International Journal of Pharmaceutics (v.316, #1-2)
Editorial Board (iii).
Evaluation of Inutec SP1 as a new carrier in the formulation of solid dispersions for poorly soluble drugs by Guy Van den Mooter; Ilse Weuts; Thomas De Ridder; Norbert Blaton (1-6).
Solid dispersions made up of itraconazole and Inutec SP1, a new polymeric surfactant, were prepared by spray drying and hot-stage extrusion. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) were used to evaluate the miscibility of the components of the dispersions, and dissolution experiments were performed in simulated gastric fluid without pepsin (SGFsp) to evaluate the pharmaceutical performance of itraconazole from the solid dispersions. DSC analysis showed that the solid dispersions are phase separated systems made up of glassy and crystalline itraconazole and amorphous Inutec SP1. The amount of crystalline drug substance was higher in the dispersions prepared by hot-stage extrusion and was clearly a function of the drug concentration. Since no crystallinity could be detected by XRD points to the fact that the crystallites formed are very small in size. Despite the presence of glassy and crystalline clusters, the dissolution properties of the solid dispersions were significantly improved in comparison to pure itraconazole (glassy or crystalline) or physical mixtures with Inutec SP1. This study proves the potential of the new polymeric surfactant as a carrier in the formulation of solid dispersions for poorly soluble drugs.
Keywords: Itraconazole; Solid dispersions; Inutec SP1; Spray drying; Hot-stage extrusion;
Isothermal titration calorimetry and 1H NMR studies on host–guest interaction of paeonol and two of its isomers with β-cyclodextrin by De-Zhi Sun; Ling Li; Xiao-Mei Qiu; Feng Liu; Bao-Lin Yin (7-13).
Thermodynamic parameters of inclusion complex of β-cyclodextrin (β-CD) with paeonol and two of its isomers in aqueous solution have been determined with nano-watt-order isothermal titration calorimetry (ITC) and the host–guest inclusion structure has been investigated by using 1H NMR spectra at 298.2 K. The analysis of thermodynamic data reveals that stoichiometry of β-CD complex with paeonol (Pae) or acetovanillone (Ace) is 1:1 whereas the inclusion complex of β-CD with 2-hydroxyl-5-methoxyacetophone (Hma) is in 1:1 coexistence with 2:1 stoichiometry. Further analysis indicates that formation of all the complexes is simultaneously driven by enthalpy and entropy, the inclusion complexation of Pae·β-CD, Ace·β-CD and Ham·β-CD2 is predominantly driven by entropy while Ham·β-CD by enthalpy. The 1H NMR spectra data provide clear evidence of the inclusion phenomena, which shows that the aromatic ring of the guest molecule insert itself into the torus from the narrow side of the cavity.
Keywords: β-Cyclodextrin; Paeonol; Molecular recognition; 1H NMR; Isothermal titration calorimetry;
Strategies for the design of hydrophilic matrix tablets with controlled microenvironmental pH by Stefanie Siepe; Barbara Lueckel; Andrea Kramer; Angelika Ries; Robert Gurny (14-20).
Incorporation of weak acids as pH modifiers enhances the release of weakly basic drugs in higher pH environments by reducing the microenvironmental pH (pHM). The objectives of this study were: (a) to investigate the relationship between pHM, drug release, and pH modifier release and (b) to achieve simultaneous release of the drug and the pH modifier over the entire dissolution time (6 h, phosphate buffer, pH 6.8). Using dipyridamole as a model drug, we investigated drug and acid release and determined the average pHM potentiometrically using tablet cryosections. The first approach was based on incorporating different concentrations of pH modifiers in conventional matrix tablets based on hydroxypropylmethylcellulose. Owing to its high acidic strength and low aqueous solubility, fumaric acid resulted in simultaneous release and maintained a constant acidic pHM. Secondly, press-coated matrix tablets, comprising an acidic reservoir, were found to be a valuable approach for retarding the diffusion of more water-soluble acids. Using the power law expression (M t /M ∞ = kt n ) it became evident that the inclusion of acids increased drug release. Higher acid concentrations tended to decrease n standing for the slope, whereas the release constant k increased. Furthermore, the medial check term parameters depended on the type of pH modifier used.
Keywords: Weakly basic drug; Dipyridamole; Microenvironmental pH; pH modifier; HPMC;
Drug delivery matrices based on scleroglucan/alginate/borax gels by Pietro Matricardi; Ilenia Onorati; Tommasina Coviello; Franco Alhaique (21-28).
