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S Benita

Publications and source records attributed to S Benita.

At least 19 recordsLinked to original sources
PubMed2006

Influence of oil droplet surface charge on the performance of antibody--emulsion conjugates.

Targeted drug delivery requires binding of (and subsequent uptake by) the carrier to target cells. The purpose of our present study is to compare the binding and uptake of emulsions with different electric surface properties to SK-BR3 cell line, which over-expresses the HER2 receptor. Cationic emulsion was prepared by incorporating 0.25% w/w of the cationic lipid, stearylamine in the formulation while the anionic emulsion formulation was identical but lacking stearylamine. Immunoemulsions were prepared by conjugating the 2-iminothiolane derivative of the monoclonal antibody trastuzumab (Herceptin) through the reactive maleimide group of the octadecyl-4-(maleimidomethyl)cyclohexane-carboxylic amide linker which was incorporated in the oil phase of the anionic and cationic emulsions. Cationic emulsion exhibited a droplet size of approximately 130 nm and a zeta potential of +50 mV compared to anionic emulsion with a droplet size of approximately 140 nm and a zeta potential of -30 mV which decreased to -5 mV following antibody coupling. There was no significant difference in the coupling efficiency of trastuzumab to anionic and cationic emulsions which was in the range of 60-70%. The cationic emulsion and immunoemulsion appeared to be physically stable over a long period of time, as indicated by particle-size measurements while the droplets of the anionic immunoemulsion coalesced with time resulting in phase separation within 20 days storage at 4 degrees C. The results of binding and uptake to cells showed that both cationic and anionic immunoemulsions bind and internalized to cells much more than the respective blank emulsions. The enhanced penetration of the probe coumarin-6 with both immunoemulsions clearly indicated that the internalization process was mainly controlled by a cell-receptor endocytosis mechanism mediated by the binding affinity of trastuzumab to the cell surface receptor since the uptake of the cationic immunoemulsion was not significantly different from the uptake of the anionic immunoemulsion. However, only the cationic immunoemulsion might be considered for further investigation in view of its long standing physical stability.

Anions↗
PubMed2005

[Colloid drug delivery systems: a response to therapeutic expectations arising from biotechnological advances?].

New and fascinating advances in biotechnology have open new perspectives since the use of monoclonal antibodies for therapeutic application, particularly cancer, has been approved. Over the last two decades, numerous research teams have demonstrated that the progression of cancer is often associated with an over-expression of one or several proteins, called tumor antigens. In order to target tumors specifically, researchers have tried to couple monoclonal antibodies with colloid vectors such as liposomes, nanoparticles, and emulsions containing cytotoxic compounds. Use of these conjugated vector-antibody systems for the treatment of cancer is designed to target cancerous cells while sparing healthy cells. We present here a discussion on the synergy between biotechnology and modern molecular pharmotechnology, opening new horizons for therapy.

Animals↗
PubMed2003

Cationic emulsions improves the delivery of oligonucleotides to leukemic P388/ADR cells in ascite.

The aim of this study was to investigate the in vivo ability of O/W cationic emulsions to deliver oligonucleotides (ON) in leukemic P388/ADR cells in ascite, after intraperitoneal (IP) administration in mice. Cationic emulsions were prepared by microfluidization as previously described by Teixeira et al. [Pharm. Res 16 (1999) 30]. The formulations consisted mainly of medium chain triglycerides, phosphatidylcholine (PC), poloxamer, and either a monocationic lipid stearylamine (PC/SA-emulsion) or a polycationic lipid RPRC(18) (PC/RPRC(18)-emulsion). A model ON (33P-pdT(16)) was associated with cationic emulsions by single addition at the end of the manufacturing process. Seven days after P388/ADR inoculation IP to mice, ON free or associated with PC/SA or PC/RPRC(18) emulsions was injected IP at a dose of 0.5 mg/kg. At different interval times, ascite including cells, blood and the main organs were collected and the radioactivity counted by liquid scintillation. The overall results showed significantly high amounts of ON in the leukemic cell pellet, 24 h after administration of ON associated to either PC/SA (AUC(0-24 h)=13634, %injected dose/min) or PC/RPRC(18) (AUC(0-24 h)=22592, % injected dose/min), contrary to the free ON solution (AUC(0-24 h)=3095, %injected dose/min), which displayed only reduced capture by cancer cells. In conclusion, complexation of ON with cationic emulsions had a beneficial effect in increasing tumor cells uptake in vivo (up to sevenfold for PC/RPRC(18)-emulsion) after IP administration. This could open interesting prospects for the treatment of ovarian cancers.

