Contact allergens in oral antihistamines.

BACKGROUND

Excipients in various formulations of active drugs occasionally include known contact allergens. Their ingestion may trigger dermatitis or cause it to become widespread or refractory to therapy.

OBJECTIVE

The aim of this study was to investigate the prevalence of common contact allergens among the excipients of oral antihistamines available in this country.

METHODS

We gathered the complete ingredient lists of 2119 different preparations of 12 oral antihistamines from the National Library of Medicine data bank and entered them into an electronic database for analysis.

RESULTS

More than half the formulations (55.0%) contained at least 1 member of the 10 allergen families assessed. Most brompheniramine and doxepin preparations included potentially allergenic excipients, whereas fexofenadine was most often free of them. Sorbitan group members, azo dyes, and propylene glycol were the allergens found most frequently in the antihistamines, each present in over 25% of the products. Elixirs, liquids, solutions, suspensions, and syrups were more likely than nonchewable caplets, capsules, and tablets to contain the allergens tabulated (100% vs 39.3%, respectively). Chewable pills frequently contained azo dyes.

CONCLUSIONS

Ingestion of antihistamines could precipitate a systemic contact dermatitis in a patient sensitized to an allergen present as an excipient in the medicine.