Dimethyl cyanocarbonimidodithioate (CAS No. 10191-60-3) a raw material for
cimetidine synthesis, is labelled as an
irritant on its storage tank. There is no information available regarding the toxic effects of human exposure. We report a case of severe
dermatitis clinically resembling
erythema multiforme following an accidental exposure to
dimethyl cyanocarbonimidodithioate in an occupational setting. A clerk sifted a handful of
dimethyl cyanocarbonimidodithioate from an unlabelled bucket through his bare hands during an inspection prior to customs clearance. Five hours later, while he was washing his hands,
pruritus,
erythema and vesicles developed over the exposed area. The skin condition worsened within two weeks, extending to his whole body with generalized
erythema and vesicles of various sizes. Some vesicles became confluent with ruptured
bullae, resembling a second degree
burn over 40% of the body. Elevation of the serum
IgE (705 mu/mL, normal less than 300 mu/mL) and lymphocyte activation with an increased 3H-thymidine uptake by the patient's mononuclear cells suggested that this episode resulted from a cell-mediated allergic skin reaction. The skin lesions improved progressively after systemic
steroid therapy for about two weeks.
Dimethyl cyanocarbonimidodithioate is used as a raw material for
cimetidine synthesis by some
pharmaceutical manufacturers. Our experience suggests that a severe reaction similar to that caused by another H2-blocker,
ranitidine and its intermediate may be caused by
dimethyl cyanocarbonimidodithioate in occupational exposures. Systemic
steroid administration is beneficial in treatment.