Titanium dioxide inclusion in backing reduce the photoallergenicity of ketoprofen transdermal patch

Ketoprofen (KP) is a widely used transdermal non-steroidal anti-inflammatory drug. However, increasing number of adverse effect case reports suggests that KP transdermal formulation can cause photoallergic reaction. The photoallergic potential of KP is attributable to the instability of KP under UV/visible light and subsequent formation of reactive degradation products. In this study, we investigated whether the inclusion of titanium dioxide (TiO₂), a well-known mineral sunscreen agent, in the KP transdermal patch can prevent the photodegradation of KP and ultimately, can reduce photoallergic reaction. TiO₂ inclusion in fabric backing effectively decreased the UV transmission through fabric patch throughout all UVA region from 320 to 380 nm and consistently, KP patch with TiO₂ exhibited significantly increased photostability of KP. This enhanced photostability of KP resulted in reduced generation of photodegradation product as determined by HPLC-UV analysis. In a good accordance with these in vitro results, photosensitization test in guinea pig in vivo demonstrated low photoallergic reactions of KP patch with TiO₂ compared to KP patch without TiO₂, indeed. This study demonstrated that KP transdermal patch with TiO₂-included backing can provide with improved photostability and photosafety over conventional fabric KP patch.