D2.296 - Allergic contact dermatitis caused by a oxybutynin in a transdermal patch

Transdermal therapeutic systems (TTS) are increasingly prescribed instead of oral formulations because of several advantages, including convenience and fewer side effects, resulting in increased patient compliance. However, adverse cutaneous reactions are common and they can have a negative impact on compliance.

Oxybutynin is an anticholinergic drug indicated among others for urinary incontinence. Currently there are oral and transdermal presentations, this last one formulated in a TTS matrix with less adverse effects.

Previously, Bershow A et al described the different skin reactions after the use of TTS, among which oxybutynin was found; they didn ́t perform patch test. The group of Taboada Paz et al described a case of a multiple widespread fixed drug eruption caused by a transdermal oxybutynin patch.

We present the case of a 59-year-old woman, nursing assistant, with medical history of undetermined dermatitis, who has urinary incontinence. Last summer she started treatment with a transdermal patch of Kentera® (oxybutynin 3,9 mg/ 24 h) and two weeks later she presented in the application areas pruritic erythematous rash that lasted several days. Until this episode, she didn ́t present any problems with adhesives.

We performed patch test with the standard series from GEIDAC (Spanish Contact Dermatitis and Skin Allergy Research Group), plastics and glues series, methacrylates series, Kentera® (oxybutynin transdermal patch) and oxybutynin diluted at 0,1 % pet. and 1 % pet (as previously described by Taboada Paz L et al.).

Positive results were obtained for nickel sulfate [+ at day (D) 2 and ++ at D 4], formaldehyde (+++ at D2 and D4), quaternium-15 (+ at D2 and D4), urea methacrylate (+ at D2 and D4), Kentera® (++ at D2 and D4) and oxybutynin 1 % (+ at D4). Oxybutynin 0,1 % was negative.

We present, as far as we know, the first case of allergic contact dermatitis caused by oxybutynin. Although the TTS increased the patient compliance, it must be taken into account, as we have seen in this case, that they can cause allergic contact dermatitis.

The patient is sensitized to formaldehyde, quaternium-15 and urea methacrylate with unknown relevance and to nickel sulfate with relevance in the past.