International Journal of Pharmaceutics (v.402, #1-2)
Editorial Board (iii).
Influence of size and surface roughness of large lactose carrier particles in dry powder inhaler formulations by Martin J. Donovan; Hugh D.C. Smyth (1-9).
The objective of this study was to determine the effect of both carrier particle size and surface roughness on the aerosol performance of dry powder formulations. Two morphologically distinct grades of lactose, anhydrous (AN) and granulated (GR), were fractionated into 11 discreet sizes up to 300 μm, and separately employed as carriers in 2% (w/w) budesonide blends. In vitro deposition studies were performed at 60 L min−1 with an Aerolizer® DPI. It was found that large carriers can improve dispersion performance, although the effect is more pronounced with greater surface roughness. AN carriers exhibited minimal surface roughness and generally behaved as predicted from the literature, with the smaller carriers outperforming their larger counterparts. In contrast, GR carriers had a high degree of surface roughness, and the dispersion performance of larger carriers exceeded that of the smaller size fractions. Comparing the two lactose grades, AN carriers deposited a greater fraction of the total dose up to the 90–125 μm size range, when they were surpassed in performance by the GR carriers. These results suggest that the mechanism of drug detachment varies with the physical properties of the carrier particle population, where surface roughness can alter the predominant detachment mechanism to favor larger carrier particle diameters.
Keywords: Binary formulations; Lactose; Carrier particles; Surface roughness; Dry powder inhalers;
Evaluation of a cationic calixarene: Solubilization and self-aggregation ability by Elena V. Ukhatskaya; Sergey V. Kurkov; Susan E. Matthews; Amani El Fagui; Catherine Amiel; Florent Dalmas; Thorsteinn Loftsson (10-19).
Water-soluble calixarenes are promising macrocyclic compounds which have found numerous applications in chemistry and biology. However, these compounds have been less studied in regard to their behavior in aqueous solutions and mechanisms of drug solubilization. The present work is devoted to the evaluation of the solubilizing properties and estimation of self-aggregation ability of positively charged 5,11,17,23-tetrakis(trimethylammoniomethyl)-25,26,27,28-tetrapropoxy-calixarene tetrachloride (aminocalix), including comparisons with a series of pharmaceutically relevant cyclodextrins. Phase-solubility measurements of the drugs with aminocalix and various cyclodextrins were carried out. Aminocalix showed a solubilizing ability comparable to the cyclodextrins. The drug solubility enhancement caused by the aminocalix was studied and was found to be maximal for steroid drugs. An attempt to understand the solubilizing mechanism of aminocalix was undertaken based on correlation analysis between physical and physico-chemical properties of the drugs from one side and the solubilizing ability of aminocalix from the other. Correlation analysis supports the supposition that the solubilizing effect of aminocalix is based on interaction of the drug with aminocalix aggregates rather than on inclusion complexation. UV-absorbance, osmolality and surface tension concentration dependences of aminocalix showed an inflection at 1% (w/v) which was initially related to the transition from monomers to micelles. However, dynamic light scattering and transmission electron microscopy measurements revealed that likely vesicles of diverse size exist at 0.1% (w/v) concentration. Thus the 1% (w/v) inflection point was interpreted to be spontaneous reordering of the vesicles between two different size populations.
Keywords: Calixarenes; Cyclodextrins; Solubilization; Surfactant; Nanoparticles;
New insights into the pore structure of poly(d,l-lactide-co-glycolide) microspheres by Kerstin Vay; Stefan Scheler; Wolfgang Frieß (20-26).
This new analytical method provides the possibility to uncover structural properties even in the submicroscopic scale thus gaining deeper insight into the application-specific functionalities of microparticles.The objective of this work was to develop a fast and significant method for the determination of the intraparticulate pore size distribution of microspheres. Poly(lactide-co-glycolide) (PLGA) microspheres prepared with a solvent extraction/evaporation process were studied. From the envelope and the skeletal volume of the microspheres the porosity was calculated. The skeletal volume was determined with nitrogen and helium pycnometry and mercury intrusion porosimetry. Based on single particle optical sensing (SPOS) a novel method was developed by which the envelope volume is calculated from the particle size distribution (PSD), provided that all particles have a spherical shape. The penetration capacity of the applied intrusion media is limited by their atomic or molecular diameter or by the surface tension and the pressure in case of mercury. A classification of the pore structure was obtained by comparing these different skeletal values with the values for the envelope volume. Two well separated pore fractions were found, a nanoporous fraction smaller than 0.36 nm and a macroporous fraction larger than 3.9 μm. The total porosity and the ratio between both fractions is controlled by the preparation process and was shown to depend on the solvent extraction temperature.
Keywords: Microspheres; Porosity; Structure; Single particle optical sensing; Gas pycnometry;
Comparison of in vitro cell models in predicting in vivo brain entry of drugs by Jenni J. Hakkarainen; Aaro J. Jalkanen; Tiina M. Kääriäinen; Pekka Keski-Rahkonen; Tetta Venäläinen; Juho Hokkanen; Jukka Mönkkönen; Marjukka Suhonen; Markus M. Forsberg (27-36).
Although several in vitro models have been reported to predict the ability of drug candidates to cross the blood–brain barrier, their real in vivo relevance has rarely been evaluated. The present study demonstrates the in vivo relevance of simple unidirectional permeability coefficient (P app) determined in three in vitro cell models (BBMEC, Caco-2 and MDCKII-MDR1) for nine model drugs (alprenolol, atenolol, metoprolol, pindolol, entacapone, tolcapone, baclofen, midazolam and ondansetron) by using dual probe microdialysis in the rat brain and blood as an in vivo measure. There was a clear correlation between the P app and the unbound brain/blood ratios determined by in vivo microdialysis (BBMEC r = 0.99, Caco-2 r = 0.91 and MDCKII-MDR1 r = 0.85). Despite of the substantial differences in the absolute in vitro P app values and regardless of the method used (side-by-side vs. filter insert system), the capability of the in vitro models to rank order drugs was similar. By this approach, thus, the additional value offered by the true endothelial cell model (BBMEC) remains obscure. The present results also highlight the need of both in vitro as well as in vivo methods in characterization of blood–brain barrier passage of new drug candidates.
Keywords: Blood–brain barrier; BBMEC; Caco-2; MDCKII-MDR1; In vivo relevance;
Synthesis and study of controlled release of ofloxacin from polyester conjugates by Marcin Sobczak; Grzegorz Nałęcz-Jawecki; Wacław L. Kołodziejski; Piotr Goś; Karolina Żółtowska (37-43).