The aim of this work is to obtain a new drug delivery matrix, especially designed for protein delivery, based on biodegradable and biocompatible polymers, and to describe its main physico-chemical properties. A polysaccharide based semi-interpenetrating polymer network (semi-IPN) was built up, composed by sodium alginate chains interspersed into a scleroglucan/borax hydrogel network. Tablets were obtained by compression of the resulting freeze-dried hydrogel. The different release and physico-chemical properties possessed by the two starting polymers in various aqueous media were combined in the new matrix. In this work, description is given of the in vitro ability of the matrix to deliver in a controlled manner a protein, Myoglobin, in distilled water, simulated gastric fluid and simulated intestinal fluid; the release, simulating a gastric passage, followed by an enteric delivery, was also carried out. Water uptake data, colorimetric experiments and scanning electron microscopy images are given for the characterization of this new solid dosage form; the importance of the borax presence is also discussed.
Keywords: Scleroglucan; Alginate; Solid dosage form; Hydrogel; Modified release; Semi-IPN;
Physicochemical characteristics and bioavailability of a novel intestinal metabolite of ginseng saponin (IH901) complexed with β-cyclodextrin by Pung Sok Lee; Jin-Yi Han; Tae Won Song; Jong Hwan Sung; Oh-Seung Kwon; Sukgil Song; Youn Bok Chung (29-36).
In an effort to improve the bioavailability (BA) of the insoluble compound 20-O-(β-d-glucopyranosyl)-20(S)-protopanaxadiol (IH901), we prepared β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complexes containing IH901. IH901 is a major metabolite formed by intestinal bacteria from protopanaxadiol ginseng saponins. We developed and validated an HPLC-based method to measure IH901 levels from samples prepared in vitro. The phase solubility profiles with both cyclodextrins (CDs) were classified as AL-type, indicating the formation of a 1:1 stoichiometric inclusion complex. Stability constants (K s) calculated from the phase solubility diagrams showed that the βCD complex was more stable than the HPβCD complex. Consequently, complexes of IH901 and βCD were prepared by a freeze-drying method and were analyzed by fourier transformation-infrared spectroscopy (FT-IR), X-ray diffraction, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). From these physicochemical characterizations, we confirmed the presence of a new solid phase in the freeze-dried samples. The IH901 released from the complex in a pH 1.2 solution, the pH range of gastric fluids, was considerably lower than the amount released in the other solutions. The IH901 released from the complex in pH 6.8 solution, the range of intestinal fluids, was 9.0-fold greater than pure IH901 powder. However, the amount of IH901 released from the complex in pH 4.0–8.0 was less than 20%. After oral administration of the IH901–βCD inclusion complex (30 mg/kg IH901) into rats, plasma concentrations were determined by LC/MS/MS. The peak concentration (C max) for the inclusion complex was 2.8-fold higher than that for pure IH901 powder. The BA, calculated from the ratio of the AUCoral to the AUCi.v., for the pure IH901 powder, the IH901–βCD physical mixture, and the inclusion complex was 3.52, 4.34, and 6.57%, respectively. These results indicate that the BA for the inclusion complex was 1.9-fold higher than that for the pure IH901 powder.
Keywords: Ginseng saponin metabolite (IH901); Cyclodextrin; Inclusion complex; Phase solubility; Physicochemical characteristics; Pharmacokinetics; HPLC; LC/MS/MS;
Characterization of diffusion of macromolecules in konjac glucomannan solutions and gels by fluorescence recovery after photobleaching technique by Felipe Alvarez-Manceñido; Kevin Braeckmans; Stefaan C. De Smedt; Josepth Demeester; Mariana Landin; Ramón Martínez-Pacheco (37-46).
Konjac glucomannan (KGM) is a neutral polysaccharide with interesting properties as gelling agent and thickener. Its peculiar biodegradability, being not degradable in the small intestine but degradable by the anaerobic human intestinal bacteria, turn it into a promising candidate for colonic drug delivery systems. In this study aqueous systems (0.5%, w/v,) of KGM from three different origins and their mixtures with xanthan gum (XG) (1:1) were evaluated as regards their rheological properties and the diffusion coefficients and mobile fraction of macromolecules (dextrans of different molecular weight). Rheological data illustrate the synergism between KGM and XG at a stoichiometric relationship 1:1. Moreover, fluorescence recovery after photobleaching (FRAP) data indicate that diffusion of probes through the polysaccharide systems cannot be completely explained by the macroscopic properties of the medium but it is related to their molecular size and as a consequence to a sieving mechanism. The strong differences between KGM from different suppliers suggest the convenience of establishing specifications for this material in order to use it as pharmaceutical excipient.
