Disposition of [¹⁴C]hydroquinone in Harlan Sprague-Dawley rats and B6C3F1/N mice: species and route comparison

Abstract

1. Hydroquinone (HQ) is present in some foods and has varied industrial, medical and consumer uses. These studies were undertaken to investigate the disposition of HQ in rats and mice following gavage, intravenous (IV) and dermal exposure. 2. [C]HQ administered (0.5, 5 or 50 mg/kg) by gavage or IV routes to male and female Harlan Sprague-Dawley (HSD) rats and B6C3F1/N mice was well absorbed and rapidly excreted primarily in urine. Radioactivity remaining in tissues at 72 h was <1% for both species at all dose levels and routes. No sex, species or route related differences in disposition were found. 3. With dermal application of 2, 10 or 20% [C]HQ, mice absorbed higher percentages of the dose than rats (37, 12, 12% versus 18.6, 4.43 and 1.79%, respectively). The HQ mass absorbed by mice increased with dose, while in rats it was more constant over the dose range. Absorbed HQ was rapidly excreted in urine of both species and urinary excretion indicated continued absorption over the exposure period. No sex differences in disposition were found. 4. The oral bioavailability of HQ at 5 mg/kg was low in both rats (1.6%) and mice (3.9%) demonstrating significant first pass metabolism. Dermal bioavailability in mice was 9.4% following application of 2% formulation. 5. Urinary metabolites for both species and all routes included the glucuronide and sulfate conjugates; no parent was found in urine.

Disposition and metabolism of N-butylbenzenesulfonamide in Sprague Dawley rats and B6C3F1/N mice and in vitro in hepatocytes from rats, mice, and humans

“…recovered. The percent total radioactivity remaining in tissues at 72 h (5%) following a single gavage administration of [ 14 C]NBBS in rats was higher than those observed previously in mass balance studies with other xenobiotics such as hydroquinone and sulfolane (1-2%) (Black et al 2018;Waidyanatha et al 2018). Unlike in rats, the percent radioactivity remaining in mice at 72 h following a gavage dose of 20 mg/kg [ 14 C]NBBS was <0.1% (Table 4) demonstrating a significant species difference in tissue retention.…”