European Journal of Pharmaceutics and Biopharmaceutics (v.69, #1)
Nanoparticles for drug delivery: The need for precision in reporting particle size parameters
by Marie Gaumet; Angelica Vargas; Robert Gurny; Florence Delie (pp. 1-9).
Polymeric drug-loaded nanoparticles have been extensively studied in the field of drug delivery. Biodistribution depends on the physicochemical properties of particles, especially size. The global message from the literature is that small particles have an enhanced ability to reach their target. The present review highlights the difficulties in validating the data from biodistribution studies without accurate particle size determination.
Keywords: Nanoparticle; Biodistribution; Size determination; Drug carrier
Recent applications of Chemical Imaging to pharmaceutical process monitoring and quality control
by A.A. Gowen; C.P. O’Donnell; P.J. Cullen; S.E.J. Bell (pp. 10-22).
Chemical Imaging (CI) is an emerging platform technology that integrates conventional imaging and spectroscopy to attain both spatial and spectral information from an object. Vibrational spectroscopic methods, such as Near Infrared (NIR) and Raman spectroscopy, combined with imaging are particularly useful for analysis of biological/pharmaceutical forms. The rapid, non-destructive and non-invasive features of CI mark its potential suitability as a process analytical tool for the pharmaceutical industry, for both process monitoring and quality control in the many stages of drug production. This paper provides an overview of CI principles, instrumentation and analysis. Recent applications of Raman and NIR-CI to pharmaceutical quality and process control are presented; challenges facing CI implementation and likely future developments in the technology are also discussed.
Keywords: Chemical Imaging; Non-destructive; Pharmaceutical; Drug; Raman; NIR
A novel gene delivery system for stable transfection of thiopurine- S-methyltransferase gene in versatile cell types
by Roman Egle; Miha Milek; Irena Mlinarič-Raščan; Alfred Fahr; Julijana Kristl (pp. 23-30).
A novel gene delivery system termed artificial viral particles (AVPs) containing a plasmid coding for a recombinant fusion protein of enhanced green fluorescent protein (EGFP) with thiopurine- S-methyltransferase (TPMT) was designed for transfection of selected cell lines to establish stable clones which express recombinant EGFP–TPMT protein for further in vitro investigation of toxic effect of thiopurine drugs. Various AVPs based on a complex of the cationic polymer polyethylenimine (PEI) and anionic liposomes were formulated and transfection conditions were adapted in order to transfect the human Jurkat, HepG2 and HEK 293 cell lines. An adequate transfection rate was achieved with AVP containing branched low molecular weight PEI at a PEI:DNA charge ratio of 4.5:1 and liposomes composed of DOPS, DLPE, cholesterol and an activated N-glutaryl-DOPE membrane anchor. Stably transfected clones were successfully established and expression of recombinant EGFP–TPMT in homogeneous cell populations was demonstrated by flow cytometry, fluorescence microscopy and immunoblotting. The level of the expressed protein in stable clones was highest in HEK 293, followed by HepG2 and Jurkat. The enzymatic activity of the TPMT moiety was demonstrated by decreased sensitivity to 6-thioguanine and increased sensitivity to 6-mercaptopurine in HEK 293 cells expressing EGFP–TPMT. Formulation of AVP as transfection vector succeeded in establishing human cell lines stably expressing EGFP–TPMT, thereby proving a successful delivery system and providing an initial step to enable investigation of the role of the clinically important drug metabolizing enzyme TPMT.
Keywords: Artificial viral particle; TPMT; Non-viral vector; Transfection; Gene delivery; Plasmid DNA; Nanoparticles; Thiopurine-; S; -methyltransferase
Charged nanoparticles as protein delivery systems: A feasibility study using lysozyme as model protein
by Cuifang Cai; Udo Bakowsky; Erik Rytting; Andreas K. Schaper; Thomas Kissel (pp. 31-42).
The aim of this study was to investigate the feasibility of negatively charged nano-carriers (nanoparticles), consisting of polymer blends of poly(lactide-co-glycolide) (PLGA) and poly(styrene-co-4-styrene-sulfonate) (PSS), to improve the loading capacity and release properties of a positively charged model protein, lysozyme, through an adsorption process. Nanoparticles were prepared by a solvent displacement method and characterized in terms of size, ζ-potential, morphology, as well as loading capacity of model protein lysozyme. Morphology of these particles was investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The loading capacity of lysozyme was evaluated as a function of polymer blend ratio, protein concentration, pH, and ionic strength; in vitro release profiles were also studied. The results show that negatively charged nanoparticles were obtained using polymer blends of PLGA and PSS, characterized by increased net negative surface charge with increasing ratios of PSS. Moreover, protein loading capacity increased as function of PSS/PLGA ratio. Increased pH facilitated the adsorption process and improved the loading capacity. Maximum loading efficiency was achieved at salt concentrations of 50mM. In vitro release of lysozyme from the polymer blend nanoparticles was dependent on drug loading and full bioactivity of lysozyme was preserved throughout the process. These findings suggest that this is a feasible method to prepare nanoparticles with high surface charge density to efficiently adsorb oppositely charged protein through electrostatic interactions.
Keywords: Charged nanoparticles; Lysozyme; Electrostatic interaction; Protein delivery; Charge density
In vivo photodynamic activity of photosensitizer-loaded nanoparticles: Formulation properties, administration parameters and biological issues involved in PDT outcome
by Angelica Vargas; Michael Eid; Mohammed Fanchaouy; Robert Gurny; Florence Delie (pp. 43-53).
Encapsulation of hydrophobic photosensitizers (PS) into polymeric nanoparticles (NP) has proven to be an effective alternative to organic solvents for their formulation. As NP size controls NP passage through endothelial barriers, it is a key parameter for achieving passive targeting of cancer tissues and choroidal neovascularization, secondary to age-related macular degeneration, the main applications of photodynamic therapy. In the present study, a hydrophobic PS, the meso-tetra( p-hydroxyphenyl)porphyrin, was encapsulated into biodegradable NP made of poly(d,l-lactide-co-glycolide) 50:50 via an emulsification-diffusion technique. NP batches having mean diameters of 117, 285, and 593nm were obtained with narrow size distribution. Using the chorioallantoic membrane (CAM) of the developing chick embryo, it was demonstrated that the increase in the NP size decreased photodynamic activity in vivo. The activity of PS-loaded NP was not influenced by the volume of injection and was kept intact at least 6h after NP reconstitution. Investigation of NP circulation after IV administration by fluorescence measurements revealed that 117nm NP reached Tmax earlier than larger NP. Confocal imaging of CAM vessels demonstrated PS uptake by endothelial cells after NP administration. It was concluded that NP size controls the photodynamic activity of the encapsulated PS.
Keywords: Photodynamic therapy; Polymeric nanoparticles; Nanoparticle size; Chick chorioallantoic membrane (CAM) model; Photosensitizer; In vivo; Vascular occlusion; Endothelial cells; Age-related macular degeneration; Cancer
Magnetite/poly(alkylcyanoacrylate) (core/shell) nanoparticles as 5-Fluorouracil delivery systems for active targeting
by José L. Arias; Visitación Gallardo; M Adolfina Ruiz; Ángel V. Delgado (pp. 54-63).
In this article, a reproducible emulsion polymerization process is described to prepare core/shell colloidal nanospheres, loaded with 5-Fluorouracil, and consisting of a magnetic core (magnetite) and a biodegradable polymeric shell [poly(ethyl-2-cyanoacrylate), poly(butylcyanoacrylate), poly(hexylcyanoacrylate), or poly(octylcyanoacrylate)]. The heterogeneous structure of these carriers can confer them both the possibility of being used as drug delivery systems and the responsiveness to external magnetic fields, allowing an active drug targeting without a concurrent systemic distribution. Zeta potential determinations as a function of ionic strength showed that the surface behaviour of the core/shell particles is similar to that of pure cyanoacrylate particles. The first magnetization curve of both magnetite and magnetite/polymer particles demonstrated that the polymer shell reduces the magnetic responsiveness of the particles, but keeps unchanged their ferrimagnetic character. Two drug loading mechanisms were studied: absorption or entrapment in the polymeric network, and surface adsorption. We found that the acidity of the medium had significant effects on the drug absorption per unit mass of polymer, and needs to be controlled to avoid formation of macroaggregates and to reach significant 5-Fluorouracil absorption. The type of polymer and the drug concentration are also main factors determining the drug incorporation to the core/shell particles. 5-Fluorouracil release evaluations showed a biphasic profile affected by the type of polymeric shell, the type of drug incorporation and the amount of drug loaded.
