International Journal of Pharmaceutics (v.344, #1-2)
Author Index Volumes 326-344 (2007) (e1-e27).
Subject Index Volumes 326-344 (2007) (e28-e44).
Editorial Board (iii).
Preface by Angelina Angelova; Jacques Barbet; Gillian Barratt; Didier Betbeder; Laurence Moine (1-2).
Tribute to Dr. Nathalie Ubrich by P.H. Maincent (3).
Formal descriptions for formulation by Hervé This (4-8).
Two formalisms used to describe the physical microstructure and the organization of formulated products are given. The first, called “complex disperse systems formalism” (CDS formalism) is useful for the description of the physical nature of disperse matter. The second, called “non periodical organizational space formalism” (NPOS formalism) has the same operators as the CDS formalism, but different elements; it is useful to describe the arrangement of any objects in space. Both formalisms can be viewed as the same, applied to different orders of magnitude for spatial size.
Keywords: Molecular gastronomy; Formalisms; Food; Disperse systems;
Purification of bioactive glycosylated recombinant glial cell line-derived neurotrophic factor by E. Garbayo; E. Ansorena; J.L. Lanciego; M.S. Aymerich; M.J. Blanco-Prieto (9-15).
Glial cell line-derived neurotrophic factor (GDNF) neuroprotective effect on dopaminergic neurons has been described in vitro and in vivo, turning up as a promising drug for the treatment of Parkinson's disease. Unglycosylated bacteria-obtained GDNF has already been successfully delivered for a long period of time through an infusion pump directly to the putamen of Parkinsonian patients. Nevertheless, improved distribution and safety issues need to be solved and alternative strategies to long-term delivery seem necessary. The use of glycosylated GDNF could eliminate some safety concerns regarding the presence of antibodies against exogenous unglycosylated GDNF used for the treatment. Therefore, we have chosen a mammalian expression system as a source of glycosylated GDNF. In the present work, we describe the purification of recombinant rat GDNF from the culture media of baby hamster kidney (BHK) cells through several purification steps. Highly pure N-glycosylated recombinant GDNF has been obtained similar to the endogenous protein. Furthermore, the purified protein is biologically active when tested its ability to induce PC12 neurite outgrowth.
Keywords: GDNF; Parkinson's disease; Protein purification;
Improvement of a bovine serum albumin microencapsulation process by screening design by L. Al haushey; M.A. Bolzinger; C. Bordes; J.Y. Gauvrit; S. Briançon (16-25).
The first objective of this study was to prepare microspheres containing a model protein by double emulsion-solvent evaporation/extraction method. This method was modified to consider the fragile nature of proteins. These modifications related to the reduction of polymer loss, of agitation duration and of contact time between protein and solvent. The polymer used was poly(ɛ-caprolactone) and the model protein was bovine serum albumin. The control of the microsphere properties constituted a second objective of this project. A screening design methodology was used to evaluate the effects of the process and formulation variables on microsphere properties. Twelve operating factors were retained, and the particle properties considered were the mean size, the encapsulation efficiency, and the surface state. The statistical analysis of the results allowed determining the most influent factors. Considering the whole results, it appeared that the polymer concentration, the osmotic pressure equilibrium and the volume of the inner, outer and organic phases were the most important parameters. Following this screening study, it was possible to produce particles of small size with high entrapment efficiency (near to 80%) and smooth surface. A good batch to batch reproductibility was obtained.
Keywords: Microspheres; Bovine serum albumin; Double emulsion; Solvent evaporation; Screening design;
Miscellaneous nanoaggregates made of β-CD esters synthesised by an enzymatic pathway by L. Choisnard; A. Gèze; B.G.J. Yaméogo; J.-L. Putaux; D. Wouessidjewe (26-32).