New polymeric conjugates were prepared coupling ofloxacin to two-, three-, four and six-arm, star-shaped poly(ɛ-caprolactone) and polylactide. The homopolymers were synthesized via ring-opening polymerization of ɛ-caprolactone, l-lactide and rac-lactide in the presence of glycerol, penthaerythritol, dipentaerythritol and poly(ethylene glycol) as initiators and stannous octoate as a catalyst. The conjugates were characterized by GPC, MALDI-TOF MS, NMR, IR and viscosity methods. Content of Sn has been investigated in polymers by electrothermal atomic absorption spectrometry. Toxicity of monomers, initiators and polymers were evaluated with bacterial luminescence test and two protozoan assays. The in vitro release of ofloxacin from obtained conjugates in pH 7 was investigated.
Keywords: Macromolecular conjugates; Aliphatic polyesters; Ofloxacin; Fluoroquinolones; Controlled release;
Skin contamination by radiopharmaceuticals and decontamination strategies by M.A. Bolzinger; C. Bolot; G. Galy; A. Chabanel; J. Pelletier; S. Briançon (44-49).
The aim of the present study was to evaluate the percutaneous penetration of five common radiopharmaceuticals (99mTc, 67Ga, 125I, 111In and 51Cr) and to evaluate the effect of decontamination by a detergent solution dedicated to hospital institutions for that purpose. The skin kinetic profiles were established by using the in vitro Franz cell method over 24 h. The skin distribution in each skin layer was quantified after 6 h exposure time and the efficacy of the detergent solution to remove radionuclides was evaluated also after 6 h. The most striking result was the repartition into two classes of kinetic profiles: 125I and 99mTc permeated quickly (∼60% of applied activity after 24 h) while the 3 other radionuclides permeated slowly (from ∼2.75% for 67Ga to ∼10% of applied activity for 111In). The lag times, i.e. the time necessary to cross the skin varied from 20 min for 99mTc to 5 h for 51Cr, which accumulated in skin compartments. Skin washings with the detergent solution were particularly efficient for this radionuclide, contrary to the others for which the washing procedure should be applied earlier. The permeation of ions was dependent on their chemical and physical forms and on their salting-in or salting-out effects (coordination state and Hofmeister series).
Keywords: Radiopharmaceuticals; Hofmeister series; Percutaneous absorption; Franz cells; Skin decontamination;
The coefficient of restitution of some pharmaceutical tablets/compacts by Rahul Bharadwaj; Carson Smith; Bruno C. Hancock (50-56).
When tablets collide during manufacturing and handling operations they rebound with a force and velocity that is determined by the collision conditions and the properties of the materials. This collision-rebound behavior of solid bodies can be described using a parameter known as the “coefficient of restitution” (CoR). In this work, the CoR of a range of pharmaceutical tablets/compacts is measured using a simple “drop test”, and the influences of material properties (elastic modulus, solid fraction, etc.) and collision conditions (substrate, energy/speed, etc.) are investigated. The compacted pharmaceutical materials have CoR values that range from 0.4 to 0.9, and the CoR generally increases with increasing compact solid fraction. The CoR varies with the mechanical properties of both colliding bodies and is lower for more plastic collisions and higher for elastic collisions. This behavior is consistent with theories developed for non-pharmaceutical solids, and can be predicted provided that the elasticity and yield stress of the samples are treated as porosity dependent parameters. In this case, the CoR varies with the impact velocity nearly raised to the fourth root. Having established a simple and reproducible test for the CoR of pharmaceutical compacts and tablets it should be possible to create more accurate engineering models and computer simulations of tablet manufacturing and packaging operations.
Keywords: Coefficient of restitution; Collision; DEM; Tablet;
Targeting human clonogenic acute myelogenous leukemia cells via folate conjugated liposomes combined with receptor modulation by all-trans retinoic acid by Hong Li; Yanhui Lu; Longzhu Piao; Jun Wu; Shujun Liu; Guido Marcucci; Manohar Ratnam; Robert J. Lee (57-63).
Our previous data demonstrated that folate receptor β (FR-β) targeted liposomal doxorubicin (FT-L-DOX) showed enhanced cytotoxicity relative to non-targeted liposomal doxorubicin (CON-L-DOX), and the effect was enhanced by selective FR-β upregulation by all-trans retinoic acid (ATRA) in AML blast cells. In this study, the enhanced cytotoxicity was investigated in the proliferating human AML clonogenic cells by combining FT-L-DOX with ATRA. Also, pharmacokinetic properties by pretreatment of ATRA were evaluated using FR-targeted liposomal calcein (FT-L-Calcein). Pharmacokinetic study showed that the area under the concentration curve (AUC) of FT-L-Calcein was decreased and total clearance was increased by pretreatment with ATRA. Meanwhile, the volume of distribution was significantly increased by pretreatment of ATRA. Moreover, calcein level in the liver, spleen and kidney was increased following intravenous administration of FT-L-Calcein by pretreatment of ATRA. In vitro cytotoxicity of FT-L-DOX was higher than that of CON-L-DOX and was increased by pretreatment with ATRA. Colony formation in AML cells was lower due to treatment with FT-L-DOX compared with CON-L-DOX and colony formation further decreased upon pretreatment with ATRA. Moreover, FT-L-DOX was more toxic to AML clonogenic cells than to AML blast cells. The results demonstrate that the efficiency of FR-mediated targeting of FT-L-DOX was preferentially enhanced by ATRA induced FR-β upregulation in AML clonogenic cells.
Keywords: Folate receptor; Liposomes; Doxorubicin; all-trans retinoic acid; Acute myeloid leukemia; Clonogenic cell; Targeted drug delivery;
Enhanced passive pulmonary targeting and retention of PEGylated rigid microparticles in rats by Hilliard L. Kutscher; Piyun Chao; Manjeet Deshmukh; Sujata Sundara Rajan; Yashveer Singh; Peidi Hu; Laurie B. Joseph; Stanley Stein; Debra L. Laskin; Patrick J. Sinko (64-71).
The lung retention of rigid 6 μm polystyrene microparticles (MPs) intravenously administered to rats was investigated. MPs with different surface groups [amine (A-), carboxylate (C-) or sulfate (S-)] or poly(ethylene glycol) (PEG) layers [single (PEG1-) or double (PEG2-)] were used. The lung retention of the unmodified MPs (A-, C- and S-MPs) is similar and their resulting AUCs are statistically different than the AUCs of the PEGylated MPs by one-way ANOVA.The current study examines the passive pulmonary targeting efficacy and retention of 6 μm polystyrene (PS) microparticles (MPs) covalently modified with different surface groups [amine (A-), carboxyl (C-) and sulfate (S-)] or single (PEG1-) and double (PEG2-) layers of α,ω-diamino poly(ethylene glycol) attached to C-MPs. The ζ-potential of A-MPs (−44.0 mV), C-MPs (−54.3 mV) and S-MPs (−49.6 mV) in deionized water were similar; however PEGylation increased the ζ-potential for both PEG1-MPs (−18.3 mV) and PEG2-MPs (11.5 mV). The biodistribution and retention of intravenously administered MPs to male Sprague–Dawley rats was determined in homogenized tissue by fluorescence spectrophotometry. PEG1-MPs and PEG2-MPs demonstrated enhanced pulmonary retention in rats at 48 h after injection when compared to unmodified A-MPs (59.6%, 35.9% and 17.0% of the administered dose, respectively). While unmodified MPs did not significantly differ in lung retention, PEGylation of MPs unexpectedly improved passive lung targeting and retention by modifying surface properties including charge and hydrophobicity but not size.
