抄録
Transdermal iontophoretic delivery of triamcinolane acetonide (TA) and tranilast (TL) was examined using a commercially available iontophoretic system (Phoresor, Iomed, Inc.) in hairless rats. In keloid therapy, TA in a suspension form is injected intralesionally by pressure jet apparatus, but this mode of administration frequently hurts patients. TL is administered orally, but the selective distribution of TL into the restricted skin tissues such as keloids is not expected. Iontophoretic delivery has many advantages such as non-invasive drug entry into the restricted local skin and underlying tissues. A drug electrode containing 1 ml of TA solution (10 mg/1 ml in N, N-dimethylacetamide-water (7 : 3 v/v) mixture), or 1.5 ml of TL solution (8 mg/ml in ethanol-water (8 : 2 v/v) mixture) was placed on the dorsal skin of anesthetized rats and was connected to the positive pole for TA or negative pole for TL. The current density of Phoresor was set at 4 mA for TA or 2 mA for TL, and was sent in a pulsatile manner (1 min interval). The transdermal penetration of TA and TL, evaluated by determining the amount of a drug retained in the skin tissues beneath of the drug electrode, was significantly facilitated. Both TA and TL, especially TL, were retained in the restricted skin tissues for a fairly long time (about 24 h in TA and 72 h in TL) at pharmacologically effective concentrations even after removing the drug electrode. No skin damage was found by a histological observation after a 30 min-iontophoresis. These results suggest that transdermal iontophoretic delivery of TA and TL using a mixture of organic solvent and water as a drug vehicle is an effective administration mode for the therapy of human keloids and hypertrophic scars as a beneficial substitute for intralesional injection of TA or oral administration of TL.