Keywords: Active targeting; Controlled release; Drug delivery; 5-Fluorouracil; Magnetic carrier technology; Poly(alkylcyanoacrylates)
Incorporation in polymeric nanocapsules improves the antioxidant effect of melatonin against lipid peroxidation in mice brain and liver
by Scheila R. Schaffazick; Ionara R. Siqueira; Alessandra S. Badejo; Denise S. Jornada; Adriana R. Pohlmann; Carlos Alexandre Netto; Sílvia S. Guterres (pp. 64-71).
It has been recently shown that the association of melatonin with polymeric nanoparticles causes a significant increase of the in vitro effect against lipid peroxidation. Hence, the aim of the present study was to compare the in vivo acute antioxidant effect of intraperitoneal administration of melatonin-loaded polysorbate 80-coated nanocapsules with that of melatonin aqueous solution in mice brain (frontal cortex and hippocampus) and liver. The lipid peroxidation through thiobarbituric acid reactive substance levels, the total antioxidant reactivity (luminol-enhanced chemiluminescence) and the free radical levels (formed dichlorofluorescein) has been carried out. Our results show that a single melatonin aqueous solution injection exerted no antioxidant activity in the evaluated range, while the administration of the melatonin-loaded polysorbate 80-coated nanocapsules caused a marked reduction on lipid peroxidation levels in all studied tissues. No differences on free radical content were found in the tissues. The melatonin-loaded nanocapsules also increased the total antioxidant reactivity in the hippocampus. These in vivo results are in accordance with our previous in vitro findings and confirm the hypothesis that polymeric nanocapsules improve the antioxidant effect of melatonin against lipid peroxidation.
Keywords: Melatonin; Polymeric nanocapsules; Lipid peroxidation; Total antioxidant reactivity; Brain; Liver
Developing an environmentally benign process for the production of microparticles: Amphiphilic crystallization
by Darragh Murnane; Christopher Marriott; Gary P. Martin (pp. 72-82).
The production of microparticles for inhalation typically employs jet-milling which can be destructive to the solid-state properties of the particles. The objective of the current work was to develop a crystallization process for the production of respirable microparticles of salmeterol xinafoate (SX) with a controlled particle size distribution (PSD). Solvation of SX in aqueous poly(ethylene glycol) 400 (PEG 400) was investigated using HPLC and FTIR. SX was crystallized from PEG 400 solutions by the addition of water under a variety of conditions of supersaturation, addition rate of antisolvent and stirring speed. The crystals were filtered, dried at 50°C and their PSDs were determined by laser diffraction. A logarithmic increase in solubility of SX was observed with increasing concentration of PEG 400 in water enabling the aqueous antisolvent crystallization of SX from PEG. Similar to antisolvent crystallization from conventional solvents, a 24 factorial study showed the particle size to decrease with increasing supersaturation. The PSD also depended on the balance of meso- and micromixing determined by the crystallization conditions. In particular a high addition rate (200gmin−1) and low stirrer speed (400rpm) minimized the median diameter (2.54±0.40μm) and produced a narrow PSD (90%<8.67±0.77μm) of SX particles. Amphiphilic crystallization provided a novel, environmentally benign method to produce microparticles of SX with a controlled size range.
Keywords: Crystallization; Antisolvent micronization; Factorial design; Poly(ethylene glycol); Salmeterol xinafoate
Microspheres containing lipid/chitosan nanoparticles complexes for pulmonary delivery of therapeutic proteins
by Ana Grenha; Carmen Remuñán-López; Edison L.S. Carvalho; Begoña Seijo (pp. 83-93).
Chitosan/tripolyphosphate nanoparticles have already been demonstrated to promote peptide absorption through several mucosal surfaces. We have recently developed a new drug delivery system consisting of complexes formed between preformed chitosan/tripolyphosphate nanoparticles and phospholipids, named as lipid/chitosan nanoparticles (L/CS-NP) complexes. The aim of this work was to microencapsulate these protein-loaded L/CS-NP complexes by spray-drying, using mannitol as excipient to produce microspheres with adequate properties for pulmonary delivery. Results show that the obtained microspheres are spherical and present appropriate aerodynamic characteristics for lung delivery (aerodynamic diameters around 2–3μm and low apparent tap density of 0.4–0.5g/cm3). The physicochemical properties of the L/CS-NP complexes are affected by the phospholipids composition. Phospholipids provide a controlled release of the encapsulated protein (insulin), which was successfully associated to the system (68%). The complexes can be easily recovered from the mannitol microspheres upon incubation in aqueous medium, maintaining their morphology and physicochemical characteristics. Therefore, this work demonstrates that protein-loaded L/CS-NP complexes can be efficiently microencapsulated, resulting in microspheres with adequate properties to provide a deep inhalation pattern. Furthermore, they are expected to release their payload (the complexes and, consequently, the encapsulated macromolecule) after contacting with the lung aqueous environment.
Keywords: Chitosan nanoparticles; Dry powders; Microspheres; Phospholipids; Pulmonary delivery; Spray-drying
Comparison of salmeterol xinafoate microparticle production by conventional and novel antisolvent crystallization
by Darragh Murnane; Christopher Marriott; Gary P. Martin (pp. 94-105).
The production of microparticles for inhalation has relied on jet-milling while the potential for crystallization of microparticles has remained underexplored until relatively recently. Aqueous antisolvent crystallization of salmeterol xinafoate (SX) from poly(ethylene glycol) (PEG) and other organic (co)solvent systems was compared in order to evaluate factors determining the resultant microparticle properties. SX was crystallized by the addition of water to solutions of SX in PEG 400, PEG 6000, propan-2-ol, acetone and methanol. Crystalline particles were characterized by laser diffraction sizing, scanning electron microscopy and differential scanning calorimetry; PEG-media were characterized by viscometry. Crystallization of SX from PEG 400 produced crystals that exhibited a narrower size distribution than those crystallized from other conventional organic solvents. SX crystallized from PEG 6000 demonstrated a smaller median particle size ( D( v,0.5)=0.92±0.04μm) than PEG 400 crystallized SX ( D( v,0.5)=4.50±0.61μm). Crystals produced from PEG 400 (Span=2.49±0.10) possessed a narrower particle size distribution (PSD) than those produced from PEG 6000 (Span=10.42±0.85). SX crystals displayed a plate-like habit with growth limited to two dimensions irrespective of the initial solvent employed. The importance of the rate of generation of SX supersaturation on the PSD was determined using HPLC analysis. DSC showed PEG-crystallized SX to be free from metastable crystal phases in contrast to SX crystallized from propan-2-ol. Crystallization of SX from PEG was shown to follow classical nucleation theory and the crystallization method represents a viable alternative to the use of conventional solvents for the production of microparticles.
Keywords: Crystallization; Antisolvent micronization; Polymorphism; Poly(ethylene glycol); Salmeterol xinafoate; Microparticles
Release pattern and structural integrity of lysozyme encapsulated in core–sheath structured poly(dl-lactide) ultrafine fibers prepared by emulsion electrospinning
by Ye Yang; Xiaohong Li; Mingbo Qi; Shaobing Zhou; Jie Weng (pp. 106-116).
The purpose of this study was to investigate the structural integrity, bioactivity and release patterns of lysozyme, as a model protein, encapsulated within the core–shell structured ultrafine fibers prepared by emulsion electrospinning. Electron microscopy and laser confocal scanning microscopy images demonstrated that the fibrous mats were very porous with integrally core–shell structured, bead-free, and randomly arrayed fibers. This structural property can pronouncedly alleviate the initial burst release and improve the sustainability of ultrafine fiber-based releasing devices. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and size exclusion chromatography were used to assess the primary structure of lysozyme, indicating that the ultra-sonication and electrospinning did not cause any remarkable denaturation of protein, while the core–shell structured fibers protected the structural integrity of encapsulated protein during incubation in the medium. Fourier transform infrared analyses showed that the electrospinning process had much less effect on the secondary structure of protein than ultra-sonication. The bioactivity assay indicated around 16% of specific activity loss during the emulsification procedure, and the protective effect of the shell materials on the activity of encapsulated protein. In vitro degradation showed that the protein entrapment led to more significant mass loss and higher molecular weight reduction.
