Brice Moulari

The targeting of surface modified silica nanoparticles to inflamed tissue in experimental colitis.

One aspect in the emerging field of nanomedicine is site specific drug delivery via nanoparticles. The use of nanoparticles allows for increased therapeutic efficiency with a lowered risk for and extent of adverse reactions resulting from systemic drug absorption. 5-Amino salicylic acid (5ASA) loaded silica nanoparticles (SiNP) are proposed here as drug delivery system for specific accumulation in inflamed colonic tissues allowing for selective medication delivery to such inflammation sites. The drug was covalently bound to SiNP by a four-step reaction process. In-vitro toxicity of modified SiNP was tested in appropriate cell culture systems, while targeting index and therapeutic efficiency were evaluated in a pre-existing colitis in mice. Particle diameter was around 140 nm after final surface modification. In-vitro drug release demonstrated significant drug retention inside the NP formulation. Toxicity of the different formulations was evaluated in-vitro cell culture exhibiting a lowered toxicity for 5ASA when bound to SiNP. In-vivo, oral SiNP were found to accumulate selectively in the inflamed tissues allowing for significant amounts of drug load. SiNP demonstrated their therapeutic potential by significantly lowering the therapeutically necessary drug dose when evaluating clinical activity score and myeloperoxidase activity (untreated control: 28.0+/-5.0 U/mg; 5ASA-solution (100mg/kg): 8.2+/-3.4 U/mg 5ASA-SiNP (25mg/kg): 5.2+/-2.4 U/mg). SiNP allow to combine advantages from selective drug targeting and prodrugs appearing to be a promising therapeutic approach for clinical testing in the therapy of inflammatory bowel disease.

Nanoparticles enhance therapeutic outcome in inflamed skin therapy

Inflammatory reactions of the skin are a major therapeutic field; however, drug delivery is nowadays only related to the use of classical formulations like ointments and creams. Here, we report the behaviour of polymeric submicron particles (NP) for selective drug delivery to the inflamed skin. NPs of nominal diameters from 50 to 1000 nm were administered to an experimental dithranol-induced dermatitis inflammation model in mice ears. The results revealed that smaller particles had an around 3-fold stronger and deeper penetration tendency with a preferential accumulation in inflamed skin hair follicles and sebaceous glands (2.8 ± 0.6% and 2.3 ± 0.4% for NP100 and NP50 compared to 0.84 ± 0.04% and 0.92 ± 0.02% for the same sizes on healthy skin). Betamethasone loaded NP confirmed the size dependency by being therapeutically more efficient from histological examination and measurement of different inflammatory markers in the skin (myeloperoxidase activity of untreated control, 1.2 ± 0.4; NP1000, 1.0 ± 0.4; NP100, 0.5 ± 0.2, all U/mg). This approach holds a high potential for a selective therapy to the inflamed skin by increasing the local intradermal availability with simultaneous reduction in systemic adverse effects.

Surfactant dependent toxicity of lipid nanocapsules in HaCaT cells.

Lipid nanocapsules (LNC) have been suggested for a variety of pharmaceutical applications. Among them approaches for drug delivery to the skin appear particularly interesting. The current standard composition has been modified to better understand their properties by selecting a variety of different surfactants. LNC have been prepared using different non-ionic surfactants (Solutol(®) HS15: Polyoxyl 15 Hydroxystearate; Cremophor(®) EL: Polyoxyl 35 Castor Oil; Simulsol(®) 4000: Polyoxyl 40 Hydrogenated Castor Oil; Vitamin E TPGS(®): alpha-tocopheryl poly(ethylene glycol) succinate; Polysorbate 20 and 80) and analysed for their size, stability, drug release and toxicity on keratinocytes in cell culture. The feasibility of LNC using different surfactant was surprisingly easy and led to a variety of stable formulations that were selected for further investigations. Surfactants led to a variability of the release kinetics (t50% release varied from Polysorbate 20: 2.5h to Simulsol(®) 4000: 5.0h), however different formulations from the same surfactant did not differ significantly. In vitro toxicity of LNC was surfactant type dependent and a correlation between LNC and the pure respective surfactant was found. This toxicity was found to be mainly independent from the surface active properties. The surfactant type in LNC is easily interchangeable from formulation point of view. LNC appear to be appropriate as carrier for cutaneous delivery however toxicity can vary distinctly depending on the surfactant used for the preparation.