Keywords: Konjac glucomannan; Xanthan gum; Fluorescence recovery after photobleaching; Colonic delivery; Diffusion coefficient; Rheology;
Effect of soluble filler on drug release from stearic acid based compacts by Bronagh U. Killen; Owen I. Corrigan (47-51).
Fatty acids are potentially suitable carriers for use in the design of drug delivery systems, being biocompatible, biodegradable, of low toxicity inexpensive, with drug release being approximately proportional to the square root of time. However, at low drug loadings, below the critical percolation threshold, release is likely to be extremely slow and incomplete. To overcome these problems, we have investigated the use of increasing amounts of the soluble filler lactose on drug release. Benzoic acid and insulin were used as model low and high molecular weight drugs, respectively. At a 10% loading, benzoic acid was an order of magnitude higher than that observed for insulin. Using lactose as soluble filler, it was possible to effect greater release with increasing lactose content in the range 10–50%. Values of F, the formation factor, increased, but not to the same extent as for increased drug loading. The Higuchi release rate constant, k, was similar at lactose loadings of 5–20%, but increased rapidly at higher lactose loadings. Quantitatively, the addition of lactose yielded release rate constants 1.2–3.6 times greater than the value for lactose-free compacts in the case of benzoic acid and two- to five-fold in the case of insulin. A linear relationship was demonstrated between k, and the percentage soluble fraction of the matrix above the percolation threshold.
Keywords: Drug release; Insulin; Benzoic acid; Stearic acid; Lactose filler;
Application of the ion pair concept to the n-octanol–water partitioning of cefepime and cefpirome by S.-A. Koufopoulou; C. Pistos; C. Giaginis; A. Tsantili-Kakoulidou (52-57).
The ion pair concept was applied for the assessment of lipophilicity of cefepime and cefpirome. Octanol–water distribution coefficients were determined in presence of different concentrations [X−] of sodium octanesulphonate. The log D x values within the linear part of the log D x/[X−] relationships were extrapolated to log D o values corresponding to the partitioning in absence of the counter ion. Measurements were feasible at pH values close to the isoelectric points of the acidic and basic functions. In that pH range the conduction of the experiments in presence of the hydrophobic counter anion facilitated the partitioning of the two cephalosporins to octanol, circumventing the problems arising from their high hydrophilicity. This procedure could not be applied at lower pH, possibly due to a further drastic decrease in the ‘intrinsic’ lipophilicity or to reduced ion pairing potential of octanesulphonate, and at higher pH due to the disruption of the zwitterionic structure. Extrapolated log D o values were compared to actual log D measurements performed for a reference quinolinium compound and for cefpirome. Extrapolated retention factors log k w close to the isoelectric point were also determined by reversed phase HPLC and compared to the log D o values.
Keywords: Cefepime; Cefpirome; Zwitterion; Ion pair; Octanol–water partitioning; Liquid chromatography;
Facilitated skin penetration of lidocaine: Combination of a short-term iontophoresis and microemulsion formulation by Amnon C. Sintov; Roy Brandys-Sitton (58-67).
The objective of this study was to demonstrate the potential of the application of a short-term iontophoresis on the topical delivery of lidocaine hydrochloride from a microemulsion-based system. Five- and 10-min durations of anodal iontophoresis applied onto porcine skin were examined in combination with a microemulsion containing 2.5% lidocaine hydrochloride. A similar combination (10-min iontophoresis with microemulsion in the anodal electrode) was also examined in vivo in a rat model. It was shown in vitro that by combining microemulsion application with a 10-min iontophoresis of 1.13 mA/cm2 electric current density, a significantly increased flux was obtained compared with a combination of aqueous drug solution with the same iontophoresis protocol. In vivo studies revealed that 57.71 ± 18.65 and 18.43 ± 9.17 μg cm−2 were reached in the epidermis and dermis, respectively, at t = 30 min of microemulsion application, when iontophoresis was applied for 10 min. In contrast, the application of aqueous solution-iontophoresis resulted in a relatively lower drug accumulation (21.44 ± 10.42 and 5.30 ± 2.25 μg cm−2 in the epidermis and dermis, respectively, at t = 30) with more rapid clearance of the drug from the skin. Ten-minute application of a low-current electric field on a new topical microemulsion appears to make significant changes in skin permeability. The potential advantages of this procedure include significantly increased flux, accumulation of a large skin drug depot, short lag times, reduced irritation (compared to long-term iontophoresis), simplicity and ease of compliance.
