PHOTODEGRADATION OF PHARMACEUTICALS STUDIED WITH UV IRRADIATION AND DIFFERENTIAL SCANNING CALORIMETRY

Kevin Menard, Witold Brostow, Noah Menard
2011 CHEMISTRY & CHEMICAL TECHNOLOGY   unpublished
Given rapidly increasing concerns about photodegradation of pharmaceuticals, we have applied accurate methods to quantitatively evaluate the drug photostability. The drugs studied were nifedrine, acetylsalicylic acid, acetaminophen, cetirizine, and pantoprazole. UV energy striking a target has been determined by using graphite. Runs were performed by placing each sample in a pan with a quartz lid and exposing it to ultraviolet (UV) light for periods of time ranging from 1 to 120 seconds.
more » ... 120 seconds. Percentage decomposition as a function of time has been determined for each pharmaceutical. Fast differential scanning calorimetry (DSC) in situ was used to evaluate changes in thermophysical behavior of the drugs and possible formation of new phases. The UV degradation rates so determined cover a very wide range, from 0.1 to 20.0 %/s. Factors affecting the photodegradability are discussed.
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