Animals↗
PubMed2002

Design and characterization of protein-based microcapsules as a novel catamenial absorbent system.

Hollow and flexible crosslinked microcapsules of soybean protein, 150-300 microm in diameter, were produced using a modified solvent evaporation method. A maximum plasma absorption of approximately 2000% was obtained. At this swelling rate though, microcapsules bursting was initiated. Thus, the effective absorption capacity may not exceed 1700%. The observed presence of residual unreacted protein inside the microcapsules, was believed to be the main osmotic driving force, to which the extensive swelling and eventual bursting of the microcapsules may be attributed. Thermal analysis of the microcapsules revealed their amorphous nature, as opposed to the significantly crystalline nature of the original protein.

Absorption↗
PubMed2001

Characterization of oligonucleotide/lipid interactions in submicron cationic emulsions: influence of the cationic lipid structure and the presence of PEG-lipids.

We have recently described how oligonucleotide (ON) stability and release from O/W cationic emulsions are governed by the lipid composition. The aim of the present paper was to investigate the properties of the ON/lipid complexes through fluorescence resonance energy transfer (FRET), size, surface tension measurements and cryomicroscopy. Starting from a typical emulsion containing stearylamine as a cationic lipid, the influence of the lipid structure (monocationic molecules bearing mono or diacyl chains, or polycations) as well as of the presence of PEGylated lipids, were studied. The presence of a positive charge on the droplet surface clearly contributed to enhance the ON interaction with lipid monolayers and to bring the ON molecules closer to the interface. Hydrophobic interactions through the acyl chains were shown to further enhance the anchorage of the ON/lipid complexes. In contrast, the incorporation of PEGylated lipids acted as a barrier against the establishment of electrostatic bindings, the polyethyleneglycol chains acting themselves as interaction sites for the ON leading to hydrophilic complexes. Similar features were observed for the polycationic lipid, and cryomicroscopy revealed the existence of bridges of various intensities between the droplets of the emulsion containing either PEG or the polycation, probably because of the configuration of the ON at the interface.

Algorithms↗
PubMed2001

Factors influencing the oligonucleotides release from O-W submicron cationic emulsions.

We recently described a positively charged O-W emulsion as a delivery system for oligonucleotides (ON) [Teixeira et al., Pharm. Res. 16 (1999) 30-36]. The present paper investigates the role of the main formulation parameters that may have an influence on the release-rate of a model ON in a protein-containing medium, i.e. the nature of the oily core, the presence of pegylated lipids, the lipid phase transition temperature, and the cationic lipid structure. The use of cationic lipids bearing diacyl chains (and especially polycations) appeared as the only efficient strategy to reduce the ON release rate. In order to have a better insight on the nature of the interactions between the ON and the interfacial lipids, adsorption isotherms at the air-water interface, fluorescence resonance energy transfer and zeta-potential measurements have been performed. Electrostatic interactions were found to play a crucial role. In contrast, the incorporation of PEG-phospholipids acted as a barrier and maintained the ON molecules distant from the interface, leading to a more rapid release. Finally, ON integrity was assessed by a competitive hybridization assay. The results suggest the existence of a transient ion-pair (ON-cationic lipids) protecting ON against nuclease degradation even after its release from the emulsions.

