FIELD: medicine. SUBSTANCE: invention relates to method of conservation of raw activity for soluble thromboplastin preparing. Method involves addition of sucrose in the amount that is necessary to obtain 2-% final solution to the raw prepared from cadaverous brain gray matter homogenate. Then sodium metabisulfite is dissolved to obtain 0.005 M solution and buffer containing citric acid/sodium citrate (pH 6.0-6.5) is added in the amount 1 ml/100 ml of supernatant. Invention provides preparing soluble thromboplastin in the frozen state up to minus 30 ± 2 C and prevents its destruction during lyophilization. EFFECT: increased storage period up to 4 weeks, increased stability. 1 cl, 3 tbl, 1 ex