Keywords: Microemulsion; Iontophoresis; Percutaneous penetration; Topical delivery; Lidocaine;
Synthesis and study of controlled release of ibuprofen from the new acrylic type polymers by Mirzaagha Babazadeh (68-73).
New acrylic type polymeric systems having degradable ester bonds linked to ibuprofen were synthesized and evaluated as materials for drug delivery. Methacryloyloxy(2-hydroxy)propyl-4-isobutyl-α-methylphenyl acetate (MOPE), a new methacrylic derivative of ibuprofen in which the drug is separated from the methacrylic backbone by an oxy(2-hydroxy)propylene spacer arm and hydrolytically labile ester bond, was synthesized from reaction of glycidyl methacrylate with ibuprofen. The resulting drug containing monomer was copolymerized with methacrylamide, 2-hydroxyethyl methacrylate, N-vinyl-2-pyrrolidone or n-butyl methacrylate by free radical polymerization method in N,N-di-methylformamide (DMF) solution, utilizing azobisisobutyronitrile as initiator at the temperature range 65–70 °C. The obtained polymers were characterized by FT-IR, 1H NMR and 13C NMR spectroscopy. Gel permeation chromatography (GPC) was used for determination of average molecular weights of drug–polymer conjugates and showed that the polydispersity indices of the polymers are in the range of 1.9–2.3. Drug release studies were performed by hydrolysis in buffered solutions (pH 1 and 8) at 37 °C. Detection of hydrolysis by UV spectroscopy at selected interval showed that the drug can be released by selective hydrolysis of the ester bond at the side of drug moiety. The release profiles indicated that the hydrolytic behavior of polymeric prodrugs is strongly based on the hydrophilicity of polymer and the pH of the hydrolysis solution. The hydrophilic polymers containing ibuprofen were hydrolyzed in buffer solutions rather than the hydrophobic polymers.
Keywords: Ibuprofen; Acrylic polymers; Polymeric prodrugs; Controlled release;
Influence of rheological behaviour of particulate/polymer dispersions on liquid-filling characteristics for hard gelatin capsules by A. Kattige; G. Rowley (74-85).
Lactose/poloxamer dispersions were prepared by mixing under vacuum to achieve a de-aerated mix with good capsule filling properties and disperse phase uniformity at 70 °C. Satisfactory capsule filling of molten dispersions was achieved up to a limiting concentration of disperse phase, dependent on particle size distribution and continuous phase viscosity. Lactose/poloxamer dispersions exhibited thixotropic shear thinning behaviour with an abrupt increase in apparent viscosity above a limiting concentration of disperse phase. There was a good correlation between satisfactory filling of molten dispersions into capsules and apparent viscosity of the formulation, whereas, the pronounced increase in apparent viscosity resulted in unsatisfactory filling above a critical concentration of disperse phase. The rheological data was analysed in detail using empirical models and also used to identify capsule filling problems at extrudate shear rates for flow from hopper to pump (12 s−1) and from nozzle to capsule (340 s−1).
Keywords: Rheology; Capsule filling; Thixotropy; Poloxamer; Solid dispersion;
Novel sustained release, swellable and bioadhesive gastroretentive drug delivery system for ofloxacin by Mahesh D. Chavanpatil; Paras Jain; Sachin Chaudhari; Rajesh Shear; Pradeep R. Vavia (86-92).
Oral sustained release gastroretentive dosage forms offer many advantages for drugs having absorption from upper gastrointestinal tract and improve the bioavailability of medications that are characterized by a narrow absorption window. A new gastroretentive sustained release delivery system was developed with floating, swellable and bioadhesive properties. All these properties were optimized and evaluated. Various release retarding polymers like psyllium husk, HPMC K100M and a swelling agent, crosspovidone in combinations were tried and optimized to get the release profile for 24 h. Formulations were evaluated for in vitro drug release profile, swelling characteristics and in vitro bioadhesion property. The in vitro drug release followed Higuchi kinetics and the drug release mechanism was found to be of anomalous or non-Fickian type. For the developed formulation, the value of n was found to be 0.5766 while for the marketed formulation the value was 0.5718 indicating the anomalous transport. The high water uptake leading to higher swelling of the tablet supported the anomalous release mechanism of ofloxacin. The similarity factor f2 was found to be 91.12 for the developed formulation indicating the release was similar to that of the marketed formulation (Zanocin OD). The swelling properties were increased with increasing crosspovidone concentration and contributed significantly in drug release from the tablet matrix. The bioadhesive property of the developed formulation was found to be significant (P < 0.005) in combination as compared to HPMC K100M and psyllium husk alone.