Keywords: Emulsion electrospinning; Core–shell structure; Ultrafine fibers; Protein structures; Structural integrity; Bioactivity; In vitro; release; Burst release
Cellular uptake and cytotoxicity of shell crosslinked stearic acid-grafted chitosan oligosaccharide micelles encapsulating doxorubicin
by Fu-Qiang Hu; Xiu-ling Wu; Yong-Zhong Du; Jian You; Hong Yuan (pp. 117-125).
Stearic acid-grafted chitosan oligosaccharide (CSO-SA) with 3.48% amino-substituted degree (SD%) was synthesized by coupling reaction. The CSO-SA could self-aggregate to form micelle with a critical micelle concentration (CMC) at 0.035mg/mL in the aqueous phase. The CSO-SA self-aggregate micelles indicated spatial structure with multi-hydrophobic core. One CSO-SA chain could form 2.8hydrophobic cores. Cellular uptakes of CSO-SA micelles by using A549, LLC, and SKOV3 cells as model tumor cell lines showed the faster cellular internalization of CSO-SA micelles, and the cellular uptakes on the LLC and SKOV3 cells were higher than that on the A549 cells. Doxorubicin (DOX) was then used as a model drug to incorporate into CSO-SA micelles. To reduce the initial burst drug release from CSO-SA micelles loading DOX (CSO-SA/DOX), the shell of CSO-SA micelles was crosslinked by glutaraldehyde. The shell crosslinking of CSO-SA micelles reduced the micelle size and surface potential, but it did not significantly affect the cellular uptake and drug encapsulation efficiency of CSO-SA micelles. The cellular inhibition experiments demonstrated that the cytotoxicity of DOX was increased by the encapsulation of CSO-SA micelles. CSO-SA/DOX displayed the best antitumor efficacy in SKOV3 cell line due to the higher cellular uptake percentage of CSO-SA micelles and the lower sensitivity of free drug to the cells. The cytotoxicities of shell crosslinked CSO-SA/DOX were highly enhanced in all cell lines than those of unmodified CSO-SA/DOX.
Keywords: Stearic acid; Chitosan oligosaccharide; Polymeric micelle; Crosslink; Cellular uptake; Cytotoxicity
Myotoxicity studies of O/W-in situ forming microparticle systems
by Wandee Rungseevijitprapa; Gayle A. Brazeau; James W. Simkins; Roland Bodmeier (pp. 126-133).
The objective of this study was to investigate the myotoxicity potential of the solvents used in the preparation of polymer solutions and O/W-in situ forming microparticle (ISM) systems. The acute myotoxicity studies of the tested solvents, emulsions of the solvents, polymer solutions as well as the O/W-ISM formulations with varying phase ratios were investigated using the in vitro isolated rodent skeletal muscle model by measuring the cumulative creatine kinase (CK) efflux. Phenytoin and isotonic sodium chloride solution served as positive and negative controls, respectively. Results from the in vitro myotoxicity studies suggested that the investigated five partially water miscible solvents caused muscle damage in the following rank order: benzyl alcohol>triethyl citrate>triacetin>propylene carbonate>ethyl acetate. Myotoxicity of ethyl acetate was found to be comparable to that of the isotonic sodium chloride solution. Emulsions of the undiluted solvents and an aqueous 0.5% Pluronic F 68 solution (ratio 1:4) could dramatically reduce the myotoxicities to 24–65%. The myotoxicity of O/W-ISM was less than those of the polymer solutions and the undiluted solvents. The cumulative CK level from the muscle treated with the O/W-ISM with phase ratio 1:4 was comparable to those from the negative controls. Area under the CK plasma curve from Sprague–Dawley rats was used to evaluate the in vivo myotoxicity following an intramuscular injection of the formulations. The in vivo myotoxicity data was well correlated with the in vitro myotoxicity data and confirmed the good muscle compatibility of the O/W-ISM formulations.
Keywords: Myotoxicity; Creatine kinase; In situ forming; Microparticles; Solvents
Methoxy poly(ethylene glycol) – Low molecular weight linear polyethylenimine-derived copolymers enable polyplex shielding
by U. Lungwitz; M. Breunig; R. Liebl; T. Blunk; A. Goepferich (pp. 134-148).
Targeted gene delivery relies on the development of materials that allow for the formation of small neutrally charged particles of sufficient colloidal stability preventing non-specific interactions with cells. In order to identify a copolymer composition that combines adequate plasmid DNA (pDNA) compaction with an efficient charge-shielding effect, we synthesized a series of copolymers by covalent linkage of activated 5 or 20kDa linear methoxy poly(ethylene glycol) (mPEG) or 10kDa two-arm-mPEG to non-toxic low molecular weight (2.6 and 4.6kDa) linear polyethylenimine (lPEI) at different molar ratios (mPEG–lPEI copolymers). All of the copolymers condensed pEGFP-N1 pDNA to form nanoparticles with hydrodynamic diameters between 150 and 420nm – sizes that were maintained for the entire duration of measurement. PEGylated complexes exhibited a reduced particle stability in comparison to the unmodified lPEI–pDNA polyplexes, determined by gel retardation assays and DNase I experiments. Copolymer–pDNA complexes exhibited a zeta potential between −4 and 6mV, strongly depending on the dispersion medium applied (0.15M NaCl or 5% glucose supplemented with serum-free cell culture medium). The transfection efficacy, determined in CHO-K1 (between 0.28±0.08% and 1.92±0.46%) and HeLa (between 1.02±0.19% and 3.53±0.30%) cells, was significantly reduced compared to lPEI–pDNA particles (between 3.2±1.3% and 38.8±5.5%). The architecture of the copolymer, the molecular weight of the lPEI residue, and the supplementation of endosomolytic agents (saccharose, chloroquine) all failed to impact the efficacy of gene transfer. Uptake studies, based on Confocal Laser Scanning Microscopy (CLSM) imaging and flow cytometry analysis, suggest that the use of mPEG5/3–lPEI2.6, mPEG10/2–lPEI2.6, and mPEG20–lPEI4.6 lowers unspecific internalization of the corresponding transfection complexes. This provides an ideal basis for the development of transfection vehicles for targeted gene transfer.
Keywords: Linear polyethylenimine; Methoxy poly(ethylene glycol)-linear polyethylenimine; PEG–PEI copolymers; Non-viral transfection; Charge shielding
Drug release mechanism of paclitaxel from a chitosan–lipid implant system: Effect of swelling, degradation and morphology
by Patrick Lim Soo; Jaepyoung Cho; Justin Grant; Emmanuel Ho; Micheline Piquette-Miller; Christine Allen (pp. 149-157).
Localized and sustained delivery of anti-cancer agents to the tumor site has great potential for the treatment of solid tumors. A chitosan–egg phosphatidylcholine (chitosan–ePC) implant system containing PLA- b-PEG/PLA nanoparticles has been developed for the delivery of paclitaxel to treat ovarian cancer. Production of volumes of ascites fluid in the peritoneal cavity is a physical manifestation of ovarian cancer. In vitro release studies of paclitaxel from the implant were conducted in various fluids including human ascites fluid. A strong correlation ( r2=0.977) was found between the release of paclitaxel in ascites fluid and PBS containing lysozyme (pH 7.4) at 37°C. The drug release mechanism for this system was proposed based on swelling, degradation and morphology data. In addition, in vitro release of paclitaxel was found to be a good indicator of the in vivo release profile (correlation between release rates: r2=0.965). Release of paclitaxel was found to be sustained over a four-week period following implantation of the chitosan–ePC system into the peritoneal cavity of healthy Balb/C mice. Also, the concentrations of paclitaxel in both plasma and tissues (e.g. liver, kidney and small intestine) were found to be relatively constant.
Keywords: Drug release; Polymer–lipid implant; Drug delivery; Paclitaxel; Ascites fluid; Ovarian cancer
Formulation and characterization of ternary solid dispersions made up of Itraconazole and two excipients, TPGS 1000 and PVPVA 64, that were selected based on a supersaturation screening study
by Sandrien Janssens; Sophie Nagels; Hector Novoa de Armas; Ward D’Autry; Ann Van Schepdael; Guy Van den Mooter (pp. 158-166).
