Iontophoresis for enhancing penetration of dermatologic and antiviral drugs.

Iontophoresis is the process of introducing ionic drugs into the body for therapeutic purposes. Although iontophoresis has the potential for systemic therapy, it has mainly been used for local therapy at body surfaces. Many ionic drugs are available including lidocaine, epinephrine, methylprednisolone succinate, dexamethasone phosphate, several antivirals, various antibiotics, and other specific drugs. The use of an indicated ionic drug by iontophoresis offers a broad potential for promoting the development of more effective therapies in dermatology. Iontophoresis of ionized drugs provided a 20-60 fold increase in penetration over topical application. Iontophoresis for dermatological use requires that: a) a charged drug be placed at an electrode having a polarity the same charge as the drug, b) the condition or disease under treatment be at or near the body surface, and c) a modern, sophisticated source of direct current, with appropriate accessories, be used. The current source must have features that make it not only effective, but also safe for application to the patient. Modern systems for application of drugs by iontophoresis have features that make the process simple and efficient for use in practice. Iontophoresis has a long history of use, having been suggested for various therapies for many years in medicine, physical therapy and dentistry. Pilocarpine iontophoresis is a preferred method for cystic fibrosis detection. Also, lidocaine iontophoresis has been advocated to anesthetize the tympanic membrane before myringotomy. Anesthesia of the skin to a depth of 1.0 cm or more has been reported in double-blind studies of human volunteers. Local anesthesia by iontophoresis was reported to be effective for: 1) cutaneous cutdowns in patients requiring kidney dialysis, 2) delicate eyelid surgery, as the sole anesthetic, 3) preinjection topical anesthesia, and 4) shave biopsies of skin lesions. The use of iontophoresis for treating difficult cases of hyperhydrosis is quite popular among dermatologists. The present report emphasizes uses of iontophoresis in dermatology and is divided into discussion of studies using iontophoresis for postherpetic neuralgia, local anesthesia, antiviral therapy, and for corticosteroid therapy of nonspecific inflammatory lesions. Over 1250 patients have been treated for postherpetic neuralgia by corticosteroid iontophoresis at 6 medical centers with 60-80% of patients showing a major therapeutic response with return to a tolerable pain level. Double-blind studies of varicella zoster (active and postherpetic) and herpes simplex have proven that iontophoresis is a valuable modality for treating viral diseases of the skin. Many other uses for iontophoresis have been proposed in the literature that involve several hundred research papers, several textbooks and many book chapters. Review of the literature supports the concept that iontophoresis provides an optimal method for drug application in therapy of surface tissues.