Metabolism of propyrisulfuron: ¹⁴C excretion, ¹⁴C concentration in plasma and tissues, and amount of metabolites in rats

Abstract

1. Metabolism of a novel sulfonylurea herbicide, propyrisulfuron [1-(2-chloro-6-propylimidazo[1,2-b]pyridazin-3-ylsulfonyl)-3-(4,6-dimethoxypyrimidin-2-yl)urea] labeled at the C-1 position of the propyl group and C-5 position of the pyrimidine ring with ¹⁴C was investigated after a single oral administration in male and female rats.

2. Administered ¹⁴C was excreted into the urine (5.7–29.8%) and feces (64.6–97.4%), respectively. ¹⁴C concentration in plasma reached a maximum level at 4 to 12 h post-administration and then decreased rapidly with a biological half-life of approximately 23 to 32 h. Total ¹⁴C residues in the whole body were <0.1–1.4%, suggesting that the residues were not accumulated in the tissues.

3. The amount of metabolites in urine, feces, and bile were quantified using high-performance liquid chromatography (HPLC). There were no differences in metabolites found between male and female rats.

4. The absorption for the low dose (5 mg/kg) and the high dose (1000 mg/kg) was estimated to be approximately 90% and 20%, respectively, suggesting a saturable absorption.

5. The plasma protein binding in male and female rats was ≥98.8%, suggesting that propyrisulfuron had a strong affinity to plasma proteins.

• Herbicide
• metabolism
• rat

Acknowledgements

The authors acknowledge Mr. Hayato Takeuchi and Ms. Mari Haneta for their technical assistance.