International Journal of Pharmaceutics (v.376, #1-2)
Editorial Board (iii).
Evaluation of the mechanical properties and drug release of cross-linked Eudragit films containing metronidazole by Nazik Elgindy; Wael Samy (1-6).
The mechanical properties of casted Eudragit E-100 films were tested for the combined effect of two cohesion promoters (succinic or citric acid) and triacetin as a plasticizer. The prepared films were elastic, self-adhesive, transparent and pale yellow in colour.Films containing either of the tested cohesion promoters showed a significant reduction in both tensile strength and Young's modulus on increasing triacetin and/or cohesion promoter concentration. Films containing 7% (w/w) succinic acid and 45% (w/w) triacetin gave the highest elongation of the tested films at any given stress with a maximum of 1050% elongation. Optimal bonding to human skin surface (tack) with the highest peel adhesion (588 cN/cm) was observed with these films denoting good self-adhesive properties.In vitro metronidazole (MN) release from the plasticized Eudragit E-100 films was monitored for the influence of incorporation of cohesion promoters, secondary polymer (Eudragit RL or RS) as well as drug loading. Both cohesion promoters were seen to improve MN release from the films with the maximum drug flux (0.334 mg cm−2 h−1) observed with 1.75% (w/w) succinic acid. The tested secondary polymers were also found to improve MN release from the tested films. The highest MN release was observed with 20% (w/w) Eudragit RL which gave 0.77 mg cm−2 released after 3 h compared with only 0.34 mg cm−2 for plain films. MN release from the films was increased by increasing drug load. Calculating the release rate constant (K r) showed a linear increase with the increase in drug load.
Keywords: Eudragit E-100 films; Plasticizers; Cohesion promoters; Mechanical properties; Metronidazole; Drug flux;
Do gastrointestinal transit parameters influence the pharmacokinetics of gefitinib? by C.G. Wilson; B. O’Mahony; S.M. Connolly; M.V. Cantarini; M.R. Farmer; P.A. Dickinson; R.P. Smith; H.C. Swaisland (7-12).
The selective EGFR tyrosine kinase inhibitor, gefitinib has been shown to be active against certain human carcinomas. It had been noted that a proportion of volunteers consistently had lower gefitinib exposure following oral administration. The shape of the elimination profile in this subset was also different, showing a monophasic elimination pattern rather than the biphasic pattern observed in the majority of subjects. A gamma scintigraphic study was conducted to examine the relationship of gastrointestinal transit and drug absorption in a cohort of rapid clearance subjects (n = 5) and normal profile volunteers (n = 7). The fasted volunteer panel received a 250 mg gefitinib tablet labelled with [111In]–DTPA together with 240 mL [99mTc]-labelled water. The rapid clearance cohorts were shown to have a faster mean gastric emptying T90 (37 min vs 74 min) and shorter small intestinal transit time (156 min vs 204 min), resulting in an earlier colonic arrival time (181 min vs 244 min). Mean plasma C max was lower (99.2 ng/mL vs 116 ng/mL) and AUC almost half in the rapid clearance group (2162 ± 81 ngh/mL vs 4996 ± 64 ngh/mL). These data suggest that gastrointestinal transit parameters play a role in the differences in the rapid clearance profile group, also contributing to the biphasic to monophasic switch. However, historical data show, at the recommended dose of 250 mg/day steady-state plasma concentrations adequate for clinical benefit are achieved in patients with non-small cell lung cancer.
Keywords: Gefitinib; Iressa®; Gastrointestinal transit; Gamma scintigraphy;
Effects of physicochemical properties of salting-out layer components on drug release by Hiroaki Tasaki; Takayuki Yoshida; Atsushi Maeda; Masataka Katsuma; Kazuhiro Sako (13-21).
A “Salting-out Taste-masking System” generates a long lag time for numbness and bitterness masking, with subsequent immediate drug release to exert pharmacological effects. In this study, the effects of physicochemical properties of salting-out agents and water-soluble polymers in the salting-out layer on the dissolution behaviors of acetaminophen were investigated and predominant factors for lag time generation (Lag time index, hereafter LI) and subsequent drug release (Rapid release index, hereafter RI) were discussed. Each prepared formulation showed a different dissolution profile of acetaminophen with a lag time and subsequent immediate release. Significant correlations between both LI and RI and ΔCST (the salting-out power of salting-out agents) (r 2 = 0.90, 0.67, respectively) and between both LI and RI and CST1 (the sensitivity of water-soluble polymers to a salting-out effect) (r 2 = 0.98, 0.71, respectively) were shown. These results suggest that the components showing a strong salting-out effect inside the beads lead to extended lag times and slow drug releases after the lag times. Results further suggest the use of CST1 to evaluate suitable combinations of salting-out agents and water-soluble polymers in this system.
Keywords: Salting-out effect; Taste-masking; Numbness; Lag time; Immediate drug release; Multiparticulate dosage form;
Mathematical modeling of the fluid dynamics in the flow-through cell by Maziar Kakhi (22-40).