Cells, Cultured↗
PubMed2000

Charge-dependent interaction of self-emulsifying oil formulations with Caco-2 cells monolayers: binding, effects on barrier function and cytotoxicity.

A positively charged self-emulsifying oil formulation (SEOF), aimed to enhance oral bioavailability of drugs poorly soluble in water, was recently developed. In the present study the Caco-2 cell model was used for the investigation of the charge-dependent interactions of this SEOF with human intestinal epithelial cells. The positively charged emulsions affected the barrier properties of the cell monolayer at high concentrations and reduced the cell viability. However, at the dilution with aqueous phase used in the present study (1:2000), the positively charged SEOF did not induce any detectable cytotoxic effect. The binding of the fluorescent dye DiIC(18)(3) was much higher from the positively charged SEOF, compared to the negatively charged formulation, suggesting an increased closer adhesion of the droplets to the cell surface due to the electrostatic attraction. No transepithelial transport of this compound across Caco-2 cell monolayers was observed with any SEOF formulation.

Amines↗
PubMed2000

Investigation of the role of macrophages on the cytotoxicity of doxorubicin and doxorubicin-loaded nanoparticles on M5076 cells in vitro.

Doxorubicin-loaded PACA nanoparticles have been shown to be more efficient than free drug in mice bearing hepatic metastasis of the M5076 tumour. Due to the high phagocytic activity of Küpffer cells in the liver, it may be that these cells played a role of drug reservoir after nanoparticle phagocytosis. Therefore, the objective of this study was to assess the role of macrophages in mediating the cytotoxicity of doxorubicin-loaded nanoparticles on M5076 cells. The growth inhibition of tumour cells was evaluated in two ways: firstly, the cells were incubated in a coculture system consisting of special wells with two compartments separated by a porous membrane. M5076 cells were seeded into the lower compartment and the macrophages J774.A1 were introduced into the upper part. The macrophages were activated or not by IFN-gamma. The drug preparations were added only in the macrophage insert. Secondly, growth inhibition was also assessed in the conventional way, i.e. in direct contact with the tumour cells to serve as a reference. After direct contact, free doxorubicin (Dox) and doxorubicin-loaded nanoparticles (NP-Dox) had the same efficacy against M5076 cell growth. The coculture experiments led to a 5-fold increase in the IC(50) for both Dox and NP-Dox. The activation of macrophages by IFN-gamma in coculture significantly decreased the IC(50) values. In conclusion, after phagocytosis of doxorubicin-loaded nanoparticles, J774.A1 cells were able to release active drug, allowing it to exert its cytotoxicity against M5076 cells. Drug efficacy was potentiated by the activation of macrophages releasing cytotoxic factors such as NO, which resulted in increased tumour cell death. Thereby, the coculture system permitted us to investigate the macrophage-mediated cytotoxicity of colloidal carriers loaded with an anticancer drug, which is of great interest when further i.v. administration is envisaged.

Animals↗
PubMed2000

A submicron emulsion of HU-211, a synthetic cannabinoid, reduces intraocular pressure in rabbits.

PURPOSE: To study the ocular hypotensive effect of a nonpsychotropic cannabinoid, HU-211 (11 -hydroxy-delta8-tetra-hydrocannabinol, dimethylheptyl), an N-methyl-D-aspartate (NMDA) agonist, in normotensive rabbits. METHODS: The cannabinoid HU-211, being lipophilic, was incorporated into a stable oil-in-water submicron sterile emulsion, consisting of 0.12% (w/w) HU-211. A single- dose, randomized and double-masked study was designed, using a Digilab 30R pneumotonometer to measure intraocular pressure (IOP) in normotensive rabbits. RESULTS: Application of a single dose of HU-211 ophthalmic preparation resulted in an IOP reduction of 5.3 mmHg (24% of baseline), first evident at 1.5 h post application and persisting for over 6 h. A small but significant lowering of pressure (12.5% of baseline) occurred in the contralateral eyes of HU-211 treated rabbits, lasting for 4 h post treatment. CONCLUSION: Our work demonstrated that HU-211, incorporated into submicron emulsion, caused a 6-h-long reduction in IOP in the treated eye, with a lesser reduction in the contralateral untreated eye.