Various β-cyclodextrin (β-CD) fatty esters with different chain lengths (C4–C14) were synthesised by transesterification of β-cyclodextrin by vinyl fatty ester using thermolysin in DMSO. For each cyclodextrin derivatives, two batches of synthesis were realized. The ability of these derivatives to form nano-organized systems was investigated through the solvent displacement technique. During the formulation step, the effects of the initial concentration of β-CD fatty esters in the organic phase and that of the final volume of the aqueous non-solvent phase were studied. Except for the β-CD C4 ester, the transesterified β-CD derivatives led to measurable nanoparticles. Cryo-electron microscopy images showed a significant morphological variability. Spherical, rod-like or more irregularly-shaped nano-objects were observed with either matricial or lamellar structures. A statistical analysis by a two-way ANOVA was computed for each class of β-cyclodextrin esters in order to determine the effects of batch and formulation on the final size of nanoparticles.
Keywords: Thermolysin transesterification; β-cyclodextrin fatty esters; Nanosystems; Quasi-elastic light scattering; Cryo-transmission electron microscopy; Variance analysis;
Influence of polymer behaviour in organic solution on the production of polylactide nanoparticles by nanoprecipitation by Philippe Legrand; Sylviane Lesieur; Amélie Bochot; Ruxandra Gref; Wouter Raatjes; Gillian Barratt; Christine Vauthier (33-43).
The aim of this study was to define the parameters determining an optimized yield of monodisperse, nanosized particles after nanoprecipitation of a biodegradable polymer, with a view to industrial scale-up the process. Poly(d,l)-lactides (PLAs) from a homologous series of different molar masses were nanoprecipitated at different initial polymer concentrations from two organic solvents, acetone and tetrahydrofuran (THF), into water without surfactant according to a standardized procedure. Quasi-elastic light scattering and gel permeation chromatography with universal detection were used respectively to size the particles and to determine the molar mass distribution of the polymeric chains forming both nanoparticles and bulk aggregates. The intrinsic viscosity of the polymers as a function of molar mass and solvent were determined by kinematic viscosity measurements in organic solutions. High yields of small nanoparticles were obtained with polymers of lower molar mass (22 600 and 32 100 g/mol). For a given polymer concentration in organic solution, the particle diameter was always lower from acetone than from THF. For initial molar masses higher than 32 100 g/mol, only dilute organic solutions gave significant yields of nanoparticles. Furthermore, polymer mass fractionation occurred with increasing initial molar mass and/or concentration: the nanoparticles were formed by polymeric chains of molar masses significantly lower than the average initial one. In general, nanoparticle production was satisfactory when the initial organic solution of polymer was in the dilute rather than the semi-dilute regime. Moreover, acetone, which acted as a theta solvent for PLA, always led to smaller particles and better yields than THF.
Keywords: Nanoparticles; Sizing; Poly(d,l-lactic acid); Dilute solution regime; Production yield; Intrinsic viscosity;
Nano-emulsions and nanocapsules by the PIT method: An investigation on the role of the temperature cycling on the emulsion phase inversion by Nicolas Anton; Pascal Gayet; Jean-Pierre Benoit; Patrick Saulnier (44-52).
This paper focuses on the phenomenological understanding of temperature cycling process, applied to the phase inversion temperature (PIT) method. The role of this particular thermal treatment on emulsions phase inversion, as well as its ability to generate nano-emulsions have been investigated. In order to propose a general study, we have based our investigations on a given formulation of nano-emulsions classically proposed in the literature [Heurtault, B., Saulnier, P., Pech, B., Proust, J. E., Benoit, J.P., 2002. A novel phase inversion-based process for the preparation of lipid nanocarriers. Pharm. Res. 19, 875; Lamprecht, A., Bouligand, Y, Benoit, J.P., 2002. New lipid nanocapsules exhibit sustained release properties for amiodarone. J. Control. Release 84, 59–68], using a polyethoxylated model nonionic surfactant, a polyoxyehtylene-660-12-hydroxy stearate, stabilizing the emulsion composed of caprilic triglycerides (triglycerides medium chains), salt water (and also phospholipidic amphiphiles neutral for the formulation). Characterization of nano-emulsions was performed by dynamic light scattering (DLS) which provides the hydrodynamic diameter, but also the polydispersity index (PDI), as a fundamental criteria to judge the quality of the dispersion. Another aspect of the characterization was done following the emulsion inversion and structure by electrical conductivity through the temperature scan. Overall, the role such a temperature cycling process on the formulation of nano-emulsions appears to be relatively important, and globally enhanced as the surfactant concentration is lowered. Actually, both the hydrodynamic diameter and the PDI decrease as a function of the number and temperature cycles up to stabilize a steady state. Eventually, such a cycling process allows the generation of nano-emulsions in ranges of compositions largely expanded when compared with the classical PIT method. These general and interesting trends emerge from the results, are discussed and essentially explained by regarding the behavior of the nonionic surfactants towards the water/oil interface, linking partitioning coefficients, temperature variation, and surfactant water/oil interfacial concentration. In that way, this paper proposes new insights into the phenomena governing the PIT method, by originally investigating the temperature cycling process.
