metabolism of the carbamate insecticide bendiocarb in the rat and in man

The metabolism of the carbamate insecticide bendiocarb (2,2‐dimethylbenzo‐1, 3‐dioxol‐4‐yl methylcarbamate) has been investigated in male and female rats and in a male human volunteer using radiolabelled material. The compound was rapidly and extensively absorbed and completely metabolised following oral administration. In man, absorption was complete, >99% of the dose being excreted in the urine within 22 h. In the rat, > 86% of the radiolabel was excreted in the urine within the first 24 h. Faecal excretion from the rat was minor (3–8% of dose) and a small amount of the compound (1–3%) was metabolised and excreted as [14C]carbon dioxide. The major metabolic pathway in both species involved cleavage of the carbamate ester group to yield the phenol,2,2‐dimethylbenzo‐1, 3‐dioxol‐4‐ol (I). This metabolite, occurring as sulphate and glucuronide conjugates, accounted for more than 95% of the dose excreted by the human volunteer. In man, small amounts of conjugates of 2, 2‐dimethylbenzo‐1, 3‐dioxol‐4‐yl N‐(hydroxymethyl)carbamate (II) were also found in early samples. In the rat, the metabolism was more complex with the formation of small amounts of conjugates of II and several minor metabolites, thought to be ring‐hydroxylated derivatives of bendiocarb and I.