Absorption of Dexamethasone Sodium Phosphate in Human Connective Tissue Using Iontophoresis

University of New Mexico School of Medicine, Department of Orthopaedics and Rehabilitation, Albuquerque, New Mexico

^* To whom correspondence should be addressed. E-mail: bgurney{at}salud.unm.edu.

	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.