Keywords: Passive pulmonary targeting; Rigid non-biodegradable microparticle; Poly(ethylene glycol); PEGylation;
Modified release from hydroxypropyl methylcellulose compression-coated tablets by Soravoot Rujivipat; Roland Bodmeier (72-77).
The goal of this study was to obtain flexible extended drug release profiles (e.g., sigmoidal, pulsatile, increasing/decreasing release rates with time) with hydroxypropyl methylcellulose (HPMC) compression-coated tablets. Drugs of varying solubility (carbamazepine, acetaminophen, propranolol HCl and chlorpheniramine maleate) were incorporated into the tablet core in order to evaluate the flexibility/limitations of the compression-coated system. The HPMC-compression-coating resulted in release profiles with a distinct lag time followed by different release phases primarily determined by the drug solubility. Carbamazepine, a water-insoluble drug, was released in a pulsatile fashion after a lag time only after erosion of the HPMC compression-coat, while the more soluble drugs were released in a sigmoidal fashion by diffusion through the gel prior to erosion. With carbamazepine, increasing the molecular weight of HPMC significantly increased the lag time because of the erosion-based release mechanism, while, in contrast, molecular weight did not affect the release of the more soluble drugs. The lag-time and the release rate could also be well controlled by varying the HPMC amount in and the thickness of the compression-coating. A pulsatile release could also be achieved for water-soluble drugs by introducing an enteric polymer coating between the drug core and the HPMC compression-coating. This novel concept of introducing an enteric subcoating eliminated drug diffusion through the gelled HPMC layer prior to its erosion. Incorporating drug in the compression-coating in addition to the tablet core in varying ratios resulted in release profiles with increasing, decreasing or constant release rates. In conclusion, a versatile single-unit delivery system for a wide range of drugs with great flexibility in release profiles was presented.
Keywords: Compression-coating; Hydroxypropyl methylcellulose; Oral controlled release; Pulsatile release; Subcoating;
In sight into tadalafil – block copolymer binary solid dispersion: Mechanistic investigation of dissolution enhancement by Mohammed M. Mehanna; Adel M. Motawaa; Magda W. Samaha (78-88).
Dissolution improvement of tadalafil was mainly due to reduction in crystalline particle size, wetting effect through intimate contact between Pluronic® carrier and tadalafil, and solubilization effect of the carrier.Tadalafil is a phosphodiesterase-5 inhibitor that is characterized by low solubility and high permeability. Solid dispersion approach represents a promising carrier system for effective enhancement of dissolution and oral bioavailability of poorly soluble drugs. In the present work, novel tadalafil-loaded solid dispersions employing various block copolymers (Pluronics®) were prepared through fusion technique. Their solubility and dissolution properties were compared to the drug alone. In order to elucidate the mechanism of dissolution enhancement, solid state characteristics were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and powder X-ray diffraction. Furthermore, contact angle measurements were carried out.The sign and magnitude of the thermodynamic parameters indicated spontaneity of solubilization process. The phase solubility studies revealed AL type of curves for the carriers. Unlike traditional solid dispersion systems, the crystal form of drug in the formulated systems could not be converted to amorphous form. Most of the studied grades showed dissolution improvement vis-à-vis pure drug, with Pluronic F-127 as the most promising carrier. Mathematical modeling of in vitro dissolution data indicated the best fitting with Korsemeyer–Peppas model. Thus, the results demonstrated that tadalafil/Pluronic F-127 solid dispersion system is a direct and feasible technology which represents a potential candidate for delivering a poorly water-soluble drug with enhanced solubility and dissolution.
Keywords: Tadalafil; Block copolymer; Solid dispersion; Pluronics®; Enhancement mechanisms;
Evaluation of liposomes coated with a pH responsive polymer by M.J. Barea; M.J. Jenkins; M.H. Gaber; R.H. Bridson (89-94).
Liposomes were coated with the pH responsive polymer Eudragit S100 and their potential for lower gastrointestinal tract targeting evaluated.Liposomes have been coated with the pH responsive polymer, Eudragit S100, and the formulation's potential for lower gastrointestinal (GI) targeting following oral administration assessed. Cationic liposomes were coated with the anionic polymer through simple mixing. The evolution of a polymer coat was studied using zeta potential measurements and laser diffraction size analysis. Further evidence of an association between polymer and liposome was obtained using light and cryo scanning electron microscopy. Drug release studies were carried out at pH 1.4, pH 6.3 and pH 7.8, representing the pH conditions of the stomach, small intestine and ileocaecal junction, respectively.The polymer significantly reduced liposomal drug release at pH 1.4 and pH 6.3 but drug release was equivalent to the uncoated control at pH 7.8, indicating that the formulation displayed appropriate pH responsive release characteristics. While the coating layer was not able to withstand the additional challenge of bile salts this reinforces the importance of evaluating these types of formulations in more complex media.
Keywords: Colonic drug delivery; Liposomes; Oral drug delivery; Targeted drug delivery;
Evaluation of hyaluronic acid–protein conjugates for polymer masked–unmasked protein therapy by Elaine L. Ferguson; Alshame M.J. Alshame; David W. Thomas (95-102).
Bioresponsive polymers may effectively be utilized to enhance the circulation time and stability of biologically active proteins and peptides, while reducing their immunogenicity and toxicity. Recently, dextrin-epidermal growth factor (EGF) conjugates, which make use of the Polymer-masked UnMasked Protein Therapy (PUMPT) concept, have been developed and shown potential as modulators of impaired wound healing. This study investigated the potential of PUMPT using hyaluronic acid (HA) conjugates to mask activity and enhance protein stability, while allowing restoration of biological activity following triggered degradation. HA fragments (Mw ∼90,000 g/mol), obtained by acid hydrolysis of Rooster comb HA, were conjugated to trypsin as a model enzyme or to EGF as a model growth factor. Conjugates contained 2.45 and 0.98% (w/w) trypsin or EGF, respectively, and contained <5% free protein. HA conjugation did not significantly alter trypsin's activity. However, incubation of the conjugate with physiological concentrations of HAase increased its activity to ∼145% (p < 0.001) that of the free enzyme. In contrast, when HA–EGF conjugates were tested in vitro, no effect on cell proliferation was seen, even in the presence of HAase. HA conjugates did not display typical masking/unmasking behavior, HA–trypsin conjugates exhibited ∼52% greater stability in the presence of elastase, compared to free trypsin, demonstrating the potential of HA conjugates for further development as modulators of tissue repair.
