Six kinds of well-prescribed admixtures of commercially available ointments and/or creams were selected from the prescribed sheets in our hospital. The skin permeability of corticosteroid from these admixtures was investigated by in vitro experiments using hairless mice skin. The permeability of corticosteroid through skin after adaptation of corticosteroid creams (Lidomex®) alone was approximately 9-fold larger as compared with that of the ointments only.The pemeability of conicosteroid in the admixture of Nedsona Universal®cream or Lidomex®ointment and urea ointments respectively was 3-and 5-fold larger than that from the cream and ointments alone. However, urea ointments did not influence the permeability of the drug in Lidomex®creams.This suggested that the w/o-type urea ointments more greatly enhanced the permeability of corticosteroid as compared with the o/w type urea ointments. The extent of the stability of the emulsion after mixing was related to the permeability. These results suggest that admixing ointments and/or creams should be carried done among bases having similar physicochemical characteristics.
