Although5-fluorouracilisoneofthemostwidelyusedcytotoxicdrugsinthetreatmentofsolidtumorsinmanyorgans,ithasaseveredrawbackinitsseriousside-effects(e.g.gastrointestinalandbonemarrowtoxicity)andtheproperties(e.g.lowlipophilicity)leadingtovariousdeliveryproblems.Thelowlipophilicityof5-fluorouracilmaybeapredominantfactorforitspoorbiomembranepermeability.