OXFENDAZOLE

Overview

Chemical Names
METHYL (5-PHENYLSULFINYL)-2-BENZIMIDAZOLE CARBAMATE
CAS number
53716-50-0
Functional Class
Veterinary Drug
ANTHELMINTHIC_AGENT

Evaluations

Evaluation year: 1999

ADI:
0-7 µg/kg bw (group ADI)

Comments:
The Committee established a group ADI of 0-7 µg/kg bw for febantel, fenbendazole, and oxfendazole on the basis of a NOEL of 0.7 mg/kg bw/d in a two-year study on oxfendazole in rats (evaluated at the 38th and 45th meetings) and a safety factor of 100. The Committee noted that this ADI provides a safety factor of 1000 for teratogenic effects in sheep, which was considered at the 38th meeting to be the most sensitive species for the teratogenic effects of oxfendazole.
MRL Comment:
Group MRLs for the sum of fenbendazole, oxfendazole and oxfendazole sulfone (as oxfendazole sulfone equivalents in mg/kg tissue, mg/l milk): Muscle, kidney and fat (cattle, horses, pigs, sheep and goats): 0.1; Liver (cattle, horses, pigs, sheep and goats): 0.5: Milk (cattle and sheep): 0.1
MRL Code:
TMRL
Intake:
TMDI: 0.24 mg/p/d
Meeting:
50
Report: 
TRS 888-JECFA 50/13
Tox Monograph: 
FAS 41-JECFA 50/23
Residues: 
FNP 41/11-JECFA 50/49

Toxicological study

Pivotal Study:
Rat dietary carcinogenicity study: Rats (strain & number/dose unspecified) were fed oxfendazole in the diet at concentrations of 0, 10, 30, or 100 mg/kg for 2 years. The only treatment-related effect noted was dose-related hepatocellular lipid vacuolation at 30 & 100 mg/kg in the diet. The NOEL was 10 mg/kg in the diet (0.7 mg/kg bw/d (males) and 0.9 mg/kg bw/d (females)).
Animal Specie:
Rat
Effect:
Hepatocellular lipid vacuolation
NOEL:
0.7 mg/kg bw/d
Point of departure:
0.7 mg/kg bw/d
Previous Years:
1995, TRS 864-JECFA 45/21, FNP 41/8-JECFA 45/99, FAS 36-JECFA 45/51. 0-0.004. GROUP TEMPORARY ADI FOR FEBANTEL, FENBENDAZOLE AND OXFENDAZOLE. MRLs (TEMPORARY, GROUP MRL FOR FEBANTEL, FENBENDAZOLE AND OXFENDAZOLE DETERMINED AS THE SUM OF FENBENDAZOLE, OXF
1995, TRS 864-JECFA 45/21, FNP 41/8-JECFA 45/99, FAS 36-JECFA 45/51. 0-0.004. GROUP TEMPORARY ADI FOR FEBANTEL, FENBENDAZOLE AND OXFENDAZOLE. MRLs (TEMPORARY, GROUP MRL FOR FEBANTEL, FENBENDAZOLE AND OXFENDAZOLE DETERMINED AS THE SUM OF FENBENDAZOLE, OXF