Bothd-α-tocopheryl polyethylene glycol 1000 (TPGS 1000) and polyvidone-vinylacetate 64 (PVPVA 64) provided an increase in the degree of supersaturation and stability of supersaturated Itraconazole solutions, compared to a blanc without excipient. Therefore, both components were combined as carrier in order to make ternary solid dispersions of Itraconazole by spray drying. This way, TPGS 1000 could be incorporated into a powder. Dissolution experiments on the ternary solid dispersions revealed that during the first hour the release was much higher than for the binary Itraconazole/PVPVA 64 solid dispersions. For some compositions a release of more than 80% was reached after 10min. However, after the first hour the drug started to precipitate. The ternary solid dispersions were all XRD amorphous, but MDSC revealed the coexistence of multiple amorphous phases and a crystalline Itraconazole phase, depending on the composition. Therefore the burst effect during the first hour can be ascribed to an accelerated dissolution of the amorphous Itraconazole fraction in the presence of TPGS 1000. The precipitation after 1h, however, is probably due to the combination of the surfactant properties of TPGS and the small crystalline Itraconazole fraction.
Keywords: Supersaturation; Ternary solid dispersion; MDSC; Powder X-ray diffraction; Dissolution; GC–MS; Itraconazole; TPGS 1000; PVPVA 64
In vitro and in vivo characteristics of a thermogelling and bioadhesive delivery system intended for rectal administration of quinine in children
by A.A. Koffi; F. Agnely; M. Besnard; J. Kablan Brou; J.L. Grossiord; G. Ponchel (pp. 167-175).
The aim of this work was to improve the rectal bioavailability of quinine hydrochloride by designing thermosensitive and mucoadhesive gels intended for rectal delivery. The rheological and mucoadhesive properties of poloxamer 407 solutions have been modulated by addition of hydroxypropylmethycellulose (HPMC) and propanediol-1,2. In vitro release and rectal absorption of quinine have been highlighted by a dialysis dissolution testing method and by the determination of bioavailability of the different formulations in rabbits. Increasing the proportions of HPMC and poloxamer in the formulations resulted in a prolonged release of quinine. Indeed, compared to the DT 50% of a rectal solution and a simple HPMC gel (27 and 65min, respectively) the DT 50% of thermosensitive ternary systems was increased and ranged between 80 and 138min, depending on the system composition. The release rate depended strongly on the elasticity of the gels after thermogelation. The absolute rectal bioavailability of quinine determined in rabbits was significantly improved with these thermosensitive and adhesive systems. It increased from 62% for the rectal solution to 98% for a ternary system 16/0.5/30 (poloxamer (16%)/HPMC (0.5%)/propanediol-1,2 (30%)). As a result of combined bioadhesion and prolonged release of quinine in vivo, higher average values of MRT and tmax (9.1±0.2h and 30min, respectively) were obtained compared to the rectal solution (6.9±0.9h and 15min, respectively). Moreover, these formulations presented a very good rectal tolerance.Modulation by HPMC of the viscoelastic and mucoadhesive properties of poloxamer 407 thermogelling solutions allowed a prolonged release of quinine hydrochloride and an improvement of bioavailability in rabbit.
Keywords: Rectal delivery; Bioavailability; Bioadhesion; Quinine; Poloxamer; HPMC
Drug release property of chitosan–pectinate beads and its changes under the influence of microwave
by Tin Wui Wong; Sumiran Nurjaya (pp. 176-188).
The effects of microwave irradiation on the drug release property of pectinate beads loaded internally with chitosan (chitosan–pectinate beads) were investigated against the pectinate beads and beads coacervated with chitosan externally (pectinate–chitosonium beads). These beads were prepared by an extrusion method using sodium diclofenac as the model water-soluble drug. The beads were subjected to microwave irradiation at 80W for 5, 10, 21 and 40min. The profiles of drug dissolution, drug content, drug–polymer interaction and polymer–polymer interaction were determined by drug dissolution testing, drug content assay, drug adsorption study, differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR) techniques. Treatment of pectinate beads by microwave did not lead to a decrease, but an increase in the extent of drug released at 4h of dissolution owing to reduced pectin–pectin interaction via the CO moiety of polymer. In addition, the extent of drug released from the pectinate beads could not be reduced merely through the coacervation of pectinate matrix with chitosan. The reduction in the extent of drug released from the pectinate–chitosonium beads required the treatment of these beads by microwave, following an increase in drug–polymer and polymer–polymer interaction in the matrix. The extent of drug released from the pectinate beads was reduced through incorporating chitosan directly into the interior of pectinate matrix, owing to drug–chitosan adsorption. Nonetheless, the treatment of chitosan–pectinate matrix by microwave brought about an increase in the extent of drug released unlike those of pectinate–chitosonium beads. Apparently, the loading of chitosan into the interior of pectinate matrix could effectively retard the drug release without subjecting the beads to the treatment of microwave. The microwave was merely essential to reduce the release of drug from pectinate beads when the chitosan was introduced to the pectinate matrix by means of coacervation. Under the influences of microwave, the drug release property of beads made of pectin and chitosan was mainly modulated via the CH, OH and NH moieties of polymers and drug, with CH functional group purported to retard while OH and NH moieties purported to enhance the drug released from the matrix.
Keywords: Chitosan; Drug–polymer interaction; Microwave; Pectin; Polymer–polymer interaction
The use of fucosphere in the treatment of dermal burns in rabbits
by A.D. Sezer; E. Cevher; F. Hatipoğlu; Z. Oğurtan; A.L. Baş; J. Akbuğa (pp. 189-198).
The aim of this study was to prepare a new microsphere (fucosphere) system based on polyion complexation of fucoidan with chitosan, and to evaluate its treatment efficiency on dermal burns.The physicochemical properties such as mean particle size and distribution, zeta potential and bioadhesive properties of the microspheres were investigated. The formulation which had the high surface charge, narrow size distribution and the highest bioadhesive property was selected and applied on seven male New Zealand white rabbits with dermal burns. Biopsy samples were taken on day 7, 14 and 21. Each burn site was evaluated macroscopically and histopathologically and the findings were compared with controls of fucoidan solution and chitosan microspheres.The microspheres between the size ranges of 367 and 1017nm were obtained. The work of bioadhesion of microspheres, with the surface charges +6.1 to +26.3mV, changed between 0.081 and 0.191mJcm−2. Macroscopically and histopathological observations indicated that the fastest healing of the burns was obtained in group treated with fucosphere after 21 days of treatment ( P<0.05). Rete peg formation values and nuclear organize regions (NORs) were higher with treated fucospheres than the other groups on day 14.In conclusion, in vitro and in vivo evaluation of fucospheres indicated that the new microsphere system shortened the treatment period of burns and provided fast and effective healing by improving regeneration and re-epithelization. Hence fucosphere may find application in the treatment of dermal burns.
Keywords: Fucoidan; Chitosan; Biopolymer; Fucosphere; Microsphere; Burn healing; Animal experiment
Transdermal delivery of penetrants with differing lipophilicities using O-acylmenthol derivatives as penetration enhancers
by Ligang Zhao; Liang Fang; Yongnan Xu; Shu Liu; Zhonggui He; Yanyan Zhao (pp. 199-213).
To develop more effective compounds as penetration enhancers, O-acylmenthol derivatives were synthesized by l-menthol and saturated fatty acid, O-ethylmenthol (MET), was also synthesized as a reference compound. Their promoting activity on the percutaneous absorption of five model drugs, 5-fluorouracil (5-FU), isosorbide dinitrate (ISDN), lidocaine (LD), ketoprofen (KP), indomethacin (IM), which were selected based on their lipophilicity represented by log KO/W, was tested in vitro across full thickness rat skin with each of the evaluated drugs in saturated donor solution. Only 2-isopropyl-5-methylcyclohexyl tetradecanoate (C14 alkyl chain) had promoting effects on the percutaneous permeation of 5-FU; 2-isopropyl-5-methylcyclohexyl hexanoate (C6 alkyl chain), which increased the permeation coefficient ( P) 1.91-fold, had the highest permeation for ISDN; in the case of LD, the highest increase in P was observed with 2-isopropyl-5-methylcyclohexyl heptanoate (C7 alkyl chain), which increased the P by 1.58-fold; MET, which increased the P by 2.02-fold, provided the best enhancement for KP; 2-isopropyl-5-methylcyclohexyl heptanoate (C7 alkyl chain) produced the highest increase in P, 3.70-fold for IM. These results suggest that some newly designed percutaneous absorption enhancers have the potential to enhance drugs with different lipophilicities. A chain length of C6–C10 seemed to be favorable for lipophilic drugs, while C14 was the most effective enhancer for hydrophilic drug (5-FU).