The fluid dynamics in the flow-through cell (USP apparatus 4) has been predicted using the mathematical modeling approach of computational fluid dynamics (CFD). The degree to which flow structures in this apparatus can be qualified as ‘ideal’ both spatially and temporally has been assessed. The simulations predict the development of the velocity field in this apparatus for configurations with and without beads during the discharge stroke of the pump. When the cell is operated only with the red ruby bead (‘open column’ mode), highly non-uniform flow is predicted just downstream of the bead in the latter stages of the pump's pulse. In contrast, a strong degree of profile uniformity and symmetry is predicted throughout the entire pulse in the region of the tablet holder for both standard configurations involving beads. However, noticeable differences in the tablet shear stress distribution are predicted at times when the same instantaneous inlet flow rates are being pumped through the apparatus. This effect is caused by flow separation in the velocity boundary layer formed around the tablet under the influence of an adverse pressure gradient, an effect not predicted with constant (non-pulsating) flow. While the degree of tablet erosion correlates with the average flow rate, during a particular pulse both the free-stream velocity and the boundary layer thickness are also influential.
Keywords: Dissolution; Flow-through cell (USP 4); Computational fluid dynamics (CFD); Flow separation; Velocity boundary layer; Adverse pressure gradient; Open/packed column modes;
A method for predicting the amount of water required for wet granulation using NIR by Akio Miwa; Kouji Makado (41-45).
The purpose of this study is to optimize the amount of water to be added as a binder solution in wet granulation. In our previous studies, we introduced a method to predict the suitable amount of water added to multi-component formulations by summing corresponding values of the components estimated by an NIR sensor prior to granulation. But in this theory, water added to a formulation is assumed to be evenly distributed to each excipient. To guarantee this theory, we used two-component mixtures as a simplified model to estimate the water distribution to each component using an NIR sensor. In cases in which the volume of water added was comparatively small, water was evenly distributed to each excipient; however, when the water added was increased it was not evenly distributed. To interpret this phenomenon, a new concept was introduced, taking the migration of water between each excipient into consideration. By introducing the concept, it turned out to be possible to predict the suitable amount of water to be added in the two-component model by summing the corresponding values of each component even in a range in which there was an uneven distribution.
Keywords: NIR; Near infrared; Water amount; Excipient; Water distribution;
The complexation between novel comb shaped amphiphilic polyallylamine and insulin—Towards oral insulin delivery by C.J. Thompson; L. Tetley; I.F. Uchegbu; W.P. Cheng (46-55).
Novel amphiphilic polyallylamine (PAA) were previously synthesised by randomly grafting palmitoyl pendant groups and subsequent quaternising with methyl iodide. The ability of these self-assembled polymers to spontaneously form nano-complexes with insulin in pH 7.4 Tris buffer was evaluated by transmittance study, hydrodynamic size and zeta potential measurements. The transmission electron microscopy images showed that non-quaternised polymer complexes appeared to form vesicular structures at low polymer:insulin concentrations. However, at higher concentrations they formed solid dense nanoparticles. The presence of quaternary ammonium moieties resulted in insulin complexing on the surface of aggregates. All polymers exhibited high insulin complexation efficiency between 78 and 93%. Incubation with trypsin, α-chymotrypsin and pepsin demonstrated that most polymers were able to protect insulin against enzymatic degradation by trypsin and pepsin. Quaternised polymers appeared to have better protective effect against trypsinisation, possibly due to stronger electrostatic interaction with insulin. Interestingly, non-quaternised polymers significantly enhanced insulin degradation by α-chymotrypsin. All polymers were less cytotoxic than PAA, with the quaternised polymers exhibiting up to 15-fold improvement in the IC50 value. Based on these results, quaternised palmitoyl graft polyallylamine polymers showed promising potential as oral delivery systems for insulin.
Keywords: Oral delivery; Proteins and peptides; Polymeric self-assemblies; Nano-complexes; Enzymatic degradation;
Approach to design push–pull osmotic pumps by Vincent Malaterre; Joerg Ogorka; Nicoletta Loggia; Robert Gurny (56-62).
Despite more than 30 years of clinical use, only few studies have been published reporting on the release mechanism underlying the drug delivery from push–pull osmotic pumps (PPOP). The aim of this study is to understand which factors have an effect on the drug delivery for modelling the drug release and to develop a mathematical model predictive of the drug release kinetics. The influence of the drug property was tested on two model drugs, isradipine (ISR) and chlorpheniramine (CPA) which are respectively practically insoluble and freely soluble. Results show that, regardless of the drug properties which do not significantly affect the drug delivery, the release kinetics is mainly controlled by four factors, (i) the PEG proportion in the membrane, (ii) the tablet surface area, (iii) the osmotic agent proportion and (iv) the drug layer polymer grade. The influence of each key formulation factors on the release mechanism was investigated defining their applicability range. A mathematical approach was developed to predict the drug delivery kinetics varying the PPOP controlling factors and helps to more efficiently design PPOP.
Keywords: Controlled drug delivery; Oral osmotic pump; Push–pull osmotic pumps;
A novel ex vivo skin model for the assessment of the potential transcutaneous anti-inflammatory effect of topically applied Harpagophytum procumbens extract by Nassima Abdelouahab Ouitas; Charles M. Heard (63-68).
