Photochemical toxicity of drugs intended for ocular use.

The present investigation was undertaken to evaluate the possible ocular phototoxicity of drugs used in ophthalmic formulations. Sulphacetamide, ketoconazole, voriconazole, diclofenac, and ketorolac were assessed in the concentrations available in the market for their ocular use. The suitable models viz Hen's Egg Test Chorioallantoic Membrane (HET-CAM) test, Isolated Chicken Eye (ICE) test, and Red Blood Cell (RBC) haemolysis test as recommended by ECVAM, ICCVAM, and OECD guidelines were performed. Results of HET-CAM and ICE tests suggest that sulphacetamide is moderately toxic in the presence of light/UV-A and very slightly irritant without irradiation. Ketoconazole and voriconazole were found slightly irritant in presence of light/UV-A and non-irritant in dark. Diclofenac and ketorolac demonstrated slight irritancy in the light and were found to be non-irritant in dark. The results suggest that some of the drugs have potential toxic effect in the presence of light. The extent of phototoxicity might get extended when used for longer time. The recommendation is that these drugs should be stored and used in the dark for a specified time and be labelled with specific instructions for patients, especially for those working longer in the sunlight.