Keywords: Ofloxacin; Gastroretentive delivery; Sustained release; Bioadhesion;
Application of aerosol solvent extraction system (ASES) process for preparation of liposomes in a dry and reconstitutable form by Sarinnate Kunastitchai; Lars Pichert; Narong Sarisuta; Bernd W. Müller (93-101).
The aerosol solvent extraction system (ASES) process was applied to prepare liposomes in a dry and reconstitutable form. Dry ASES microparticles containing miconazole (MCZ) as a model drug were prepared by an optimized ASES process with various compositions of spraying solution containing phosphatidylcholine, cholesterol, and Poloxamer 407. The influence of such compositions and the pH of hydration medium on the physico-chemical properties of the produced microparticles were investigated before and after hydration. At optimized conditions, partially crystalline, spherical, and nonporous microparticles associated in aggregates varying from a few microns to 40 μm were produced with the residual content of methylene chloride and methanol lower than 30 and 86 ppm, respectively. The percentage of drug recovered in the produced microparticles was increased with an increase of the drug concentration in the spraying solution. The entrapment efficiency of hydrated MCZ microparticles was improved by increasing the pH of the hydration medium.
Keywords: Supercritical carbon dioxide; Aerosol solvent extraction system; ASES; Liposomes;
Effects of pretreatment of needle puncture and sandpaper abrasion on the in vitro skin permeation of fluorescein isothiocyanate (FITC)-dextran by Xue-Ming Wu; Hiroaki Todo; Kenji Sugibayashi (102-108).
Microneedle systems have gained attention as having many advantages over transdermal patches and hypodermic needles. The procedure provides adequate skin permeation rates without pain or severe infection. To obtain information for designing a microneedle system, macroneedles were used instead of microneedles to investigate the effects of pretreatment of needle puncture in the skin barrier stratum corneum on in vitro skin permeation of fluorescein isothiocyanate (FITC)-dextrans (4.3, 9.6 and 42.0 kDa) (FD-4, FD-10 and FD-40). The effect of sandpaper abrasion was also investigated for comparison. Both pretreatments on the skin barrier significantly increased the skin permeation of FDs. Lactate dehydrogenase (LDH) leaching was measured after pretreatment of macroneedle and sandpaper abrasion on the skin to evaluate the skin damage by these pretreatment methods. Lower leaching of LDH was observed after macroneedle puncture than after sandpaper abrasion. Next, a parallel permeation-resistance model of the skin barrier was established. Skin permeation of FD-10 was predicted by the model as a function of the number of pores in the skin barrier. Our results suggest that needle puncture may provide a safe, efficient and controllable alternative for increasing transdermal drug delivery.
Keywords: Microneedle; Macroneedle; Sandpaper abrasion; Skin permeation; Penetration enhancement; LDH leaching;
Design, synthesis and gene delivery efficiency of novel oligo-arginine-linked PEG-lipids: Effect of oligo-arginine length by Masahiko Furuhata; Hiroko Kawakami; Kazunori Toma; Yoshiyuki Hattori; Yoshie Maitani (109-116).
The design, synthesis, and evaluation of in vitro gene delivery efficacy of a novel series of oligo-Arg-lipid conjugates are described. 3,5-Bis(dodecyloxy)benzamide (BDB) was employed as the lipid component, and a poly(ethylene glycol) (PEG) spacer was introduced between the C-terminal of oligo-Arg and the amide group of BDB. Four derivatives with various oligo-Arg lengths (ArgN-PEG-BDB; N = 4, 6, 8, 10: the number of arginine residues) were prepared, and the effect of oligo-Arg length on the gene transfection was investigated in HeLa cells. Transfection efficiency increased as the number of arginine residues increased. Arg10-PEG-BDB showed the highest transfection efficiency, without severe toxicity to cells. These findings well corresponded to the cellular association of the Arg-PEG-BDB/DNA complex determined by flow cytometry. Even in the presence of serum, Arg10-PEG-BDB achieved appreciable cellular association and attained high gene expression. Thus, Arg10-PEG-BDB is potentially a simple and useful gene delivery tool, because one need only to mix it with plasmid DNA and apply the complexes to the cells even in a serum-containing medium.