Using ex vivo skin as a model, this work tested the hypothesis that the major pharmacologically active components of topically applied Harpagophytum procumbens (H. procumbens) can elicit anti-inflammatory responses in deeper tissues post-transcutaneous delivery. Using Franz-type diffusion cells, ethanol extract of powdered H. procumbens tuber was dosed onto freshly excised porcine skin. After 24 h the receptor phase was recovered, analysed for the major glycosides of DC, then used directly to dose further freshly excised skin membranes. After 6 h the skin was recovered and probed for the expression of the three major enzymes involved in the inflammatory factors: cyclooxygenase (COX-2) and its product prostaglandin E2 (PGE-2), lipoxygenase (5-LOX), and inducible nitric oxide (iNOS), using immunocytochemistry and Western blotting analyses. It was found that the receptor phase at 24 h contained (0.8, 25, 1.8, 3 × 10−3) μmol mL−1 of harpagoside, harpagide, verbascoside, 8-O-p-coumaroyl-harpagide, respectively. When applied to skin, this solution effectively inhibited the expression of COX-2 and its product PGE-2. However, it did not have a significant effect on either 5-LOX or iNOS compared to control samples (PBS only). These data support the hypothesis that the transcutaneous delivery of H. procumbens can treat inflammation in deeper tissues such as in arthritis. Moreover, a novel ex vivo model has been described for assessing the potential anti-inflammatory activity of permeants delivered to deeper subcutaneous regions.
Keywords: Skin; Transcutaneous delivery; Inflammation; Devil's Claw; H. procumbens; COX-2; PGE-2; 5-LOX; iNOS;
Heparin-functionalized chitosan–alginate scaffolds for controlled release of growth factor by Yi-Cheng Ho; Fwu-Long Mi; Hsing-Wen Sung; Pi-Li Kuo (69-75).
Controlled long-term release of basic fibroblast growth factor (bFGF) has shown a combined effect on the stimulation of regenerating a number of tissues including cartilage, nerve, skin and liver. In this study, three-dimensional scaffolds prepared from the polyelectrolyte complexes (PEC) of chitosan and alginate were developed for the delivery of bFGF. The bFGF-binding efficiency of the chitosan–alginate PEC scaffold, after being conjugated with high concentration of heparin (83.6 μg/mg scaffold), was increased up to 15 times higher than that of original scaffold (65.6 ng bFGF/mg scaffold vs. 4.5 ng bFGF/mg scaffold). The release of bFGF from the original scaffold was quick and the initial burst release was obvious. By functionalizing the scaffold with various concentrations of heparin (17.6 μg, 50.3 μg and 83.6 μg heparin/mg scaffold), the rate of bFGF release from the scaffold decreased in a controlled manner with reduced burst effect. The released bFGF retained its biological activity as assessed by the in vitro proliferation of human foreskin fibroblast (HFF). This study shows that a novel bFGF delivery system using the heparin-functionalized chitosan–alginate PEC scaffold exhibits controllable, long-term release of bFGF and could prevent the growth factor from inactivation.
Keywords: Heparin-functionalized; Chitosan; Alginate; Scaffold; Basic fibroblast growth factor (bFGF);
A new micro/nanoencapsulated porphyrin formulation for PDT treatment by Daiana K. Deda; Adjaci F. Uchoa; Eduardo Caritá; Maurício S. Baptista; Henrique E. Toma; Koiti Araki (76-83).
The highly hydrophobic 5,10,15-triphenyl-20-(3-N-methylpyridinium-yl)porphyrin (3MMe) cationic species was synthesized, characterized and encapsulated in marine atelocollagen/xanthane gum microcapsules by the coacervation method. Further reduction in the capsule size, from several microns down to about 300–400 nm, was carried out successfully by ultrasonic processing in the presence of up to 1.6% Tween 20 surfactant, without affecting the distribution of 3MMe in the oily core. The resulting cream-like product exhibited enhanced photodynamic activity but negligible cytotoxicity towards HeLa cells. The polymeric micro/nanocapsule formulation was found to be about 4 times more phototoxic than the respective phosphatidylcholine lipidic emulsion, demonstrating high potentiality for photodynamic therapy applications.
Keywords: Cationic porphyrin; Polymeric encapsulation; PDT; HeLa cells;
Liposomal dexamethasone–diclofenac combinations for local osteoarthritis treatment by Inbar Elron-Gross; Yifat Glucksam; Rimona Margalit (84-91).
