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Bringing the Light to Photostability in Three Parts - Part Two

Part II: Forced Degradation Studies to Support Photostability  

In Part One of this photostability blog series, a high level review on the background of photostability was presented.  In this second part, work leading up to the execution of a photostability study on Active Pharmaceutical Ingredient (API) and pharmaceutical products will be discussed. 

Prior to execution of a photostability study, the analytical test procedures (TP) must demonstrate the ability to detect degradants caused by photolysis (photodegradation).  Not all compounds are susceptible to photolysis; a molecule must absorb the UV or visible light energy to be susceptible to this phenomenon.  For example, if the absorption spectrum of a molecule has a maximum of ~254 nm and with minimal or no absorption above 300 nm, this molecule would not be susceptible to photodegradation during an ICH photostability study as the lowest wavelength of exposure is ~320 nm. 

Topics: Stability Blogs

Bringing the Light to Photostability in Three Parts

Part 1: Basic Requirements – Setting the Stage

ICH Guidance Q1B was published in 1996 describing a harmonized approach to photostability studies.  Although it has been 20+ years since its publishing, questions still arise on how to execute a photostability study and how to interpret the results.  In this blog series, I will address common questions and detail how a photostability study is executed.  At Alcami, photostability is conducted at three laboratory sites: Wilmington, NC; Edison, NJ; and St. Louis, MO.

A photostability study is performed using either a full spectrum light source that produces a spectrum similar to D65/ID65 emission standard, or two separate light sources: one for near UV radiation with a spectral distribution from 320 nm to 400 nm with a maximum energy emission between 350 nm and 370 nm, and a second light source that is a cool white fluorescent lamp designed to produce an output similar to that specified in ISO 10977.  Regardless of which approach is taken, the objective is to expose samples to an integrated amount of NLT 200 Watt·hrs/m2 of near-ultraviolet energy and NLT 1.2 million lux·hours of visible light. 

Topics: Stability Blogs