Propionic acid-derived non-steroidal antiinflammatory drugs are phototoxic in vitro

Clinical photosensitivity reactions have been reported for several non-steroidal antiinflammatory drugs (NSAID). 11 such commercial preparations were studied spectrophotometrically and assayed for phototoxicity using 2 in vitro methods. Photohemolysis of human red blood cells was measured following exposure to longwave (UVA) and medium-wave (UVB) ultraviolet radiation. Growth inhibition of Candida albicans was assayed after exposure to drug and UVA. A majority of the drugs were phototoxic. Propionic acid-derived NSAIDs were the most active in the photohemolysis assays as well as in the Candida test. With UVA 43.2 J/cm2 ketoprofen was one order of magnitude more potent that the other compounds; with increasing UVB doses and a standard drug concentration of 10 micrograms/ml the same was true for benoxaprofen. Several compounds were protective against UVB hemolysis. Candida growth inhibition was strongest with naproxen. Again, propionic acid derivatives generally were the more effective. No photoactivity was noted for indomethacin, piroxicam and sulindac. Azapropazone caused UVA hemolysis only. Members of the NSAID group, and in particular derivatives of propionic acid, are capable of inducing phototoxic reactions with UVA as well as UVB in vitro. These results confirm clinical reports of photoreactions to members of this group.