International Journal of Pharmaceutics (v.472, #1-2)
Editorial board (iii).
Self-assembled drug delivery systems. Part 7: Hepatocyte-targeted nanoassemblies of an adefovir lipid derivative with cytochrome P450-triggered drug release by Lina Du; Lailong Wu; Yiguang Jin; Junwei Jia; Miao Li; Yu Wang (1-9).
Display OmittedA novel strategy was used in the design of self-assembled drug delivery systems (SADDSs) in this study. The nanoassemblies of an amphiphilic adefovir lipid derivative were prepared and demonstrated to have the functions of hepatocyte targeting, enzyme-triggered drug release and high anti-hepatitis effect. An amphiphilic adefovir lipid derivative, N-lauroyl-1-(3-chlorophenyl)-1,3-propanyl phosphonyl adefovir (LCPA) was prepared and formed the nanoassemblies by injecting the mixture of LCPA and another amphiphilic polymer, d-galactide polyoxyethylene (20) cetyl ether (GPCE) (ca. 20:1, mol/mol) into water. The nanoassemblies were very stable and showed negative charge. LCPA was sensitive to the cytochrome P450 isozymes that were expressed predominantly in the hepatocytes to produce adefovir. GPCE contained a long hydrophilic chain and a galactose ligand targeting the asialoglycoprotein receptors overexpressed on the surface of hepatocytes. The nanoassemblies showed the long-circulating and liver targeting effects according to the results of pharmacokinetics, tissue distribution and fluorescence imagination after bolus intravenous administration of the nanoassemblies to the mice. The highly efficient hepatitis B treatment was achieved by 10 day continuous administration of the nanoassemblies to the HBV-infected mice. Many functions were combined in the nanoassemblies, including prodrug, molecular self-assembly, nanotechnology, long-circulating, hepatocyte targeting and hepatocyte over expressing enzyme-triggered drug release.
Keywords: Drug targeting; HBV; HepDirect; Molecular self-assembly; Nucleosides;
Development and characterization of mucoadhesive chitosan films for ophthalmic delivery of cyclosporine A by Kris Hermans; Dave Van den Plas; Sabina Kerimova; Robert Carleer; Peter Adriaensens; Wim Weyenberg; Annick Ludwig (10-19).
Display OmittedOcular chitosan films were prepared in order to prolong ocular delivery of cyclosporine A. The mucoadhesive films were prepared using the solvent casting evaporation method. A 24 full factorial design was used to evaluate the effect of 4 preparation parameters on the film thickness, swelling index and mechanical properties. Moreover, uniformity of content and in vitro drug release were investigated. Possible interactions between the film excipients were studied by FTIR analysis. In vitro experiments were performed in order to evaluate the cytotoxicity and anti-inflammatory activity of the chitosan films.Film thickness, water uptake, mechanical properties and in vitro release of cyclosporine A were dependent on film composition, especially on the amount of plasticizer. Lower drug release was measured from chitosan films containing a higher amount of plasticizer as glycerol decreased the swelling of chitosan films. FTIR spectra suggest a reorganization of hydrogen bonds between chitosan chains in the presence of glycerol and cyclodextrins. None of the film formulations showed significant cytotoxicity as compared to the negative control using human epithelial cells (HaCaT). Cyclosporine A dispersed in the various film formulations remained anti-inflammatorily active as significant suppression of interleukin-2 secretion in concanavalin A stimulated Jurkat T cells was measured.
Keywords: Chitosan; Films; Ocular; Cyclosporine A;
In vivo evaluation of an oral self-microemulsifying drug delivery system (SMEDDS) for leuprorelin by Fabian Hintzen; Glen Perera; Sabine Hauptstein; Christiane Müller; Flavia Laffleur; Andreas Bernkop-Schnürch (20-26).
Display OmittedThe objective of this study was to develop a self-microemulsifying drug delivery system (SMEDDS) for the model peptide drug leuprorelin to prove a protective effect against luminal enzymatic metabolism. In order to incorporate leuprorelin into microemulsion droplets (o/w), the commercially available hydrophilic leuprolide acetate was modified by hydrophobic ion paring with sodium oleate. The obtained hydrophobic leuprolide oleate was dissolved in the SMEDDS formulation (30% (m/m) Cremophor EL, 30% (m/m) Capmul MCM, 10% (m/m) propylene glycol and 30% (m/m) Captex 355) in a concentration of 4 mg/g showing a mean droplet size of 50.1 nm when dispersed in a concentration of 1% (m/v) in phosphate buffer pH 6.8. The microemulsion was able to shield leuprolide oleate from enzymatic degradation by trypsin and α-chymotrypsin, so that after 120 min 52.9% and 58.4%, respectively, of leuprolide oleate were still intact. Leuprolide acetate dissolved in an aqueous control solution was completely metabolized by trypsin within 60 min and by α-chymotrypsin within 5 min. Moreover, an in vivo study in rats showed a 17.2-fold improved oral bioavailability of leuprolide oleate SMEDDS compared to a leuprolide acetate control solution. This is the first time, to our knowledge, that hydrophobic ion pairing is utilized in order to incorporate a peptide drug in SMEDDS and evidence of a protective effect of oil-in-water (o/w) microemulsion droplets against enzymatic degradation of a peptide drug was provided. According to these results, the system could be likely a novel platform technology to improve the oral bioavailability of peptide drugs.
Keywords: Self-microemulsifying drug delivery system; Protection against enzymatic degradation; Leuprorelin; Hydrophobic ion pairing;
Controlled-release triple anti-inflammatory therapy based on novel gastroretentive sponges: Characterization and magnetic resonance imaging in healthy volunteers by Mina Ibrahim Tadros; Rania Hassan Fahmy (27-39).
Display OmittedThe current work aimed to develop novel composite sponges of chitosan (CH)–chondroitin sulfate (CS) as a low-density gastroretentive delivery system for lornoxicam (LOR). This triple anti-inflammatory therapy-loaded matrices are expected to expand and float upon contact with gastric fluids for prolonged times. CH and CS solutions (3%, w/w) were prepared, mixed in different ratios, lyophilized, coated with magnesium stearate and compressed. The CH:CS interpolymer complex (IPC) was evaluated via FT-IR, DSC, and XRD. The compressed-sponges were evaluated for appearance, structure, porosity, pore diameter, density, wetting-time, floating characteristics, adhesion-retention, and LOR-release. The gastroretentivity of the best achieved magnetite-loaded sponges was monitored in healthy volunteers via MRI. The interaction between CH (protonated amino groups) and CS (anionic carboxylate/sulfate groups) proved IPC formation. DSC and XRD studies confirmed loss of LOR crystallinity. The sponges possessed interconnecting porous-network structures. The porosity, mean pore diameter, and bulk density of CH:CS (10:3) IPC sponges were 11.779%, 25.4 nm, and 0.670 g/mL, respectively. They showed complete wetting within seconds, gradual size-expansion within minutes and prolonged adhesion for hours. Controlled LOR-release profiles were tailored over 12 h to satisfy individual patient needs. Monitoring of sponges via MRI proved their gastroretentivity for at least 5 h.
Keywords: Lornoxicam; Chitosan–chondroitin sulfate interpolymer complex; Triple anti-inflammatory therapy; Gastroretentive sponges; Magnetic resonance imaging;
Solid self-microemulsifying dispersible tablets of celastrol: Formulation development, charaterization and bioavailability evaluation by Xiaole Qi; Jiayi Qin; Ning Ma; Xiaohua Chou; Zhenghong Wu (40-47).
