The invention relates to the implementation of a method for loading, without a vehicle, a naturally crystalline substance solubilised by a solvent mixture in a lipophilic medium in a mixture of granulated polymers, for forming, without a plasticiser, a polymer support for the long-term controlled distribution of the naturally crystalline substance in the stable solubilised state, without permanent crystallisation on the surface of said support. Said substance according to the invention can be insecticides and pesticides of the group of pyrethroids (e.g. deltamethrin), formamidines (e.g. amitraz) and carbamates (e.g. propoxur), or the mixture thereof, or cosmetics of the group of alkaloids (e.g. caffeine), or medicaments (e.g. ibuprofen). The permanent non-crystallisation state on the surface of the polymer support is only ensured when said substance is solubilised in the solvent mixture consisting of an oxygenated solvent of dibasic esters of methylenic fatty acids and an oxygenated methylenic cosolvent in an active lipophilic solution incorporated into a polymer mixture consisting of a polyether block amide (PEBA) and a thermoplastic polyurethane elastomer (TPU). Said support can be shaped as a collar, as an ear tag for animals, a band, a patch, a tag, a polymer block or any other device for the distribution of the active substances. It is shaped by any one of the plastic processing techniques known by a person skilled in the art. It is advantageous in that it is loaded with a quantity of active substance of between 30% and 50% less than the previous devices for at least the same active efficiency.
