Systemic toxicity potential
Short-term, sub-chronic and chronic oral toxicity studies were submitted for rats, mice and dogs, plus one 21-
day dermal toxicity study in rats. The repeat-dose dermal study in rats did not result in any systemic toxicity
or other treatment related findings. The lowest dose in repeat-dose oral studies that resulted in treatment
related findings was at a dose of 100 mg/kg bw/d in a 52-week oral (dietary) study in Beagle dogs. The liver
and the choledochus were identified as the main target organs of toxicity regardless of duration of exposure.
The lowest NOEL for short term oral toxicity was 51.4/56.6 mg/kg bw/d (M/F) from a 4-week F344 rat dietary
study. For sub-chronic toxicity, the NOELs were similar between rats and mice at 71.9/79.9 mg/kg bw/d
(M/F) and 68.6/79.0 mg/kg bw/d (M/F) respectively. For chronic toxicity, the lowest NOEL was 10 mg/kg bw/d
from a 52 week oral (capsule) dog study. Male rats and mice appeared to be more sensitive across all
studies, which is consistent with the higher rate of elimination in males compared to females as
demonstrated in rat ADME studies. Although the NOELs for males and females were at similar doses, more
effects were generally observed in males at these doses.