Conventional chronic and acute treatments for osteoarthritis (OA) are by oral NSAIDs (such as diclofenac) and intra-articular injected glucocorticosteroids (such as dexamethasone). In free form, diclofenac and dexamethasone generate severe adverse effects with risks of toxicity. To reduce these drawbacks, we investigated local injections of liposomal formulations for diclofenac and dexamethasone (each alone, and their combination). Bioadhesive liposomes carrying hyaluronan (HA-BAL) or collagen (COL-BAL) as their surface-anchored ligand were used for the task. Each drug alone or their combination showed high efficiency encapsulations (≥80%) and performance as slow-release depots (half-lives in the range of 1–3 days under the fastest conditions). Employing RIA and immunoblot assay techniques, it was verified that the encapsulated drugs retained their biological activities: inhibitions of Cyclooxygenases enzyme-activity (diclofenac) and of Cyclooxygenases protein-expression (dexamethasone). Using live-animal MRI, a single intra-articular injection of each liposome-drug(s) formulation sufficed to reduce knee joint inflammation in OA rats over a time span of 17 days, HA-BAL better than COL-BAL. The most effective treatment was by the combination of both drugs in HA-BAL, a single dose reducing the inflammation volume down to 12.9% from initial over that time span. We find all three HA-BAL formulations worthy of further studies.
Keywords: Liposome; Osteoarthritis; Diclofenac; Dexamethasone; Cyclooxygenase; MRI;
Facile fabrication of well-defined hydrogel beads with magnetic nanocomposite shells by Hongxia Liu; Chaoyang Wang; Quanxing Gao; Jianxin Chen; Biye Ren; Xinxing Liu; Zhen Tong (92-98).
Well-defined magnetic nanocomposite beads with alginate gel cores and shells of iron oxide (γ-Fe2O3) nanoparticles were prepared by self-assembly of colloidal particles at liquid–liquid interfaces and subsequent in situ gelation. Fe2O3 nanoparticles could spontaneously adsorb onto the water droplet surfaces to stabilize water-in-hexane emulsions. Water droplets containing sodium alginate were in situ gelled by calcium cations, which were released from calcium-ethylenediamine tetraacetic acid (Ca-EDTA) chelate by decreasing pH value through slow hydrolysis of d-glucono-δ-lactone (GDL). The resulting hybrid beads with a core–shell structure were easily collected by removing hexane. This facile and high efficient fabrication had a 100% yield and could be carried out at room temperature. Insulin microcrystal was encapsulated into the hybrid beads by dispersing them in the aqueous solution of alginate sodium in the fabrication process. The sustained release could be obtained due to the dual barriers of the hydrogel core and the close-packed inorganic shell. The release curves were nicely fitted by the Weibull equation and the release followed Fickian diffusion. The hybrid beads may find applications as delivery vehicles for biomolecules, drugs, cosmetics, food supplements and living cells.
Keywords: Alginate hydrogel bead; Magnetic nanoparticle; Core–shell structure; Self-assembly; Nanocomposite;
Effects of carriers on transgene expression from plasmids containing a DNA sequence with high histone affinity by Hiroyuki Kamiya; Satoki Fukunaga; Takashi Ohyama; Hideyoshi Harashima (99-103).
The intranuclear disposition of plasmid DNA is highly important for transgene expression. The effects of a left-handedly curved sequence with high histone affinity on transgene expression were examined in COS-7 cells with two kinds of carriers (Lipofectamine Plus and TransIT-LT1). Three plasmids containing the curved sequence at different positions were transfected. The transgene expression was affected by the position of the left-handedly curved sequence, and the sequence at appropriate locations enhanced the expression from plasmid DNAs. However, the position effects on the expression differed from those obtained by electroporation of the same plasmid DNAs in a naked form. In addition, the degree of expression enhancement seemed to depend on the carriers. These results suggest that the left-handedly curved sequence with high histone affinity could increase the transgene expression from a plasmid delivered with carriers.
Keywords: Left-handedly curved DNA; Histones; Plasmid DNA; Intranuclear disposition; Carriers;
Chitosan solutions and particles: Evaluation of their permeation enhancing potential on MDCK cells used as blood brain barrier model by Juliane Hombach; Andreas Bernkop-Schnürch (104-109).
It was the aim of the present study to investigate the potential of chitosan of different molecular weight in solution and as particles to enhance the transport into the brain. FITC-dextran 4 (FD4) transport with and without chitosans of different molecular weight across MDCK cell monolayers, a model for the blood brain barrier, was compared. In the following particles of chitosan exhibiting the most appropriate molecular weight were prepared and their particle size and stability were evaluated. Furthermore permeation studies, MDCK cell toxicity test and red blood cell lysis test were performed. The rank order for chitosan for permeation enhancement across MDCK cells was determined to be 20 kDa ∼ 150 kDa > 400 kDa ∼ 600 kDa. Moreover particles showed a higher permeation enhancement than the corresponding solution and the smaller the particles were the higher the permeation of FD4 was. All particles were stable for 72 h. Particles displayed increased MDCK cell toxicity and red blood cell lysis compared to chitosan in solution. The smaller the particles were, the higher their toxicity was. According to these results chitosan particles are more potent in absorption enhancement than chitosan solutions.
Keywords: Chitosan; MDCK; Permeation; Blood brain barrier; Nanoparticles;
Development of PMMA membranes functionalized with hydroxypropyl-β-cyclodextrins for controlled drug delivery using a supercritical CO2-assisted technology by M. Temtem; D. Pompeu; G. Jaraquemada; E.J. Cabrita; T. Casimiro; A. Aguiar-Ricardo (110-115).
