EN
Screening tests revealed that aniline increased urine trimethoprim (TMP) excretion in rat. The study attempted to investigate the effect of aniline under conditions of repeated exposure on the course of TMP excretion with urine. Two variants, A and B, of exposure were used. Aniline vapour concentration: 100 mg/m3. TMP p.o. dose: 16 mg/kg b.w. Three groups of rats (10 rats each) were exposed to aniline vapours 1, 4 and 10 times, 6 h a day. After the exposure series they were administered a single dose of TMP. Urine was collected at pre-determined intervals over 24-h period and TMP concentration was determined. An increase of urinary TMP concentration correlating with the number of inhalations was shown to occur. Kinetic parameters were calculated from the Bateman formula. No effect of aniline on the kinetics of TMP removal was observed. Three groups of rats (10 rats each) were used. Group I was exposed for 12 days (6 h a day) to aniline vapour. Group II received TMP only. Group III was exposed both to aniline and TMP. Concentrations of TMP and p-aminophenol (an aniline metabolite) were determined in the 24-h urine samples after 1, 6 and 12 days. The exposure to aniline vapours was found to cause almost 3-fold increase of TMP removal. No effect of TMP on p-aminiphenol excretion was observed.