Display OmittedThe aims of this study were to choose a suitable adsorbent of self-microemulsion and to develop a fine solid self-microemulsifying dispersible tablets for promoting the dissolution and oral bioavailability of celastrol. Solubility test, self-emulsifying grading test, droplet size analysis and ternary phase diagrams test were performed to screen and optimize the composition of liquid celastrol self-microemulsifying drug delivery system (SMEDDS). Then microcrystalline cellulose KG 802 was added as a suitable adsorbent into the optimized liquid celastrol-SMEDDS formulation to prepare the dispersible tablets by wet granulation compression method. The optimized formulation of celastrol-SMEDDS dispersible tablets was finally determinated by the feasibility of the preparing process and redispersibility. The in vitro study showed that the dispersible tablets could disperse in the dispersion medium within 3 min with the average particle size of 25.32 ± 3.26 nm. In vivo pharmacokinetic experiments of rats, the relative bioavailability of celastrol SMEDDS and SMEDDS dispersible tablets compared to the 0.4% CMC-Na suspension was 569 ± 7.07% and 558 ± 6.77%, respectively, while there were no significant difference between the SMEDDS and SMEDDS dispersible tablets. The results suggest the potential use of SMEDDS dispersible tablets for the oral delivery of poorly water-soluble terpenes drugs, such as celastrol.
Keywords: Celastrol; Solid self-microemulsifying system (S-SMEDDS); Dispersible tablets; Oral bioavailability;
Sustained delivery of cytarabine-loaded vesicular phospholipid gels for treatment of xenografted glioma by Na Qi; Cuifang Cai; Wei Zhang; Yantao Niu; Jingyu Yang; Lihui Wang; Bin Tian; Xiaona Liu; Xia Lin; Yu Zhang; Yan Zhang; Haibing He; Kang Chen; Xing Tang (48-55).
Display OmittedThis study described the development of vesicular phospholipid gels (VPGs) for sustained delivery of cytarabine (Ara-C) for the treatment of xenografted glioma. Ara-C-loaded VPGs in the state of a semisolid phospholipid dispersion looked like numerous vesicles tightly packing together under the freeze-fracture electron microscopy (FF-TEM), their release profiles displayed sustained drug release up to 384 h in vitro. The biodistribution of Ara-C in the rat brain showed that Ara-C-loaded VPGs could maintain therapeutic concentrations up to 5 mm distance from the implantation site in brain tissue within 28 days. At the same time, fluorescence micrograph confirmed drug distribution in brain tissue visually. Furthermore, after single administration, Ara-C-loaded VPGs group significantly inhibited the U87-MG glioma growth in right flank in comparison with Ara-C solution (p < 0.01). It was explained that the entrapped drug in VPGs could avoid degradation from cytidine deaminase and sustained release of drug from Ara-C-loaded VPGs could maintain the effective therapeutic levels for a long time around the tumor. In conclusion, Ara-C-loaded VPGs, with the properties of sustained release, high penetration capacity, nontoxicity and no shape restriction of the surgical cavity, are promising local delivery systems for post-surgical sustained chemotherapy against glioma.
Keywords: Vesicular phospholipids gels; Cytarabine; Sustained release; Glioma; Local delivery;
Enhancement in corneal permeability of riboflavin using calcium sequestering compounds by Peter W.J. Morrison; Vitaliy V. Khutoryanskiy (56-64).
Display OmittedEthylenediaminetetraacetic acid, ethylenediamine-N,N′-disuccinic acid and ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid are polyaminocarboxylic acids that are able to sequester metal ions. Calcium is implicated in maintenance of intercellular matrix, zonula occludens (tight junctions) and zonula adherens of epithelium and endothelium cells. Corneal epithelium is impervious to many aqueous formulations due to it being lipophilic, whereby transcellular drug transit is resisted, whilst tight junctions restrict access via the paracellular route. Research has shown that integrity of tight junctions breaks down through loss of Ca2+ for endothelial and epithelial cells. This study investigates different Ca2+ sequestering compounds and their effect on corneal permeability of riboflavin at physiological pH. Riboflavin is a topically administered ocular drug applied during UV-induced corneal cross-linking for the treatment of keratoconus.
Keywords: Cornea; Epithelium; Calcium chelators; Permeability; Riboflavin; Ocular drug delivery;
A proposed model membrane and test method for microneedle insertion studies by Eneko Larrañeta; Jessica Moore; Eva M. Vicente-Pérez; Patricia González-Vázquez; Rebecca Lutton; A. David Woolfson; Ryan F. Donnelly (65-73).
Display OmittedA commercial polymeric film (Parafilm M®, a blend of a hydrocarbon wax and a polyolefin) was evaluated as a model membrane for microneedle (MN) insertion studies. Polymeric MN arrays were inserted into Parafilm M® (PF) and also into excised neonatal porcine skin. Parafilm M® was folded before the insertions to closely approximate thickness of the excised skin. Insertion depths were evaluated using optical coherence tomography (OCT) using either a force applied by a Texture Analyser or by a group of human volunteers. The obtained insertion depths were, in general, slightly lower, especially for higher forces, for PF than for skin. However, this difference was not a large, being less than the 10% of the needle length. Therefore, all these data indicate that this model membrane could be a good alternative to biological tissue for MN insertion studies. As an alternative method to OCT, light microscopy was used to evaluate the insertion depths of MN in the model membrane. This provided a rapid, simple method to compare different MN formulations. The use of Parafilm M®, in conjunction with a standardised force/time profile applied by a Texture Analyser, could provide the basis for a rapid MN quality control test suitable for in-process use. It could also be used as a comparative test of insertion efficiency between candidate MN formulations.
Keywords: Microneedles; Insertion tests; Polymeric films; Optical coherence tomography;
Oral sustained-release suspension based on a novel taste-masked and mucoadhesive carrier–ion-exchange fiber by Jing Yuan; Tiaotiao Liu; Heran Li; Tianyu Shi; Jie Xu; Hongzhuo Liu; Zhiguo Wang; Qifang Wang; Lu Xu; Yan Wang; Sanming Li (74-81).
Display OmittedThe purpose of this study was to evaluate the feasibility of ion-exchange fiber ZB-1 as a novel carrier in oral taste-masked mucoadhesive sustained-release suspensions. Propranolol (PPN) hydrochloride was selected as a model drug with good water solubility, short half life and bitter taste. The PPN-fiber complexes (PF) were prepared by a batch process and coated with Eudragit® RS100. Gamma scintigraphy was performed on fasted volunteers revealed about 30% ZB-1 and more than 50% coated ZB-1 were still remaining in the stomach at 6 h. In vitro results showed the releases of PF and coated PPN-fiber complexes (C-PF) were sustained. The release, drug content and particle size of C-PF were influenced by coat to core ratio, concentration of coating material and rotation rate. The suspension was stable after standing for 30 days in 0.5% Carbopol® with no release rate and taste changed. The administration of C-PF suspension to rats resulted a significant different (P < 0.05) improvement of the plasma drug level and prolongation of the release. However, because of the burst effect, the C max values of PF suspension didn't differ from drug solution (P > 0.05). Furthermore, a linear relationship between in vitro dissolution and in vivo absorption was observed.
Keywords: Ion-exchange fiber; Propranolol hydrochloride; Sustained-release suspension; Gamma scintigraphy; Mucoadhension; Taste masking;
Microfluidics-assisted engineering of polymeric microcapsules with high encapsulation efficiency for protein drug delivery by Jenni Pessi; Hélder A. Santos; Inna Miroshnyk; JoukoYliruusi; David A. Weitz; Sabiruddin Mirza (82-87).
Display OmittedIn this study, microfluidic technology was employed to develop protein formulations. The microcapsules were produced with a biphasic flow to create water–oil–water (W/O/W) double emulsion droplets with ultrathin shells. Optimized microcapsule formulations containing 1% (w/w) bovine serum albumin (BSA) in the inner phase were prepared with poly(vinyl alcohol), polycaprolactone and polyethylene glycol. All the particles were found to be intact and with a particle size of 23–47 μm. Furthermore, the particles were monodisperse, non-porous and stable up to 4 weeks. The encapsulation efficiency of BSA in the microcapsules was 84%. The microcapsules released 30% of their content within 168 h. This study demonstrates that microfluidics is a powerful technique for engineering formulations for therapeutic proteins.
Keywords: Microcapsules; Polycaprolactone; Microfluidics; Therapeutic proteins; Drug delivery;
Validation of the combined ATR-FTIR/tape stripping technique for monitoring the distribution of surfactants in the stratum corneum by Magdalena Hoppel; Dieter Baurecht; Evelyn Holper; Denise Mahrhauser; Claudia Valenta (88-93).