Administration, Topical↗
PubMed2000

Reversion of multidrug resistance by co-encapsulation of doxorubicin and cyclosporin A in polyalkylcyanoacrylate nanoparticles.

Individual and combined polyalkylcyanoacrylate nanoparticle formulation of cyclosporin A and doxorubicin were prepared and evaluated in an attempt to show improved growth inhibition efficacy in a resistant cell culture line. The drug loaded nanoparticles were prepared using the well established emulsion polymerization process without using any modification for the hydrophilic doxorubicin drug whereas the incorporation of cyclosporin A needed to wait a moment after the polymerization reaction started. This was necessary to avoid cyclosporin A precipitation and polymer aggregation. Cyclosporin A release from the nanoparticles was rapid probably because the drug was adsorbed onto the nanoparticles surface rather than embedded into the polymeric core. Doxorubicin displayed also a burst effect but with a slower second phase probably related with the nanoparticles bioerosion rate owing to its entrapment in the polymeric network. Finally, it was shown in resistant cell culture experiments that the association of both cyclosporin A and doxorubicin within a single nanoparticle formulation elicited the most effective growth rate inhibition as compared to other combinations of both drugs while using a lower amount of polymer compared to separated nanoparticle formulations. This result was probably due to the synergistic effect achieved by combining the chemo-sensitizing compound cyclosporin A, with an effective cytotoxic drug like doxorubicin.

Animals↗
PubMed2000

Self-dispersing lipid formulations for improving oral absorption of lipophilic drugs.

The main purpose of this review is to provide a current and general overview of the existing self-dispersing formulations resulting from dilution into emulsions, microemulsions and surfactant dispersions. The systematic approach used and the presentation of the various physico-chemical and biopharmaceutical aspects should facilitate the comprehension of this interesting field and clarify the main considerations involved in designing and characterizing a specific self-dispersing drug delivery system. Studies have shown that the self-emulsification process is specific to the nature of the oil/surfactant pair, surfactant concentration, oil/surfactant ratio and temperature at which self-emulsification occurs. It was suggested that the ease of emulsification could be associated with the ease by which water penetrates into the various liquid crystalline (LC) or gel phases formed on the surface of the droplet. Numerous bioavailability studies carried out in animals and humans, reviewed in the present study, suggest that hydrophobic drugs are better absorbed when administered in self-dispersing lipid formulations (SDLFs). Examples which illustrate the beneficial use of SDLFs for drug absorption enhancement are presented. This review outlines SDLFs as one of the most promising approaches to overcome the formulation difficulties of these hydrophobic/lipophilic drugs.

Administration, Oral↗
PubMed2000

Influence of emulsion droplet surface charge on indomethacin ocular tissue distribution.

The aim of this study was to compare the corneal penetration of indomethacin from Indocollyre [a marketed hydro-poly(ethylene glycol) (PEG) ocular solution] to that of a negatively and a positively charged submicron emulsion. Male albino rabbits were separated randomly into three groups and each group (N = 15) was treated with either one drop of radiolabeled 0.1% Indocollyre, or 0.1% indomethacin positively or negatively charged submicron emulsion, respectively. The rabbits were sacrificed at selected time points and the eyes were enucleated. The eyes were dissected into the different tissues: cornea, conjunctiva, aqueous humor, iris, lens, vitreous, sclera, and retina. The samples were weighed before radioactivity counting. Regardless of the preparation instilled, the highest concentration of indomethacin was achieved in the cornea followed by conjunctiva, sclera retina, and aqueous humor. However, the positively charged emulsion provided significantly higher drug levels than the control solution and negatively charged emulsion only in the aqueous humor and sclera-retina. Furthermore, the spreading coefficient of the positively charged emulsion on cornea is four times higher than that of the negatively charged emulsion. It was therefore deduced that the positively charged submicron emulsions have better wettability properties on the cornea compared to either saline or the negatively charged emulsion. The positive charge may prolong the residence time of the drop on the epithelial layer of the cornea and thus enable better drug penetration through the cornea to the internal tissues of the eye, as confirmed by the animal studies.