Cyclodextrin-containing polymers have proved themselves to be useful for controlled release. Herein we describe the preparation of membranes of poly(methylmethacrylate) (PMMA) containing hydroxypropyl-β-cyclodextrins (HP-β-CDs) using a supercritical CO2-assisted phase inversion method, for potential application as drug delivery devices. Results are reported on the membrane preparation, physical properties, and drug elution profile of a model drug. The polymeric membranes were obtained with HP-β-CD contents ranging from 0 to 33.4 wt%, by changing the composition of the casting solution, and were further impregnated with ibuprofen using supercritical carbon dioxide (scCO2) in batch mode. The influence of the membrane functionalization in the controlled release of ibuprofen was studied by performing in vitro experiments in buffer solution pH at 7.4. The release of the anti-inflammatory drug could be tuned by varying the cyclodextrin content on the membranes.
Keywords: Membrane; Poly(methylmethacrylate); Cyclodextrin; Controlled drug release; Phase inversion; Supercritical CO2;
Micronization of silybin by the emulsion solvent diffusion method by Zhi-Bing Zhang; Zhi-Gang Shen; Jie-Xin Wang; Hai-Xia Zhang; Hong Zhao; Jian-Feng Chen; Jimmy Yun (116-122).
Micronized silybin particles were successfully prepared by emulsion solvent diffusion method. Uniform spherical and rod-shaped particles with a mean size of 2.48 and 0.89 μm could be obtained using sodium dodecyl sulfate (SDS) concentration of 0.1 wt% at 30 and 15 °C, respectively. The characterization of silybin particles by SEM and particle size distribution (PSD) indicated that with the increase of temperature from 15 to 30 °C, the as-prepared particles became bigger and had a tendency to turn into spherical shapes; with the increase of SDS concentration from 0.02 to 0.1 wt%, the span of PSD became narrower while the mean particle size kept almost unchanged. XRD patterns and FT-IR spectra showed that the spherical and rod-shaped silybin particles possessed decreased crystallinity; however, the chemical structure and components were similar to those of the commercial silybin powder. Dissolution tests demonstrated that both of the spherical and rod-shaped silybin particles exhibited significantly enhanced dissolution rate when compared to the commercial silybin powder.
Keywords: Silybin; Emulsion solvent diffusion; Poorly water-soluble drug; Amphiphilic compound; Morphology;
Synthesis of cationic derivatives of Quil A and the preparation of cationic immune-stimulating complexes (ISCOMs) by Hoang L. Pham; Benjamin P. Ross; Ross P. McGeary; P. Nicholas Shaw; Nigel M. Davies (123-133).
The aim of the study was to prepare cationic ISCOMs using cationic derivatives of the saponin Quil A. The polyamines ethylenediamine, spermidine and spermine were conjugated with the glucuronic acid moiety of Quil A. The aqueous solubility of the derivatives increased with decreasing pH, and the pK a values were between 6 and 7. The CMCs of the ionised derivatives were around 0.5–1.0 mg/mL. Using the method of hydration of freeze-dried monophase systems, the interaction of each of the Quil A derivatives with phosphatidylcholine and cholesterol, at a mass ratio of 4:4:2 and a pH of 3 and 7.4, was investigated. A few ISCOM-like structures were present in the systems prepared at pH 7.4, hence the ternary system of Quil A spermine derivative, phosphatidylcholine and cholesterol was further investigated at pH 7.4 using a variety of mass ratios. A relatively high number of cationic ISCOM-like structures were observed at the mass ratio of 6:2:2. These ISCOM-like structures were less homogeneous and more irregular in shape than ISCOMs prepared from unmodified Quil A. Colloidal particles with positive zeta potential were produced and may find application in the delivery of nucleic acids or anionic proteins.
Keywords: ISCOMs; Immune-stimulating complexes; Quil A; Quil A derivatives;
pH-sensitive properties of surface charge-switched multifunctional polymeric micelle by Kyung Taek Oh; Dongin Kim; Hyeon Hee You; Yong Sik Ahn; Eun Seong Lee (134-140).
A surface charge-switched polymeric micelle with a pH signal was developed as a drug-carrying nanovehicle for tumor targeting. The micelles (particle size: ∼85 nm), constructed from poly(l-lactic acid)-b-poly(ethylene glycol)-b-poly(l-lysine-Nɛ-(2,3-dimethyl maleic acid)) (PLA-b-PEG-b-PLys-DMA) and formed by self-assembly in an aqueous pH 7.4 solution, consisted of a hydrophobic core (PLA core) and two hydrophilic shells (PEG shell and PLys-DMA shell). An anionic charge can be built on the surface of the micelle at a physiological pH (∼pH 7.4) due to 2,3-dimethyl maleic acid (DMA). However, DMA becomes chemically dissociated from the micelle under mild acidic conditions (pH 6.5–7.0) such as that found in solid tumors, which results in the formation of a cationic surface due to the poly(l-lysine) (PLys). This pH-triggered switch in surface charge may enhance cellular uptake of micelles to solid tumors, via an adsorptive endocytotic pathway due to the electrostatic interaction between micelles and cells. In addition, blending of the poly(l-histidine) (polyHis) into the hydrophobic core provides a mechanism for endosomal pH-triggered drug-release from the polymeric micelle. These combined properties of the polymeric micelle may aid in tumor-specific drug accumulation and allow it to be used as an effective treatment for tumors.