Display OmittedThe physical presence of surfactants in the skin is linked to their skin irritation potential. Combined ATR-FTIR spectroscopy and tape stripping experiments in vitro on porcine ear skin were used to investigate the spatial distribution of sodium lauryl ether sulfate (SLES) in the stratum corneum and to assess its effects on conformational order of stratum corneum intercellular lipids, secondary structure of keratin and skin hydration. It was possible to monitor the spatial distribution of SLES in the stratum corneum for the first time by subtracting spectra of untreated from treated skin samples and without the need of a perdeuterated form. This method of analysis was evaluated by addressing potential error sources such as differences in removed amounts of corneocytes and intra-individual changes in stratum corneum composition as a function of depth. The obtained results indicate a penetration of SLES into deep layers of the stratum corneum. Furthermore, SLES treatment led to significantly decreased skin hydration levels, whereas the secondary structure of keratin remained nearly unaffected. The reliability of this semi-quantitative method of analysis was confirmed by receiving a coefficient of determination of 0.9963 after making a correlation of deep depended absorbances of two different characteristic bands with different absorption coefficients.
Keywords: ATR-FTIR; Tape stripping; Sodium lauryl ether sulfate (SLES); Skin penetration; Skin hydration;
Chitosan-coated liposomes for topical vaginal therapy: Assuring localized drug effect by May Wenche Jøraholmen; Željka Vanić; Ingunn Tho; Nataša Škalko-Basnet (94-101).
Display OmittedThe choice of drug therapy in pregnant patients suffering from vaginal infections is limited by the safety profile of the drug. Assuring the efficient topical therapy to avoid systemic absorption is considered the best therapy option. Chitosan-coated liposomes have been developed and optimized to assure localized therapy of clotrimazole. Chitosan was selected as mucoadhesive polymer both to prolong system's retention at the vaginal site and act on biofilms responsible for high recurrence of infections. Sonicated liposomes were coated with chitosan in three different concentrations, namely 0.1, 0.3 and 0.6% (w/v). Clotrimazole-containing (22 μg/mg lipid) chitosan-coated liposomes were in the size range of 100–200 nm. The in vitro release studies confirmed prolonged release of clotrimazole from both non-coated and chitosan-coated liposomes as compared to control. The ex vivo penetration experiments performed on the pregnant sheep vaginal tissue showed that coated liposomes assured increased clotrimazole tissue retention and reduced its penetration as compared to the control. Mucin studies revealed that the coating with lower chitosan concentration increased the system's mucoadhesive potential, as compared to coating with higher concentrations. These results provide a good platform for further in vivo animal studies on mucoadhesive liposomes destined to localized vaginal therapy.
Keywords: Mucoadhesive liposomes; Vaginal therapy; Penetration; Pregnancy; Clotrimazole;
Fabrication of polyelectrolyte multilayered vesicles as inhalable dry powder for lung administration of rifampicin by Maria Letizia Manca; Donatella Valenti; Octavio Diez Sales; Amparo Nacher; Anna Maria Fadda; Maria Manconi (102-109).
Display OmittedA polyelectrolyte complex based on chitosan and carrageenan was used to coat rifampicin-loaded vesicles and obtain a dry powder for inhalation by spray-drying. The polymer complexation on vesicle surface stabilized them and improved their adhesion on airways and epithelia cells. Uncoated liposomes were small in size, negatively charged and able to incorporate large amounts of rifampicin (70%). Coated vesicles were still able to load adequate amounts of drug (∼70%) but the coating process produced larger particles (1 μm) that were positively charged and with a spherical shape. Aerosol performances, evaluated using the next-generation impactor, showed that coated vesicles reached the 50% of fine particle fraction and the smallest mass median aerodynamic diameter (2 μm). Rifampicin-loaded uncoated and coated vesicles slowly reduced the A549 cell viability over a 48-h incubation time. Moreover, in vitro coated formulations had a strong ability to be easily internalized and to greatly prolong the residence time of their components in A549 cells compared to uncoated liposomes that were rapidly internalized and just as quickly removed.
Keywords: Rifampicin; Coated liposomes; Chitosan; Carrageenan; Pulmonary delivery; Next-generation impactor;
Development of novel benznidazole formulations: Physicochemical characterization and in vivo evaluation on parasitemia reduction in Chagas disease by Ricardo Palmeiro-Roldán; Cristina Fonseca-Berzal; Alicia Gómez-Barrio; Vicente J. Arán; José A. Escario; Susana Torrado-Durán; Santiago Torrado-Santiago (110-117).
Display OmittedThis work aims to develop novel benznidazole (BZN) solid dispersions (SD) to improve its solubility and bioavailability properties. Low-substituted hydroxypropylcellulose (L-HPC) and sodium deoxycholate (NaDC) were evaluated as carriers. BZN solid dispersions containing different ratios of carrier were prepared by a freeze-drying process and characterized by SEM, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC) and dissolution studies. The reduced BNZ crystallinity in the new formulations was confirmed by XRD, and supported by DSC. BNZ:L-HPC solid dispersion at a 1:3 ratio (w/w) (SD-1:3 L-HPC) improved the BNZ dissolution rate (85% at 5 min) in comparison with BNZ raw material (23% at 5 min). However, NaDC formulations showed a prolonged release (24% at 30 min for SD-1:3 NaDC), due to the formation of a sustained release matrix in acidic medium. In vivo studies performed in a murine model of Chagas disease showed that the formulation achieving the highest parasitemia suppression at a low dose of 25 mg/kg/day after five days of treatment was SD-1:3 L-HPC (60% of parasitemia suppression versus 33% of suppression exerted by BNZ), suggesting that BNZ:L-HPC systems enhance the bioavailability of the drug.
Keywords: Benznidazole; Solid dispersions; Physicochemical characterization; Dissolution study; Trypanocidal activity;
Colloidal particles containing labeling agents and cyclodextrins for theranostic applications by Nadiah Zafar; Hatem Fessi; Abdelhamid Elaissari (118-129).
Display OmittedThis review aims to give to the reader some new light on cyclodextrin (CD)-based theranostic agents in order to complete our recently published review dedicated to CD-particles conjugates in drug delivery systems (Zafar et al., 2014). CDs are biocompatible sugar-based macrocycles used in a wide range of biomedical applications. Here, we mainly focus on fundamental theranostic approaches combining the use of cyclodextrin molecules and colloidal particles as theranostic agents. The system’s key features are discussed and a few recent pertinent applications are presented. CDs are used in order to enhance theranostic properties by providing apolar cavities for the encapsulation of hydrophobic moieties. Thus, CD molecules are used to enhance the loading capacity of particles by hosting active molecules. The relevance of CDs in enhancing the labeling properties of particles and the preparation of controlled drug release particles is also highlighted.
Keywords: Theranostics; Cyclodextrins; Encapsulation efficiency; Release rate; Pore control motifs;
A combined bottom–up/top–down approach to prepare a sterile injectable nanosuspension by Xi Hu; Xi Chen; Ling Zhang; Xia Lin; Yu Zhang; Xing Tang; Yanjiao Wang (130-139).
Display OmittedTo prepare a uniform nanosuspension of strongly hydrophobic riboflavin laurate (RFL) allowing sterile filtration, physical modification (bottom–up) was combined with high-pressure homogenization (top–down) method. Unlike other bottom–up approaches, physical modification with surfactants (TPGS and PL-100) by lyophilization controlled crystallization and compensated for the poor wettability of RFL. On one hand, crystal growth and aggregation during freezing was restricted by a stabilizer-layer adsorbed on the drug surface by hydrophobic interaction. On the other hand, subsequent crystallization of drug in the sublimation process was limited to the interstitial spaces between solvent crystals. After lyophilization, modified drug with a smaller particle size and better wettability was obtained. When adding surfactant solution, water molecules passed between the hydrophilic groups of surface active molecules and activated the polymer chains allowing them to stretch into water. The coarse suspension was crushed into a nanosuspension (MP = 162 nm) by high-pressure homogenization. For long term stability, lyophilization was applied again to solidify the nanosuspension (sorbitol as cryoprotectant). A slight crystal growth to about 600 nm was obtained to allow slow release for a sustained effect after muscular administration. Moreover, no paw-licking responses and very slight muscular inflammation demonstrated the excellent biocompatibility of this long-acting RFL injection.