Keywords: Polymer therapeutics; Hyaluronic acid; Bioresponsive; Nanomedicines; PUMPT;
Development and evaluation of a monolithic drug-in-adhesive patch for valsartan by Naohiro Nishida; Kazuhiro Taniyama; Toshihiro Sawabe; Yoichi Manome (103-109).
The purpose of this study was to investigate the feasibility of a monolithic drug-in-adhesive (DIA) patch as a transdermal therapeutic system for the administration of valsartan (VAL). To improve the penetration of VAL in the patch, several chemical penetration enhancers were investigated by in vitro hairless mouse and Yucatan micro pig (YMP) skin permeation studies. A combination of isopropyl myristate (IPM)/diisooctyl sodium sulfosuccinate (AOT) most strongly enhanced the permeation of VAL. Since the concentration of VAL through the patch in hairless rat (HR) in vivo was correlated with that in HR skin in vitro, VAL that permeated through the skin could effectively pass into the systemic circulation. The plasma concentration–time profile of VAL after the patch was applied in humans was estimated by a convolution technique from the results of the in vitro YMP study, which indicated that the concentration of VAL could be sufficient to produce a pharmacological effect. These results demonstrate that the combination of IPM/AOT may be useful for the development of a practical DIA patch for VAL.
Keywords: Drug-in-adhesive patch; Valsartan; Diisooctyl sodium sulfosuccinate; Yucatan micro pig; Transdermal;
Studies on mechanism of thermal crystal transformation of sitafloxacin hydrates through melting and recrystallization, yielding different anhydrates depending on initial crystalline forms by Tetsuya Suzuki; Tetsuya Araki; Hiroaki Kitaoka; Katsuhide Terada (110-116).
Torsion of quinolone ring (left) and conformation of 5-membered ring of sitafloxacin observed in monohydrate and β-form. Upper: observed in monohydrate, lower: observed in β-form. Quinolone ring in monohydrate takes opposite torsion to that in β-form. Amino group takes equatorial position in monohydrate while it takes axial position in β-form.The polymorphic and pseudopolymorphic forms of sitafloxacin, a novel fluoroquinolone antibiotic, were characterized by infrared spectroscopy, X-ray diffractometry, and thermal analysis. Hydrates of sitafloxacin underwent thermal transformation during the course of heating to 300 °C. Monohydrate melted at 130 °C and crystallized at 147 °C to yield α-form (anhydrate) while sesquihydrate melted at 127 °C and crystallized at 146 °C to yield β-form (anhydrate). The crystal structural analysis revealed that monohydrate and sesquihydrate had opposite torsion at quinolone ring and the conformation of quinolone ring tended to be retained during hydrates to anhydrates crystal conversion. The infrared spectroscopy showed that hydrates and anhydrate α-from exists in zwitterion while β-from is consist of neutral molecule. Detail investigation of thermal behavior of hydrates suggested that water vapor also affected anhydrous crystal forms obtained by heating hydrates, though promoting ionization at carboxyl group and amine group.
Keywords: Crystal transformation; Thermal properties; Crystallographic analysis; Torsion at quinolone ring; Protonation;
Inorganic-polymer nanohybrid carrier for delivery of a poorly-soluble drug, ursodeoxycholic acid by Goeun Choi; Ji-Hee Lee; Yeon-Ji Oh; Young Bin Choy; Myung Chul Park; Hee Chul Chang; Jin-Ho Choy (117-122).
Delivery of poorly soluble drugs has been problematic due to its low absorption profile and bioavailability. In this work, ursodeoxycholic acid (UDCA), a poorly-soluble drug, was intercalated into inorganic nanovehicle, layered double hydroxides (LDHs), with a molecular level to enhance its solubility in biological fluid. The UDCA-loaded nanovehicle (i.e., UDCA-LDHs) was also coated with an anionic polymer, Eudragit® S100, to increase the dissolution rate of UDCA. According to the powder X-ray diffraction (PXRD) patterns of UDCA-LDHs, the gallery height of LDHs was expanded from 3.6 Å to 28.3 Å, indicating that the UDCA molecules were successfully intercalated into the interlayer space of LDHs. Fourier transform infrared (FT-IR) spectra also revealed that the UDCA molecules were well stabilized in the LDHs through electrostatic interaction. The in vitro dissolution test in a simulated biological fluid (pH = 6.8) showed that the total dissolved fraction of UDCA for the first 2 h was about 60.2% for the Eudragit® S100 coated UDCA-LDHs, which was a dramatic increase as compared with 19.0% dissolution from intact UDCA. It is, therefore, concluded that LDHs nanovehicle coated with an anionic polymer is a promising delivery system for improving aqueous solubility of poorly soluble drugs.
Keywords: Drug delivery; Layered double hydroxide; Nanovehicle; Polymer-coating; Poorly-soluble drugs; Solubility enhancement;
Release of paeonol-β-CD complex from thermo-sensitive poly(N-isopropylacrylamide) hydrogels by Jung-Ying Tsao; Hsieh-Ho Tsai; Chien-Pang Wu; Pi-Yun Lin; Shan-Yu Su; Lieh-Der Chen; Fuu-Jen Tsai; Yuhsin Tsai (123-128).
As three-dimensional, cross-linked networks of water-solublepolymers, hydrogels can be made from a water-soluble polymer, encompassing a wide range of chemical compositions and bulk physical properties.By preparing an inclusion complex of paeonol (PAE) with β-cyclodextrin (β-CD), this study investigated its release behavior from thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The PAE–β-CD complex was prepared via coprecipitation. According to differential scanning calorimeter (DSC) and X-ray diffraction (XRD) results, the solid PAE–β-CD complex was found in the amorphous state, indicating that each PAE molecule was encapsulated by a β-CD molecule. The change of chemical shifts of H3 and H5 in proton nuclear magnetic resonance (H NMR) spectra indicated that PAE was inside the CD cavity. PNIPAAm hydrogels containing different cross-linker contents were then synthesized and had a similar lowest critical solution temperature (LCST) of around 33 °C. Experimental results of swelling and deswelling indicated that increasing the cross-linker content of the hydrogel decreased the swelling ratio and increased the water retention. According to experimental results of PAE–β-CD complex release, the release rate at 45 °C (>LCST) was higher than at 25 °C (<LCST). Moreover a lower cross-linker content the hydrogel contained implies a higher rate of PAE–β-CD complex release. Above results suggest that the release of PAE–β-CD complex is related to the volume contraction of the hydrogel, which is affected by hydrogel compositions and release temperatures.
Keywords: Poly(N-isopropylacrylamide); Release; Paeonol; Cyclodextrin; Inclusion complex;
Design and evaluation of a novel formulation prediction system by Jin Guan; Rongwu Xiang; Yusheng Pan; Hao Pan; Xiangdong Su; Liying Zhou; Yuni Cui; Weisan Pan (129-139).