Keywords: pH-responsive polymeric micelle; pH-triggered surface charge switching; 2,3-Dimethyl maleic aicd; Poly(l-histidine);
Hyperbranched polysiloxysilane nanoparticles: Surface charge control of nonviral gene delivery vectors and nanoprobes by Won Jin Kim; Adela C. Bonoiu; Teruaki Hayakawa; Cheng Xia; Masa-aki Kakimoto; Haridas E. Pudavar; Kwang-Sup Lee; Paras N. Prasad (141-152).
New hyperbranched polysiloxysilane (HBPS) materials containing terminal carboxylic acid and quaternary ammonium groups were designed and synthesized to obtain fluorescent-dye-encapsulated nanoparticles. These polymers exhibited desirable characteristics, including amphiphilicity for nanoparticle formation, and contained various terminal groups for surface-charge control on the nanoparticles or for further bioconjugation for targeted imaging. Nanoprobes composed of polysiloxysilane nanoparticles encapsulating two-photon dyes were also prepared for optical bioimaging with controlled surface charge density (zeta potential) for modulation of cellular uptake. Intracellular delivery of these structurally similar polysiloxysilane nanoparticles, with substantially different surface charges, was investigated using confocal and two-photon fluorescence microscopy as well as flow cytometry. Finally, the use of these nanoparticles as efficient gene delivery vectors was demonstrated by means of in vitro transfection study using β-galactosidase plasmid and pEGFP-N1 plasmid and the most efficient combination was obtained using HBPS-CN30:70.
Keywords: Polymer nanoparticle; Surface charge controllable nanoparticle; Nonviral gene delivery vector; Nanoprobe; Hyperbranched polysiloxysilane; Multi-photon cellular imaging;
Enhanced bioavailability of the poorly water-soluble drug fenofibrate by using liposomes containing a bile salt by Yaping Chen; Yi Lu; Jianming Chen; Jie Lai; Jing Sun; Fuqiang Hu; Wei Wu (153-160).
The main purpose of this study was to evaluate oral bioavailability of the poorly water-soluble drug fenofibrate when liposomes containing a bile salt were used as oral drug delivery systems. Liposomes composed of soybean phosphotidylcholine (SPC) and sodium deoxycholate (SDC) were prepared by a dry-film dispersing method coupled with sonication and homogenization. Several properties of the liposomes, including particle size, entrapment efficiency and membrane fluidity, were extensively characterized. In vitro release experiments indicated that no more than 20% of total fenofibrate was released from SPC/cholesterol (CL) and SPC/SDC liposomes at 2 h, in contrast with near complete release for micronized fenofibrate capsules. Strikingly, in vivo measurements of pharmacokinetics and bioavailability demonstrated higher rates of fenofibrate absorption from both SPC/SDC and SPC/CL liposomes than micronized fenofibrate. The bioavailability of SPC/SDC and SPC/CL liposomes was 5.13- and 3.28-fold higher, respectively, than that of the micronized fenofibrate. The disparity between oral bioavailability and in vitro release for liposomes strongly suggests alternative absorption mechanisms rather than enhanced release. Importantly, SPC/SDC liposomes exhibited a 1.57-fold increase in bioavailability relative to SPC/CL liposomes, indicating that liposomes containing bile salts may be used to enhance oral bioavailability of poorly water-soluble drugs.
Keywords: Liposome; Bile salt; Sodium deoxycholate; Fenofibrate; Oral; Bioavailability;
Synthesis, characterization, drug-loading capacity and safety of novel octyl modified serum albumin micelles by Jian Gong; Meirong Huo; Jianping Zhou; Yong Zhang; Xiaoling Peng; Di Yu; Hui Zhang; Jing Li (161-168).
A novel albumin derivative octyl modified serum albumin (OSA) which can form a core–shell structure in aqueous media by self-assembling due to core segregation and a combination of intermolecular forces has been synthesized. The chemical structure and physical properties of OSA were characterized by FTIR, 1H NMR and TG. The degree of substitution (DS) was in the range of 52.4–69.7% and 48.9–65.8% determined by elemental analysis and fluorescamine assay, respectively. With the increase in the DS of octyl group, the critical micelle concentration (CMC) decreased from 30.1 to 14.7 mg/L because of the increasing hydrophobicity. In the light of the hydrophobic core as a microreservoir for poorly water-soluble drugs, paclitaxel (PTX) was successfully loaded into OSA micelles by the dialysis method with a high drug-loading (33.1 wt%) and entrapment efficiency (90.5%) due to the synergistic effect of micellar encapsulation and binding interaction between drug and OSA. Compared with PTX-loaded unmodified BSA preparation, PTX-loaded OSA micelles are characterized by small size, narrow size distribution, great drug-loading capacity and enhanced stability. The size of PTX-loaded micelles was in the range of 123.3–152.8 nm and smaller than their corresponding blank micelles. Hemolysis and cytotoxicity studies showed that OSA was safer than Tween-80 and Cremophor EL as an injectable pharmaceutic adjuvant for PTX. In terms of the greater drug-loading capacity and safer character, the novel albumin derivative OSA is a prospective injectable delivery system for PTX.
