Drug products photostability studies

Drew, H.D., Brower, J.F., Juhl, W.E., and Thornton, L.K. (1998). Quinine photochemistry a proposed chemical actinometer system to monitor UV-A exposure in photostability studies for pharmaceutical drug substance and drug product photostability studies. Pharmacopoeial Forum, 24, 6334—6346. 

Stress Testing (drug product) — Studies undertaken to assess the effect of severe conditions on the drug product. Such studies include photostability testing (see ICH Q1B) and specific testing of certain products (e.g., metered dose inhalers, creams, emulsions, refrigerated aqueous liquid products). 

Drew HD. Photostability of drug substances and drug products a validated reference method for implementing the ICH photostability study guidelines. In Albini A, Fasani E. Drugs Photochemistry and Photostability. Cambridge The Royal Society of Chemistry, 1998 227-242. 

Sequeira F, Vozone C. Photostability studies of drug substances and products. Pharm Tech 2000 30-35. 

Anderson NH. Light Stability Studies 11. APQ Symposium American Association of Pharmaceutical Scientists Eighth Annual Meeting and Exposition, Nov 14-18,1993. Anderson NH, Jackson SL, Small A. Comparison of a xenon source with full spectrum fluorescent tubes for pharmaceutical product photostability. Photostability 95,1st International Meeting, Photostability of Drugs, Oslo, NO, June 8-9,1995. 

In some cases, a drug product can even be exposed to direct sunlight. Clearly, it is difficult to predict the amount of UV and VIS irradiation to which the product is exposed during the shelf life. The spectral power distribution and the overall illuminance used in a photostability study should therefore provide a "worst-case" exposure. 

In this chapter, various aspects of drug photoreactivity are presented. Common photochemical reactions by which drugs have been found to decompose are described. The influence of formulation factors, e.g., excipients, on product stability is discussed. Finally, variables that have to be considered in photostability studies are noted. 

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