Keywords: Nano-emulsion; PIT method; Emulsion; Temperature cycling; Nonionic;
Effect of the microencapsulation of nanoparticles on the reduction of burst release by A. Sheikh Hasan; M. Socha; A. Lamprecht; F. El Ghazouani; A. Sapin; M. Hoffman; P. Maincent; N. Ubrich (53-61).
The initial burst release is one of the major problems in the development of controlled release formulations including drug-loaded micro- and nanoparticles, especially with low molecular weight drugs. The objective of the present work was to encapsulate, by the W/O/W emulsion, polymeric nanoparticles into polymeric microparticles by using non-water soluble polymers and appropriate organic solvents for the preparation of these composite microparticles. They were characterized in vitro (encapsulation efficiency, mean diameter and release kinetics) and compared with nanoparticles and classical microparticles prepared by the same method. Poly-ɛ-caprolactone (PCL) dissolved in methylene chloride was used to make nanoparticles, whereas ethylcellulose and Eudragit RS dissolved in ethyl acetate, a non-solvent of poly-ɛ-caprolactone, were used for the preparation of microparticles. Ibuprofen and triptorelin acetate were chosen as lipophilic and hydrophilic model drugs, respectively. High entrapment efficiencies were obtained with ibuprofen whereas lower amounts of triptorelin acetate were encapsulated, mainly with formulations prepared with poly-ɛ-caprolactone and Eudragit RS used alone or blended with ethylcellulose. The burst was significantly lower with composite microparticles and may be explained by the slower diffusion of the drugs through the double polymeric wall formed by the nanoparticle matrix followed by another diffusion step through the microparticle polymeric wall.
Keywords: Burst release; Nanoparticles; Microparticles; Controlled release;
Liposomal formulation of a glycerolipidic prodrug for lymphatic delivery of didanosine via oral route by M. Lalanne; K. Andrieux; A. Paci; M. Besnard; M. Ré; C. Bourgaux; M. Ollivon; D. Desmaele; P. Couvreur (62-70).
Didanosine is a polar drug with poor membrane absorption and high hepatic first pass metabolism. This study aimed at developing a lipidic formulation of a glycerolipidic prodrug of didanosine in order to improve its bioavailability. In the course of a preformulation study, the glycerolipidic prodrug of didanosine was characterized by microscopy, DSC and XRDT. In anhydrous conditions, the prodrug displayed a polymorphic behaviour similar to that of triglycerides. Then, we evaluated three types of lipidic formulations (emulsions, mixed micelles and liposomes) in order to encapsulate the prodrug. Solubilities in water – even in the presence of taurocholate micelles – but also in some oils were very low (max 244 μg/mL) as the prodrug was found to be amphiphilic (log P = 2). On the contrary, the prodrug was found to be perfectly incorporated in dipalmitoylphosphatidylcholine (DPPC) multilamellar liposomes up to a ratio of 1:5 (mol:mol) prodrug:DPPC as suggested by HPLC-UV and DSC experiments. Moreover, these liposomes could be freeze-dried whereas the chemical integrity of the prodrug was preserved. Then, the freeze-dried liposomal preparation could be formulated as gastro-resistant capsules to prevent didanosine from acidic degradation. Further experiments are on the way to evaluate in vitro the absorption of prodrug incorporated in liposomes by enterocytes.
