Impact of Light Shielding on Photo-Degradation of Dacarbazine during the Preparation Process

: Dacarbazine (DTIC) is converted to the photo-degradation product 4-diazoimidazole-5-carboxamide (Diazo-IC) by light. Diazo-IC production is often responsible for the pain reactions observed during peripheral intravenous infusion of DTIC in clinical settings. Although light shielding during infusion decreases the photo-degradation of DTIC, its usefulness for the preparation of DTIC has not yet been fully clarified. The aim of this study was to investigate the light conditions during the preparation of DTIC solution in the compounding room from the viewpoint of the production amount of Diazo-IC. DTIC solution was prepared in the compounding room. Various light and temperature conditions and dissolving solutions during the preparation were investigated. The amounts of DTIC and Diazo-IC in solutions were determined using an HPLC coupled to UV detection. The photo-degradation of DTIC was estimated by the amount of Diazo-IC. Diazo-IC production in the dissolving solutions increased in a time-dependent manner at 4 and 25°C under light shielding. Light exposure during the dissolving process did not affect the DTIC and Diazo-IC concentrations. Light shielding during dissolution did not alter the Diazo-IC production until 4 h after dilution. In conclusion, short duration light exposure did not affect Diazo-IC production. These findings suggest that light shielding is not needed in the preparation of DTIC in the compounding room from the viewpoint of Diazo-IC production.