chapter 1 The History of Pharmaceutical Photostability Development / chapter 2 The International Conference on Harmonization Photostability Guideline / chapter 3 Terminology / chapter 4 Basic Principles of Drug Photostability Testing / chapter 5 Spectra / chapter 6 Sources / chapter 7 Glasses, Filters, and Containers / chapter 8 Chemical Actinometry / chapter 9 Radiometry/Photometry / chapter 10 Sample Presentation for Photostability Studies: Problems and Solutions / chapter 11 Determining the Kinetics and Mechanism of a Photochemical Reaction / chapter 12 Unexpected Photochemistry in Pharmaceutical Products: A Review on the Role of Diluents, Excipients, and Product Components in Promoting Pharmaceutical Photochemistry / chapter 13 Chambers and Mapping / chapter 14 Current Methods for the Analytical Investigation of the Photodegradation of Active Pharmaceutical Ingredients and Products / chapter 15 Photostabilization by Packaging / chapter 16 Photostabilization of Solid and Semisolid Dosage Forms / chapter 17 Photostability Studies of Solutions and Methods of Preventing Photodegradation / chapter 18 Photostability of Cosmetic Sunscreens / chapter 19 Photodegradation and Photoprotection in Clinical Practice