Keywords: Glycerolipidic prodrug; DSC; XRDT; Liposomes; Didanosine;
Encapsulation of gemcitabine lipophilic derivatives into polycyanoacrylate nanospheres and nanocapsules by Barbara Stella; Silvia Arpicco; Flavio Rocco; Véronique Marsaud; Jack-Michel Renoir; Luigi Cattel; Patrick Couvreur (71-77).
The aim of this study was to develop both a physical and a chemical protection of the anticancer drug gemcitabine, which suffers from a rapid plasmatic metabolization. For this purpose, we used a series of lipophilic derivatives of gemcitabine in which an acyl chain is covalently coupled to the 4-amino group of gemcitabine; moreover, a physical protection of the drug was attempted by incorporating these lipophilic derivatives into poly(H2NPEGCA-co-HDCA) nanospheres and nanocapsules. Nanoparticles were prepared by nanoprecipitation of the poly(H2NPEGCA-co-HDCA) copolymer and their size, zeta potential and encapsulation efficiency were further characterized. These results have been relied on lipophilicity and flexibility studies. Data showed that only the more lipophilic derivative, 4-(N)-stearoylgemcitabine, was incorporated with a high yield. Thus, 4-(N)-stearoylgemcitabine-containing nanospheres and nanocapsules were further analyzed by differential scanning calorimetry. Their cytotoxicity was tested on two human cancer cell lines and compared to that of gemcitabine and free 4-(N)-stearoylgemcitabine.
Keywords: Polycyanoacrylate; Nanospheres; Nanocapsules; Gemcitabine; Cytotoxicity;
Tetrapyrrole-photosensitizers vectorization and plasma LDL: A physico-chemical approach by Stéphanie Bonneau; Christine Vever-Bizet; Halina Mojzisova; Daniel Brault (78-87).
A photosensitizer is defined as a chemical entity able to induce, under light-irradiation effect, a chemical or physical alteration of another chemical entity. Thanks to their preferential retention in proliferating tissues, some photosensitizers are therapeutically used such as in photodynamic therapy (PDT). Besides, this method has already been approved for several indications. The selectivity of photosenzitizers for cells in proliferation involves both their association with low density lipoproteins (LDLs) and their ability to cross membranes under various pH conditions. The photosensitizers used are in most cases based on the porphyrin structure, but other compounds, of which far-red-light absorption properties are most compatible with biological tissues irradiation, have been developed, such as phthalocyanines. This paper presents physico-chemical studies of the interaction of a disulfonated aluminium phthalocyanine (AlPcS2) with human LDLs. The data obtained are compared with the parameters of the interaction of these lipoproteins with deuteroporphyrin (DP) and chlorin e6 (Ce6). A close attention is paid to the dynamic aspects of these phenomena. The data obtained on these simple systems then allowed us to interpret the sub-cellular localization of the photosensitizers on a human line of fibroblasts, and to evaluate the influence of LDLs on the intracellular distribution of the compounds. This last point is of major importance because the localization of such photosensitizers (in particular AlPcS2) in endocytic vesicles and their subsequent ability to induce a release of the contents of these vesicles – including externally added macromolecules – into the cytosol is the basis for a recent method for macromolecule activation, named photochemical internalization (PCI). PCI has been shown to potentiate the biological activity of a large variety of macromolecules. The comprehension of the mechanisms governing this particular sub-cellular localization could allow the design of better candidates for PCI.
Keywords: Vectorization; Photosensitizers; Low density lipoproteins (LDL); Sub-cellular localization; Photochemical internalization (PCI);
PEGylated quaternized copolymer/DNA complexes for gene delivery by Benoît Vroman; Isabel Ferreira; Christine Jérôme; Robert Jérôme; Véronique Préat (88-95).
The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of ɛ-caprolactone and quaternized ɛ-caprolactone. For this purpose, diblock 50/50 copolymer was used to generate complexes with DNA by either the solvent evaporation technique and by dialysis. The size, surface charge and degree of interaction of the plasmid-loaded formulations were measured. Then, polyplexes were combined with a poly(CL)-b-PEG copolymer to create a hydrophilic corona on the surface of the complexes. The cytotoxicity, transfection efficiency and cellular uptake of polyplexes and their association with PEG were evaluated on HeLa cells. The dialysis method did not allow to reduce the size of complexes as compared to the solvent evaporation method. The zeta potential of polyplexes became positive from a charge ratio of 4. The degree of interaction of copolymer with plasmid DNA was very high. Cytotoxicity and transfection efficiency were found to be comparable to polyethylenimine 50 kDa. Association of polyplexes with poly(CL)-b-PEG copolymer led to a small increase in particle size and a sharp decrease of charge surface. Cytotoxicity, transfection efficiency and cellular uptake were significantly reduced relative to unshielded copolymer/DNA complexes. The PEGylated formulations may be an attractive approach for an in vivo application.
