Hydrogel allergic contact dermatitis and imidazolidinyl urea/diazolidinyl urea.

Hydrogels contain modified carboxymethylcellulose polymer together with propylene glycol as known components. Nowadays, they are common agents used in the treatment of leg ulcer patients, and a possible cause of allergic contact dermatitis. However in the published data, not all the patients with positive patch tests to hydrogels were sensitized to propylene glycol, remaining some allergens to be identified. The authors describe two leg ulcer patients sensitized for different commercial available hydrogels tested "as is", with concomitant patch tested positivity to imidazolidinyl urea (IU) and diazolidinyl urea (DU). Patient A was an 84-year-old male, and patient B was a 77-year-old female, both with a known history of leg ulcer for more than 8 weeks. Patient A was sensitized for Intrasite Gel(®), Hydrogel Nu-Gel(®), Askina Gel(®), neomycin and budesonide. Patient B was sensitized for Intrasite Gel(®), Hydrogel Nu-Gel(®), Askina Gel(®), Hydrosorb Gel(®), Fragance mix 1 and 2, Amerchol, geraniol and citral. They were negative to propylene glycol tested in 5% pet. and 20% aq. IU and DU are formaldehyde-releasing agents, used as antimicrobial preservatives in the formulation of pharmaceutical creams and ointments and are known to cause contact dermatitis. Also, in many studies performed, it has been shown that contact allergy is high in patients with leg ulcers. As result, assessment of the relevance of positive patch test reactions in these patients can be difficult. Although we were not able to get the complete ingredient list of the hydrogels tested, attending to these observations, could be of importance to evaluate the presence of IU/DU in patients with suspected contact dermatitis to hydrogels.