A novel formulation prediction system can immediately obtain the optimal formulation region for preparation of MOPTs after entering the dose of some water-insoluble drug.The purpose of this study is to design and evaluate a novel formulation prediction system for formulation study of monolithic osmotic pump tablets (MOPTs).Ternary-component diagram was originally brought forward to evaluate MOPTs formulations. Optimal formulation regions were delimited in ternary-component diagrams. Water-insoluble drug gliclazide was chosen as a model drug for selecting most suitable suspending agent. With five model drugs, we obtained five ternary-component diagrams. By MATLAB® software, a triangular prism model was then established regarding doses as vertical coordinate and the five diagrams as cross-sections, with the formation of an optimal formulation channel in it, followed by the design of formulation prediction software (FPS 1.0). The practicality of the system was finally validated.After entering the drug information, we immediately obtained the optimal formulation region for preparing MOPTs with interpolation algorithm. The dissolution test results of the four randomly selected formulations all met the evaluating conditions.Ternary-component diagram is useful for MOPTs formulation optimization. The predictive ability of the system is tentatively confirmed and the experiment efficiency is greatly improved.
Keywords: Formulation prediction system; Ternary-component diagram; Optimal formulation region; Triangular prism model; Interpolation algorithm; Monolithic osmotic pump tablets;
Stabilizing protein formulations during air-jet nebulization by Yacoub Y. Albasarah; Satyanarayana Somavarapu; Kevin M.G. Taylor (140-145).
Total and active lactate dehydrogenase (LDH) deposited in the lower stage of a twin-stage impinger following nebulization of LDH solution, LDH with 0.1% Tween 80 and LDH with 0.1% chitosan 1k, 3–5k and 10k and 0.1% Tween 80.Whilst some proteins can be effectively administered to the lungs using a nebulizer, others, such as lactate dehydrogenase (LDH) are degraded during air-jet nebulization. In order to deliver LDH by nebulization a protective delivery system or carrier may therefore be appropriate. The aim of this study was to produce and characterize a formulation of LDH, which retains enzyme activity during nebulization. Chitosan, a biocompatible, biodegradable and bioadhesive polysaccharide polymer, was included in the formulations studied as a potential protective agent. Complexes of LDH with chitosan of different molecular weights and concentrations were assessed for size, zeta potential, aerosol droplet size and delivery from a jet nebulizer. The highest molecular weight chitosan had the greatest complex size and a net positive charge of +29.7 mV. Jet nebulization resulted in aerosol droplets with median size in the range 2.36–3.52 μm. Nebulization of LDH solution resulted in enzyme denaturation and reduced activity. The stability of LDH was greatly improved in formulations with chitosan; with greater than 50% total LDH available in a nebulizer delivered to the lower stage of a two-stage impinger, with up to 62% retained enzyme activity. The nonionic surfactant Tween 80 also improved the stability of LDH to nebulization and had an additive protective effect when included, with chitosan, in formulations. These findings suggest chitosan may be a useful excipient in the preparation of stable protein formulations for jet nebulization.
Keywords: Chitosan; Impinger; Lactate dehydrogenase; Jet nebulizer; Polysorbate; Protein; Pulmonary delivery; Tween 80;
Different effects of l- and d-menthol on the microstructure of ceramide 5/cholesterol/palmitic acid bilayers by Hiroshi Watanabe; Yasuko Obata; Yoshinori Onuki; Kenya Ishida; Kozo Takayama (146-152).
Different effect of optically active menthol on the hydrocarbon chain packing in the CER5/CHOL/PA bilayers. The opened and closed bars represent hexagonal and orthorhombic hydrocarbon chain packing, respectively.The optical activity of transdermal permeation enhancers is one of the crucial factors for the enhancement of drug permeation via the skin. We investigated the effects of optically active menthols on a lipid bilayer model composed of ceramide 5, cholesterol, and palmitic acid. We first examined the fluidizing effects of l- and d-menthols on the lipid bilayers. The fluorescence anisotropy and thermodynamic parameters, such as the transition temperature and transition enthalpy, were significantly reduced by treatment with the optically active menthols. The effects of d-menthol were stronger than those of l-menthol. To discuss further, we also performed a detergent insolubility study and measured wide angle X-ray scattering. The amount of liquid-ordered phase membranes in the bilayers was significantly reduced by treatment with d-menthol. Whereas, l-menthol did not affected to the liquid-ordered phase membranes. The apparent ratio of orthorhombic hydrocarbon chain packing was substantially reduced by treatment with l-menthol. Thus, the distinct effects of optically active menthols on lipid bilayers were clarified: l-menthol acts on orthorhombic hydrocarbon chain packing with high selectivity, whereas d-menthol has no such specific effect. These findings extend our understanding of the mechanisms by which menthols affect the intercellular lipids in the stratum corneum.
Keywords: Lipid bilayers; Stratum corneum; Synchrotron X-ray scattering; Menthol; Ceramide; Optical activity;
Extrusion–spheronisation of highly loaded 5-ASA multiparticulate dosage forms by G. Di Pretoro; L. Zema; A. Gazzaniga; S.L. Rough; D.I. Wilson (153-164).
A route to generate pellets with high loading (≥90 wt%) of 5-aminosalicylic acid and acceptable quality by extrusion–spheronisation was developed by controlling particle shape and binder liquid redistribution.The aim of the current work was to develop an extrusion–spheronisation (E–S) route to manufacture pellets with a high loading (≥90 wt%) of 5-aminosalicylic acid (5-ASA). Ram extrusion studies, supported by centrifuge testing, were employed to investigate the effect of the chemical (acidity) and physical (particle size and shape) characteristics of 5-ASA on the ability of microcrystalline cellulose (MCC)-based pastes to retain water when subjected to pressure. Liquid phase migration (LPM) within the paste during the extrusion, and hence variation in water content of extrudates and reproducibility of the final E–S product, was generally observed. The extent of LPM was found to be related to both the drug loading and its physical properties, most notably the particle shape (needle-like). A reduction in particle size, combined with a change in the shape of the 5-ASA particles, allowed LPM to be reduced considerably or eliminated. The performance of colloidal grades of MCC (Avicel RC591 and CL611) as alternative extrusion aids to the standard Avicel PH101 was also investigated: these proved to be superior aids for the highly loaded 5-ASA pastes as their greater water retention capacity mitigated LPM. Combining these results yielded a route for manufacturing pellets with 5-ASA loading ≥90 wt%.
Keywords: 5-Aminosalicylic acid; Ram extrusion; Liquid phase migration; Microcrystalline cellulose; Granulation;
Incorporation of PVMMA to PLGA MS enhances lectin grafting and their in vitro activity in macrophages by Laura León-Rodriguez; Jose Leiro-Vidal; José Blanco-Méndez; Asteria Luzardo-Álvarez (165-174).
