Tissue distribution, excretion and metabolism of o-anisidine in rats.

OBJECTIVES: The principal commercial use of o-anisidine is believed to be as an intermediate in the manufacture of dyes. It has also been reported to be an intermediate in the manufacture of synthetic guaiacol and its derivatives. o-Anisidine is an urinary bladder carcinogen in mice and rats. The aim of the study was to investigate the kinetics of body distribution, excretion and biotransformation of o-anisidine in rats following a single, intraperitoneal administration. MATERIALS AND METHODS: The tissue distribution and excretion of o-anisidine following i.p. administration of a single dose of 10 mg/kg was investigated using radiotracer [3H]. Metabolism of o-anisidine was investigated in the rats following i.p. administration of a single dose of 50 mg/kg using GC/MS technique. RESULTS: After 72 h, about 72% of the given dose was excreted in urine. As indicated, urine proved to be the main route of tritium excretion. In all examined tissues, the highest concentrations of tritium were found 12 h after injection and the highest accumulation was detected in the liver, kidneys and in the muscle tissue. In urine, the following substances were identified and quantified by GC peak areas: N-acetyl-2-methoxyaniline and N-acetyl-4-hydroxy-2-methoxyaniline. CONCLUSIONS: Prolonged tritium retention observed in the majority of tissues indicated that o-anisidine, especially in the case of repeated exposure, might accumulate in the body. The metabolism encompasses amine group acetylation and ring oxidation.

Disposition and metabolism of 1,6-dimethylnaphthalene in rats.

The distribution, excretion and metabolism of 1,6-dimethylnaphthalene following i.p. administration of a single dose of 20 mg/kg to rats, was investigated using radiotracer [3H] and a gas chromatography-mass spectrometry technique (GC-MS). After 72 h, about 94% of the given dose was excreted in urine and feces. In organs and tissues, the highest concentration during the first hours after administration was detected in fat, liver, spleen and kidneys. Then gradual decline of tritium was noticed in all examined tissues. In urine, the following substances were identified and quantified by GC peak areas: unchanged 1,6-dimethylnaphthalene, 1-methyl-hydroxynaphthalenes, 1-hydroxymethyl-6-methylnaphthalene, 1,6-dimethyl-thionaphthalene, 6-methyl-1-naphthoic aldehyde, 6-methyl-1-naphthoic acid, 1,6-dimethyl-thionaphthalene and 1,6-dimethyl-methylthionaphthalene.

Comparison of tissue distribution and metabolism of 1,2- and 1,4-dibromobenzenes in female rats.

The distribution, excretion and metabolism of 1,4-dibromobenzene (1,4-DBB) and 1,2-dibromobenzene (1,2-DBB), following a single intraperitoneal administration to female Wistar rats, were investigated using radiotracer 3H and GC-MS technique. The maximum level of 3H after 1,4-DBB administration was detected in all examined rat tissues between 4 and 24 h foltowing the injection. The highest concentrations of 3H were found in fat tissue, muscles, adrenal glands and sciatic nerve. About 50% of administered dose was still retained in the rat 72 h after injection. For 1,2-DBB, the highest level of 3H was in the liver, kidneys and fat tissue 4 and 8 h after administration. Three days after injection, less than 2% of the given dose was retained in the rat body. Urine turned out to be the main route of 3H excretion following the injection of both compounds (30% and 82%, after 1,4-DBB and 1,2-DBB, respectively), and about 4% of the given dose was excreted in feces. In urine of rats the following substances were identified (in sequence 1,4-dBB and 1,2-dBB): (1) unchanged parent compounds (5 and 11%); (2) dibromophenols (84 and 73%); (3) dibromothiophenols (5 and 10%) and (4) monobromophenols (1.9 and 0.7%). This study suggests that 1,2-DBB is characterized by a relatively high turnover rate, whereas 1,4-DBB shows a tendency for long-term retention in the body.