Keywords: Octyl modified serum albumin (OSA); Polymeric micelles; Paclitaxel; Drug-loading; Hemolysis; Cytotoxicity;
Nanoparticle formation from probucol/PVP/sodium alkyl sulfate co-ground mixture by C. Wanawongthai; A. Pongpeerapat; K. Higashi; Y. Tozuka; K. Moribe; K. Yamamoto (169-175).
Nanoparticles of a poorly water-soluble drug, probucol, have been obtained by co-grinding with PVP and SDS. The purpose of this study was to investigate the effect of the alkyl chain length of sodium alkyl sulfates (CnS, n = 6, 8, 12, 16 and 18) on probucol nanoparticle formation. From the results of particle size determination and quantitative measurement of nanoparticle fraction of probucol by HPLC, it was found that the alkyl chain length of the sodium alkyl sulfate affected the probucol nanoparticle formation. The efficiency, based on the quantitative determination of nanoparticles, was in the order: C18S > C16S > C12S > C8S > C6S. Probucol nanoparticles of less than 800 nm were effectively produced (more than 95%) with the increase of the amount of surfactants. 13C solid-state NMR of co-ground mixtures showed a new peak originating from the probucol interaction with PVP together with the existence of probucol crystal peaks. Excess amounts of surfactants were expected to play an important role for stabilizing the probucol nanoparticles in the suspension via the electrostatic repulsive effect.
Keywords: Nanoparticles; Grinding; Solid-state NMR; Probucol; Surfactants; Polyvinylpyrrolidone;
Paclitaxel-loaded Pluronic P123/F127 mixed polymeric micelles: Formulation, optimization and in vitro characterization by Zhang Wei; Junguo Hao; Shi Yuan; Yajuan Li; Wu Juan; Xianyi Sha; Xiaoling Fang (176-185).
The objective of this study was to optimize and characterize a novel polymeric mixed micelle composed of Pluronic P123 and F127 loaded with paclitaxel (PTX). A Doehlert matrix design was utilized to investigate the effect of four variables, namely P123 mass fraction, amount of water, feeding of PTX and hydration temperature on the responses including drug-loading coefficient (DL %), encapsulation ratio (ER %) and the percentage of PTX precipitated from the drug-loaded mixed micelles after 48 h at 37 (PTX precipitated %) for improvement of drug solubilization efficiency and micelle stability. PTX-loaded P123/F127 mixed micelles were prepared by thin-film hydration method. The optimized formulation showed a particle size of about 25 nm with ER % > 90%, and a sustained release behavior compared to Taxol. Micelle formation was confirmed by NMR spectroscopy. The mixed micelles had a low CMC of 0.0059% in water. In addition, micelle stability studies implied that introduction of Pluronic F127 (33 wt%) into P123 micelle system significantly increased the stability of PTX-loaded micelles. More importantly, in vitro cytotoxicity was assessed using human lung adenocarcinoma cell lines SPC-A1 and A-549 and was compared to Taxol and the free drug. The cell viability assay against A-549 cells exhibited the 50% inhibition concentration (IC50) of PTX-loaded P123/F127 mixed micelles (0.1 μg/ml) was much lower than those of Taxol injection (0.4 μg/ml) and the free PTX (1.7 μg/ml). Therefore, PTX-loaded P123/F127 mixed micelles may be considered as an effective anticancer drug delivery system for cancer chemotherapy.
Keywords: Polymeric micelles; Paclitaxel; Pluronic; Doehlert matrix design;
Chemical stability and phase distribution of all-trans-retinol in nanoparticle-coated emulsions by Nasrin Ghouchi Eskandar; Spomenka Simovic; Clive A. Prestidge (186-194).
The influence of silica nanoparticle coating on the chemical stability and phase distribution of all-trans-retinol in submicron oil-in-water emulsions is reported. The chemical stability was studied as a function of UVA + UVB irradiation, and storage temperature (4 °C, ambient temperature, and 40 °C) for emulsions stabilised with lecithin and oleylamine as the initial emulsifier with and without silica nanoparticle layers. The chemical stability of all-trans-retinol was highly dependent on the emulsifier type and charge, with negligible influence of the initial loading phase of silica nanoparticles. A significant stability improvement (∼2-fold increase in the half-life of the drug) was observed by nanoparticle incorporation into oleylamine-stabilised droplets (i.e. electrostatically coated), with no considerable effect for partially coated lecithin-stabilised droplets. The chemical stability of all-trans-retinol incorporated into nanoparticle-coated emulsions was well-correlated to the phase distribution of the active agent, and the interfacial structure of emulsions as determined by freeze fracture-SEM. Specifically engineered nanoparticle layers can be used to enhance the chemical stability of active ingredients in emulsion carriers.
