Addition of UVA-absorber butyl methoxy dibenzoylmethane to topical ketoprofen formulation reduces ketoprofen-photoallergic reaction

Topical application of ketoprofen (KP) clinically evokes the allergic type of photocontact dermatitis. To avoid this adverse reaction, we investigated the beneficial effect of each ultraviolet (UV) filter that was included in topical ketoprofen formulation. We first tested the inhibitory effects of four UVA filters by a modified local lymph node assay following KP application on the mouse skin and UVA irradiation on the same site. In this assessment, butyl methoxy dibenzoylmethane (BMDBM), when included in KP application, exerted the most effective inhibitory effect on stimulation with KP and UVA. We manufactured topical patch and gel KP applicants containing BMDBM, which retained KP penetration through the skin and KP stability toward UVA. The ability of BMDBM in these formulations to inhibit KP photosensitivity was evaluated by a modified adjuvant and strip method in guinea pigs, and the photoallergic reactions induced by the BMDBM-containing KP applicants were lower than the non-containing ones. It is known that KP has a cross-reactivity with benzophenone upon UVA exposure, but such a photocross-reactivity of BMDBM with KP was not observed in a mouse ear swelling model. The anti-inflammatory effect of the BMDBM-containing KP patch applicant was comparable to the non-containing one. These results suggest that the addition of BMDBM into KP topical formulations is efficacious for inhibition of KP photocontact dermatitis.