Absorption↗
PubMed1999

Positively and negatively charged submicron emulsions for enhanced topical delivery of antifungal drugs.

Charged submicron emulsions are a priori interesting candidates for the delivery of drugs in and/or through the skin. In the present study, it was possible by using stearylamine or deoxycholic acid (DCA) to incorporate either econazole or miconazole nitrate, respectively, in positively and negatively charged submicron emulsions. The investigation of the relationship between the physicochemical properties of the vehicles, especially the charge of the emulsion and skin permeation, was conducted ex vivo during percutaneous absorption experiments using hairless female rat skin. In addition, drug quantification was carried out using two different analytical techniques (HPLC and radioactivity measurements) in order to examine if the drug analysis approach might affect the results. The results clearly indicate that the surface-modified droplets have a significant influence on the diffusion through the skin. Furthermore, the method of preparation of the formulation and subsequently the analytical method of drug concentration measurement are able to influence the results of percutaneous experiment.

Administration, Topical↗
PubMed1999

The characterization and release kinetics evaluation of baclofen microspheres designed for intrathecal injection.

Baclofen, a water soluble drug advocated for the treatment of spinal spasticity, was microencapsulated, using the oil/water emulsion extraction process in an attempt to identify the appropriate experimental conditions capable of producing microspheres releasing baclofen over 2-4 weeks. Individual microspheres ranging in size from 15 to 30 microns were formed exhibiting smooth surfaces at low drug payload (12.8% w/w), irregular and rough surface at high drug content (33.9% w/w). The microencapsulation yield remained practically unchanged (85-90%) up to theoretical payloads of 37.5% w/w, and decreased markedly to 70% when the initial theoretical payload was 50% w/w. The in vitro release profile of baclofen from the poly(D,L-lactide-co-glycolide) microspheres was biphasic only for the high drug payload microspheres with a rapid release of 70% within 48 h, followed by a slower release rate over at least 25 days. In contrast, the microspheres containing low baclofen contents (12.8% w/w) exhibited a gradual and progressive release rate over the course of the experiment. The baclofen release data did not fit either the general equation which describes the diffusional release of dispersed tiny drug particles from spherical micromatrices, or to the kinetic equations which describe the release of dissolved drug from monolithic microspherical devices. It appears that the release of baclofen from the present microspheres is not governed by a unique mechanism. This should be attributed either to the presence of some uncoated drug particles or to the large size of the embedded drug particles compared with the relatively small size of the spherical micromatices, or to some polymeric erosion occurring after several days incubation in the release medium.

Baclofen↗
PubMed1999

Evaluation of a positively charged submicron emulsion of piroxicam on the rabbit corneum healing process following alkali burn.

The effect of piroxicam in three different formulations was tested on rabbits for 28 days in an alkali burn model. The ulceration healing process was determined by evaluating the severity of the burn (scored from 0 to 5), and the re-epithelization healing process was measured by the area of the defects. The results indicated that the piroxicam positively charged submicron emulsion was the most effective formulation in lowering the ulcerative cornea score while the piroxicam positively charged emulsion and the blank emulsion were more effective in promoting the re-epithelization healing process. The piroxicam solution elicited the slowest healing re-epithelization rate after 28 days and was unable to complete the entire healing process. The new positively charged submicron emulsion formulation of piroxicam had a pronounced effect on both the ulceration rate and epithelial defects in the management of corneal alkali-burning.