Keywords: Cell penetrating peptides; Oligo-arginine; Gene delivery;
Analysis of the molecular interaction between mannosylated proteins and serum mannan-binding lectins by Takeshi Terada; Makiya Nishikawa; Fumiyoshi Yamashita; Mitsuru Hashida (117-123).
The kinetics and specificity of the molecular interaction between proteins modified with varying numbers of mannose residues and isolated rabbit mannan-binding lectin (MBL) were characterized by using surface plasmon resonance spectroscopy (SPR). Mannosylated bovine serum albumin (Man-BSA) with different numbers of mannoses and other mannosylated derivatives of lysozyme (LZM), soybean trypsin inhibitor (STI), superoxide dismutase (SOD) and bovine γ-immunoglobulin (IgG) were synthesized. Rabbit MBL was isolated by affinity column chromatography and immobilized on the SPR sensor chip via avidin–biotin binding. Binding of Man-BSAs to immobilized rabbit MBL increased with an increase in the number of mannose residues, primarily due to the reduction in dissociation rate. On the other hand, the association rate constant was similar for five mannosylated proteins investigated, whereas the dissociation rate constant differed markedly in spite of the same degree of mannosylation. Specific binding of mannosylated proteins to MBL may depend on the number of mannose residues and their steric configurations.
Keywords: Serum mannan-binding lectins; Surface plasmon resonance; Mannosylated proteins; Intermolecular interaction;
Synergistic absorption enhancement of salmon calcitonin and reversible mucosal injury by applying a mucolytic agent and a non-ionic surfactant by Shinya Takatsuka; Takahiro Morita; Atsushi Koguchi; Yuji Horikiri; Hiroshi Yamahara; Hiroyuki Yoshino (124-130).
The present study investigated the intestinal absorption enhancement of salmon calcitonin (SCT) and the intestinal mucosal damage when a mucolytic agent and a non-ionic surfactant were administered simultaneously to rats. N-acetylcysteine (NAC) and p-t-octyl phenol polyoxyethylene-9.5 (Triton X®-100, TX-100) were chosen as the model mucolytic agent and the non-ionic surfactant, respectively. Dosing solutions containing these agents were administered directly into the rat jejunum, and the bioavailability of SCT up to 2 h was determined. NAC and TX-100, when they were used alone at a dose of 1 mg/head, did not show the apparent enhancement compared to the control. However, simultaneous use of NAC and TX-100 enhanced the intestinal absorption of SCT in a synergistic manner, and absolute bioavailability increased 12.5-fold compared to the control. The effect of NAC and TX-100 on SCT absorption was not dependent on their doses over the range of 0.2–2 mg/head, and the maximum effect was obtained at a dose of 1 mg/head. Absorption enhancement of SCT by a combination of NAC and TX-100 was compared to those from the classical absorption enhancers. Absorption-enhancing ability of the combination of NAC and TX-100 was significantly higher than those of sodium deoxycholate, citrate, and the combination of citrate and taurocholate, and was comparable with that of the combination of citrate and taurodeoxycholate. Finally, the intestinal mucosal damage caused by the combination of NAC and TX-100 was assessed using a capsule device. Acute damage on intestinal mucosa was observed when they were exposed into rat intestine, but this morphological damage was found to be reversible. All these results suggest that simultaneous use of a mucolytic agent and a non-ionic surfactant would offer a potentiality for peroral delivery of peptide drugs like SCT.
Keywords: Peroral delivery; Salmon calcitonin; Mucolytic agent; Non-ionic surfactant; Simultaneous use;
Emitted dose estimates from Seretide® Diskus® and Symbicort® Turbuhaler® following inhalation by severe asthmatics by Walid Y. Tarsin; Stanley B. Pearson; Khaled H. Assi; Henry Chrystyn (131-137).
Keywords: Diskus®; Turbuhaler®; Asthma; Electronic Lung™; Dose;
Nanoparticles in inflammatory bowel disease: Particle targeting versus pH-sensitive delivery by Yvette Meissner; Yann Pellequer; Alf Lamprecht (138-143).