Keywords: Gene therapy; Polyplexes; DNA; Polyethylene glycol; Transfection;
Lipoplex and peptide-based strategies for the delivery of steric-block oligonucleotides by Sarah Resina; Saïd Abes; John J. Turner; Paul Prevot; Adrian Travo; Philippe Clair; Michael J. Gait; Alain R. Thierry; Bernard Lebleu (96-102).
Synthetic oligonucleotides offer interesting prospects for the control of gene expression but clinical applications have been severely limited by their poor bioavailability.Cationic lipids have been widely used for the delivery of charged oligonucleotide (ON) analogues but most of the commercial formulations are toxic and poorly stable in the presence of serum proteins. We have developed a DOGS/DOPE liposome formulation named DLS (for delivery liposomal system), that allows for the efficient nuclear delivery of negatively charged antisense ON analogues as monitored by fluorescence microscopy and by their ability to correct deficient pre-mRNA splicing, even in serum-supplemented cell culture.Uncharged DNA mimics such as peptide nucleic acids (PNA), or phosphorodiamidate morpholino (PMO) ON are particularly interesting for their high metabolic stability and affinity for complementary RNA targets but they cannot be delivered with cationic lipids. Cell penetrating peptides (CPP), such as Tat or penetratin, have been used widely as conjugates for the delivery of various biomolecules and might be appropriate for neutral ON analogues. However, entrapment within endocytic vesicles severely limits the efficiency of PNA delivery by CPPs in the absence of endosomolytic drugs, such as chloroquine. The conjugation of new arginine-rich CPPs to PNA allows efficient nuclear delivery in the absence of chloroquine as monitored in a splicing correction assay.Both strategies have their advantages but DLS-mediated delivery remains more efficient than CPP delivery for the nuclear targeting of splice correcting ON analogues in vitro.
Keywords: Antisense oligonucleotide; Splice correction; Lipoplex; Cell penetrating peptide;
Influence of surface charge and inner composition of porous nanoparticles to cross blood–brain barrier in vitro by Youssef Jallouli; Archibald Paillard; Jiang Chang; Emmanuel Sevin; Didier Betbeder (103-109).
The aim of these studies was to evaluate the binding, uptake and transcytosis of 60 nm porous nanoparticles (NPs) that differed in their surface charge and inner composition on the blood–brain barrier (BBB). They were prepared from maltodextrins derived with or without a cationic ligand. In the cationic NPs an anionic lipid was inserted in their core to give DPPG-NPs. The data showed that at 4 °C the three NPs bind in different areas on endothelial cells: cationic NPs were found mainly around the paracellular area, while neutral NPs were mainly on the cell surface and DPPG-NPs binding was found at both paracellular areas and on the surface of the cells. At 37 °C neutral and cationic NPs had similar degrees of binding and uptake and were transcytosed. Filipin treatment increased their binding and uptake suggesting that sterols are implied in their efflux. Neutral NPs transcytosis was also inhibited by filipin. This inhibition shows that neutral NPs, like LDL in this model, use the caveolae pathway. Neutral and cationic 60 nm porous NPs are potential candidates for drug delivery to the brain.
Keywords: Nanoparticles; Blood–brain barrier; Binding and uptake; Transcytosis;
Doubly radiolabeled liposomes for pretargeted radioimmunotherapy by M. Mougin-Degraef; C. Bourdeau; E. Jestin; C. Saï-Maurel; M. Bourgeois; P. Remaud-Le Saëc; P. Thédrez; J.-F. Gestin; J. Barbet; A. Faivre-Chauvet (110-117).
