Transdermal iontophoretic delivery of triamcinolone acetonide: a preliminary study in hairless rats

Transdermal iontophoretic delivery of triamcinolone acetonide was examined using a commercially available iontophoretic system (Phoresor, Iomed) in hairless rats. A drug electrode containing triamcinolone acetonide 10 mg dissolved in 1 ml of N,N-dimethylacetamide and water (7/3 v/v) was connected to the positive pole of a Phoresor (set at 4 mA) and direct current was applied for 10, 30, or 90 minutes. The amount delivered to the skin tissues increased with time at a constant rate. Even after the drug electrode had been removed, triamcinolone acetonide was retained in the local skin tissues beneath where it had been for about 24 hours after 30 minutes iontophoresis. These results suggest that the iontophoresis with an organic solvent used as a drug vehicle is useful to increase transdermal absorption of compounds that do not dissolve completely in water.