Comparative metabolism and urinary excretion of N-mononitrosopiperazine and N,N′-dinitrosopiperazine in the rat

Abstract

The metabolism of N-mononitrosopiperazine (NPz) and N,N′-dinitrosopiperazine (DNPz) was investigated in Sprague — Dawley rats. When an oral dose of 50 μg/rat NPz was administered, 10.5 % of the dose was recovered unchanged in urine together with N-nitroso-3-hydroxypyrrolidine (NHPYR, 1.3 % of administered NPz dose) and N-nitrosodiethanolamine (NDELA, 0.3%). For DNPz, 7.7% of the administered dose together with NPz (0.04%), NHPYR (2.9%), NDELA (6.7%) and N-nitroso(2-hydroxyethyl)glycine (NHEG, 20.2%) was recovered in urine after 24 h. These results show extensive metabolism of both NPz and DNPz and suggest that both NPz and NHPYR could be analysed in urine as markers for the endogenous nitrosation of piperasine in patients receiving antihelminthic treatment with piperazine.