The aim of this study was to design liposomes as radioactivity carriers for pretargeted radioimmunotherapy with favorable pharmacokinetic parameters. To monitor the liposomes integrity in vivo, their surface was radiolabeled with indium-111 bound to DTPA-derivatized phosphatidylethanolamine (DSPE-DTPA) and the aqueous phase was labeled by using an original active loading technique of radioiodinated Bolton–Hunter reagent (BH) that reacts with pre-encapsulated arginine to form a positively charged conjugate (125I-BH-arginine). Different formulations of doubly radiolabeled liposomes were tested in vitro and in vivo to evaluate radiolabeling stability, integrity of the vesicles and their pharmacokinetics.Radiolabeling yields were high (surface >75%, encapsulation >60%) and stable (>85% after 24 h in serum 37 °C). In vivo, the pharmacokinetic behavior of doubly radiolabeled liposomes was strongly dependant on the formulation. Blood clearance of PEGylated liposomes (DSPC/Chol/DSPE-DTPA/DSPE-PEG5%) was 0.15 mL/h compared to a conventional formulation (DSPC/Chol/DSPE-DTPA: clearance 1.44 mL/h). Non-encapsulated BH-arginine conjugate was quickly eliminated in urine (clearance 6.04 mL/h). Blood kinetics of the two radionuclides were similar and radiochromatographic profiles of mice serum confirmed the integrity of circulating liposomes. The significant reduction of activity uptake in organs after liposome catabolism (liver and spleen), achieved by the rapid renal elimination of 125I-BH-arginine, should bring significant improvements for targeted radionuclide therapy with sterically-stabilized liposomes.
Keywords: Liposomes; Radiolabeling; Bolton–Hunter; Pharmacokinetics; Biodistribution;
Sterically stabilized superparamagnetic liposomes for MR imaging and cancer therapy: Pharmacokinetics and biodistribution by V. Plassat; M.S. Martina; G. Barratt; C. Ménager; S. Lesieur (118-127).
Pharmacokinetics of magnetic-fluid-loaded liposomes (MFLs) with mean hydrodynamic diameter of 200 nm sterically stabilized by poly(ethylene glycol) (PEG) and labelled by a fluorescent lipid probe, N-(lissamine rhodamine B sulfonyl) phosphatidylethanolamine (Rho-PE) was studied. The loading consisted in an aqueous suspension of maghemite nanocrystals close to 8 nm in size at 1.7 Fe(III) mol/mol total lipids ratio. Double tracking of MFL in blood was performed versus time after intravenous administration in mice. Lipids constituting vesicle membrane were followed by Rho-PE fluorescence spectroscopy while iron oxide was determined independently by relaxometry. MFLs circulating in the vascular compartment conserved their vesicle structure and content. The pharmacokinetic profile was characterized by two first-order kinetics of elimination with distinct plasmatic half-lives of 70 min and 12.5 h. Iron biodistribution and organ histology clearly highlighted preferential MFL accumulation within liver and spleen. The pathway in spleen supported that elimination was governed by the mononuclear phagocyte system (MPS). PEG coating was essential to prolong MFL circulation time whereas iron oxide loading tends to favour uptake by the MPS. Despite partial uptake in the earlier times after administration, MFLs exhibited long circulation behaviour over a 24-h period that, coupled to magnetic targeting, encourages further use in drug delivery.
Keywords: Magnetic-fluid loaded liposomes; Fluorescence; Relaxometry; Ferrofluid; Histology; Long-circulating vesicles;
Potentialities of silica/alginate nanoparticles as Hybrid Magnetic Carriers by Michel Boissière; Joachim Allouche; Corinne Chanéac; Roberta Brayner; Jean-Marie Devoisselle; Jacques Livage; Thibaud Coradin (128-134).
The possibility to associate traditional bio-organic capsules, such as polymer nanoparticles or liposomes, with silica has been recently demonstrated, opening the route to the design of novel nanocomposites that exhibit promising properties as drug carriers. In this context, we describe here the elaboration of silica/alginate nanoparticles incorporating magnetic iron oxide colloids and fluorescent carboxy-fluoroscein. These nanocomposites were characterized by electron microscopy, X-ray diffraction and magnetic measurements. The release of the fluorophore was investigated in vitro and was demonstrated to occur in 3T3 fibroblast cells. Further grafting of organic moieties on particle surface is also described. These data suggest that hybrid nanoparticles are flexible platforms for the developments of multi-functional bio-capsules.
