Stability chambers photostability

Figure 24 PSC062 Pharma-Safe". (A) Stability test chamber, photostability model (B) custom built walk-in unit (C) exposure equilization filter. Source. Courtesy of Weirs Gallenkarmup.

Boxhammer J. Design and validation characteristics of environmental chambers for photostability chambers. Photostability A 1997 Update—Scientific, Regulatory and Practical Issues, AAl 1997 Seminar Series, Arlington, VA, Feb 24-25, 1997. Boxhammer J. Technical requirements and equipment for photostability testing. In Tonnesen HH, ed. Photochemical Stability of Drugs and Drug Formulations. London, UK Taylor Francis, 1996 39-61. 

Chapter 14 introduces stability chambers. It also discusses factors to be considered for chamber validation, calibration, and maintenance. This chapter also elaborates on ICH QIB guideline, which established the requirements for photostability condition. 

Changes in physicochemical properties of the drug substance (e.g., color, crystal modification) may take place upon irradiation. Efforts should be made to observe such changes during the in vitro assay. The sample absorption spectrum should be recorded before and after irradiation surface color of solid samples should be evaluated by appropriate methods and the identity of the sample crystal modification should be confirmed when the drug is irradiated in the solid state. The humidity in the test chamber can influence the photochemical stability of certain solid samples, as demonstrated for mefloquine. The photoinduced yellowing of uncoated mefloquine tablets is accelerated by an increase in humidity. These tablets are mainly used in tropical countries and the real in-use conditions will include high relative humidity. In such cases, the influence of the humidity on the photostability must be taken into account (Tpnnesen et al., 1997). 

---