Iontophoretic delivery of calcium for experimental hydrofluoric acid burns

OBJECTIVE: To examine the efficacy of iontophoretic delivery of calcium to experimental hydrofluoric acid burns. DESIGN: Prospective, controlled study. SETTING: Institutional laboratory. SUBJECTS: Male nude rats. INTERVENTIONS: For the in vitro experiment, a full-thickness skin from the back was set in a vertical flow-through diffusion cell. Calcium chloride was applied to the donor chamber, and transdermal transport of calcium was examined with or without a voltage gradient of 1.5 V. Either intact skin or skin whose stratum corneum was stripped with adhesive tapes was used. For the in vivo experiment, hydrofluoric acid burns were induced by dispensing 50% hydrofluoric acid (50 microL) on the backs of the nude rats, who were under pentobarbital anesthesia. Rats were divided into four groups (n = 5 for each group): control group (burned but not treated); topical group (treated with calcium gluconate jelly); infiltration group (intradermal and subcutaneous injection of calcium gluconate); and iontophoresis group (treated with iontophoresis of calcium chloride at 1.5 V). Burn areas were measured and pathologic findings were classified microscopically into five stages at 1 wk: stage 1, epidermal burn; stage 2, superficial dermal burn; stage 3, deep dermal burn; stage 4, full-thickness burn; and stage 5, burn affecting the skeletal muscle. MEASUREMENTS AND MAIN RESULTS: In the in vitro experiment, calcium concentrations increased significantly only in stripped skins with a 1.5-V gradient. In the in vitro experiment, burn areas were reduced significantly in the iontophoresis group compared with the other three groups. Pathologic findings were significantly improved in the iontophoresis group compared with the control group. This efficacy of iontophoresis was observed when it was initiated within 30 mins after hydrofluoric acid burn. CONCLUSIONS: These results show that transdermal transport of calcium was enhanced in stripped skins by iontophoresis and that iontophoresis was more efficacious than topical or infiltration therapy for experimental hydrofluoric acid burns. Iontophoretic delivery of calcium seems to be easier than intra-arterial infusion and may be effective for the lesions where intra-arterial infusion is difficult.