Keywords: O/W emulsion; All-trans-retinol; Silica nanoparticles (Aerosil®380); Chemical stability improvement; Interfacial tension; Contact angle;
Optimization of epirubicin nanoparticles using experimental design for enhanced intravesical drug delivery by Li-Ching Chang; Shu-Chin Wu; Jen-Wei Tsai; Tsan-Jung Yu; Tong-Rong Tsai (195-203).
The aim of this study was to develop poly(ethyl-2-cyanoacrylate) (PECA) epirubicin-loaded nanoparticles (EPI-NP). A 23 factorial design was adopted with the type of surfactant, surfactant concentration and the pH of the polymerization medium as independent variables. The particle size, entrapment efficacy and polydispersity index of eight formulations were then evaluated. Two optimal EPI-NP formulations, 2% Tween 80 EPI-NP (TW80 EPI-NP) and 0.5% pluronic F68 EPI-NP (F68 EPI-NP) at pH 2.5 were developed. The sizes of TW80 EPI-NP and F68 EPI-NP at maximum intensity were 90 and 220 nm, respectively. Both TW80 EPI-NP and F68 EPI-NP showed potent cytotoxicity against human bladder cancer T24 and RT4 cells, compared with aqueous solutions of epirubicin (EPI-AQ). The penetration and accumulation of EPI-NPs in pig urothelium were studied by tissue concentration-depth profiles and fluorescence microscopy. The cumulative amounts of epirubicin following EPI-AQ, TW80 EPI-NP and F68 EPI-NP treatments were 842.48 ± 24.66, 1314.66 ± 33.07 and 595.21 ± 24.16 μg, respectively. The current study showed the successful development of urothelium adhesive and penetrative PECA EPI-NPs. This has potential for the in vivo application of epirubicin-loaded nanoparticles for intravesical instillation in bladder cancer therapy.
Keywords: Epirubicin; Nanoparticles; Bladder cancer; Intravesical instillation;
Advantages of celecoxib nanosuspension formulation and transformation into tablets by Andrej Dolenc; Julijana Kristl; Saša Baumgartner; Odon Planinšek (204-212).
Drugs with low aqueous solubility and high permeability (BCS class II) present a high proportion of all drugs. This study examines the critical issues regarding engineering of a nanosuspension tailored to increase drug dissolution rate and its transformation into dry powder suitable for tabletting. Nanosuspensions of celecoxib, a selective COX-2 inhibitor with low water solubility, were produced by the emulsion-diffusion method using three different stabilizers (Tween® 80, PVP K-30 and SDS) and characterized by particle size analysis, dissolution testing, scanning electron microscopy imaging, differential scanning calorimetry and X-ray powder diffraction. Spray-dried nanosuspension was blended with microcrystalline cellulose, and compressed to tablets, and their tensile strength, porosity and elastic recovery of tablets were investigated. The selection of solvent and stabilizers is critical, firstly to achieve controlled crystallization and size, and secondly to increase the wettability of the hydrophobic drug. The crystalline nano-sized celecoxib alone or in tablets showed a dramatic increase of dissolution rate and extent compared to micronized. SEM images showed that the nanoparticle morphology was influenced by the choice of stabilizers. Celecoxib nanosuspension stabilized with PVP K-30 and SDS showed advantages over Tween® 80 due to sticking of the dried product and unexpected changes observed on DSC curves. Markedly lower compaction forces are needed for nano-sized compared to micro-sized celecoxib to produce tablets of equal tensile strength.
Keywords: Celecoxib; Nanoparticles; Emulsion-diffusion method; Cyclooxygenase 2 inhibitor; Dissolution; Particle engineering; Tablet; Spray drying; Oral administration;
Effect of gamma-ray irradiation on degradation of di(2-ethylhexyl)phthalate in polyvinyl chloride sheet by Rie Ito; Naoko Miura; Masaru Ushiro; Migaku Kawaguchi; Hiroko Nakamura; Hirofumi Iguchi; Jun-ichi Ogino; Manabu Oishi; Nobuyuki Wakui; Yusuke Iwasaki; Koichi Saito; Hiroyuki Nakazawa (213-218).
The risk assessment of di(2-ethylhexyl)phthalate (DEHP) migration from polyvinyl chloride (PVC) medical devices is an important issue for patients. The aim of this study was to determine DEHP degradation and migration from PVC sheets. To this end, the method for the simultaneous determination of DEHP and its breakdown products (mono(2-ethylhexyl)phthalate (MEHP) and phthalic acid (PA)) was improved. Their migration levels from 0 to 50 kGy gamma-ray irradiated PVC sheets were determined. DEHP migration level decreased in proportion to the dose of gamma-ray irradiation, while MEHP and PA migration levels increased. The hardness and the elastic modulus of PVC sheets were examined, but no clear relationship between DEHP migration and these parameters was observed.
Keywords: Liquid chromatography tandem mass spectrometry (LC–MS/MS); Di(2-ethylhexyl)phthalate (DEHP); Plasticizer; Gamma ray; Degradation;