Like mebendazole, the biggest challenge in repurposing niclosamide is going to be pharmacokinetics."Niclosamide has low toxicity in mammals (oral median lethal dose in rats >5000 mg/kg), which is obviously associated with poor absorption. The safety of niclosamide needs to be re-evaluated if it is translated to chemotherapy for cancer patients by systemic intravenous administration.""Absorption:Not significantly absorbed from the gastrointestinal tract.""Absorption Niclosamide appears to be minimally absorbed from the gastrointestinal tract—neither the drug nor its metabolites have been recovered from the blood or urine."