Keywords: Alginate; Silica; Maghemite; Hybrid materials; Nanoparticles;
Biodistribution of intravenously administered amphiphilic β-cyclodextrin nanospheres by A. Gèze; L. Tieu Chau; L. Choisnard; J.-P. Mathieu; D. Marti-Batlle; L. Riou; J.-L. Putaux; D. Wouessidjewe (135-142).
Amphiphilic β-cyclodextrin (βCDa) nanospheres (mean diameter 90–110 nm) prepared by the solvent displacement method were developed as a colloidal drug delivery system. In order to survey the fate of these nanoparticles, the amphiphilic β-cyclodextrin was first iodinated by a two-step procedure involving iodination of the primary face followed by an acylation of the secondary face. After radiolabeling of this derivative with 125I, nanospheres made of βCDa/βCDa 125I were formulated. After a single intravenous injection of labeled nanoparticles in mice, the organ distribution was analyzed from 10 min to 6 days. A rapid clearance of 125I-labeled βCDa nanospheres from the blood circulation to the mononuclear phagocyte system was visualized by non-invasive planar imaging study. Radioactivity measurements in organs showed that the nanospheres mainly concentrated in the liver and the spleen where 28 and 24% of the radioactivity per gram of organ was, respectively, found 10 min after injection. At the opposite, the blood activity was low at that time and become negligible thereafter. Finally, the fact that no particular sign of toxicity is observed in injected animals should be emphasized since it is the first report on intravenous administration of βCDa nanoparticles.
Keywords: Amphiphilic β-cyclodextrin; Nanosphere suspension; Cryo-TEM; Radiolabeling; γ-Scintigraphy; In vivo tissue distribution;
In vivo evaluation of lipid nanocapsules as a promising colloidal carrier for paclitaxel by F. Lacoeuille; F. Hindre; F. Moal; J. Roux; C. Passirani; O. Couturier; P. Cales; J.J. Le Jeune; A. Lamprecht; J.P. Benoit (143-149).
Paclitaxel-loaded lipid nanocapsules (PX-LNC) exhibit interesting in vitro characteristics with improved antitumoral activity compared with free PX formulation. Biodistribution studies were realized with the use of 14C-trimyristin (14C-TM) or 14C-phosphatidylcholine (14C-PC) whereas antitumoral activity of PX-LNC formulations was based on the animal survival in a chemically induced hepatocellular carcinoma (HCC) model in Wistar rats. Blood concentration–time profiles for both labeled 14C-TM-LNC and 14C-PC-LNC were similar; the t 1/2 and MRT values (over 2 h and close to 3 h, respectively, for both formulations) indicated the long circulating properties of the LNC carrier with a slow distribution and elimination phase. Survival curves of paclitaxel treated groups showed a statistical significant difference compared to the control survival curve (P = 0.0036 and 0.0408). Animals treated with 4× 70 mg/m2 of PX-LNC showed the most significant increase in mean survival times compared to the controls (ISTmean 72%) and cases of long-term survivors were preferentially observed in the PX-LNC treated group (37.5%; 3/8). These results demonstrate the great interest to use LNC as drug delivery system for paclitaxel, permitting with an equivalent therapeutic efficiency to avoid the use of excipients such as polyoxyethylated castor oil for its formulation.
Keywords: Lipid nanocapsules; Drug delivery system; Biodistribution; Hepatocellular carcinoma; Paclitaxel;
Liposomal amphotericin B eye drops to treat fungal keratitis: Physico-chemical and formulation stability by K. Morand; A.C. Bartoletti; A. Bochot; G. Barratt; M.L. Brandely; F. Chast (150-153).