Keywords: O; -acylmenthol derivatives; Penetration enhancers; Saturated fatty acid; Percutaneous absorption; Lipophilicity
Human skin penetration of the major components of Australian tea tree oil applied in its pure form and as a 20% solution in vitro
by Sheree E. Cross; Michael Russell; Ian Southwell; Michael S. Roberts (pp. 214-222).
The safety of topical application of Australian tea tree Oil (TTO) is confounded by a lack of transdermal penetration data, which adequately informs opinions and recommendations. In this study we applied TTO in its pure form and as a 20% solution in ethanol in vitro to human epidermal membranes from three different donors, mounted in horizontal Franz-type diffusion cells, using normal ‘in use’ dosing conditions (10mg/cm2). In addition, we examined the effect of partially occluding the application site on the penetration of TTO components. Our data showed that only a small quantity of TTO components, 1.1–1.9% and 2–4% of the applied amount following application of a 20% TTO solution and pure TTO, respectively, penetrated into or through human epidermis. The largest TTO component penetrating the skin was terpinen-4-ol. Following partial occlusion of the application site, the penetration of terpinen-4-ol increased to approximately 7% of the applied TTO. Measurement of the rate of evaporation of tea tree oil from filter paper (7.4mg/cm2) showed that 98% of the oil evaporated in 4 hours. Overall, it is apparent that the penetration of TTO components through human skin is limited.
Keywords: Transdermal delivery; Essential oil; Risk assessment; Tea tree oil; Epidermal permeability
Increasing the oral bioavailability of the poorly water soluble drug itraconazole with ordered mesoporous silica
by Randy Mellaerts; Raf Mols; Jasper A.G. Jammaer; Caroline A. Aerts; Pieter Annaert; Jan Van Humbeeck; Guy Van den Mooter; Patrick Augustijns; Johan A. Martens (pp. 223-230).
This study aims to evaluate the in vivo performance of ordered mesoporous silica (OMS) as a carrier for poorly water soluble drugs. Itraconazole was selected as model compound. Physicochemical characterization was carried out by SEM, TEM, nitrogen adsorption, DSC, TGA and in vitro dissolution. After loading itraconazole into OMS, its oral bioavailability was compared with the crystalline drug and the marketed product Sporanox® in rabbits and dogs. Plasma concentrations of itraconazole and OH–itraconazole were determined by HPLC-UV. After administration of crystalline itraconazole in dogs (20mg), no systemic itraconazole could be detected. Using OMS as a carrier, the AUC0–8 was boosted to 681±566nMh. In rabbits, the AUC0–24 increased significantly from 521±159nMh after oral administration of crystalline itraconazole (8mg) to 1069±278nMh when this dose was loaded into OMS. Tmax decreased from 9.8±1.8 to 4.2±1.8h. No significant differences (AUC, Cmax, and Tmax) could be determined when comparing OMS with Sporanox® in both species. The oral bioavailability of itraconazole formulated with OMS as a carrier compares well with the marketed product Sporanox®, in rabbits as well as in dogs. OMS can therefore be considered as a promising carrier to achieve enhanced oral bioavailability for drugs with extremely low water solubility.
Keywords: Ordered mesoporous silica; Enhanced dissolution; Poorly water soluble drugs; Oral bioavailability; Itraconazole
Enhanced nasal absorption of hydrophilic markers after dosing with AT1002, a tight junction modulator
by Keon-Hyoung Song; Alessio Fasano; Natalie D. Eddington (pp. 231-237).
AT1002 is a six-mer synthetic peptide, H-FCIGRL-OH, that retains the delta G and Zot biological activity of reversibly opening tight junctions and increases the paracellular transport of drugs. The objective of this study was to evaluate the possible use of AT1002 in enhancing the nasal availability of macromolecules using large paracellular markers as model agents. Male Sprague–Dawley rats cannulated in the jugular vein were randomly assigned to receive radiolabelled paracellular markers, [14C]PEG4000 or [14C]inulin, with/without AT1002, for each intranasal study. The plasma concentration of PEG4000 with AT1002 (10mg/kg) was significantly higher than that from PEG4000 control over 360min following intranasal administration. The AUC0–360min and Cmax from the PEG4000/AT1002 (10mg/kg) treatment were statistically ( p<0.05) increased to 235% and 357%, of control, respectively. When inulin was administered with AT1002 (10mg/kg), the plasma concentration was significantly higher ( p<0.05) than control over 360min, and increases ( p<0.05) of 292% and 315% for AUC0–360min and Cmax over control were observed, respectively. AT1002 significantly increased the nasal absorption of molecular weight markers, PEG4000 and inulin. This study suggests that AT1002 may be used to enhance the systemic availability of macromolecules when administered concurrently.
Keywords: AT1002; PEG4000; Inulin; Intranasal administration; Zot
Selection of drug candidates for gastroretentive dosage forms: Pharmacokinetics following continuous intragastric mode of administration in a rat model
by Leonid Kagan; Amnon Hoffman (pp. 238-246).
The purpose of the study was to evaluate the pharmacokinetic effects obtained by gastroretentive dosage form (GRDF) for drugs absorbed by passive paracellular diffusion (atenolol, acyclovir) or active transport (valacyclovir). Model drugs were delivered as gastric infusion (GInf) through an implanted catheter (resembling GRDF), intravenous, oral (PO), and colonic administration to rats. For atenolol (highly soluble drug), GInf resulted in a prolonged Tmax and reduced Cmax in comparison to PO, whereas bioavailability was similar. Bioavailability after colonic bolus was significantly lower. Results were also simulated by a pharmacokinetic model. For acyclovir, GInf and PO demonstrated almost the same pharmacokinetic profile with low bioavailability, most probably due to the solubility-limited absorption. Valacyclovir demonstrated the significant change in the shape of pharmacokinetic profile as a function of the rate of gastric delivery, without variation in bioavailability. Valacyclovir was not absorbed from colon. Experimental and theoretical methodologies to assess the pharmacokinetic influences of GRDF mode of administration were developed, avoiding the need to compound the drug in a dosage form. GRDF provides a mean for controlled release of compounds that are absorbed by active transport in the upper intestine. It also enables controlled delivery for paracellularly absorbed drugs without a decrease in bioavailability.
Keywords: Pharmacokinetic model; Controlled release; Absorption mechanism; Intestinal transit; Absorption window
In vitro and in vivo evaluation of tegaserod maleate pH-dependent tablets
by Shuang-Qing Zhang; Sridhar Thumma; Guo-Hua Chen; Wei-Bin Deng; Michael A. Repka; San-Ming Li (pp. 247-254).
The purpose of this study was to prepare tegaserod maleate (TM) pH-dependent tablets and evaluate their advantages as a sustained release delivery system. TM, insoluble in water and unstable in gastric milieu, was formulated into pH-dependent tablets coated with combinations of two methacrylic acid copolymers – Eudragit® L100 and Eudragit® S100. The influence of core tablet compositions, polymer combination ratios and coating levels on the in vitro release rate of TM from coated tablets was investigated. The optimum formulation was evaluated for in vitro release rate and in vivo bioavailability study on beagle dogs. In addition, physico-chemical properties of the drug, including solubility at different pH and temperatures, and dissociation constant were determined. The results showed that no drug was released in 0.1mol/L hydrochloric acid within 2h, and about 90% of the drug was released in the pH 6.8 phosphate buffer within 12h in a sustained manner. The pharmacokinetic investigation showed that TM pH-dependent tablets exhibited a sustained plasma concentration, a lag time of approximately 2.3h and a relative bioavailability of 159% compared to plain tablets. A close correlation existed between the in vitro release rate of the pH-dependent system and its in vivo absorption percentage. The results of the present study have demonstrated that the pH-dependent tablet system is a promising vehicle for preventing rapid hydrolysis in gastric milieu and improving oral bioavailability of TM for the treatment of irritable bowel syndrome.
Keywords: Tegaserod maleate; pH-dependent; Bioavailability
Design and evaluation of floating multi-layer coated tablets based on gas formation
by Srisagul Sungthongjeen; Pornsak Sriamornsak; Satit Puttipipatkhachorn (pp. 255-263).
