DEET (N,N-diethyl-m-toluamide) alone and in combination with permethrin increased urinary excretion of 6β-hydroxycortisol in rats, a marker of hepatic CYP3A induction

In this study, the ratio of 6 beta -hydroxycortisol (6 beta -OHF) to free cortisol (F) was determined in urine following a single dermal dose of 400 mg/kg of DEET (N,N-diethyl-m-toluamide), and 1.3 mg/kg of permethrin, alone and in combination, in rats. Urine samples were collected at 2, 4, 8, 16, 24, 48, and 72 h after application. Recoveries of 6 beta -OHF and cortisol (F) from control urine samples were between 75 and 85%, with limits of detection at 30 and 10 ng/ml for cortisol and 6 beta -OHF, respectively. A single dermal dose of DEET alone and in combination with permethrin significantly increased urinary excretion of 6 beta -hydroxycortisol 24 h after dosing. Permethrin did not significantly alter the urinary excretion of 6 beta -hydroxycortisol. These results indicate that DEET, alone and in combination with permethrin, increased urinary excretion of 6 beta -OHF in rats following a single dermal dose application.