The invention relates to pharmacology and concerns a composition for preparing an antitumour agent that is a complex of bivalent platinum salts and alloferon peptide, and to pharmaceutical compositions containing said complexes. The invention may be used to produce preparations used in oncology.The technical result of the invention is the possibility of using the composition as the basis for different types of preparations for injection or for a lyophilisate, which have both antitumour effectiveness and reduced toxicity.Said technical result is achieved by the fact that a composition is claimed for the preparation of an antitumour agent in the form of a solution for injection or a lyophilisate containing alloferon, characterised in that a complex compound of bivalent platinum with an alloferon oligopeptide is used as the active component.A method of preparing an antitumour agent on the basis of the above-described composition is characterised in that alloferon is gradually introduced into a solution of cis-platin in 0.9% sodium chloride, and then the solution is mixed for 15 minutes, after which it is sterilised by filtration through a filter having 0.2-mcm pores, then poured into ampoules and sealed. A preparation can be produced in the form of a lyophilisate with mannitol as the filler.
