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The following discussion of metabolic data has been taken from the US-EPA HED human health risk assessment on amicarbazone (2005):

 

In a rat metabolism study 95% of the radioactive dose was recovered within 72 hrs post dosing. Urinary excretion accounted for 64% of the dose, indicating substantial absorption and faecal excretion accounted for 27% of the dose within 24 hours of dosing. The parent compound only accounted for approximately 3% of the radioactive dose, indicating rapid metabolism. Three major metabolites were identified in the excreta, iPr-2-OH DA MKH, tBu-OH DA MKH and glucronic acid conjugates. Based on the metabolic profile, the metabolism of MKH 3586 in rats primarily involves deamination followed by hydroxylation with elimination in the urine. The parent also undergoes glucronic acid conjugate and eliminated in the faeces.

 

In a further rat metabolism study performed on the environmental degradate of amicarbazone, 4-methyl MKH 3586. The routes of excretion for this compound are similar to that of the parent. Over 90% of the radioactive dose was eliminated within 96 hours, the majority of eliminated through the urine and faeces within 24 hours of administration. The pathway of metabolism in rats primarily involves a series of hydroxylation reactions, no conjugates were detected.

iPr-2 -OH DA MKH: N-(1,1 -dimethylethyl)-4,5 -dihydro-3 -(1 -hydroxy-1 -methylethyl)-5 -oxo-1H-1,2,4 -triazole-1 -carboxamide

t Bu-OH DA MKH: 4,5 -dihydro-N-(2 -hydroxy-1,-dimethylethyl)-3 -(1 -methylethyl)-5 -oxo-1H-1,2,4 -triazole-1 -carboxamide

 

Reference:

US EPA (2005). Amicarbazone: HED human health risk assessment for new food use herbicide on field corn. PC code: 114004, Petition #: 0F6131, DP barcode: D288216. HED Records Center Series 361 Science Reviews – File R112623.