Attachment of lectins, especially those that are recognized and bounded by macrophages and other antigen presenting cells onto biodegradable microspheres surface, may serve as support for a wide variety of applications. The aim of this work was: (1) to prepare microspheres (MS) based on two biodegradable copolymers, poly (lactide-co-glicolide) acid (PLGA) and poly[(methyl vinyl ether)-co-(maleic anhydride)] (PVMMA) with their surface functionalized with Concanavalin A (Con A) and, (2) to evaluate their behaviour in macrophage culture. The incorporation of PVMMA was studied in order to augment the lectin coupling efficiency. MS were obtained by spray-drying and bovine serum albumin (BSA) was loaded as protein model. Particles were characterized for size, morphology, surface charge, entrapment efficiency, FTIR, in vitro protein release and conjugation efficiency. Finally, functionalized MS were tested in vitro with raw 264.7 murine macrophages (Mф) in terms of cytotoxicity, phagocytosis, nitric oxide (NO) production, and oxygen consumption. Conjugated Con A microspheres showed increased grafting efficiency up to four times compared to PLGA alone. The retention of Con A after coupling was confirmed by desorption studies. The attachment of Con A to microspheres induced oxygen consumption, increased phagocytosis efficiency and even NO production by macrophages. The results suggest that Con A and possibly, other lectins, grafted onto PLGA–PVMMA microspheres may serve as potential adjuvants by modulating protein delivery and macrophage activation.
Keywords: Microspheres; PLGA; PVMMA; Concanavalin A; Functionalization; Macrophage;
Characterization of the developed antimicrobial urological catheters by Dorota Kowalczuk; Grażyna Ginalska; Joanna Golus (175-183).
Antimicrobial urological catheters were developed by the mixed, covalent and non-covalent binding of sparfloxacin (SPA) to heparin (HP) film which was first deposited on the latex surface of biomaterial. The SPA-HP modified surface was characterized by SEM analysis and ATR-Fourier transform infrared spectroscopy. For the antimicrobial prevention, SPA as an antibiotic with a broad antimicrobial spectrum was chosen. Antimicrobial activity of antibiotic-modified catheter against Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli strains was assessed using various procedures. On the basis of the inhibition zone and diffusion assays the efficacy around the modified catheters was demonstrated. The test samples clearly showed an antibacterial activity against all tested bacterial stains for a least one month. Inhibition of the bacterial colonization on the modified catheter surface was proved by the biofilm test. Antimicrobial activity of SPA-treated catheter surface was also quantitatively evaluated according to standard method of ISO based on JIS. The R-values were found to be higher than 3.8. The performed research indicated that the immobilization of SPA on the catheter surface by means of the mixed-type bonds resulted in stable antibacterial protection of the urological catheters for a long time.
Keywords: Antimicrobial protection; Surface characterization; Catheters; Sparfloxacin;
Local implantation of doxorubicin drug eluting beads in rat glioma by S. Vinchon-Petit; D. Jarnet; S. Michalak; A. Lewis; J.-P. Benoit; P. Menei (184-189).
We evaluated the safety and the efficacy of doxorubicin drug eluting beads “CM-BC1” when used locally in a 9L glioma model. Twenty microlitres of 1 mg/ml CM-BC1 (4 μg/rat), 10 mg/ml CM-BC1 (40 μg/rat) or unloaded beads were injected into the brain of 27 rats which was analyzed on day 8, month 3 or month 6. Then, after tumor implantation, rats were treated locally: (1) control group; (2) a group receiving 20 μl of unloaded beads, (3) a group “3 × 6 Gy whole-brain irradiation” (WBI), (4) a group receiving 20 μl of 1 mg/ml CM-BC1 and (5) a group receiving 20 μl of 1 mg/ml CM-BC1 followed by a WBI. Both the unloaded beads and the lower dose of 1 mg/ml CM-BC1 were well tolerated with no early deaths in opposite to 10 mg/ml CM-BC1. Medians of survival for the “1 mg/ml CM-BC1” group and the combination group are respectively 28.9 and 64.4 days. These results were significant compared to the “unloaded beads” group. The rat's survival was not significantly improved in comparison with the radiotherapy group. This preliminary evidence suggests that 1 mg/ml CM-BC1 could be interesting for recurrent high-grade gliomas. Further work is necessary to improve this seducing tool.
Keywords: Glioma; Radiotherapy; Concomitant therapy; DC beads; Local chemotherapy; Doxorubicin;
In vivo evaluation of safety of nanoporous silicon carriers following single and multiple dose intravenous administrations in mice by T. Tanaka; B. Godin; R. Bhavane; R. Nieves-Alicea; J. Gu; X. Liu; C. Chiappini; J.R. Fakhoury; S. Amra; A. Ewing; Q. Li; I.J. Fidler; M. Ferrari (190-197).
Porous silicon (pSi) is being extensively studied as an emerging material for use in biomedical applications, including drug delivery, based on the biodegradability and versatile chemical and biophysical properties. We have recently introduced multistage nanoporous silicon microparticles (S1MP) designed as a cargo for nanocarrier drug delivery to enable the loaded therapeutics and diagnostics to sequentially overcome the biological barriers in order to reach their target. In this first report on biocompatibility of intravenously administered pSi structures, we examined the tolerability of negatively (−32.5 ± 3.1 mV) and positively (8.7 ± 2.5 mV) charged S1MP in acute single dose (107, 108, 5 × 108 S1MP/animal) and subchronic multiple dose (108 S1MP/animal/week for 4 weeks) administration schedules. Our data demonstrate that S1MP did not change plasma levels of renal (BUN and creatinine) and hepatic (LDH) biomarkers as well as 23 plasma cytokines. LDH plasma levels of 145.2 ± 23.6, 115.4 ± 29.1 vs. 127.0 ± 10.4; and 155.8 ± 38.4, 135.5 ± 52.3 vs. 178.4 ± 74.6 were detected in mice treated with 108 negatively charged S1MP, 108 positively charged S1MP vs. saline control in single and multiple dose schedules, respectively. The S1MPs did not alter LDH levels in liver and spleen, nor lead to infiltration of leukocytes into the liver, spleen, kidney, lung, brain, heart, and thyroid. Collectively, these data provide evidence of a safe intravenous administration of S1MPs as a drug delivery carrier.
Keywords: Nanoporous silicon; Biocompatibility; Multistage carrier;
Pep-1 peptide-conjugated elastic liposomal formulation of taxifolin glycoside for the treatment of atopic dermatitis in NC/Nga mice by Myung Joo Kang; Jae Yoon Eum; Sang Han Park; Mean Hyung Kang; Kwan Hee Park; Sun Eun Choi; Min Won Lee; Kyung Ho Kang; Chil Hwan Oh; Young Wook Choi (198-204).