Keywords: Nanosuspension; Physical modification; Controlled crystallization; Wettability; High-pressure homogenization;
Effect of crystal habits on the surface energy and cohesion of crystalline powders by Umang V. Shah; Dolapo Olusanmi; Ajit S. Narang; Munir A. Hussain; John F. Gamble; Michael J. Tobyn; Jerry Y.Y. Heng (140-147).
Display OmittedThe role of surface properties, influenced by particle processing, in particle–particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1 cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°. This is attributed to variations in surface chemical functionality at specific facets, and confirmed using X-ray photoelectron spectroscopy (XPS). Using a finite dilution inverse gas chromatography (FD-IGC) approach, the surface energy heterogeneity of powders was determined. The surface energy profile of different mefenamic acid crystal habits was directly related to the relative exposure of different crystal facets. Cohesion, determined by a uniaxial compression test, was also found to relate to surface energy of the powders. By employing a surface modification (silanisation) approach, the contribution from crystal shape from surface area and surface energy was decoupled. By “normalising” contribution from surface energy and surface area, needle shaped crystals were found to be ∼2.5× more cohesive compared to elongated plates or hexagonal cuboid shapes crystals.
Keywords: Crystal habit; Surface energy heterogeneity; Macroscopic single crystal; Solvent polarity; Crystal aspect ratio; Cohesion;
Stability of an anti-stroke peptide: Driving forces and kinetics in chemical degradation by Rui Li; Fengzhen Wang; Li Chen; Shuning Zhu; Lin Wu; Sunmin Jiang; Qunwei Xu; Dongya Zhu (148-155).
Display OmittedNR2B9c (Lys-Leu-Ser-Ser-Ile-Glu-Ser-Asp-Val) is a 9-amino acid peptide that has been illustrated to be a potential anti-stroke drug. For more effective treatment, suitable drug delivery systems should be developed. However, little is known about the stability of NR2B9c which is essential to its formulation. In this study, a reversed-phase high-performance liquid chromatography (HPLC) was applied to study the forced degradation behavior and stability of NR2B9c. HPLC studies were performed with an C8 column using a mobile phase consisting of acetonitrile (14.5:85.5, v/v) and aqueous solution (0.1% trifluoroacetic acid (TFA) and 0.05 M KH2PO4). The flow rate and the wavelength set during HPLC detection were 1.0 mL/min and 205 nm, respectively. The degradation pattern of NR2B9c aqueous solution followed pseudo first-order kinetics. The degradation rate at pH 7.5 was the slowest according to the plotting V-shaped pH-rate profile. The influence of temperature on the rate of reactions was interpreted in terms of Arrhenius equation (r 2 > 0.98). Thermodynamic parameters were calculated based on Eyring equation (r 2 > 0.98). The concentrations of drug, buffer species, buffer concentrations, oxidation and organic solvents have noticeable effects on the degradation of NR2B9c while ultrasound shows little impact under the experimental conditions. In a word, this study may give a detailed description of stability of NR2B9c.
Keywords: HPLC; Forced degradation; Stability; Solution;
The effect of palmitoylation on the conformation and physical stability of a model peptide hormone by Edoardo Longo; Emiliana De Santis; Rohanah Hussain; Christopher F. van der Walle; Jose Casas-Finet; Shahid Uddin; Ana Dos Santos; Giuliano Siligardi (156-164).
Display OmittedPeptides are ideal drug candidates due to their potency and specificity, but suffer from a short half-life and low membrane permeability. Acylation can overcome these limitations but the consequences to stability under different formulation conditions and stresses are largely unreported. Using synchrotron radiation circular dichroism (SRCD), we show that palmitoylation of a 28 amino acid peptide hormone (pI 9.82) induced a structural transition from 310-helix to α-helix, irrespective of buffer type and pH investigated (5.5–8.0) when compared to the non acylated analogues. These conformational preferences were retained in the presence of non-ionic micelles but not anionic micelles, which induced an α-helical structure for all peptides. Palmitoylation promoted an irreversible peptide denaturation under thermal stress at pH ≥ 6.5 and increased the propensity for loss of helical structure under high photon flux (here used as a novel accelerated photostability test). The presence of either ionic or non-ionic micelles did not recover these conformational changes over the same irradiation period. These results demonstrate that acylation can change peptide conformation and decrease thermal-/photo-stability, with important consequences for drug-development strategies.
Keywords: Vasoactive intestinal peptide; Circular dichroism; Photo-degradation; Conformation; Accelerated stability studies; Drug development;
Hybrid liposomal PEGylated calixarene systems as drug delivery platforms for curcumin by Elena Drakalska; Denitsa Momekova; Yana Manolova; Dessislava Budurova; Georgi Momekov; Margarita Genova; Liudmil Antonov; Nikolay Lambov; Stanislav Rangelov (165-174).
Display OmittedThe tremendous therapeutic potential of curcumin as a chemopreventive, antineoplastic and chemosensitizing agent has failed to progress towards clinical development and commercialization due to its unfavorable physicochemical properties, low aqueous solubility, chemical instability, and pharmacokinetics. The present contribution is focused on the feasibility of using PEGylated calixarene, in particular polyoxyethylene-derivatized tert-butylcalixarene, to prepare various platforms for delivery of curcumin such as inclusion complex, supramolecular aggregates, and hybrid liposomal systems. The inclusion complex is characterized by UV–vis and FT-IR spectroscopy as well as thermal gravimetrical analysis and differential scanning calorimetry. At concentrations exceeding the critical micellization concentration of PEGylated calixarene, the tremendous solubility enhancement of curcumin is attributed to additional solubilization and hydrophobic non-covalent interactions of the drug with supramolecular aggregates. A hybrid liposomal system is created via encapsulation of the inclusion complex in dipalmitoylphosphatidylcholine:cholesterol liposomes. Bare and liposomal curcumin:BEC-X inclusion complexes, as well as free curcumin were additionally investigated for cytotoxicity and apoptogenic activity against human tumor cell lines.
Keywords: Calixarenes; Curcumin; Inclusion complexes; Liposomes; Hybrid liposomal system; Cytotoxicity;
Anginex lipoplexes for delivery of anti-angiogenic siRNA by Afrouz Yousefi; Meriem Bourajjaj; Negar Babae; Paula I. van Noort; Roel Q.J. Schaapveld; Judy R. van Beijnum; Arjan W. Griffioen; Gert Storm; Raymond M. Schiffelers; Enrico Mastrobattista (175-184).
Display OmittedAngiogenesis is one of the hallmarks of cancer which renders it an attractive target for therapy of malignancies. Tumor growth suppression can be achieved by inhibiting angiogenesis since it would deprive tumor cells of oxygen and vital nutrients. Activation of endothelial cells of tumor vasculature is the first step in angiogenesis which is mediated by various factors. One of the major triggers in this process is vascular endothelial growth factor (VEGF) which binds to VEGF receptors on endothelial cells of tumor vessels. This induces a series of signaling cascades leading to activation of cellular processes involved in angiogenesis, and therefore down-regulation of VEGF receptor-2 (VEGFR-2) expression seems a viable option to inhibit angiogenesis. In our investigations, this aim has been pursued by using siRNA interfering with the expression of VEGFR-2. Since the discovery of RNA interference (RNAi) as a gene regulation process, successful delivery of small non-coding RNA has presented itself as a major challenge. In the current study, we have characterized a galectin-1 targeted anginex-coupled lipoplex (Angiplex) containing siRNA against the gene of VEGFR-2 as an angiostatic therapeutic. Angiplex particles had a size of approximately 120 nm with a net negative charge and were stable in vitro. These particles were internalized in a specific manner by HUVECs compared to a non-targeted lipoplex system, and their uptake was higher than Lipofectamine 2000. Gene silencing efficiency of Angiplex was shown to be 61%.
Keywords: siRNA; Nucleic acid delivery; Liposome; Lipoplex; Angiogenesis; Anginex;
Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs by Peng Zhang; Johan Forsgren; Maria Strømme (185-191).