Zinc-pectinate beads as an in vivo self-assembling system for pulsatile drug delivery

Zinc-pectinate beads are interesting drug carriers for oral delivery. In order to investigate their in vitro and in vivo release behaviour, ionotropic gelation was used to entrap theophylline into calcium- or zinc-pectinate beads. Beads were investigated in vitro for their particle properties, especially the release kinetic in different media, and their in vivo pharmacokinetic parameters were tested in rats. Particle size varied between 1.8 and 2.8mm and encapsulation rates between 27 and 30% for Ca- and Zn-pectinate beads, respectively. While Ca-pectinate beads revealed a relative fast disintegration, drug release profiles from Zn-pectinate beads were very much release medium-dependent. Especially, in the presence of phosphate ions, the release from Zn-pectinate beads was blocked at 20% and 40% of the total drug load when tested in phosphate buffer or simulated colonic medium. In vivo Zn-pectinate beads (t(max): 12.0 ± 0.1h) led to a significant lag time for the theophylline absorption compared to Ca-pectinate (t(max): 6.0 ± 2.8h) or free theophylline (t(max): 2.5 ± 2.1h). This delayed release was attributed to the formation of a zinc phosphate coating in vitro and in vivo inducing the retention of theophylline release. Zn-pectinate beads exhibit interesting properties due to its potential as pulsatile delivery system induced by the in situ formation of Zn phosphate, while Ca-pectinate was found to be of limited suitability for controlled release of theophylline.

Coadministration of P-Glycoprotein Modulators on Loperamide Pharmacokinetics and Brain Distribution

The efflux transporter P-glycoprotein, expressed at high levels at the blood-brain barrier, exerts a profound effect on the disposition of various therapeutic compounds in the brain. A rapid and efficient modulation of this efflux transporter could enhance the distribution of its substrates and thereby improve central nervous system pharmacotherapies. This study explored the impact of the intravenous coadministration of two P-glycoprotein modulators, tariquidar and elacridar, on the pharmacokinetics and brain distribution of loperamide, a P-glycoprotein substrate probe, in rats. After 1 hour postdosing, tariquidar and elacridar, both at a dose of 1.0 mg/kg, increased loperamide levels in the brain by 2.3- and 3.5-fold, respectively. However, the concurrent administration of both P-glycoprotein modulators, each at a dose of 0.5 mg/kg, increased loperamide levels in the brain by 5.8-fold and resulted in the most pronounced opioid-induced clinical signs. This phenomenon may be the result of a combined noncompetitive modulation by tariquidar and elacridar. Besides, the simultaneous administration of elacridar and tariquidar did not significantly modify the pharmacokinetic parameters of loperamide. This observation potentially allows the concurrent use of low but therapeutic doses of P-gp modulators to achieve full inhibitory effects.

Potentiation of the bactericidal activity of Harungana madagascariensis Lam. ex Poir. (Hypericaceae) leaf extract against oral bacteria using poly (D, L-lactide-co-glycolide) nanoparticles: in vitro study.

Harungana madagascariensis Lam. ex Poir. (Hypericaceae) is known to have biological properties with mainly antibacterial, antifungal, and antiviral effects. The objective of this study was to investigate the in vitro bactericidal activity of the ethyl acetate H. madagascariensis leaf extract (HLE) on the main oral bacterial strains largely implicated in dental caries and gingivitis infections, and the possibility of potentialization of HLE antibacterial effects using the poly (D,L-lactide-co-glycolide) nanoparticles (PLG-NP). The microdilution technique and the interfacial polymer deposition following the solvent diffusion method were used to investigate the in vitro bactericidal activity of ethyl acetate HLE and to prepare nanoparticles, respectively. HLE showed significant bactericidal effects against the bacterial strains tested, with minimal bactericidal concentration (MBC) to 5×102 mg/l or less, except for Lactobacillus casei with 7.5×102 mg/l. With the HLE incorporated into PLG nanoparticles (HLE-PLG-NP), we observed diminution of the bactericidal concentration compared to HLE, the upper MBC being of 1.875×102 mg/l. Incorporation of the HLE into a colloidal carrier optimized its antibacterial performance.

Lectin-decorated nanoparticles enhance binding to the inflamed tissue in experimental colitis.

A major limitation in the drug treatment of inflammatory bowel disease is the inability to deliver the drug selectively towards the inflamed tissues. Nanotechnology-based drug delivery systems have led to an amelioration of the therapeutic selectivity but still the majority of the entrapped drug is eliminated without exercising a therapeutic effect. Here, lectin-decorated drug loaded nanoparticles (NP) are suggested for active targeting and selective adhesion to the inflamed tissue in experimental colitis. Peanut (PNA) and wheat germ (WGA) lectins were covalently bound to the surface of NP and were tested for their stability and degree of bioadhesion in cell culture. In-vivo, the selectivity of bioadhesion and distribution of NP throughout the intestinal tract as well as the therapeutic benefit for glucocorticoid loaded lectin-NP was studied in murine colitis models. Quantitative adhesion analyses showed that lectin-conjugated NP exhibited a much higher binding and selectivity to inflamed tissue compared to plain NP (PNA conjugates: 52.2±5.6%; WGA conjugates: 22.0±0.8%; plain NP: 18.6±9.8%). Lectin-associated NP revealed a further increase in the selectivity of bioadhesion towards inflamed tissues which partially translates into increased therapeutic efficiency. In terms of therapeutic efficiency, all glucocorticoid containing formulations revealed an enhanced therapeutic effect with lectin conjugates especially PNA-NP (myeloperoxidase: 55±37U/g; TNF-alpha: 3880±380U/g) compared to plain NP (myeloperoxidase: 145±98U/g; TNF-alpha: 6971±1157U/g). Targeted NP by using lectins, especially with PNA, as stable targeting moiety in the gastrointestinal tract appears to be a very promising tool in future treatment of inflammatory bowel disease.

