This is clearly shown by the multitude of insurance companies that won't reimburse it's use due to "lack of efficacy" (yet they gladly pay for the cheaper ultrasound). Now there is a new study recently published in the American Journal of Sports Medicine by A. Burke Gurney, PT and Daniel C. Wascher, MD that was very cleverly done. Here is the abstract:
Iontophoresis is a means of administering an ionic medication transdermally using a low electrical current to "push" it along. There is research out there that show it actually occurs and that "long wear", ultra low current, iontophoresis may deliver the medication to a greater depth; but using a skin model (pig skin to be exact). However, the general consensus in the literature tends to be that it doesn't make much of difference in musculoskeletal pain. Anecdotally, though, I have found success when very selectively applying it to areas where the intended tissue is plausibly close to the surface such as the lateral epicondyle, MCL (in thinner pt's), and tendons of the hand. Unfortunately, this practice has not been supported by the literature.
Now, we next have to show that that dexamethasone has a significant impact on tissue inflammation, but this a step in a good direction for iontophoresis as used by physical therapists.
Absorption of Dexamethasone Sodium Phosphate in Human Connective Tissue Using Iontophoresis
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.