Atrial natriuretic peptide in the fetus.

Comment This study showed an unexpectedly high rate (10%) of allergic contact dermatitis to transdermal hyoscine in healthy men treated for several months. Allergic contact dermatitis (type IV delayed hypersensitivity) was diagnosed by well established clinical criteria and was further confirmed by the absence ofany reaction to a placebo patch. Our results contrast with those of studies conducted by the manufacturer (Alza Corporation, California, United States), in which no delayed contact sensitisation occurred. In those studies 203 subjects were examined according to a protocol that included the consecutive application of nine hyoscine patches and the application of a tenth patch after two weeks' rest. The design of these studies, however, does not rule out the possibility of delayed type IV hypersensitivity occurring as a result of more prolonged use of transdermal hyoscine. Studies of the long term use of transdermal clonidine showed an incidence of allergic contact dermatitis of 10-38% after three to 12 months of continuous treatment.3 On the other hand, delayed hypersensitivity to transdermal glyceryltrinitrate, which is commonly used in long term and repeated regimens, is rare. We conclude that delayed hypersensitivity may be a serious disadvantage of giving drugs transdermally. Evaluation of new transdermal treatments should exclude the possibility of delayed hypersensitivity, which in our experience may develop even after several months of repeated application.