Simultaneous detection of 4-chloro-5-sulfamoyl-2',6'-salicyl-oxylidide (Xipamide) and 2,4,7-triamino-6-phenyl-pteridine (Triamterene) in urine specimen of healthy volunteers was achieved by means of a new high performance liquid chromatography (HPLC) method. Pharmacokinetics of both substances in combination (Neotri, dose ratio xipamide: triamterene = 1:3) did not significantly differ from those of the sole substances. Peak urine elimination of unaltered xipamide was 2.5 +/- 0.7 mg/h when given alone and 2.0 +/- 0.7 mg/h in the presence of triamterene. The data for the triamterene excretion were 0.7 +/- 0.1 mg/h and 1.0 +/- 0.3 mg/h, respectively within 1-3 h post application. Assuming a two-compartment pharmacokinetic model the terminal elimination half-lives of unchanged xipamide were 5.3 +/- 1.9 h (monosubstance) and 4.0 +/- 0.6 h (combination). The corresponding data for unchanged triamterene were 6.4 +/- 1.3 h (monosubstance) and 5.5 +/- 1.8 h (combination).