Display OmittedOne attractive approach to increase the aqueous solubility and thus the bioavailability of poorly soluble drugs is to formulate them in their amorphous state since amorphous compounds generally exhibit higher apparent solubilities than their crystalline counterparts. In the current work, mesoporous magnesium carbonate was used to stabilise the amorphous state of the model substance ibuprofen. Crystallisation of the drug was completely supressed in the formulation, resulting in both a higher apparent solubility and a three times faster dissolution rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly soluble drugs.
Keywords: Mesoporous; Magnesium carbonate; Poorly soluble drug; Bioavailability; Ibuprofen;
A review of monitoring methods for pharmaceutical wet granulation by E.M. Hansuld; L. Briens (192-201).
High-shear wet granulation is commonly used in the pharmaceutical industry to improve powder properties for downstream processes such as tabletting. Granule growth, however, is difficult to predict because the process is sensitive to raw material properties and operating conditions. Development of process analytical technologies is encouraged by regulatory bodies to improve process understanding and monitor quality online. The primary technologies investigated for high-shear wet granulation monitoring include power consumption, near-infrared spectroscopy, Raman spectroscopy, capacitance measurements, microwave measurements, imaging, focused beam reflectance measurements, spatial filter velocimetry, stress and vibration measurements, as well as acoustic emissions. This review summarizes relevant research related to each of these technologies and discusses the challenges associated with each approach as a possible process analytical technology tool for high-shear wet granulation.
Keywords: Monitoring; Pharmaceuticals; Granulation; High-shear; Process analytical technologies;
Instability of bacteriophages in spray-dried trehalose powders is caused by crystallization of the matrix by Dieter Vandenheuvel; Joke Meeus; Rob Lavigne; Guy Van den Mooter (202-205).
Display OmittedSpray drying is a valuable technique in pharmaceutical dosage formulation, capable of producing amorphous, spherical powders, suitable for pulmonary deposition and further downstream processing. In this study, we show that spray drying bacteriophages together with trehalose results in an amorphous powder matrix with high glass transition temperature (between 116 and 118 °C), typical for amorphous trehalose. These powders are stable at low temperatures (4 °C) and relative humidity (0%). However, high humidity causes crystallization of the amorphous matrix, destroying the embedded phages. Furthermore, storage at higher temperature (25 °C) causes thermal instability of the embedded phages. The results show that storage conditions are important parameters to take into account in phage therapy development. The resulting particles are hollow spheres, with suitable aerodynamic diameters for deposition into the deep lungs. This opens possibilities to use these phage-containing powder formulations to tackle pulmonary infectious diseases, especially caused by antibiotic resistant pathogens.
Keywords: Bacteriophage; Crystallinity; Long-term Storage; Spray drying; Trehalose;
Enhancement of the in vitro penetration of quercetin through pig skin by combined microneedles and lipid microparticles by Roberto Paleco; Sonja R. Vučen; Abina M. Crean; Anne Moore; Santo Scalia (206-213).
Display OmittedSilicon microneedle patches were investigated, alone or in combination with lipid microparticles (LMs), as a system to improve the in vitro skin penetration of the antioxidant flavonoid, quercetin. LMs loaded with quercetin were prepared by melt emulsification and sonication. The flavonoid content of LMs was 11.7 ± 0.3% and their mean diameter and polydispersity index were 8.1 μm and 0.66, respectively. Emulsions containing quercetin, free or microencapsulated, were applied to untreated- or microneedle-treated pig skin mounted in Franz diffusion cells. The amount of flavonoid penetrated into the stratum corneum and viable epidermis were measured by HPLC, after validated tape-stripping and bead mill homogenization procedures, respectively. Compared to intact skin, a marked increase in quercetin levels permeated into the stratum corneum (from 1.19 ± 0.12 μg/cm2 to 2.23 ± 0.54 μg/cm2) and viable epidermis (from 0.10 ± 0.01 μg/cm2 to 0.56 ± 0.27 μg/cm2) was achieved when skin was treated with the flavonoid-loaded LMs in combination with microneedle arrays. Conversely, perforation of the cutaneous surface by microneedles did not produce any significant improvement in the skin penetration of non-encapsulated quercetin. The enhanced (5.5-fold) intra-epidermal delivery of quercetin attained by the LM/microneedle strategy described here, is particularly relevant since the main quercetin site of action is in the epidermis.
Keywords: Quercetin; In vitro skin penetration; Microneedles; Lipid microparticles;
Oral delivery of paclitaxel nanocrystal (PNC) with a dual Pgp-CYP3A4 inhibitor: Preparation, characterization and antitumor activity by Ketan Patel; Anand Patil; Miten Mehta; Vikram Gota; Pradeep Vavia (214-223).
Display OmittedSeveral molecular inheritances have severely restrained the peroral delivery of taxanes. The main objective of the present investigation was to develop a paclitaxel (PTX) formulation which can circumvent the hurdles of its extremely poor solubility and permeability, Pgp efflux and high pre-systemic metabolism. Positively charged PTX nanocrystals of 209 nm were prepared by sonoprecipitation with high pressure homogenization technique, wherein an arginine based surfactant was explored as a stabilizer. The BET surface area analysis revealed that the surface area of PNC was 8.53 m2/gm, reflecting significant rise in surface area with nanonization of PTX. The DSC and XRD pattern suggested that the PTX is in the form of the most stable dihydrate crystal. The PNC showed very rapid dissolution profile compared to plain PTX in both sinks and non-sink conditions. Clarithromycin (CLM) was evaluated as a better alternative to cyclosporin A in improving PTX permeability. The PNC-CLM showed remarkable enhancement of 453% in relative bioavailability along with maintaining the therapeutic concentration of PTX for 8 h. Efficacy data in B16 F10 melanoma tumor bearing mice showed substantial reduction in tumor volume and improvement in percentage survival compared to the control group.
Keywords: Paclitaxel; Oral delivery; Pgp inhibitors; Nanosuspension; Cationic nanoparticles; Oral anticancer;
Statistically designed nonionic surfactant vesicles for dermal delivery of itraconazole: Characterization and in vivo evaluation using a standardized Tinea pedis infection model by Neeraj Kumar; Shishu Goindi (224-240).
Display OmittedThe study aims to statistically develop a hydrogel of itraconazole loaded nonionic surfactant vesicles (NSVs) for circumventing the shortcomings and adverse effects of currently used therapies. Influential factors were screened using first-order Taguchi design, thereafter, optimization was performed via D-optimal design involving screened factors (surfactant type, content and molar ratio of cholesterol: surfactant). Response variables investigated were percent drug entrapment, vesicle size, drug skin retention and permeation in 6 h. Suspensions of NSVs were gelled to improve topical applicability. Characterization of formulations was performed using vesicle shape, size, surface charge, texture analysis and rheology behavior. Ex vivo studies in rat skin depicted that optimized formulation augmented drug skin retention and permeation in 6 h than conventional cream and oily solution of itraconazole. Standardized Tinea pedis model in Wistar rats exhibited in vivo antifungal efficacy of optimized formulation, observed in terms of physical manifestations, fungal-burden score and histopathological profiles. Also, a unique investigation involving studying local oxidative stress of infected paw skins as an indicator of fungal infection was performed. Rapid alleviation of infection in animals treated with optimized hydrogel was observed in comparison to commonly prescribed therapies. Therefore, the optimized NSVs may be a promising and efficient alternative to available antifungal therapies.
Keywords: Itraconazole; D-optimal; Optimization; Oxidative stress; Nonionic surfactant vesicles;
Solubility of crystalline organic compounds in high and low molecular weight amorphous matrices above and below the glass transition by zero enthalpy extrapolation by Youness Amharar; Vincent Curtin; Kieran H. Gallagher; Anne Marie Healy (241-247).
