Allergic contact dermatitis and reactivation phenomenon from iontophoresis of 5-fluorouracil

Patch-test-induced "flare-up" reactions to neomycin at prior biopsy sites

"Recall dermatitis" classically refers to the uncommon phenomenon of chemotherapy-induced reactivation of skin damage originally induced by radiotherapy months or years earlier. We compare this condition to ectopic flare-up reactions presenting as dermatitis at existing or previous sites by an inducing agent. Enhanced sensitization of an existent allergen by patch testing is rarely described. We describe a case of a 61-year-old man's developing localized allergic contact dermatitis at previous neomycin-treated sites following the diagnosis of neomycin sensitivity on patch testing, which we attribute to a "flare-up" phenomenon.

Iontophoresis and electroporation: comparisons and contrasts

The techniques of iontophoresis and electroporation can be used to enhance topical and transdermal drug delivery. Iontophoresis applies a small low voltage (typically 10 V or less) continuous constant current (typically 0.5 mA/cm2 or less) to push a charged drug into skin or other tissue. In contrast, electroporation applies a high voltage (typically, ?100 V) pulse for a very short (micros-ms) duration to permeabilize the skin. This electric assistance of drug delivery across skin will expand the scope of transdermal delivery to hydrophilic macromolecules such as the drugs of biotechnology. These two techniques differ in several aspects such as the mode of application and pathways of transport but can be used together for effective drug delivery. Iontophoresis is already used clinically in physical therapy clinics and is close to commercialization for development of a systemic delivery patch with miniaturized circuits and similar in overall size to a passive patch. The use of electroporation for drug delivery is relatively new and is being actively researched.