The repellents are natural or synthetic molecules whose aim is to prevent theapproach of arthropods to avoid transmission of vector-borne diseases. A typicalexample is the transmission of Leishmania infantum responsible for canineLeishmaniasis, which is contracted after a sandfly bite on a dog. The arthropod repellentsmarketed for topical application have all a short action duration, requiring repeatedapplications of basic formulations (solution).The formulation of active molecules having repellent properties, incorporated intonanoparticle systems and having a prolonged action in time was selected. Nanoparticles arecolloidal carriers interesting in the pharmaceutical technology field due to their ability to formcomplexes with hydrophobic molecules, such as repellent molecules (DEET, Picaridin®,IR3535®...). Targeting, protection against degradation and control of the release are the mainadvantages provided by the nanoparticles containing an active ingredient.The nanoparticle physicochemical characteristics (size and zeta potential) permitting theirstorage in the upper dog skin layers and a along the hairs were determined. For that reasoncationic nanoparticles of 200 nm in diameter were formulated. This original formulationinspired from the nanoprecipitation process has allowed us to obtain one single stepconcentrated suspensions (above 10% of active molecules in the final product) and withoutstabilizer addition. A correlation between the release profiles and the effectiveness of modelinsect (Drosophila) has been verified. Therefore the percentage of polymer regulates therelease of encapsulated active molecules. Repellent efficacy of nanoparticulate formulationgreater than 15 days has been validated experimentally. The scale transposition of thenanoprecipitation process makes conceivable an industrial development for the formulation ofan innovative arthropod repellent having a long lasting effect.