Tacrolimus proved its distinct mitigating potential in the treatment of inflammatory bowel disease (IBD). Due to the risk for severe adverse effects and to achieve increased efficiency and tolerability, a selective delivery to the site of inflammation is of interest. Tacrolimus nanoparticles (NP) were tested for their efficiency in local treatment of inflamed bowel tissue in IBD. Drug loaded NP were prepared from either biodegradable poly(lactide-co-glycolide) (PLGA) or pH-sensitive Eudragit P-4135F by using a simple oil/water emulsification method. Tests on the therapeutic effect were conducted using dextran sulfate model colitis in mice receiving tacrolimus formulations daily for 12 days. Clinical activity score and myeloperoxidase activity decreased while colon length increased significantly after administration of all tacrolimus containing formulations. Oral NP formulations were less efficient in mitigating the experimental colitis compared to subcutaneous drug solution (PLGA: 7.88 ± 0.83; P-4135F: 7.48 ± 0.42; subcutaneous: 5.27 ± 0.68 U/mg) but superior to drug solution given by oral route (oral: 8.75 ± 1.34; untreated colitis control: 9.95 ± 0.92, all U/mg tissue). Tacrolimus solution groups (oral/subcutaneous) exhibited increased levels of adverse effects, whereas both NP groups demonstrated their potential to reduce nephrotoxicity. Both strategies showed similar mitigating effects while nephrotoxic adverse effects were slightly less expressed with pH-sensitive NP.
Keywords: Nanoparticles; Drug delivery; Inflammation; Colon delivery; Inflammatory bowel disease;
Intratracheal and subcutaneous liposomal VIP normalizes arterial pressure in spontaneously hypertensive hamsters by Israel Rubinstein; Hiroyuki Ikezaki; Hayat Önyüksel (144-147).
We determined whether a single intratracheal and subcutaneous administration of biocompatible and biodegradable vasoactive intestinal peptide self-associated with sterically stabilized liposomes (VIP-SSL) normalizes mean arterial pressure (MAP) in spontaneously hypertensive hamsters (SHH). We found that VIP-SSL (0.1 nmol) administered by either routes normalizes MAP (p < 0.05). Maximal effect was observed within 10–20 min and lasted for 6 h. VIP-SSL had no significant effects on heart rate. VIP alone (0.1 nmol) and empty SSL had no significant effects on MAP. VIP-SSL (0.1 nmol) had no significant effects on MAP and heart rate in age/genetically-matched control hamsters. Given these data, we suggest that pulmonary and subcutaneous delivery of VIP-SSL should be further developed as peptide nanomedicine for essential hypertension.
Keywords: Formulation; Drug delivery; DSPE-PEG; Sterically stabilized liposomes;
A folate receptor-targeted liposomal formulation for paclitaxel by Jun Wu; Qing Liu; Robert J. Lee (148-153).
A novel liposomal formulation of paclitaxel targeting the folate receptor (FR) was synthesized and characterized. This formulation was designed to overcome vehicle toxicity associated with the traditional Cremophor EL-based formulation and to provide the added advantages of prolonged systemic circulation time and selective targeting of the FR, which is frequently overexpressed on epithelial cancer cells. The formulation had the composition of dipalmitoyl phosphatidylcholine/dimyristoyl phosphatidylglycerol/monomethoxy-polyethylene glycol (PEG)2000-distearoyl phosphatidylethanolamine/folate-PEG3350-distearoyl phosphatidylethanolamine (DPPC/DMPG/mPEG-DSPE/folate-PEG-DSPE) at molar ratios of (85.5:9.5:4.5:0.5) and a drug-to-lipid molar ratio of 1:33. The liposomes were prepared by polycarbonate membrane extrusion. The mean particle size of the liposomes was 97.1 nm and remained stable for at least 72 h at 4 °C. FR-targeted liposomes of the same lipid composition entrapping calcein were shown to be efficiently taken up by KB oral carcinoma cells, which are highly FR+. FR-targeted liposomes containing paclitaxel showed 3.8-fold greater cytotoxicity compared to non-targeted control liposomes in KB cells. Plasma clearance profiles of paclitaxel in the liposomal formulations were then compared to paclitaxel in Cremophor EL formulation. The liposomal formulations showed much longer terminal half-lives (12.33 and 14.23 h for FR-targeted and non-targeted liposomes, respectively) than paclitaxel in Cremophor EL (1.78 h). In conclusion, the paclitaxel formulation described in this study has substantial stability and favorable pharmacokinetic properties. The FR-targeted paclitaxel formulation is potentially useful for treatment of FR+ tumors and warrants further investigation.
Keywords: Paclitaxel; Liposomes; Folate receptor; Targeted drug delivery; Cancer;
Preparation and characterization of mucoadhesive polymer-coated nanoparticles by Fuying Cui; Feng Qian; Chunhua Yin (154-161).
