FIELD: organic chemistry. SUBSTANCE: invention relates to derivatives of pyrazine of the formula (I) 
where R1 - H or C1-8-alkyl; R2 is C1-8-alkyl that can be free or substituted with C1-4-alkoxyl, hydroxyl, phenoxy-group that can be substituted in turn with a single or multiple C1-4-alkyl, C1-4-alkoxyl, alkoxyalkyl or cyano-group, amino-group 
where R3 - H or C1-4-alkyl; R4- - phenyl multiple substituted with C1-4-alkyl, dichlorophenylsulfonyl substituted with amino-group, C1-4-alkyl that can be free or substituted with residues taken from a group: hydroxyl, phenoxy-group that in turn is substituted multiple with halide or alkoxyalkyl, carbonyl radical of the formula (II) 
where X - oxygen or -NH-, piperidyl radical that is N-substituted with C1-8-alkyl and phenyl that can be free or substituted with C1-4--alkoxyl, amidino-group of the formula HN=
where R5 - - phenyl substituted with halide or C1-4-alkyl, and also a group of the formula (III) 
; if R1 is H or R1 and R2 together with nitrogen atom with which they are bound form piperazine ring that can be nonsubstituted or substituted at position 4 with a group (IV) 
, (V) 
or O=
where Y is 2-pyrrolyl, 3-pyridyl or 2-furyl, or C1-8-alkyl, or alkoxyalkyl and α-naphthoxy-group; if R1 is H then R2 does not mean alkyl, benzyl, fluorine or chlorobenzyl, phenethyl, hydroxyethyl or 
; or if R1 is C1-3-alkyl then R2 does not mean C1-4-alkyl, and their acid-additive salts. Compounds of the formula (I) inhibit exchanges Na+/H- and Na+/Li+ and they can be used as an antihypertensive, mucolytic, diuretic and anticancer agents. EFFECT: improved method of synthesis, enhanced effectiveness of compounds. 2 cl, 6 tbl, 4 ex