Floating multi-layer coated tablets were designed based on gas formation. The system consists of a drug-containing core tablet coated with a protective layer (hydroxypropyl methylcellulose), a gas forming layer (sodium bicarbonate) and a gas-entrapped membrane, respectively. The mechanical properties of acrylic polymers (Eudragit® RL 30D, RS 30D, NE 30D) and ethylcellulose were characterized by the puncture test in order to screen a suitable film for the system. Eudragit® RL 30D was chosen as a gas-entrapped membrane due to its high flexibility and high water permeability. The obtained tablets enabled to float due to the CO2-gas formation and the gas entrapment by polymeric membrane. The effect of formulation variables on floating properties and drug release was investigated. The floating tablets using direct-compressed cores had shorter time to float and faster drug release than those using wet-granulated cores. The increased amount of a gas forming agent did not affect time to float but increased the drug release from the floating tablets while increasing coating level of gas-entrapped membrane increased time to float and slightly retarded drug release. Good floating properties and sustained drug release were achieved. These floating tablets seem to be a promising gastroretentive drug delivery system.
Keywords: Floating tablets; Gastroretentive drug delivery system; Gas formation; Gas-entrapped membrane; Sustained release
The manufacture and characterisation of hot-melt extruded enteric tablets
by Gavin P. Andrews; David S. Jones; Osama Abu Diak; Colin P. McCoy; Alan B. Watts; James W. McGinity (pp. 264-273).
The aim of this highly novel study was to use hot-melt extrusion technology as an alternative process to enteric coating. In so doing, oral dosage forms displaying enteric properties may be produced in a continuous, rapid process, providing significant advantages over traditional pharmaceutical coating technology. Eudragit® L100-55, an enteric polymer, was pre-plasticized with triethyl citrate (TEC) and citric acid and subsequently dry-mixed with 5-aminosalicylic acid, a model active pharmaceutical ingredient (API), and an optional gelling agent (PVP® K30 or Carbopol® 971P). Powder blends were hot-melt extruded as cylinders, cut into tablets and characterised using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and dissolution testing conducted in both pH 1.2 and pH 6.8 buffers. Increasing the concentration of TEC significantly lowered the glass transition temperature ( Tg) of Eudragit® L100-55 and reduced temperatures necessary for extrusion as well as the die pressure. Moreover, citric acid (17% w/w) was shown to act as a solid-state plasticizer. HME tablets showed excellent gastro-resistance, whereas milled extrudates compressed into tablets released more than 10% w/w of the API in acidic media. Drug release from HME tablets was dependent upon the concentration of TEC, the presence of citric acid, PVP K30, and Carbopol® 971P in the matrix, and pH of the dissolution media. The inclusion of an optional gelling agent significantly reduced the erosion of the matrix and drug release rate at pH 6.8; however, the enteric properties of the matrix were lost due to the formation of channels within the tablet. Consequently this work is both timely and highly innovative and identifies for the first time a method of producing an enteric matrix tablet using a continuous hot-melt extrusion process.
Keywords: Enteric coating; Eudragit; ®; Hot-melt extrusion; Polymer processing
Alginate-based pellets prepared by extrusion/spheronization: Effect of the amount and type of sodium alginate and calcium salts
by Pornsak Sriamornsak; Jurairat Nunthanid; Manee Luangtana-anan; Yossanun Weerapol; Satit Puttipipatkhachorn (pp. 274-284).
Pellets containing microcrystalline cellulose (MCC), a model drug (theophylline) and a range of levels of sodium alginate (i.e., 10–50% w/w) were prepared by extrusion/spheronization. Two types of sodium alginate were evaluated with and without the addition of either calcium acetate or calcium carbonate (0, 0.3, 3 and 10% w/w). The effects of amount and type of sodium alginate and calcium salts on pellet properties, e.g., size, shape, morphology and drug release behavior, were investigated. Most pellet formulations resulted in pellets of a sufficient quality with respect to size, size distribution and shape. The results showed that the amounts of sodium alginate and calcium salts influenced the size and shape of the obtained pellets. However, different types of sodium alginate and calcium salt responded to modifications to a different extent. A cavity was observed in the pellet structure, as seen in the scanning electron micrographs, resulting from the forces involved in the spheronization process. Most of pellet formulations released about 75–85% drug within 60min. Incorporation of calcium salts in the pellet formulations altered the drug release, depending on the solubility of the calcium salts used. The drug release data showed a good fit into both Higuchi and Korsmeyer–Peppas equations.
Keywords: Alginate; Calcium salts; Pellets; Extrusion; Spheronization
Drug release behaviour from methyl methacrylate-starch matrix tablets: Effect of polymer moisture content
by I. Bravo-Osuna; C. Ferrero; M.R. Jiménez-Castellanos (pp. 285-293).
The aim of this work was to study the effect of the initial moisture content of the polymer on the tabletting and drug release behaviour of controlled release inert matrices elaborated with methyl methacrylate (MMA)-starch copolymers. The copolymers, obtained by free radical polymerisation and dried by two different methods (oven-drying or freeze-drying), were equilibrated at different relative humidities (0%, 25%, 50% and 75% RH) at room temperature. From these copolymers, matrix systems were directly compressed containing either a slightly water-soluble drug (anhydrous theophylline) or a freely water-soluble drug (salbutamol sulphate), and their compaction properties and in vitro dissolution profiles were evaluated. The release profiles were compared following model-independent methods, such as the Qt parameter and the similarity factor f2. Moreover, several kinetic models were employed to evaluate the possible changes in the release mechanism. For anhydrous theophylline, the initial moisture content of the copolymers did not affect the release characteristics from the inert matrices under study, and a typical Fickian diffusion mechanism was observed for the different formulations. However, in case of salbutamol sulphate, the presence of moisture might induce a fast drug dissolution, promoting the weakness of the matrix structure and hence, its partial disintegration. So, an “anomalous” mixed phenomenon of diffusion and erosion was found, influenced by the initial moisture content of the copolymer.
Keywords: Methyl methacrylate-starch copolymers; Moisture content; Matrix tablets; Drug release profiles; Model-dependent methods; Model-independent methods
Biphasic release of indomethacin from HPMC/pectin/calcium matrix tablet: II. Influencing variables, stability and pharmacokinetics in dogs
by Baojian Wu; Daoyin Deng; Yi Lu; Wei Wu (pp. 294-302).
The pectin/calcium interaction, which is the basis for biphasic release of indomethacin from the HPMC/pectin/calcium chloride matrix tablet, is susceptible to influence of a variety of variables that is supposed to be encountered by the oral route. In this study, the effect of influencing variables on biphasic release characteristics, the stability and the pharmacokinetics of the hybrid matrix tablet were investigated. An increasing tendency of the overall release rate was observed from pH 1.2 to 7.4. The power law correlation n values increased with pH, while the release lag time or 10% release time ( T0.1) decreased at pH 6.8 and 7.4. Ionic strength in the release media also influenced the biphasic release significantly at sodium chloride levels of over 0.5%. Obvious increase in overall release rate was observed at sodium chloride level of 0.9% with an n value of 1.20 and a T0.1 of 3.4h. At sodium chloride levels of over 2%, the pectin/calcium interaction was disrupted resulting in very fast release of indomethacin. Release in gradient pH media was similar to that in pH 6.8 citrate buffer. When pectinase (Pectinex Ultra SP-L) was added into the release medium in 22.2pg/ml or over, obvious triggering on drug release was observed. The stress testing showed increased release at extreme relative humidity of 92.5%. Both accelerated testing for 6m and long-term testing for 12m affirmed fine stability, especially in release characteristics. Pharmacokinetic study in dogs gave Tmax/ Cmax of 4h/604ng/ml and 3h/1662ng/ml for HPMC/pectin/calcium and HPMC/pectin tablet, respectively. The plasma indomethacin level of the calcium-containing tablet was maintained at a much lower level for 3h with a MRT of 7.13h, longer than 3.97 and 5.61h for indomethacin crude drug and HPMC/pectin tablet, confirming delayed absorption. The AUC of the HPMC/pectin/calcium tablet was lower than that of the HPMC/pectin tablet and indomethacin crude drug showing incomplete absorption. It is concluded that the HPMC/pectin/calcium matrix tablet is potentially useful for colon-specific drug delivery.
Keywords: Pectin; HPMC; Calcium; Matrix; Biphasic release; Pharmacokinetics
Subcoating with Kollidon VA 64 as water barrier in a new combined native dextran/HPMC–cetyl alcohol controlled release tablet
by Eddy Castellanos Gil; Antonio Iraizoz Colarte; José Lizardo Lara Sampedro; Bernard Bataille (pp. 303-311).
