Contact dermatitis and prolonged photosensitivity induced by ketoprofen and associated with sensitivity to benzophenone-3

Greater allergenicity of topical ketoprofen in contact dermatitis confirmed by use

The use of topical non-steroidal anti-inflammatory drugs (NSAIDs) is very popular in spite of their doubtful efficacy and high number of generally not serious, but preventable, adverse effects, especially photoallergy. The allergenic potential of different topical NSAIDs was determined by performing a retrospective observational study of the period 1996-2001 and comparing the cases of allergy and photoallergy with the use of each topical NSAID. The diagnoses were obtained from a review of the clinical records of patch/photopatch testing carried out in the dermatology departments of 2 public hospitals in Bizkaia (Spain). The use of the different topical NSAIDs was obtained from invoices sent to the National Health System and the Reporting odds ratio (ROR) and Proportional reporting ratio (PRR) disproportionality estimates of the FEDRA database of the Spanish Pharmacovigilance System. A total of 139 contact reactions to topical NSAIDs were found with ketoprofen being responsible for 28% of the allergies and 82% of the contact photoallergies in spite of not being the most used topical NSAID (third in the ranking, diclofenac was the first). The ROR for ketoprofen was 3.9 (2.4-6.4) and the PRR 3.4 (2.1-5.5), thus confirming the possibility of a warning signal. The results support the need for regulatory action on topical ketoprofen.

Photoallergic contact dermatitis

PURPOSE

To determine whether photoallergic contact dermatitis is as uncommon as it is usually considered to be and to review the associated clinical features.

METHODS

We reviewed the literature on photoallergic reactions induced by the topical contact of the skin with a chemical in the presence of, or followed by, exposure to UV or visible light. Some of the more recently observed photo-allergens and those presenting special clinical features are discussed.

RESULTS

The literature cites several topical substances that give rise to photoallergic contact dermatitis, some of them only exceptionally but others quite frequently. The clinical features are not always those of a eczematous eruption, and several parts of the body may be affected.

CONCLUSIONS

Many topical photoallergic culprits have been reported in the literature, the most important of which are sunscreen agents and, recently, non-steroidal anti-inflammatory agents (NSAIDs). Not at all exceptional is the occurrence of photoaggravation and recurrent transient or even persistent light reactions on previously exposed as well as non-exposed areas (often sparing the original application site), particularly with the NSAID ketoprofen. Moreover, cross-reactions with chemically-related as well as non-chemically related molecules are common. The potentially misleading clinical features observed in some cases, the diversity of the casual substances identified, and the low frequency with which photopatch testing is carried out in general indicate that the occurrence of photoallergic contact dermatitis might well be underestimated.

Photosensitivity to ketoprofen: mechanisms and pharmacoepidemiological data

The topical use of nonsteroidal anti-inflammatory drugs (NSAIDs), widely used for moderate acute and chronic painful conditions, is one of several strategies used to improve the tolerability profile of NSAIDs, particularly with regard to gastric and renal adverse effects. However, topical NSAIDs can induce photosensitivity. Among the different NSAIDs used topically, ketoprofen has often been implicated in photosensitivity reactions. Photosensitivity includes both phototoxic and photoallergic reactions. Phototoxicity can be studied in the cell system and on biological targets such as cellular membranes or DNA. In hepatocyte cultures, data suggest that radical intermediates play a role in ketoprofen-photosensitised damage by cell membrane lysis. Photosensitised lysis of red blood cells has been employed as an indicator of membrane damage. Ketoprofen irradiation promotes the photolysis of erythrocyte suspensions. The drug is able to induce photoperoxidation of linoleic acid in the photo-induced lipid peroxidation process. The results obtained from the addition of radical scavengers suggest the involvement of free radicals in these processes. Ketoprofen may induce DNA damage in vitro upon irradiation. DNA, in the presence of ketoprofen, undergoes single strand breaks involving hydroxyl radicals as evidenced by the use of scavengers. Simultaneously with single strand breaks, pyrimidine dimers are formed by an energy transfer mechanism. The oxygen-dependence of both processes suggest competition between a radical process leading to DNA cleavage and a poorly efficient energy transfer between ketoprofen and pyrimidines at the origin of the dimerisation process. Photoallergy is due to a cell-mediated hypersensitivity response involving immunological reactions. Therefore, it only occurs in previously sensitised individuals and requires a latency period of sensitisation. Among NSAIDs, ketoprofen is the main drug involved in this photoallergic contact dermatitis. Cross-sensitivity reactions with other arylpropionic acid derivatives, such tiaprofenic acid, fenofibrate or oxybenzone-harbouring benzoyl ketone or benzophenone may also occur. Finally, the higher frequency of such adverse reactions with ketoprofen could be accounted for by its chemical structure and the variety of chemical reactions that give rise to phototoxic effects. The widespread and repeated use of these agents may lead to sensitisation, incurring a greater risk of systemic allergic reactions with oral NSAIDs or other drugs recognised to induce cross-reactions. Physicians and pharmacists should advise patients and inform them of the risks of topical NSAIDs which are often dispensed as over the counter drugs.