Acute, subacute and chronic toxicity/Carcinogenicity of lofexidine

Acute, subacute and chronic toxicity-carcinogenicity studies of 2-[1-(2,6-dichlorphenoxy)-ethyl]-2-imidazoline hydrochloride (lofexidine, Lofetensin and Loxacor) were conducted in rats, dogs, and/or mice. The oral LD50 values for these species were similar. Lofexidine given orally to rats and dogs for up to 12 months produced no significant adverse effects at doses up to 1 mg/kg and only marginal effects at 3 mg/kg; moderate to severe effects were noted at doses of 5-25 mg/kg. When given orally to rats for 24 months at doses of 0.1-1.0 mg/kg, lofexidine failed to elicit any evidence of carcinogenicity. Phentolamine and tolazoline may be useful as antidotes in cases of overdosage.