Display OmittedPharmaceutical applications which require knowledge of the solubility of a crystalline compound in an amorphous matrix are abundant in the literature. Several methods that allow the determination of such data have been reported, but so far have only been applicable to amorphous polymers above the glass transition of the resulting composites. The current work presents, for the first time, a reliable method for the determination of the solubility of crystalline pharmaceutical compounds in high and low molecular weight amorphous matrices at the glass transition and at room temperature (i.e. below the glass transition temperature), respectively.The solubilities of mannitol and indomethacin in polyvinyl pyrrolidone (PVP) K15 and PVP K25, respectively were measured at different temperatures. Mixtures of undissolved crystalline solute and saturated amorphous phase were obtained by annealing at a given temperature. The solubility at this temperature was then obtained by measuring the melting enthalpy of the crystalline phase, plotting it as a function of composition and extrapolating to zero enthalpy. This new method yielded results in accordance with the predictions reported in the literature.The method was also adapted for the measurement of the solubility of crystalline low molecular weight excipients in amorphous active pharmaceutical ingredients (APIs). The solubility of mannitol, glutaric acid and adipic acid in both indomethacin and sulfadimidine was experimentally determined and successfully compared with the difference between their respective calculated Hildebrand solubility parameters. As expected from the calculations, the dicarboxylic acids exhibited a high solubility in both amorphous indomethacin and sulfadimidine, whereas mannitol was almost insoluble in the same amorphous phases at room temperature.This work constitutes the first report of the methodology for determining an experimentally measured solubility for a low molecular weight crystalline solute in a low molecular weight amorphous matrix.
Keywords: Solubility; Amorphous; Polymer; Drug; Excipient; Thermal analysis;
Double barrier as an effective method for slower delivery rate of ibuprofen by Joanna Kurczewska; Dawid Lewandowski; Anna Olejnik; Grzegorz Schroeder; Izabela Nowak (248-250).
Display OmittedIbuprofen (IBU) was chosen as a model drug to investigate the drug delivery rate. Mesoporous MCM-41 has been charged with ibuprofen (MCM-41_IBU). Calcium alginate was applied to encapsulate free drug and the mesoporous material. The system with double barrier demonstrated a slower release of IBU than free ibuprofen-loaded alginate beads and MCM-41_IBU. The IBU release from alginate matrix can be controlled by adjusting the free IBU/MCM-41_IBU ratio.
Keywords: Alginate; MCM-41; Ibuprofen; Controlled release;
Establishment of powder dustiness evaluation method by dustmeter with small amount of pharmaceutical ingredients by Tomoaki Ohta; Hiroyuki Maeda; Ryuji Kubota; Akiko Koga; Katsuhide Terada (251-256).
Display OmittedThe ratio of high potent materials in the new chemical entities has recently increased in the pharmaceutical industry. Generally, most of them are highly hazardous, but there is little toxicity information about the active pharmaceutical ingredients in the early development period. Even if their handling amount is quite small, the dustiness of high potent powder generated in the manufacturing process has an important impact on worker health; thus, it is important to understand the powder dustiness.The purpose of this study was to establish a method to evaluate the powder dustiness by the consumption of small amount of samples. The optimized measurement conditions for a commercially available dustmeter were confirmed using lactose monohydrate and naproxen sodium.The optimized test conditions were determined: the dustmeter mode, the flow rate, the drum rotation speed, the total measurement time, and sample loaded weight were type I mode, 4 L/min, 10 rpm, 1 min and 1–10 g, respectively. The setup conditions of the dustmeter are considerably valuable to pharmaceutical industries, especially, at the early development stage and especially for expensive materials, because the amount of air-borne dust can be evaluated with accuracy by the consumption of small amount of samples.
Keywords: Powder dustiness; Heubach; Dustmeter; High potent material;
Effect of liquid crystals with cyclodextrin on the bioavailability of a poorly water-soluble compound, diosgenin, after its oral administration to rats by Masaki Okawara; Fumie Hashimoto; Hiroaki Todo; Kenji Sugibayashi; Yoshihiro Tokudome (257-261).
β-CD solution increases diosgenin and lipid release from LCs.Display OmittedDiosgenin, found in wild yam (Dioscorea villosa), has been shown to ameliorate diabetes and hyperlipidemia, increase cell proliferation in a human 3D skin model, and inhibits melanin production in B16 melanoma cells. It is also an active element in cosmeceutical and dietary supplements. Although the bioavailability of diosgenin is low due to its poor solubility and intestinal permeability, it was subsequently improved using a β-cyclodextrin (β-CD) inclusion complex. Recently liquid crystals (LCs) were shown to enhance the bioavailability of poorly water-soluble drugs. The purpose in the present study was to prepare diosgenin LCs and investigate the interaction between LC and β-CD in order to improve its bioavailability of diosgenin. Crystallinity and particle diameters of LCs in water were determined by small angle X-ray scattering (SAXS) and Zetasizer. Pharmacokinetic parameters were calculated using the plasma content of diosgenin after its oral administration to Wistar rats. Regarding the formation of glyceryl monooleate (GMO) and phytantriol (PHY) LC, SAXS patterns showed the hexagonal and cubic phases, respectively. Bioavailability was significantly enhanced after oral administration of LCs prepared by GMO than after diosgenin alone. The bioavailability was further improved with the combination of LC and β-CD than LC and water.
Keywords: Diosgenin; Liquid crystal; Glyceryl monooleate; Phytantriol; β-cyclodextrin; Oral administration;
Thermoresponsive polymers: Insights into decisive hydrogel characteristics, mechanisms of gelation, and promising biomedical applications by Maja Radivojša Matanović; Julijana Kristl; Pegi Ahlin Grabnar (262-275).
Display OmittedThermally induced gelling systems have gained enormous attention over the last decade. They consist of hydrophilic homopolymers or block copolymers in water that present a sol at room temperature and form a gel after administration into the body. This article reviews the main types of thermoresponsive polymers, with special focus on decisive hydrogel characteristics, mechanisms of gelation, and biocompatibility. Promising biomedical applications are described with a focus on injectable formulations, which include solubilization of small hydrophobic drugs, controlled release, delivery of labile biopharmaceutics, such as proteins and genes, cell encapsulation, and tissue regeneration. Furthermore, combinations of thermoresponsive hydrogels and various nanocarriers as promising systems for sustained drug delivery are discussed through selected examples from the literature. Finally, there is a brief overview of current progress in nano-sized systems incorporating thermoresponsive properties.
Keywords: Thermosensitive hydrogels; In situ forming systems; Controlled release; Protein delivery; Nanocarriers; Tissue regeneration;
A continuous flow method for estimation of drug release rates from emulsion formulations by Lotta Salmela; Clive Washington (276-281).
Display OmittedWe present a continuous-flow method that allows the release of drugs from submicron colloidal carriers to be estimated on a millisecond timescale. The technique is applied to the study of release of a model drug (tetracaine) from lipid emulsions, and shows that the solute drug is released in this timescale, and thus is primarily controlled by the rapid diffusion of the drug within the oil droplet. This confirms our previous claims that existing methods, such as dialysis or centrifugation, are too slow to provide useful release data for drug-containing emulsions, and demonstrates that it is unlikely that a simple emulsion could be used as a circulating sustained-release formulation, as has been suggested by some workers.
Keywords: Drug delivery; Emulsion; Drug release; Lipid; Colloid; Triglyceride;
Sulfobutylether-β-cyclodextrin/chitosan nano- and microparticles and their physicochemical characteristics by Zoltán Fülöp; Phennapha Saokham; Thorsteinn Loftsson (282-287).
Display OmittedMetastable polymer/cyclodextrin nano- and microparticles (NPs) were prepared from low molecular weight chitosan (CS), Mw about 10 kDa, and sulfobutylether β-cyclodextrin (SBEβCD). CS is a cationic polysaccharide containing numerous protonated amino groups (pK a about 6.5). SBEβCD is a β-cyclodextrin derivative with six to seven negatively charged sulfobutyl ether groups per cyclodextrin molecule. Ionotropic gelation technique was used to prepare the NPs. The NP matrix was composed of low molecular weight cationic CS polysaccharide cross-linked with polyvalent anions (SBEβCD). The diameter of the NPs ranged from 200 to almost 1000 nm and was controlled by the CS:SBEβCD molar ratio during NP preparation. Hydrocortisone (HC) is a lipophilic drug with limited aqueous solubility (0.3 mg/ml). HC displayed A L-type phase-solubility diagrams in aqueous solutions containing either SBEβCD or CS, although CS had negligible solubilizing effect. The ability of the NPs to encapsulate HC decreased with increasing CS concentration during preparation of the NPs even though the SBEβCD content of the NPs increased with increasing CS concentration. This decrease in HC encapsulation was related to the concentration; the ionic crosslinking provides better encapsulation at low initial SBEβCD and CS concentrations.