Changes in TEWL in NC/Nga mice after topical administration of various formulations: drug-free cream (Base), TXG solution (Soln) and TXG-loaded Pep1-EL (Pep1-EL).In order to develop topical preparations of taxifolin glycoside (TXG) for the treatment of atopic dermatitis (AD), formulations of Pep-1 peptide-conjugated elastic liposomes (Pep1-EL) were examined for their in vitro skin permeation profile and in vivo therapeutic efficacy. TXG-loaded Pep1-EL – a nanovesicle consisting of phosphatidylcholine, Tween 80, N-[4-(p-maleimidophenyl)butyryl]-phosphatidylethanolamine (MPB-PE), and Pep-1 peptide – is 130 nm in size, and has a zeta potential of 25 mV and a deformability index value of 60. Here, we examined the skin permeability of several topical preparations using a Franz diffusion cell mounted with depilated mouse skin and found that formulations of Pep1-EL exhibited superior absorption when compared to aqueous solution, EL or Pep-1 peptide-admixed EL formulations. Both transepidermal water loss and skin surface hydration were also measured using AD-induced NC/Nga mice, and the TXG-loaded Pep1-EL treatment group displayed a significantly expedited recovery in skin barrier function when compared to the controls treated with a TXG aqueous solution (p < 0.05). AD-associated immune responses – including serum interleukine-4, immunoglobulin E, and interferon-gamma – were also regulated by topical application of TXG-loaded Pep1-EL. In conclusion, the novel Pep1-EL formulation of TXG shows substantial promise in the treatment of AD as a result of its desirable skin delivery-promoting capability.
Keywords: Taxifolin glycoside; Elastic liposomes; Pep-1 peptide; Atopic dermatitis; NC/Nga mice;
Penetration and distribution of PLGA nanoparticles in the human skin treated with microneedles by Wei Zhang; Jing Gao; Quangang Zhu; Min Zhang; Xueying Ding; Xiaoyu Wang; Xuemei Hou; Wei Fan; Baoyue Ding; Xin Wu; Xiying Wang; Shen Gao (205-212).
The penetration of nanoparticles into the human skin was enhanced by microneedles and most of the nanoparticles deposited in the epidermis.This study was designed to investigate the penetration and the distribution of poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles in the human skin treated with microneedles. Fluorescent nanoparticles were prepared to indicate the transdermal transport process of the nanoparticles. Permeation study was performed on Franz-type diffusion cells in vitro. The distribution of nanoparticles was visualized by confocal laser scanning microscopy (CLSM) and quantified by high performance liquid chromatography (HPLC). CLSM images showed that nanoparticles were delivered into the microconduits created by microneedles and permeated into the epidermis and the dermis. The quantitative determination showed that (i) the permeation of nanoparticles into the skin was enhanced by microneedles, but no nanoparticle reached the receptor solution; (ii) much more nanoparticles deposited in the epidermis than those in the dermis; (iii) the permeation was in a particle size-dependent manner; and (iv) the permeation increased with the nanoparticle concentration increasing until a limit value was reached. These results suggested that microneedles could enhance the intradermal delivery of PLGA nanoparticles. The biodegradable nanoparticles would sustain drug release in the skin and supply the skin with drug over a prolonged period. This strategy would prove to be useful for topical drug administration.
Keywords: Skin; Microneedles; PLGA; Nanoparticles; Topical drug delivery;
Optimization of formulation and process variable of nanosuspension: An industrial perspective by Dhananjay S. Singare; Seshasai Marella; K. Gowthamrajan; Giriraj T. Kulkarni; Rajesh Vooturi; Parchuri Srinivasa Rao (213-220).
Ratio of polymer to drug and milling speed affected significantly to the zeta potential, whereas milling time and milling speed affected significantly to the PSD d(90) of nanosuspension.The objective of this study was to identify and optimize formulation and process variables affecting characteristic and scale up of nanosuspension manufacturing process on bead mill considering industrial perspective. Box–Behnken design was used for this study. Formulation factors evaluated were ratio of polymer to drug and ratio of surfactant to drug, whereas process parameters were milling time and milling speed. Responses measured in this study include zeta potential and, particle size distribution d(90). The ANOVA test reveals that ratio of polymer to drug and milling speed has significant effect on zeta potential whereas milling time and milling speed has significant effect on the particle size distribution of nanosuspension. The X-RD pattern of drug milled at high and low speed reveals no form conversion when compared to unmilled drug. The Box–Behnken design used in this study helped in identifying the factors affecting the particle size distribution d(90), zeta potential and, scalability of nanosuspension. The derived polynomial equation and contour graph aid in predicting the values of selected independent variables for preparation of optimum nanosuspension formulations with desired properties.
Keywords: Nanosuspension; Zeta potential; Bead mill; Box–Behnken design; Particle size distribution d(90); Analysis of variance (ANOVA);
Silicalites and Mesoporous Silica Nanoparticles for photodynamic therapy by Ouahiba Hocine; Magali Gary-Bobo; David Brevet; Marie Maynadier; Simon Fontanel; Laurence Raehm; Sébastien Richeter; Bernard Loock; Pierre Couleaud; Céline Frochot; Clarence Charnay; Gaëlle Derrien; Monique Smaïhi; Amar Sahmoune; Alain Morère; Philippe Maillard; Marcel Garcia; Jean-Olivier Durand (221-230).
The synthesis of silicalites and Mesoporous Silica Nanoparticles (MSN), which covalently incorporate original water-soluble photosensitizers for PDT applications is described. PDT was performed on MDA-MB-231 breast cancer cells. All the nanoparticles showed significant cell death after irradiation, which was not correlated with 1O2 quantum yield of the nanoparticles. Other parameters are involved and in particular the surface and shape of the nanoparticles which influence the pathway of endocytosis. Functionalization with mannose was necessary to obtain the best results with PDT due to an active endocytosis of mannose-functionalized nanoparticles. The quantity of mannose on the surface should be carefully adjusted as a too high amount of mannose impairs the phototoxicity of the nanoparticles. Fluorescein was also encapsulated in MCM-41 type MSN in order to localize the nanoparticles in the organelles of the cells by confocal microscopy. The MSN were localized in lysosomes after active endocytosis by mannose receptors.
Keywords: Nanoparticles; Mesoporous; Organized porosity; Silica; PDT; Targeting; Mannose;
New chimeric advanced Drug Delivery nano Systems (chi-aDDnSs) as doxorubicin carriers by Konstantinos Gardikis; Chrisiida Tsimplouli; Konstantinos Dimas; Maria Micha-Screttas; Costas Demetzos (231-237).
