IN-VITRO PERCUTANEOUS-ABSORPTION OF METRONIDAZOLE AND GLUCOSE - COMPARISON OF O W, W/O/W AND W/O SYSTEMS/

The percutaneous absorption of model hydrophilic drugs with intermedia te and high polarity, metronidazole and glucose, respectively, from th ree emulsion types (o/w, w/o/w and w/o) has been studied. All the emul sions were prepared with exactly the same composition in order to avoi d the influence of the formulation and to study the role of the emulsi on type alone. The yield of the w/o/w emulsion containing glucose was high (95.8%), while that of the w/o/w emulsion containing metronidazol e was lower (77.6%), although the multiple character of the emulsion w as not in question. Absorption of metronidazole across hairless rat sk in over 24 h ranged from 55 to 69% of the applied dose and was similar for the three emulsions studied. Absorption of glucose ranged from 1 to 4% and was found to be greater from the o/w emulsion than that obse rved from the w/o/w or w/o emulsions. The amount of glucose found in t he dermis seems to be dependent on the emulsion type: o/w > w/o/w cong ruent to w/o. The differences between the emulsions cannot be attribut ed only to the evaporation rate of water alone. X-ray diffraction patt erns obtained after treatment of the stratum corneum with the three em ulsions did not display any difference, but were somewhat different fr om that observed with untreated stratum corneum.