Colloidal silica-induced hypersensitivity: myth or reality.

BACKGROUND: Many excipients have been reported to induce drug hypersensitivity (e.g. colouring additives, preservatives). Colloidal silica has never been reported to induce drug hypersensitivity reactions. CASE REPORT: We report herein a 40-year-old patient who developed a skin eruption 2 days after Voltarene(®) (diclofenac) intake, confirmed by a positive patch test. Investigation of cross reactivity, assessed by patch testing to other non steroidal anti-inflammatory drugs, have showed a positive reaction only to piroxicam (Piroxen(®)), ketoprofen (Oki(®)) and indometacin (Indocid(®)). A hypersensivity to colloidal silica, a common excipient, was suspected. A patch test to this compound was performed showing a positive reaction.
CONCLUSION: Colloidal silica, a compound widely used in drug manufacturing, could be another culprit excipient in inducing skin hypersensitivity reactions.