Keywords: Cyclodextrin; Chitosan; Nanoparticle; Complex; Drug delivery;
Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs by Kailas S. Khomane; Arvind K. Bansal (288-295).
Display OmittedIn the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3) kg f/cm2], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1 > I_S2 > I_S3 > II_S1 ≈ II_S2 ≈ II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to ‘granule hardening’ during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new ‘clean’ surfaces and higher contact points that negated the effect of granule hardening.
Keywords: Roller compaction; Polymorphism; Tabletability; Granule hardening; Clopidogrel bisulphate; Compressibility;
Near infrared spectroscopic (NIRS) analysis of drug-loading rate and particle size of risperidone microspheres by improved chemometric model by Jia Song; Jing Xie; Chenliang Li; Jia-hui Lu; Qing-fan Meng; Zhaogang Yang; Robert J. Lee; Di Wang; Le-sheng Teng (296-303).
Near infrared spectroscopy (NIRS) combined with radical basis function neural network (RBFNN) is successfully applied to monitor particle size and drug loading rate during risperidone poly(d,l-lactide-co-glycolide) (PLGA) microspheres preparation.Display OmittedMicrospheres have been developed as drug carriers in controlled drug delivery systems for years. In our present study, near infrared spectroscopy (NIRS) is applied to analyze the particle size and drug loading rate in risperidone poly(d,l-lactide-co-glycolide) (PLGA) microspheres. Various batches of risperidone PLGA microspheres were designed and prepared successfully. The particle size and drug-loading rate of all the samples were determined by a laser diffraction particle size analyzer and high performance liquid chromatography (HPLC) system. Monte Carlo algorithm combined with partial least squares (MCPLS) method was applied to identify the outliers and choose the numbers of calibration set. Furthermore, a series of preprocessing methods were performed to remove signal noise in NIR spectra. Moving window PLS and radical basis function neural network (RBFNN) methods were employed to establish calibration model. Our data demonstrated that PLS-developed model was only suitable for drug loading analysis in risperidone PLGA microspheres. Comparatively, RBFNN-based predictive models possess better fitting quality, predictive effect, and stability for both drug loading rate and particle size analysis. The correlation coefficients of calibration set (R c 2) were 0.935 and 0.880, respectively. The performance of optimum RBFNN models was confirmed by independent verification test with 15 samples. Collectively, our method is successfully performed to monitor drug-loading rate and particle size during risperidone PLGA microspheres preparation.
Keywords: Risperidone; Microspheres; Near infrared spectroscopy; Partial least squares; Radical basis function neural network;
Nano-transfersomal ciprofloxacin loaded vesicles for non-invasive trans-tympanic ototopical delivery: In-vitro optimization, ex-vivo permeation studies, and in-vivo assessment by Abdulaziz Mohsen Al-mahallawi; Omneya Mohammed Khowessah; Raguia Ali Shoukri (304-314).
Display OmittedCiprofloxacin is a synthetic fluoroquinolone antibiotic that has been used for systemic treatment of otitis media in adults. It was approved for topical treatment of otorrhea in children with tympanostomy tubes. The aim of this work was to enhance the local non-invasive delivery of ciprofloxacin to the middle ear across an intact tympanic membrane (TM) in an attempt to treat acute otitis media (AOM) ototopically. In order to achieve this goal, ciprofloxacin nano-transfersomal vesicles were prepared by thin film hydration (TFH) technique, using several edge activators (EAs) of varying hydrophilic–lipophilic balance (HLB) values. A full factorial design was employed for the optimization of formulation variables using Design-Expert® software. The optimal formulation was subjected to stability testing, ex-vivo permeation studies (through ear skin and TM of rabbits), and in-vivo evaluation. Results revealed that the optimal formulation (composed of phospholipid and sodium cholate as an EA at a molar ratio of 5:1) exhibited enhanced ex-vivo drug flux through ear skin and TM when compared with the commercial product (Ciprocin® drops). It demonstrated a greater extent of in-vivo drug deposition in the TM of albino rabbits relative to Ciprocin®. Consequently, transfersomes could be promising for the non-invasive trans-tympanic delivery of ciprofloxacin.
Keywords: Transfersomes; Thin film hydration; Acute otitis media; Ex-vivo tympanic membrane permeation; In-vivo drug deposition studies;
Carboxymethyl and hydrazide functionalized β-cyclodextrin derivatives: A systematic investigation of complexation behaviours with the model hydrophobic drug dexamethasone by Rabia Mateen; Todd Hoare (315-326).
Display OmittedCyclodextrins (CDs) are typically functionalized to increase their solubility or provide reactive functional groups suitable for grafting onto polymer supports designed for controlled release applications. In this work, a systematic investigation was performed on the binding behaviour of the model drug dexamethasone with βCD derivatives functionalized with a small, negatively charged moiety (carboxyl groups, CM) and a large, neutral, reactive moiety (hydrazide groups, Hzd), both free and grafted to dextran. Solubilization capacities and thermodynamic parameters were examined through phase solubility analysis, the method of continuous variation, and isothermal titration calorimetry. Alternate mechanisms of solubilization were also investigated by probing aggregation of both free and complexed βCD derivatives using nanoparticle tracking analysis. CM/βCD and Hzd/βCD derivatives exhibited similar complexation behaviours with dexamethasone: 1:1 stoichiometry, linear phase solubility profiles, and consistent binding enthalpies. Increased functionalization reduced the complex stability constant as well as the complexation efficiency, while polymer grafting resulted in no significant change in binding properties. CM/βCD derivatives complexed with dexamethasone formed more and larger aggregates, while Hzd/βCD derivatives formed significantly fewer, smaller aggregates and dextran-grafted βCD did not aggregate. Such characterization of βCD derivatives provides a framework for designing βCDs as pharmaceutical excipients or drug binding sites in drug delivery vehicles.
Keywords: Functionalized cyclodextrins; Dexamethasone; Inclusion complexes; Solubilization; Host–guest interactions; Binding parameters;
Nanostructured biocompatible thermal/electrical stimuli-responsive biopolymer-doped polypyrrole for controlled release of chlorpromazine: Kinetics studies by Ehsan Shamaeli; Naader Alizadeh (327-338).
Display OmittedBiocompatible nanostructured conductive heparin-doped polypyrrole film was fabricated and employed as a high-capacity cation exchanger for programmable release of neuroleptic drug, chlorpromazine (CPZ) with thermally and electrical dual-stimulation. Releasing behavior were studied at different applied potentials and temperatures by in-situ monitoring of UV absorbance measurements. Three mathematical models (Higuchi, Power, and Avrami equation) were employed to investigate kinetics of the release. Based on the obtained results, the Avrami model found to be more comprehensive than two other ones for mathematical description of electro-stimulated release of CPZ. A quantitative relationship between activation energy parameters (E a, ΔG≠, ΔH≠, and ΔS≠) and release conditions (applied potential and temperature) has been developed and established to predict release rate constants at various applied conditions.
Keywords: Drug delivery; Electrochemically controlled release; Release kinetics; Activation parameters; Dual stimuli-responsive polymer; Biopolymer-doped polypyrrole;
Utilization of microfluidic V-junction device to prepare surface itraconazole adsorbed nanospheres by Israfil Kucuk; Zeeshan Ahmad; Mohan Edirisinghe; Mine Orlu-Gul (339-346).
