FIELD: medicine, virology, pharmacy. SUBSTANCE: composition has 21,31-deoxypurine nucleoside as an active component taken from the group involving 21,31-deoxyadenosine, 21,31-deoxyinosine and 21,31-deoxyguanosine and/or their pharmaceutically acceptable salts and/or their hydrates and water-insoluble antacid buffer system and special additions. Buffer system provides pH value in stomach about 5 and consists of water-insoluble antacid compound of magnesium in combination with sodium dihydroxyaluminocarbonate at mass ratio = 1:(2-4) or in combination with calcium carbonate at mass ratio of magnesium compound and calcium carbonate = 1:(1.5-3), respectively. Mass ratio of 21,31-deoxypurine nucleoside and special additions in combination with buffer system = (0.005-0.375):(1.9-6), respectively. Composition is prepared as tablet or powder for preparing the dispersion in liquid. EFFECT: enhanced biological availability of an active component. 7 cl, 3 tbl