Alkalies↗
PubMed1999

Prevention of topical and ocular oxidative stress by positively charged submicron emulsion.

A positively charged submicron emulsion with zeta potential values ranging from 35 to 45 mV and mean droplet size around 150-250 nm has recently been developed and characterized. This formulation is based on three surface-active agents, an egg yolk phospholipid mixture, poloxamer 188, and stearylamine, a cationic lipid with a pKa of 10.6. The emulsion toxicity was evaluated in three animal studies. The results of the ocular tolerance study in the rabbit eye indicated that hourly administration of one droplet of the positively charged emulsion vehicle was well tolerated without any toxic or inflammatory response to the ocular surface during the five days of the study. No marked acute toxicity was observed when 0.6 mL of positively charged emulsion was injected intravenously to BALB/c mice. Furthermore, no difference was noted between this group of animals and the group injected with the marketed and clinically well accepted negatively charged Intralipid emulsion. These observations were further confirmed in a four week toxicity study following intravenous administration to rats of 1 mL/kg of the positively charged emulsion as compared to Intralipid. No toxic effect was noted in any of the various organs examined, whereas the results of the hematological and blood chemistry tests remained in the normal range for both emulsions, confirming the preliminary safety study findings. In addition, it was demonstrated by means of a non-invasive technique that alpha-tocopherol positively charged emulsions prevented oxidative damage in rat skin subjected to UVA irradiation. The intrinsic ability of positively charged emulsified oil droplets to protect against reactive oxygen species cannot be excluded, and could act synergistically with the antioxidant alpha-tocopherol itself. The effect of blank and piroxicam positively charged emulsions on rabbit eye following alkali burn was also evaluated. The blank emulsion showed a very rapid healing rate during the first three days with a breakdown in day 14. Complete re-epithelialization was observed in day 28. The same behavior (albeit less pronounced), was noted in piroxicam emulsion, although piroxicam is known to inhibit the epithelial healing process. It can therefore be deduced that the positively charged emulsion vehicle prevented piroxicam from interfering with the epithelial healing process due to the intrinsic free radical scavenger ability of the positively charged submicron emulsion previously demonstrated. Finally, the efficacy of this promising emulsion vehicle containing effective cosmetic ingredients in preventing skin damage and aging following oxidative stress is evaluated.

Amines↗
PubMed1999

Submicron cationic emulsions as a new delivery system for oligonucleotides.

PURPOSE: The main purpose of the present study was to investigate submicron emulsions as potential oligonucleotide (ON) delivery system. METHODS: Submicron emulsions containing various concentrations of stearylamine (SA) were prepared by microfluidization. After association with model oligothymidylates, these emulsions were characterized in terms of particle size, zeta-potential, association efficiency and release upon dilution. The interactions between ON and SA were investigated by partitioning studies between water and oily phases, with ON of three different lengths (pdT16, pdT30, pdT50). The stability of pdT16 in the presence of nucleases was evaluated by incubation in cell culture medium supplemented with 10% of foetal calf serum. RESULTS: The ON association efficiency was much higher with emulsions containing SA (E(SA)) than with control emulsions (E0), whatever the ON length. In addition, E(SA) was shown to protect ON against degradation for up to 3 hours in culture medium. ON and SA were able to form ion-pairs and the resulting complex was found to be insoluble both in water and in oil. Zeta potential was maintained constant when increasing the ON concentration, until flocculation occurred (up to 250 microM in the case of pdT16 for example). This has been explained by the presence of SA in excess, soluble in the oily core of droplets, able to migrate towards the interface and replacing SA neutralized in ion-pairs. CONCLUSIONS: ESA appears to be a valuable system for delivery of ON and might even be improved by selecting an oily phase in which the SA/ON complex would be soluble.

Cations↗