Display OmittedItraconazole is widely used as an anti-fungal drug to treat infections. However, its poor aqueous solubility results in low bioavailability. The aim of the present study was to improve the drug release profile by preparing surface itraconazole adsorbed polymethylsilsesquioxane (PMSQ) nanospheres using a V-junction microfluidic (VJM) device. In order to generate nanospheres with rough surface, the process flow rate of perfluorohexane (PFH) was set between 50 and 300 μl min−1 while the flow rate of PMSQ and itraconazole solution were constant at 300 μl min−1. Variations in the PFH flow rate enable the controlled size generation of nanospheres. PMSQ nanospheres adsorbing itraconazole were characterized by SEM, FTIR and Zetasizer. The release of itraconazole from PMSQ nanosphere surface was measured using UV spectroscopy. Nanosphere formulations with a range of sphere size (120, 320 and 800 nm diameter) were generated and drug release was studied. 120 nm itraconazole coated PMSQ nanospheres were found to present highest drug encapsulation efficiency and 13% drug loading in a more reproducible manner compared to 320 nm and 800 nm sized nanosphere formulations. Moreover, 120 nm itraconazole coated PMSQ nanospheres (encapsulation efficiency: 88%) showed higher encapsulation efficiency compared to 320 nm (encapsulation efficiency: 74%) and 800 nm (encapsulation efficiency: 62%) sized nanosphere formulations. The itraconazole coated PMSQ nanospheres were prepared continuously at the rate of 2.6 × 106 per minute via VJM device. Overall the VJM device enabled the preparation of monodisperse surface itraconazole adsorbed nanospheres with controlled in vitro drug release profile.
Keywords: Surface drug adsorbed; Nanospheres; Drug delivery; Itraconazole; V-junction microfluidic device;
Compaction properties of crystalline pharmaceutical ingredients according to the Walker model and nanomechanical attributes by M. Egart; I. Ilić; B. Janković; N. Lah; S. Srčič (347-355).
Display OmittedThis study investigates the extent to which single-crystal mechanical properties of selected active ingredients (famotidine, nifedipine, olanzapine, piroxicam) influence their bulk compressibility and compactibility. Nanomechanical attributes of oriented single crystals were determined with instrumented nanoindentation, and bulk deformational properties were assessed with the Walker and Heckel models as well as the elastic relaxation index. Good correlations were established between bulk and single-crystal plasticity parameters: the Walker coefficient and indentation hardness. The Walker model showed more practical value for evaluating bulk deformational properties of the APIs investigated because their properties differed more distinctly compared to the Heckel model. In addition, it was possible to predict the elastic properties of the materials investigated at the bulk level because a correlation between the elastic relaxation index and compliance was established. The value of using indentation hardness for crystalline APIs was also confirmed because their compactibility at the bulk level was able to be predicted. Mechanically interlocked structures were characteristic of most polymorphic forms investigated, resulting in single crystals having isotropic mechanical properties. It was revealed that in such cases good correlations between single and bulk mechanical properties can be expected. The results imply that innate crystal deformational properties define their compressibility and compactibility properties to a great extent.
Keywords: Compressibility; Compactibility; Nanoindentation; Walker coefficient; Indentation hardness; Young’s modulus;
Antimicrobial preservatives induce aggregation of interferon alpha-2a: The order in which preservatives induce protein aggregation is independent of the protein by Regina L. Bis; Krishna M.G. Mallela (356-361).
Display OmittedAntimicrobial preservatives (APs) are included in liquid multi-dose protein formulations to combat the growth of microbes and bacteria. These compounds have been shown to cause protein aggregation, which leads to serious immunogenic and toxic side-effects in patients. Our earlier work on a model protein cytochrome c (Cyt c) demonstrated that APs cause protein aggregation in a specific manner. The aim of this study is to validate the conclusions obtained from our model protein studies on a pharmaceutical protein. Interferon α-2a (IFNA2) is available as a therapeutic treatment for numerous immune-compromised disorders including leukemia and hepatitis C, and APs have been used in its multi-dose formulation. Similar to Cyt c, APs induced IFNA2 aggregation, demonstrated by the loss of soluble monomer and increase in solution turbidity. The extent of IFNA2 aggregation increased with the increase in AP concentration. IFNA2 aggregation also depended on the nature of AP, and followed the order m-cresol > phenol > benzyl alcohol > phenoxyethanol. This specific order exactly matched with that observed for the model protein Cyt c. These and previously published results on antibodies and other recombinant proteins suggest that the general mechanism by which APs induce protein aggregation may be independent of the protein.
Keywords: Interferon alpha-2a; Preservatives; Aggregation; Formulation; Benzyl alcohol; m-Cresol;
Vehicle influence on permeation through intact and compromised skin by Meera Gujjar; Ajay K. Banga (362-368).
Display OmittedThe purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10 mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p < 0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intact < microneedles < tape stripping < delipidization. A study with hairless rats comparing both vehicles found the same trend, with hydrophilic vehicle having greater delivery. In conclusion, phosphate buffered saline vehicle resulted in higher permeation into and across skin compared to mineral oil vehicle for all simulated models of compromised skin.
Keywords: Transdermal; Percutaneous; Vehicle; Compromised skin; Diclofenac;
Design of lipotomes as a novel dual functioning nanocarrier for bioavailability enhancement of lacidipine: In-vitro and in-vivo characterization by Nermeen Adel ElKasabgy; Ibrahim Elsayed; Ahmed Hassen Elshafeey (369-379).
Display OmittedLipotomes were designed to enhance lacidipine’s oral bioavailability by improving its solubility and enhancing the oral lymphatic uptake. Lipotomes were prepared using cetyl alcohol and Tween® 80 using a thin film hydration technique. Cetyl alcohol was chosen for imparting a lipophilic environment that would enforce the lymphatic uptake while Tween® 80 would improve drug solubility within the lipotomes. Lipotomes were characterized by analyzing their particle size, solubilization efficiency and in-vitro drug release. Central composite design was applied to statistically optimize the formulations using Design-Expert® software. The optimum formula (OLT) was made up of excipients:drug ratio of 36.59:1 w/w and Tween® 80:cetyl alcohol ratio of 4:1 w/w. OLT was lyophilized and filled into Eudragit® L100 enteric coated capsules. Mannitol (10% w/v) was the ideal cryoprotectant to retain the physicochemical characteristics of the OLT formulation after lyophilization. In conclusion, the selected lyophilized formula (L3) succeeded in enhancing drug’s oral bioavailability in human volunteers compared to the commercial product confirming the success of lipotomes as a novel oral nanocarrier for insoluble drugs having extensive first pass metabolism.
Keywords: Lipotomes; Lacidipine; Central composite; Lyophilization; Enteric coating;
Development and comparison of intramuscularly long-acting paliperidone palmitate nanosuspensions with different particle size by Donglei Leng; Hongming Chen; Guangjing Li; Mengran Guo; Zhaolu Zhu; Lu Xu; Yongjun Wang (380-385).
Display OmittedThe main purpose of this study was to develop and compare the pharmacokinetic behavior of two paliperidone palmitate (PP) nanosuspensions with different particle size after intramuscular (i.m.) administration. PP nanosuspensions were prepared by wet media milling method and the mean particle size of nanosuspension was controlled as 1041 ± 6 nm (A) and 505 ± 9 nm (B), respectively. The morphology of nanosuspensions was observed by scanning electron microscope (SEM). Differential scanning calorimeter (DSC) and powder X-ray diffraction (PXRD) confirmed the crystallinity of PP in nanosuspensions. The physical and chemical stabilities of nanosuspensions A and B were investigated by particle analyzer and HPLC after storage for 2 months at 25 °C, 4 °C and mechanical shaking condition. No obvious change in particle size and chemical degradation of drug were observed. Following single-dose i.m. administration to beagle dogs, the release of paliperidone lasted for nearly 1 month. The T max of nanosuspensions A and B was 6 (d) and 10 (d). The AUC0–t and C max of nanosuspensions A was 2.0-fold and 1.8-fold higher than nanosuspensions B (p < 0.05). The results demonstrated that PP nanosuspensions formulation had long-acting effect. Nanosuspension A with a larger particle size performed better than nanosuspension B. As a result, it is important to design appropriate particle size of nanosuspensions for i.m. administration in order to produce larger therapeutic effect.
Keywords: Paliperidone palmitate; Nanosuspensions; Pharmacokinetics; Particle size;