A novel oral controlled delivery system for propranolol hydrochloride (PPL) was developed and optimized using wet granulation process. We are studying the ability of subcoating with Kollidon VA 64 as a barrier to water penetration in matrix cores combined hydrophilic (native dextran–HPMC)/hydrophobic (cetyl alcohol) prior to film coating with Opradry II-YS-30-18056. The copovidone (i.e., Kollidon VA 64) not only increases the mechanical properties of tablets (less friability) but also reduces the amount of absorbed water from the air in tropical stability condition (25°C and 75% relative humidity). The in vitro dissolution profiles of coated sustained-release matrix tablets of racemic PPL were determined and compared with uncoated tablet cores according to the United States Pharmacopeia (USP) Tolerance Specifications for Propranolol Hydrochloride Extended-Release Capsules. A comparative kinetic study of the present matrix tablets (coated and uncoated cores) and commercial SUMIAL RETARD capsules (reference formulation ( R) (Spain) was established). The values for the similarity factor ( f2=61.756, f2=72.326 and f2=88.509 for initial time, one year and two years, respectively (uncoated cores vs. capsule) and f2=63.904, f2=69.502 and f2=76.348 (coated tablets vs. capsule) for initial time, one year and 2 two years, respectively) suggested that the dissolution profiles of the present three sustained-release oral dosage forms are similar and stable during two years under stability condition.
Keywords: Coating tablets; Dissolution profiles; Kollidon VA 64; Native dextran; Sustained release
Influence of formulation and process parameters on the release characteristics of ethylcellulose sustained-release mini-matrices produced by hot-melt extrusion
by E. Verhoeven; T.R.M. De Beer; G. Van den Mooter; J.P. Remon; C. Vervaet (pp. 312-319).
Mini-matrices (multiple unit dosage form) with release-sustaining properties were developed by hot-melt extrusion (cylindrical die: 3mm) using metoprolol tartrate as model drug and ethylcellulose as sustained-release agent. Dibutyl sebacate was selected as plasticizer and its concentration was optimized to 50% (w/w) of the ethylcellulose concentration. Xanthan gum, a hydrophilic polymer, was added to the formulation to increase drug release. Changing the xanthan gum concentration modified the in vitro drug release: increasing xanthan gum concentrations (1%, 2.5%, 5%, 10% and 20%, w/w) yielded a faster drug release. Zero-order drug release was obtained at 5% (w/w) xanthan gum. Using kneading paddles, smooth extrudates were obtained when processed at 60°C. At least one mixing zone was required to obtain smooth and homogeneous extrudates. The mixing efficacy and drug release were not affected by the number of mixing zones or their position along the extruder barrel. Raman analysis revealed that metoprolol tartrate was homogeneously distributed in the mini-matrices, independent of screw design and processing conditions. Simultaneously changing the powder feed rate (6–25–50g/min) and screw speed (30–100–200rpm) did not alter extrudate quality or dissolution properties.
Keywords: Hot-melt extrusion; Sustained-release; Multiple-unit dosage form; Matrix system; Xanthan gum
Coprocessing via spray drying as a formulation platform to improve the compactability of various drugs
by Y. Gonnissen; E. Verhoeven; E. Peeters; J.P. Remon; C. Vervaet (pp. 320-334).
It was evaluated if coprocessing via spray drying can be used as a formulation platform to improve the compactability of formulations containing drug substance (acetaminophen, ibuprofen, cimetidine) and excipients (carbohydrates, disintegrant, glidant, surfactant). Experimental design was applied to optimise the drug concentration and solid content of the feed suspension. In addition, scaling-up of acetaminophen- and ibuprofen-containing formulations was performed on a production-scale spray dryer. Optimised acetaminophen (drug concentration: 70% w/w), ibuprofen (drug concentration: 75% w/w) and cimetidine (drug concentration: 70% w/w) powders were obtained via co-spray drying of aqueous suspensions with a high solid content of the feed (35% w/w) and the resulting powders were directly compressed. Scaling-up of optimised acetaminophen and ibuprofen formulations was performed successfully, resulting in a robust and reproducible manufacturing process. It can be concluded that a combination of mannitol, erythritol, Glucidex® 9, Kollidon® CL, colloidal silicon dioxide and polyoxyethylene 20 sorbitan monooleate allowed the spray drying of highly dosed drug substances (acetaminophen, ibuprofen, cimetidine) in order to obtain ‘ready-to-compress’ powder mixtures on lab-scale and production-scale equipment.
Keywords: Co-spray drying; Scaling-up; Continuous processing; Compression; Acetaminophen; Ibuprofen; Cimetidine; Carbohydrates
Fast dispersible/slow releasing ibuprofen tablets
by Adamo Fini; Valentina Bergamante; Gian Carlo Ceschel; Celestino Ronchi; Carlos Alberto Fonseca de Moraes (pp. 335-341).
Eight formulations were developed containing ibuprofen in the form of orally disintegrating tablets. To prevent bitter taste and side effects of the drug, the drug was associated with Phospholipon 80H, a saturated lecithin, by wet granulation. The granules were then coated using different film forming agents (Kollicoat SR 30, Amprac 01, Kollidon 90F, Eudragit RD 100) obtaining four lots 1–4. Coated granules were then formulated with a sweetener (Aspartame), a mannitol-based diluent (Pearlitol SD 200) and Kollidon CL (1-4K) or Explotab (1-4E) were added as superdisintegrants and compacted under low compression force. The eight lots of tablets, 1-4K and 1-4E, were assessed if suitable as oral disintegrating tablets by determination of a range of technological parameters. Wetting and disintegregation time matched with the requirements of EP IV Ed., for almost all these formulations. Dissolution profiles suggested that the combined action of the hydrophobic lecithin and the coating delay the release of the drug from tablets with respect to when it is free or in the form of simple granules. By an appropriate combination of excipients it was thus possible to obtain orally disintegrating tablets and a delayed release of ibuprofen using simple and conventional techniques.
Keywords: Orally disintegrating tablets; Ibuprofen; Lecithin; Taste masking; Slow release; Gastroprotection; Fast dispersing tablets
Improvement of dissolution properties of Carbamazepine through application of the liquisolid tablet technique
by Saadia A. Tayel; Iman I. Soliman; Dina Louis (pp. 342-347).
The aim of the work was to improve the dissolution properties of the practically insoluble antiepileptic drug, Carbamazepine (CBZ) by adopting the liquisolid compaction technique. Reported liquid load factors, and excipient ratios were used to calculate the required amounts of excipients necessary to prepare the compacts or tablets according to a mathematical model. Avicel PH 102, and Aerosil 200 were used as the carrier and the coating materials, respectively, and explotab was used as disintegrant to prepare four tablet formulae, out of which formula 1 was successfully compressed into tablets. The dissolution patterns of liquisolid CBZ tablets, carried out according to the USP, were comparable to those of Tegretol®. The protection of male albino mice against the convulsion, induced by electroshock, was lower in case of liquisolid tablets compared to Tegretol® suspension and tablets probably due to the precipitation of CBZ in the silica pores resulting from its high dose.
Keywords: Carbamazepine (CBZ); Liquisolid; Liquid load factor; Excipient ratio; Carrier; Coating material; Tablets; Compacts
New spray congealing atomizer for the microencapsulation of highly concentrated solid and liquid substances
by Beatrice Albertini; Nadia Passerini; Franco Pattarino; Lorenzo Rodriguez (pp. 348-357).
A new pneumatic atomizer for spray congealing, called wide pneumatic nozzle (WPN), was developed. To evaluate its performance, microparticles containing highly concentrated either solid drug (Propafenone hydrochloride, PRF) or liquid nutraceutical (Vitamin E, VE) have been prepared and characterized. The results showed that the spray congealing nozzle enabled the production of spherical and not aggregated microparticles with high yields (95% w/w) and relatively narrow size distributions; moreover, increasing the viscosity of the suspension from 50 to 500mPas, the particle size increased. The loading of the drug was high for microspheres (50% for PRF and 30% for VE) and the encapsulation efficiency was good for all formulations. The drug release was easily modified according to the nature of the used excipients, as both lipophilic (carnauba wax, cetearyl and stearyl alcohols) and hydrophilic (PEG 4000) carriers were employed. Moreover the results evidenced that it was possible to encapsulate actives (VE) that are in a liquid form and to enhance their availability. In conclusion the developed spray congealing nozzle was able to nebulize very viscous systems that are usually not processed by conventional apparatus and to produce microspheres with high and uniform drug content.
Keywords: Spray congealing; Air pressure nozzle; Microparticles; Propafenone hydrochloride; Vitamin E acetate
Cryo-irradiation as a terminal method for the sterilization of drug aqueous solutions
by Aubert Maquille; Jean-Louis Habib Jiwan; Bernard Tilquin (pp. 358-363).
