FIELD: chemistry.SUBSTANCE: claimed invention relates to biodegradable and bioabsorbable block-copolymers in form of solid powder or wax-like powder. Described is composition of block-copolymer of AB, ABA or BAB type for introduction of medication, with said block-copolymer containing: at least first block-copolymer component of AB, ABA or BAB type, containing first hydrophobic A-block and first hydrophilic B-block, with first hydrophobic A-block representing biodegradable polyester, containing at least 60% of caprolacton and at least one second polyester-forming monomer, with said first hydrophilic B-block having first average molecular weight and containing polyethylene glycol； at least second block-copolymer component of AB, ABA or BAB type, containing second hydrophobic A-block and second hydrophilic B-block, with said second hydrophobic A-block containing biodegradable polyester, and second hydrophilic B-block having second average molecular weight and containing polyethylene glycol, with second average molecular weight being different from first average molecular weight； and total weight average molecular weight of block-copolymer composition constitutes from 1500 to 10000 Dalton, total content of A-block in composition constitutes approximately from 60 to 85% by weigh, and total content of B-block in composition constitutes approximately from 15 to 40% by weight, with total weight average molecular weight of B-block in composition constituting from 300 to 2000 Dalton, and said block-copolymer composition is solid at room temperature, is capable of reversible thermal gel-formation with obtaining in form of water polymer solution and is capable of converting into water polymer solution in less than thirty minutes with mixing without application of additives or heating above 60°C. Also claimed is method of introduction to warm-blooded animal of at least one medication in form with controlled release, including (1) provision of composition of block-copolymer of A
