ABSTRACT: Corticosteroids are highly effective in reducing inflammation and present an appropriate pharmacotherapeutic option for many musculoskeletal disorders. However, systemic administration carries the risk of collateral damages. Transdermal administration of corticosteroids via iontophoresis allows for localized delivery, thus bypassing many of the problems with systemic administration. The potential safety benefits are compelling, but efficacy data have been conflicting. Most data suggest that iontophoresis facilitates dexamethasone(Drug information on dexamethasone) penetration into human tissues. We reviewed 13 clinical trials that met criteria for muscle soreness, carpal tunnel syndrome, osteoarthritis of the knee, rheumatoid arthritis of the knee, plantar fasciitis, trapeziometacarpal arthritis, Achilles tendon pain, and epicondylitis. (J Musculoskel Med. 2011;28:410-421)
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Musculoskeletal pain is common. In one analysis, 33% of adults reported musculoskeletal pain from overuse as a chief complaint. Morbidity resulting from musculoskeletal pain contributes to 29% of lost workdays because of illness and is second only to cardiovascular disease in terms of economic burden.1 Chronic symptoms related to musculoskeletal pain affect not only patients’ physical function but also their mental and emotional well-being.2
Corticosteroids are used widely to benefit patients who experience musculoskeletal pain, as monotherapy or as part of a multifaceted approach. Injection is the most widely used method for delivering corticosteroids to a localized area.
Corticosteroids are highly effective in reducing inflammation and therefore present an appropriate pharmacotherapeutic option for many musculoskeletal disorders. Systemic administration of corticosteroids carries the risk of a variety of collateral damages, especially with repeated use. The systemic adverse effects include glucose dysregulation, psychosis, immunosuppression, osteonecrosis, hypertension, hyperlipidemia, and appearance changes.3 In addition, receiving corticosteroid injections may be painful and traumatic.
Transdermal administration of corticosteroids via iontophoresis allows for localized delivery, thus bypassing many of the unwanted toxicities and nuisances, as well as the invasiveness of an injection. In this article, we provide a concise review of the literature related to iontophoresis of dexamethasone in musculoskeletal conditions.
A patient with epicondylitis is receiving dexamethasone via iontophoretic administration. The electrodes are placed strategically to facilitate treatment. (Photograph courtesy of Krupalee Brunetti, DPT.)
BACKGROUND
Iontophoresis of corticosteroids has been used clinically since the 1950s (Figure).4 The mechanism involves active transport within an electric field. The basic principles are based on the physical phenomenon that “like charges repel and opposite charges attract.” Anionic drugs are forced across the skin by using a negatively charged working electrode. Similarly, cationic drugs enter the skin when a positively charged electrode is used. Once the drug permeates the skin, it reaches its target tissue by rapidly diffusing into the local circulation.
The delivery of corticosteroids using the technology of iontophoresis has several advantages over parenteral administration. Transdermal administration with iontophoresis avoids systemic administration and bypasses the hepatic “first pass” metabolism, which ultimately reduces the variation of absorption seen with oral administration. As an alternative to systemic administration, iontophoresis minimizes some of the unwanted consequences related to injections (eg, tendon rupture and skin and fat pad atrophy).
In addition, patients may be more willing to receive local treatments than an invasive injection. Drug delivery is programmed by the amount of voltage of the current applied, allowing the administrator to deliver a very precise dose. The iontophoretic delivery system also may be turned off, leading to, if needed, rapid termination of the medication.
