1. The composition of prolonged action for the treatment of an animal in need of it, which contains a therapeutically effective amount of a biologically active agent, a non-aqueous carrier and a solvent system containing castor oil and at least one cyclic amide. The composition according to claim 1, characterized in that the cyclic amide is pyrrolidone. 3. A composition according to claim 1 or 2, characterized in that at least one cyclic amide in the composition is N-methylpyrrolidone (NMP). The composition according to claim 1 or 2, characterized in that the cyclic amide is present in the composition in an amount of from 1 to 50% w / v. 5. The composition according to paragraphs. 1 or 2, characterized in that the castor oil is present in the composition in an amount of from 1 to 20% wt./about.6. The composition according to paragraphs. 1 or 2, characterized in that it is a composition for injection. 7. A composition according to claim 1 or 2, characterized in that the biologically active agent is an anthelmintic agent. The composition according to claim 7, characterized in that the anthelmintic agent is selected from the group consisting of avermectin, moxidectin, milbemycin, ivermectin, abamectin, doramectin, eprinomectin, selamectin. 9. The composition according to p. 8, characterized in that the anthelmintic agent is present in the composition in an amount of from 005 to 5% wt./about.10. The composition according to claim 8, characterized in that the anthelmintic agent is moxidectin. 11. Composition according to claim 8, characterized in that the non-aqueous carrier comprises oil selected from the group consisting of canola oil, corn oil, palm oil, olive oil, peanut oil, sesame oil, soybean oil, safflower oil, coconut oil, sunflower oil, palm oil oils, monoglycerides, diglycerides and triglycerides, medium chain triglycerides of succinic acid1. Состав пролонгированного действия для лечебной обработки животного, нуждающегося в этом, который содержит терапевтическ
