Absorption of Dexamethasone Sodium Phosphate in Human Connective Tissue Using Iontophoresis

Abstract

Background Iontophoresis ostensibly facilitates the delivery of medications through the skin to underlying tissues using a direct electrical current. Dexamethasone is the most commonly used medication with iontophoresis to treat a variety of connective tissue disorders. Hypothesis Iontophoresis will facilitate the absorption of dexamethasone into connective tissue compared with diffusion. Study Design Controlled laboratory study. Methods Twenty-nine adults undergoing anterior cruciate ligament reconstructive surgery using the semitendinosus/gracilis autograft were randomly assigned to either a true iontophoresis (TI) or sham iontophoresis (SI). In the TI group, a 40-mA/min dose of iontophoresis using a 0.4% (4 mg/mL) solution of dexamethasone was used targeting the semitendinosus tendon just before surgery. The SI group underwent the same treatment, but the machine was not turned on. Tissue was extracted within 4 hours of treatment and analyzed for dexamethasone. In addition, 2 control samples were sent to the laboratory for analysis. Results There was a statistically significant difference in dexamethasone concentrations between the groups ( P = .0216). Of the 16 samples in the TI group, 8 had measurable amounts of dexamethasone, with an average concentration of 2.906 ng/g of tendon tissue. In the SI group, 1 of the 13 samples had measurable amounts of dexamethasone with an average concentration of 0.205 ng/g of tendon tissue. The control samples contained no dexamethasone. Conclusion Iontophoresis facilitates the transmission of dexamethasone to connective tissues in humans. Clinical Relevance Iontophoresis can deliver dexamethasone to connective tissues in humans.