1.1- (2-Ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d ] pyrimidine-3-carboxamide, or a pharmaceutically acceptable salt thereof, for use in the treatment of end-stage chronic renal failure. 1- (2-Ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d] pyrimidine -3-carboxamide, or a pharmaceutically acceptable salt thereof, and at least one carrier, diluent or excipient for use in the treatment of end-stage chronic renal failure. 3. 1- (2-Ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d] pyrimidine -3-carboxamide, or a pharmaceutically acceptable salt thereof, for use in the treatment of diabetic nephropathy. 4. 1- (2-Ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d] pyrimidine -3-carboxamide, or a pharmaceutically acceptable salt thereof, and at least one carrier, diluent or excipient for use in the treatment of diabetic nephropathy. 5. 1- (2-Ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d] pyrimidine -3-carboxamide or a pharmaceutically acceptable salt thereof, for use in the treatment of chronic kidney disease. 6. The use of claim 5, wherein the chronic kidney disease is stage 3 or 4.7. 1- (2-ethoxyethyl) -5- (ethyl (methyl) amino) -7 - ((4-methylpyridin-2-yl) amino) -N- (methylsulfonyl) -1H-pyrazolo [4,3-d] pyrimidine -3-carboxamide, or a pharmaceutically acceptable salt thereof, and at least one carrier, diluent or excipient for use in the treatment of chronic kidney disease. The use of claim 7, wherein the chronic kidney disease is stage 3 or 4.9.1. 1-(2-Этоксиэтил)-5-(этил(метил)амино)-7-((4-метилпиридин-2-ил)амино)-N-(метилсульфонил)-1Н-пиразоло[4,3-d]пиримидин-3-карбоксамид, или его фармацевтически приемлемая соль, для примен
