) nanoparticles prepared by an emulsion-diffusion technique

In this study, the purification by cross-flow filtration (CFF) and freeze drying of poly(D,L-lactic acid) (PLA) nanoparticles prepared by an emulsion-diffusion technique using poly(vinyl alcohol) (PVAL) or poloxamer 188 (P-188) were investigated. The stability of the suspensions was correlated to the affinity of the stabilizers for the nanoparticle surface, the resistance of the coating layer to continuous filtration and to freeze-thawing procedures. The results indicated a clear difference between the two stabilizers, suggesting that the nature of the coating layer has a very important role during CFF and freeze-drying. Nanoparticles prepared with PVAL were filtered and freeze-dried without nanoparticle fusion. This behaviour was attributed to the formation of a stable thick layer (similar to that found for polystyrene latex). In contrast, aggregation of nanoparticles was observed during CFF for the batches prepared with P-188, indicating that the polypropylene oxide blocks present in the copolymer have little affinity for the PLA surface. However, these suspensions were successfully recovered when using stabilizer solutions as diafiltration media, suggesting a dynamic exchange between the P-188-adsorbed chains and those of the identical polymer remaining in the bulk solution. The presence of P-188 did not prevent nanoparticle aggregation after freeze-drying. Therefore, the use of cryoprotectants was necessary. Aggregation may have been due to an increase in the solubility of P-188 in the bulk solution, which provokes a destabilization of the suspension by desorption and partial coverage of the surface. The best cryoprotectants were found to be sugars containing glucose units. The cryoprotective effect was related to the hydrogen bonding capability of these sugars, which prevented aggregation by dehydration of P-188 forcing it to the PLA surface.

Optimization of the formulation design of chitosan microspheres containing cisplatin

This study describes an orthogonal experimental design to optimize the formulation of cisplatin (CDDP)-loaded chitosan microspheres (namely, CDDP-DAC-MS) which were produced by an emulsion-chemical cross-linking technique. Seven factors and three levels for each factor that might affect the formulation of microspheres were selected and arranged in an L27(3(13)) orthogonal experimental table. A desirability function (df) calculated according to the trapping efficiency of CDDP, the drug content (%, w/w), and the size distribution of each batch of microspheres was introduced as an index of the microsphere formulation. The overall desirability functions (DF) were produced and treated by a statistic analytical system to optimize the formulation. Moreover, the contour maps were produced to analyze the influence of the seven factors on the size distribution, the drug content, and the drug trapping efficiency. The established optimum procedure was reproducible. Scanning electron micrographs showed that CDDP-DAC-MS were spherical with a coarse surface. The average diameter, drug content, and drug trapping efficiency of CDDP-DAC-MS were 74.8 microns, 20.8% (w/w), and 77.5%, respectively. The in vitro release of cisplatin from chitosan microspheres in saline was retarded compared with that from saline solution; the release of CDDP from chitosan microspheres was suggested to be controlled by the dissolution and diffusion of the drug from the chitosan matrix.

Factors affecting the oral uptake and translocation of polystyrene nanoparticles: histological and analytical evidence

Quantitative and qualitative evidence from our laboratories on the absorption and translocation of polystyrene latex nanoparticles both by histological (qualitative) and analytical measurement of levels of polystyrene (quantitative) is briefly reviewed in this paper. We have previously compared the uptake of nonionized polystyrene latex ranging in size from 50nm to 3 microns, and made some comparisons of uptake between carboxylated microspheres and nonionic systems, showing the lower uptake of the former through the lymphoid tissue of the gastrointestinal tract. Size is a key parameter, uptake increasing with decreasing particle diameter. Early evidence suggested that uptake is by way of the Peyer's patches and other elements of the gut associated lymphoid tissue (GALT). Adsorption of hydrophilic block-copolymers onto polystyrene markedly reduces the uptake by intestinal GALT. Modification of the surface with specific ligands such as by covalent attachment of tomato lectin molecules has indicated widespread uptake by non-GALT tissues, following their binding to and internalisation by enterocytes. The ability to decrease and increase uptake is clear evidence of a phenomenon which has the potential for further control to allow it to be exploited fully for drug or vaccine delivery. The evidence to date with nanoparticles as carriers systems for labile drugs such as proteins by the oral route remains to be substantiated.