Surface-Charge-Dependent Nanoparticles Accumulation in Inflamed Skin

Polymeric nanoparticles (NPs) are interesting drug carriers for dermal application and drug targeting to certain skin structures. NP interactions with diseased skin and the associated benefits and risks have been hardly explored. Today, we study the behavior of polymeric NPs for selective drug delivery to inflamed skin. Neutral, cationic, and anionic NPs of nominal diameters around 100 nm were administered to an experimental dithranol-induced dermatitis inflammation model in mice ears. The results showed that the surface charge had an important influence on the penetration and accumulation tendency in the inflamed skin compared with the neutral and cationic (2.8 ± 0.3%, 2.1 ± 0.2%, and 1.9 ± 0.3% for anionic, neutral, and cationic particles, respectively). Confocal laser scanning microscopy showed that all particles were accumulated in the inflamed pilosebaceous units. Betamethasone-loaded NPs showed that both charged particles were therapeutically more efficient than the neutral ones. Treatment with anionic and cationic particles led to the reduction of the inflammatory enzyme alkaline phosphatase activity by 50.7 ± 2% and 57.7 ± 5%, respectively, in comparison with the inflamed control. Noncharged particles had a lower therapeutic impact where the activity was only reduced by a factor of 75%. Histological sections examination had also confirmed these results. Therefore, it was concluded that the presence of charge could enhance skin-NPs adhesion and interaction leading to higher therapeutic effect on inflamed skin.

Surfactant-dependence of nanoparticle treatment in murine experimental colitis.

Inflammatory bowel disease is a chronic relapsing inflammation of the gut with the two main forms being ulcerative colitis and Crohns disease. Nanoparticulate drug carrier systems have been proven to enhance the therapeutic efficiency and to diminish adverse effects of the anti-inflammatory treatment due to their size dependent accumulation in the inflamed regions of the gut. The influence of surface properties on the accumulation selectivity and intensity of such nanoparticles is mainly unclear. Accordingly sized particles (~200 nm) were prepared by the emulsification solvent evaporation technique using different surfactants (polysorbate 20, sodium dodecyl sulphate, sodium cholate, cetyltrimethylammonium bromide, polyvinyl alcohol). In a murine colitis model the particles prepared with polysorbate 20 as surfactant led to a 34.8-fold higher particle content in the inflamed areas of the colon compared to the healthy gut and to a 4.5-fold increase of the particle content in the inflamed segments compared to particles prepared with sodium dodecyl sulphate. This effect translates also into a significantly higher mitigating effect when entrapping betamethasone into such nanoparticles. This study shows the importance of surface properties for the passive targeting approach in experimental colitis. The influence seems to be as important as the influence of the particle size.

Colonic delivery of carboxyfluorescein by pH-sensitive microspheres in experimental colitis.

The colonic drug delivery in inflammatory bowel disease (IBD) by microcarriers has been suggested over the past decade; however, pharmacokinetic and biopharmaceutical details are hardly known. A model colitis was induced to male Wistar rats by trinitrobenzenesulfonic acid. Carboxyfluorescein (CF) was entrapped into microspheres (MS) prepared with the pH-sensitive polymer Eudragit® S100, in order to simulate drug delivery to the colon. Pharmacokinetic behaviour of CF-MS was compared to oral or rectal administration of CF as solution in healthy or colitis group. Colitis lowered the oral bioavailability of CF solution, compared to healthy controls (healthy: 8.4±1.5; colitis: 3.0±0.9; all μg/mlh), and similar results were obtained after rectal administration of CF solution (healthy: 5.6±2.1; colitis: 1.8±0.8). Surprisingly, CF-MS showed only minor differences between colitis and healthy controls (healthy: 1.9±0.8; colitis: 2.3±0.4). In contrary, the intra-tissue concentrations of CF of the various formulations in colitis showed lower levels than the comparable healthy group after oral drug administration. Pharmacokinetic outcome was largely disease-dependent, while CF-MS confirmed their ability to local drug delivery.