Evaluation of gliadins nanoparticles as drug delivery systems: a study of three different drugs.

In this paper, biopolymer nanoparticles are studied, which unlike many synthetic carriers used for controlled release, are biocompatible and biodegradable systems. Gliadins nanoparticles are obtained by a desolvatation method, also known as drawning-out precipitation. These particles have been shown to be interesting as drug release systems for all-trans-retinoic acid. The aim of this paper was to study the influence of the polarity of different drugs on nanoparticle characteristics such as size and drug loading efficiency. Three drugs of three different polarities were studied: the hydrophobic Vitamin E (VE), the slightly polar mixture of linalool and of linalyl acetate (LLA) and the cationic amphiphilic benzalkonium chloride (BZC). This comparative work shows that the amount of the entrapped VE and LLA is higher than that of the cationic BZC, confirming a strong interaction between gliadins and apolar compounds, due to the apolarity of the proteins. This interaction results in a low diffusion coefficient and a partition coefficient in favour of gliadins, resulting in a low permeability coefficient. The drug release kinetics of two substances, LLA and BZC, are observed, in showing a burst effect, then a diffusion process, which can be modelled assuming that the particles are homogeneous spheres.

Alpha-tocopherol encapsulation and in vitro release from wheat gliadin nanoparticles.

Alpha-tocopherol, or vitamin E (VE), is widely used as a strong antioxidant in many medical and cosmetic applications, but is rapidly degraded, because of its light, heat and oxygen sensitivity. Thus, all of its formulation has to avoid contact with light, heat or air. Drug loaded carriers are an attractive opportunity, especially if they are made for bioacceptable macromolecules such as vegetal proteins. For instance, gliadins, extracted from wheat gluten, generate nanoparticles by a desolvatation method and may interact with epidermal keratin for therapeutic or cosmetic formulations. Their lipophilic drug loading capacities have been investigated. The VE loaded gliadin nanoparticles have been characterized by their size, by their zeta potential, by their VE payload, and by their entrapment efficiency. When VE loaded, the gliadin particle size is approximately 900 nm and their charge is close to zero. They are suitable VE drug carriers with an optimum encapsulation rate approximately 100 VE microg/gliadin mg with an efficiency of more than 77%. The release behaviour of VE loaded nanoparticles may be interpreted as a 'burst effect', followed by a diffusion process through an homogeneous sphere.

Charcoal suspension for tumor labelling modifies macrophage activity in mice.

We have previously developed a charcoal suspension for injection into human breast cancers in order to facilitate their location during surgery. We observed that charcoal particles were ingested by intra and peritumoral macrophages, some of which carried the particles at some distance from the injection site. We studied the influence of the formulation parameters of the charcoal suspension for intratumoral injection on in vitro and in vivo activation and in vivo mobilization of mouse peritoneal macrophages after intra-peritoneal injection of 2 mL of each preparation. The influence of the charcoal origin (peat vs wood), granulometry, suspension vehicle (water for parenteral injection, vs saline), concentration and excipients were studied. Micronized peat charcoal in water for injection at the highest studied concentration reduced macrophage activation in vitro and in vivo. However, macrophage mobilization was weaker than after thioglycolate injection and did not seem to be charcoal dose-dependent. The additives incorporated in the charcoal suspension led in vivo to increased peritoneal macrophage activation and mobilization (mannitol, and glucose), only increased activation (polysorbate 80 and pluronic F68) or mobilization (dextran 40, egg lecithin, and cabosil), or inhibited both activation and mobilization (cremophor EL).

Formulation of a charcoal suspension for intratumoral injection. Study of galenical excipients.

To tattoo human breast cancer prior to chemotherapy, radiotherapy, or surgery, thus allowing a better localization of the remaining tumor by the surgeon, we developed a formulation containing 10% charcoal suspended in water for parenteral preparations. The present study concerns a new step in the development of the charcoal suspension. We sought to determine whether the addition of various excipients could improve the formulation properties and affect the labeling of tumor by the suspension. We have tested surfactants (egg lecithin, polysorbate 80, Cremophor EL, and Pluronic F68), isotonisants (sugars such as glucose and mannitol), polysaccharides (dextrans 20 and 40), and Cabosil, a pyrogenated silica. Except for glucose and mannitol, which were added at a 5% concentration, the other excipients were added at a 0.1% concentration, they were dissolved in water for parenteral injection and sterilized at 120 degrees C for 20 min. We then measured diffusion in vivo in mammary tumor. In vivo, when injected intratumorally in mice, a greater diffusion of charcoal particles was noted within the tumor (in the case of egg lecithin, polysorbate 80, dextran 20 and 40, and glucose) and sometimes in some organs (e.g., Cremophor EL and mannitol). Pluronic F68 slightly improved the stability of the suspension and did not lead to marked diffusion at the injection site, but it showed slight toxicity and cannot be used in the formulation. We concluded that the best formulation was an aqueous 10% micronized peat charcoal suspension.