Allergic contact dermatitis to topical drugs--epidemiological risk assessment.

PURPOSE: Estimation of the population-based relative incidence (RI) of contact sensitization to a set of topical drug allergens (cases/100,000 defined daily doses (DDDs) per year) (1995-2004) and comparison of the RI for drugs with a similar therapeutic scope.

METHODS

Clinical data regarding the frequency of contact sensitization to important topical drug allergens in Germany were obtained from the Information Network of Departments of Dermatology (IVDK). This was extrapolated to the general population level using the 'clinical epidemiology and drug utilization research' (CE-DUR) approach. As denominator of exposure, national prescription data (DDDs of topical drug specialties) provided by the WIdO Research Institute (Bonn) were aggregated per substance.

RESULTS

The probable RIs of contact sensitization to topical 'skin' corticosteroids ranged from 0.3 (dexamethasone phosphate disodium salt) to 23.3 (amcinonide) cases/100,000 DDDs per year. Concerning topical aminoglycoside antibiotics, the RI of framycetin sulphate was about threefold higher than that of gentamicin sulphate. Regarding topical ophthalmic use, the RI of kanamycin sulphate was higher compared to gentamicin sulphate. Active principles marketed over-the-counter (OTC) had, in general, lower RIs, with the exception of bufexamac, benzocaine, clioquinol and phenylephrine.

CONCLUSIONS

The population-based risk assessment--quantitatively considering exposure in the RI estimation--revealed a ranking of contact sensitization risk to topical drugs which partly differed from the respective frequencies in the clinical patch test population. Some drugs available OTC carry non-negligible risk, too. The current findings should contribute to differential therapeutic considerations regarding topical drug use.