The aim of this study is to evaluate the specificities of the irradiation of drugs in frozen aqueous solution. The structures of the degradation products were determined to gain insight into the radiolysis mechanisms occurring in frozen aqueous solutions. Metoclopramide hydrochloride and metoprolol tartrate were chosen as models. The frozen solutions were irradiated at dry ice temperature by high energy electrons at various doses. The drug purity (chemical potency) and the radiolysis products were quantified by HPLC-DAD. Characterization of the degradation products was performed by LC–APCI–MS–MS. The structures of the radiolysis products detected in irradiated frozen aqueous solutions were compared to those detected in solid-state and aqueous solutions (previous studies). For both metoclopramide and metoprolol, solute loss upon irradiation of frozen aqueous solutions was negligible. Five radiolysis products present in traces were identified in irradiated metoclopramide frozen solutions. Three of them were previously identified in solid-state irradiated metoclopramide crystals. The two others were formed following reactions with the hydroxyl radical (indirect effect). Only one fragmentation product was observed in irradiated metoprolol frozen solutions. For both drugs, radiosterilization of frozen solutions, even at high doses (25kGy), was found to be possible.
Keywords: Metoclopramide; Metoprolol; Radiolysis; HPLC-DAD; LC–MS; Frozen solutions; Sterilization; Cryo-irradiation
An investigation into the effects of thermal history on the crystallisation behaviour of amorphous paracetamol
by Sheng Qi; Paolo Avalle; Robert Saklatvala; Duncan Q.M. Craig (pp. 364-371).
The effects of thermal history and sample preparation on the polymorphic transformation profile from amorphous paracetamol have been investigated. The crystallisation behaviour of slow and quench cooled amorphous paracetamol was studied using DSC. Quench cooled paracetamol showed a glass transition ( Tg) at 25.2°C, a single exothermic transition at 64.9°C and an endotherm at 167.7°C. The initial degree of crystallinity was calculated as a function of time and recrystallisation circa 20°C below Tg was demonstrated. Slow cooled material in pinholed or hermetic pans (sealed under nitrogen) showed a Tg at 25.1°C, two exothermic transitions at circa 80–85°C and 120–130°C followed by melting at 156.9°C; a single exotherm at 83°C was observed for material sealed in hermetic pans under ambient conditions. Hot stage microscopy yielded complementary information on crystal growth and transformation profile. A transformation scheme is proposed which indicates that amorphous paracetamol may transform into Form III, II or I depending on the thermal history and the gaseous environment in which recrystallisation takes place. The study has demonstrated that the thermal history and encapsulation method may profoundly influence the polymorphic forms generated from amorphous paracetamol.
Keywords: Amorphous; Crystallisation; Glass; Paracetamol; Thermal
Influence of compression forces on tablets disintegration by AC Biosusceptometry
by Luciana A. Corá; Paulo R. Fonseca; Madileine F. Américo; Ricardo B. Oliveira; Oswaldo Baffa; José Ricardo A. Miranda (pp. 372-379).
Analysis of physical phenomena that occurs during tablet disintegration has been studied by several experimental approaches; however none of them satisfactorily describe this process. The aim of this study was to investigate the influence of compression force on the tablets by associating the AC Biosusceptometry with consolidated methods in order to validate the biomagnetic technique as a tool for quality control in pharmaceutical processes.Tablets obtained at five compression levels were submitted to mechanical properties tests. For uncoated tablets, water uptake and disintegration force measurements were performed in order to compare with magnetic data. For coated tablets, magnetic measurements were carried out to establish a relationship between physical parameters of the disintegration process. According to the results, differences between the compression levels were found for water uptake, force development and magnetic area variation measurements. ACB method was able to estimate the disintegration properties as well as the kinetics of disintegration process for uncoated and coated tablets. This study provided a new approach for in vitro investigation and validated this biomagnetic technique as a tool for quality control for pharmaceutical industry. Moreover, using ACB will also be possible to test these parameters in humans allowing to establish an in vitro/ in vivo correlation (IVIVC).
Keywords: AC Biosusceptometry; Compression force; Disintegration force; Water uptake; Magnetic tablets; Disintegration
In-line monitoring of granule moisture in fluidized-bed dryers using microwave resonance technology
by Caroline Buschmüller; Wolfgang Wiedey; Claas Döscher; Jochen Dressler; Jörg Breitkreutz (pp. 380-387).
This is the first report on in-line moisture measurement of pharmaceutical products by microwave resonance technology. In order to meet the FDA’s PAT approach, a microwave resonance sensor appropriate for pharmaceutical use was developed and implemented into two different fluidized-bed dryers. The novel sensor enables a continuous moisture measurement independent from the product density. Hence, for the first time precise real time determination of the moisture in pharmaceutical granules becomes possible. The qualification of the newly developed sensor was performed by drying placebo granules under experimental conditions and the validation using drug loaded granules under real process conditions. The results of the investigations show good correlations between water content of the granules determined by the microwave resonance sensor and both reference methods, loss on drying by infrared light exposure and Karl Fischer titration. Furthermore, a considerable time saving in the drying process was achieved through monitoring the residual water content continuously by microwave resonance technology instead of the formerly used discontinuous methods.
Keywords: Process analytical technology; Microwave resonance technology; Moisture measurement; Granule water content; Fluidized-bed dryer; Wet granulation
Characterization of drug–chitosan interaction by1H NMR, FTIR and isothermal titration calorimetry
by Yaowalak Boonsongrit; Bernd W. Mueller; Ampol Mitrevej (pp. 388-395).
Electrostatic interaction between opposite charge of drugs (insulin and benzoic acid) and chitosan was studied by1H NMR, FTIR and isothermal titration calorimetry (ITC). No ionic interaction between the carboxyl group of benzoic acid and the amine group of chitosan could be detected. There was a minor change in the FTIR spectra of insulin–chitosan microparticles made of different concentrations of insulin. Exothermic heat of reaction between insulin and chitosan was obtained by ITC. However, the measured interaction enthalpy change (Δ H) was possibly due to the conformational changes and the adsorption phenomena of insulin onto the surfaces of the particles but not to a binding interaction. The binding of tripolyphosphate, a widely used cross-linking agent, to pH 3.3 and pH 5 chitosan was also studied by ITC. The interaction enthalpy change of the binding between tripolyphosphate and chitosan indicated that tripolyphosphate provided a stronger interaction to pH 5 chitosan than to pH 3.3 chitosan. However, it can be stated that the electrostatical interaction forces between the tested molecules insulin, benzoic acid, and tripolyphosphate and chitosan are found to be very weak.
Keywords: Chitosan; Ionic interaction; Insulin; Benzoic acid; 1; H NMR; FTIR; Isothermal titration calorimetry
Compound profiling for ABCC2 (MRP2) using a fluorescent microplate assay system
by Frank Förster; Astrid Volz; Gert Fricker (pp. 396-403).
Purpose: To establish a fluorescent dye (Glutathione methylfluorescein, GSMF) based assay to rapidly screen compounds for drug efflux interactions with the ABC-protein ABCC2 (MRP2). Methods: MDCK-cells overexpressing ABCC2 were cultured until confluency in 96-well plates. Cells were incubated with chloromethylfluorescein-diacetate (CMFDA) in the absence and presence of increasing concentrations of potential substrates and inhibitors of ABCC2. After formation of GSMF the extent of intracellular fluorescence was monitored with a fluorescence plate reader in a time- and a concentration-dependent manner. Results: MDCK cells showed stable expression of ABCC2 and, as a consequence, GSMF was extruded by the cells across the apical membrane in an energy-dependent manner. The incubation conditions (optimum CMFDA concentration; glutathione dependency, membrane toxicity) were elaborated. Determination of intracellular glutathione concentration indicated that under the chosen conditions glutathione is not rate limiting for the assay performance. Known inhibitors of ABCB1 (P-GP) and ABCG2 (BCRP) did not influence intracellular fluorescence intensity, but a significant increase of intracellular fluorescence was observed in the presence of MRP2-substrates and inhibitors accompanied with a concomitant decrease of GSMF efflux. Conclusions: The GSMF-assay based on fluorescence accumulation in MRP2-overexpressing MDCK cells can be used as a rapid microplate screening system for interactions of drugs with MRP2 and therefore represents a useful tool in drug profiling.
Keywords: MRP2; ABCC2; CMFDA; Fluorescence assay; ABC-protein