PURPOSE: To provide a novel triamterene derivative having excellent diuretic activity to sodium and retaining activity to potassium as parenterally applicable diuretics.

CONSTITUTION: A compound of formula I [R is SO3M or formula II; M is H or pharmacologically acceptable cation; R0 is H or lower alkyl; R1 is H, OH, lower alkyl, COOH, NR4R5, CONR5R5, N+(CH3)3 or formulae II-V; R2 is H, OH, lower alkyl or COOH; R3-R5 is H, lower alkyl or benzyl; and m is 1-10.], e.g. 2,4,7-triamino-6-(p-acetoxy-phenyl)-pteridine. A compound can be prepared by the conventionally known methods or by reacting 2,4,6-triamino-5- nitrosopyrimidine with a compound of formula VI [R' is formula VII or (CH2)nCOOH; Q is O, S, NR3, etc.; R1 and R3 are H, methyl, ethyl, etc.; R2 is H, OH or 1-4C alkyl; m is 0-3; p is 0 or 1; and n is 0-4].