Local fungal infections with Candida, Fusarium, Curvularia and Aspergillus can lead to serious ulceration of the cornea and must be treated rapidly. The current treatment consists of 0.15% (w/v) amphotericin B eye drops prepared from Fungizone®, containing deoxycholate, irritant for the cornea, which reduces patient compliance. Eye drops based on liposomal amphotericin B (AmBisome®) would be a convenient alternative; however, according to the manufacturer's instructions, AmBisome® can only be kept refrigerated for 1 week after reconstitution. A longer shelf-life at ambient temperature would be preferable for a preparation made in a hospital pharmacy and delivered to patients. Thus, the possibility of storing an ophthalmic preparation of 0.5% (w/v) liposomal amphotericin B after reconstitution was investigated. After 6 months at room temperature or at +2–8 °C, the hydrodynamic diameter measured by quasi-elastic light scattering remained constant at 108 ± 30 nm with a polydispersity index lower than 0.15. Amphotericin B content, checked by a validated HPLC method, was maintained between 94 and 107%. Amphotericin B and soy phosphatidylcholine proportions remained constant, indicating that the liposomes remained intact and retained the drug. These results show the feasibility of an ophthalmic preparation based on liposomal amphotericin B developed in hospital pharmacies.
Keywords: Liposomes; Amphotericin B; Fungal infections; Eye drops;
Layersome: Development and optimization of stable liposomes as drug delivery system by M. Ciobanu; B. Heurtault; P. Schultz; C. Ruhlmann; C.D. Muller; B. Frisch (154-157).
This paper describes the development of stable drug delivery systems named layersomes. The layersomes are conventional liposomes coated with one or multiple layers of biocompatible polyelectrolytes in order to stabilise their structure. The formulation strategy is based on an alternative coating procedure of positive poly(lysine) (pLL) and negative poly(glutamic acid) (pGA) polypeptides on initially charged small unilamellar liposomes (SUVs). The size distribution and the zeta potential of the final entity depend on the number of polyelectrolyte layers and the charge of the last coating layer. Morphological studies were achieved by flux cytometry and cryo electron microscopy. Release studies of encapsulated hydrophilic 5(6)-carboxyfluorescein (5,6CF) in the presence of Triton® or ethanol showed an increased membrane resistance of the layersomes compared to classical SUVs. Finally, encapsulation of piroxicam (PX) was performed with success.
Keywords: Stable liposomes; Layersomes; Coating; Charged polymers;
Influence of a lipophilic drug on the stability of emulsions: An important approach on the development of lipidic carriers by F.R. Formiga; I.A.A. Fonseca; K.B. Souza; A.K.A. Silva; J.P.F. Macedo; I.B. Araújo; L.A.L. Soares; E. Socrates T. Egito (158-160).
The aim of this work was to investigate the influence of a lipophilic drug, Ibuprofen, on the stability of o/w emulsions. Five formulations were prepared by the phase inversion temperature (PIT) method, and Ibuprofen was incorporated into their oil phase. Emulsion stability was evaluated by short- and long-term studies. Concerning the former, stability under centrifugation showed an improved profile for Ibuprofen-loaded emulsions. The latter confirmed such findings. In conclusion, a rather resistant interfacial film may take place when Ibuprofen was incorporated into the emulsions. Therefore, the critical hydrophilic–lipophilic-balance (HLB) of o/w emulsions can be affected by a lipophilic drug into their oil phase. Such approach is of great importance on the development of lipid carriers for therapeutic drug targeting.
Keywords: Emulsions; HLB; Stability; Lipophilic drugs; Ibuprofen;
Albumin–alginate-coated microspheres: Resistance to steam sterilization and to lyophilization by Maïté Callewaert; Dominique Laurent-Maquin; Florence Edwards-Lévy (161-164).
The paper describes the effect of different thermal treatments on the morphology and binding properties of particles prepared using a transacylation reaction between two biocompatible polymers, namely propylene glycol alginate and human serum albumin.Compared to control alginate gel microspheres, albumin–alginate covalent network offers a better resistance to the microspheres towards freezing, lyophilization and sterilization. The binding properties for methylene blue were not altered by the treatments. Moreover, stability in physiological environments opens interesting applications in biological and pharmaceutical fields.
Keywords: Alginate; Binding properties; Lyophilization; Microsphere; Transacylation; Sterilization;