Doxorubicin was incorporated into two new liposomal chimeric advanced Drug Delivery nano Systems (chi-aDDnSs) incorporating the synthesized dendrimer PG1, composed of DOPC/CHOL or EPC/CHOL. It was also incorporated into conventional (free of PG1) liposomal formulations, the physicochemical characteristics, and the in vitro drug release in RPMI 5% medium over time were assessed. The results revealed a different modulation release effect of doxorubicin from the chi-aDDnS, compared to the conventional formulations. In vitro cytotoxicity concerning all the liposomal formulations were also assessed against MB231 and MCF7 human breast cancer cell lines.Since the late 1960s, the field of drug delivery has focused on the creation of new formulations with improved properties, taking much attention to drug release from the carrier. Liposomes and dendrimers represent two of the most studied drug carriers. A Modulatory Liposomal Controlled Release System (MLCRS) combining liposomal and dendrimeric technology has been recently published as well as Liposomal locked-in Dendrimers (LLDs) technology which was considered to be a class of MLCRSs. Chimeric advanced Drug Delivery nano Systems (chi-aDDnSs) can be defined as mixed nanosystems due to the combination of the bionanomaterials used and can offer advantages as drug carriers. This work deals with the production of two new chi-aDDnSs incorporating the newly synthesized dendrimer PG1. One of the two formulations bears the exact lipidic composition as the commercial liposomal drug “Myocet”. Doxorubicin (Dox) was incorporated into conventional (free of dendrimer) liposomal formulations and into the corresponding chi-aDDnSs, and the physicochemical characteristics, the in vitro drug release and the in vitro cytotoxicity against human cancer cell lines were assessed. The results revealed a different modulation release effect of doxorubicin from the chi-aDDnS, compared to the Myocet replica. Pharmacological cytotoxicity concerning all the chi-aDDnSs was very close to that of the conventional liposomal systems.
Keywords: Chimeric advanced Drug Delivery nano System (chi-aDDnS); Myocet; In vitro cytotoxicity; Liposome; Dendrimer;
Enhanced anti-glioblastoma efficacy by PTX-loaded PEGylated poly(ɛ-caprolactone) nanoparticles: In vitro and in vivo evaluation by Hongliang Xin; Liangcen Chen; Jijin Gu; Xiaoqing Ren; Zhang wei; Jieqi Luo; Yanzuo Chen; Xinyi Jiang; Xianyi Sha; Xiaoling Fang (238-247).
The aim of this work was to investigate the anti-tumor effect of paclitaxel (PTX)-loaded methoxy poly(ethylene glycol)-poly(ɛ-caprolactone) nanoparticles (MPEG-NP/PTX) against glioblastoma multiforme (GBM). MPEG-NP/PTX was prepared by the emulsion and evaporation technique with particle size of 72.5 ± 2.2 nm and did not change remarkably during the period of 21-day storage at 4 °C. The drug-loading coefficient and encapsulation ratio of optimized formulation were 8.2 ± 0.6% and 90.4 ± 2.3%, respectively. The in vitro release behavior exhibits a biphase release manner and was affected by PEG segment. In vitro cytotoxicity was assessed using C6 cell lines and was compared to Taxol and PTX-loaded poly(ɛ-caprolactone) conventional nanoparticles (NP/PTX). Cell viability assay against C6 cells exhibited higher or at least comparable cytotoxicity than that of Taxol and NP/PTX. More importantly, in vivo real-time fluorescence imaging analysis in intracranial C6 glioblastoma bearing mice showed that the methoxy poly(ethylene glycol)-poly(ɛ-caprolactone) nanoparticles (MPEG-NP) displayed much stronger fluorescence signal and 3-fold larger Area-Under-Curve (AUC) than poly(ɛ-caprolactone) conventional nanoparticles (NP) in tumor-bearing brain. Furthermore, in vivo anti-glioblastoma effect exhibited the mean survive time of MPEG-NP/PTX (28 days) was much longer than those of Taxol injection (20 days) and NP/PTX (23 days). Therefore, MPEGylated poly(ɛ-caprolactone) nanoparticles significantly enhanced the anti-glioblastoma activity of PTX and might be considered a promising drug delivery system against advanced glioblastoma.
Keywords: Polymeric nanoparticles; MPEGylated poly(ɛ-caprolactone); Paclitaxel; Glioblastoma;
Thiolated nanostructured lipid carriers as a potential ocular drug delivery system for cyclosporine A: Improving in vivo ocular distribution by Jie Shen; Yanping Deng; Xuefeng Jin; Qineng Ping; Zhigui Su; Lejun Li (248-253).
The prolonged pre-corneal retention time of thiolated NLC would provide an intimate contact between drugs and ocular surface tissues, thus, could really deliver CyA into intraocular eye tissues.Ophthalmic drug delivery with long pre-corneal retention time and high penetration into aqueous humor and intraocular tissues is the key-limiting factor for the treatment of ocular diseases and disorders. Within this study, the conjugate of cysteine-polyethylene glycol monostearate (Cys-PEG-SA) was synthesized and was used to compose the thiolated nanostructured lipid carrier (Cys-NLC) as a potential nanocarrier for the topical ocular administration of cyclosporine A (CyA). The rapid cross-linking process of Cys-PEG-SA in vitro was found in simulated physiological environment. The in vitro CyA release from Cys-NLC was slower than that of non-thiolated nanostructured lipid carriers (NLC) due to the cross-linking of thiomers on the surface of nanocarriers. After topical ocular administration in rabbits, the in vivo ocular distribution of CyA was investigated in comparison of Cys-NLC with non-thiolated NLCs and oil solution. The results showed that CyA concentration in systemic blood was very low and close to the detection limit. The area-under-the-curve (AUC0–24 h) and mean retention time (MRT0–24 h) of Cys-NLC group in aqueous humor, tear and eye tissues were significantly higher than that of oil solution, non-thiolated NLCs (p < 0.05). These results demonstrated that the thiolated NLC could deliver high level of CyA into intraocular tissues due to its bioadhesive property and sustained release characteristics.
Keywords: Cyclosporine A; Nanostructured lipid carrier; Thiolated modification; Sustained drug release; Mucoadhesive; Ocular distribution;
Nanosponge formulations as oxygen delivery systems by Roberta Cavalli; Ansari Khalid Akhter; Agnese Bisazza; Pierangela Giustetto; Francesco Trotta; Pradeep Vavia (254-257).
Three types of cyclodextrin nanosponges were synthetized cross-linking α, β or γ cyclodextrin with carbonyldiimidazole as cross-linker. Nanosponges are solid nanoparticles previously used as drug carriers. In this studies cyclodextrin nanosponges were developed as oxygen delivery system. For this purpose the three types of nanosponges suspended in water were saturated with oxygen and in vitro characterized. The nanosponge safety was tested on Vero cells. Their ability to release oxygen in the presence and in the absence of ultrasound (US) was determined over time. Oxygen permeation through a silicone membrane was obtained using a β-cyclodextrin nanosponge/hydrogel combination system. Nanosponge formulations might be potential gas delivery systems showing the ability to store and to release oxygen slowly over time.
Keywords: Nanosponges; Ultrasound; Oxygen release; Cyclodextrin; Hydrogel;