The transmucosal routes such as pulmonary, nasal and oral routes are most important and common routes for drug delivering to the body. However, peptide and protein drugs are degraded before they reach the blood stream and cannot cross the mucosal barriers. The mucoadhesive polymer-coated nanoparticles colloidal carriers can solve these problems. In the present investigation, mucoadhesive polymer-coated nanoparticles were prepared by emulsion polymerization process. A detailed preparation procedure of the mucoadhesive polymer-coated nanoparticles was provided. The parameters such as portion of the mucoadhesive polymers and concentration of the radical initiator were investigated. The resulting chitosan-coated nanoparticles colloids possessed positive surface charge, while poly(acrylic acid)-coated nanoparticles colloids and carbopol-coated nanoparticles colloids had negative surface charge. These nanoparticles were suitable for carrying hydrophilic protein or peptide drugs. Chitosan-coated nanoparticles were stable when pH value below 11, while poly(acrylic acid)-coated nanoparticles and carbopol-coated nanoparticles were stable under physiological pH conditions. Therefore, they are promising for transmucosal drug delivery.
Keywords: Nanoparticles; Mucoadhesive polymer-coated nanoparticles; Emulsion polymerization; Surface charge; Drug delivery;
Potential use of drug carried-liposomes for cancer therapy via direct intratumoral injection by Ande Bao; William T. Phillips; Beth Goins; Xiangpeng Zheng; Sarmad Sabour; Mohan Natarajan; F. Ross Woolley; Cristina Zavaleta; Randal A. Otto (162-169).
Liposomes have recognized advantages as nano-particle drug carriers for tumor therapy. In this study, the pharmacokinetics and distribution of intratumorally administered liposomes were investigated as drug carriers for treating solid tumors via direct intratumoral administration. 99mTc-liposomes were administered intratumorally to nude rats bearing human head and neck squamous cell carcinoma xenografts. Planar gamma camera images were analyzed to evaluate the local retention of the intratumorally administered liposomes. Co-registered pinhole micro-single photon emission computed tomography (SPECT)/computed tomography (CT) images were acquired of the whole animal as well as the dissected tumors to determine intratumoral distribution of the 99mTc-liposomes. For 99mTc-liposomes, there was an initial retention of 47.4 ± 11.0% (n = 4) in tumors and surrounding tissues. At 20 h, 39.2 ± 10.6% (n = 4) of 99mTc-activity still remained in the tumor. In contrast, only 18.7 ± 3.3% (n = 3) of the intratumoral 99mTc-activity remained for unencapsulated 99mTc-complex at 20 h. Pinhole micro-SPECT images demonstrated that 99mTc-liposomes also have a superior intratumoral 99mTc-activity diffusion compared with unencapsulated 99mTc-complex. Higher intratumoral retention of 99mTc-liposomes accompanied by an improved intratumoral diffusion suggests that intratumorally administered liposomal drugs are potentially promising agents for solid tumor local therapy.
Keywords: Liposomes; Intratumoral administration; Drug delivery; Nuclear imaging; Micro-SPECT; Micro-CT;
Elaboration and characterization of thiolated chitosan-coated acrylic nanoparticles by Irene Bravo-Osuna; Thierry Schmitz; Andreas Bernkop-Schnürch; Christine Vauthier; Gilles Ponchel (170-175).
The aim of the present work was to investigate the use of thiolated chitosan in the development of polysaccharide-coated nanoparticles in order to confer specific functionality to the system. After chemical modification of commercial and hydrolysed chitosan (400,000 and 9400 g/mol respectively), thiolated chitosans were used to elaborate particles in the nano-range. They were characterized in terms of size and surface charge measurement. Both analysis showed nanoparticles of mean hydrodynamic diameter around 200 nm and positive zeta potential values, indicating the presence of the cationic polysaccharide at the nanoparticle surface. Moreover, the Ellman's reaction was used to demonstrate the presence of thiol groups at the particle surface. The observation of nanoparticles by scanning electronic microscopy (SEM) showed spherical nanoparticles for all formulations. This new system, combining both the advantages of thiolated polymers and colloidal particles can be proposed as an original drug carrier system for mucosal delivery of biotechnology products.
Keywords: Thiolated chitosan; 2-Iminiothiolane (TBA); Nanoparticles; Poly(alkylcyanoacrylate); Emulsion radical polymerisation;