Scheme 4.11 Photodegradation of ketoprofen.

Photodegradation of ketoprofen by decarboxylation (reaction 1) and subsequent reduction (reaction 2), and also by dimerisation of the ketoprofen (reaction 3).

Reproduced from H. H. T0nnesen, Int. J. Pharm., 225, 1 (2001).

protected from photoinduced decomposition by the use of coloured glass containers and storage in the dark. Amber glass excludes light of wavelength <470 nm and so affords considerable protection of compounds sensitive to ultraviolet light. Coating tablets with a polymer film containing ultraviolet absorbers has been suggested as an additional method for protection from light. In this respect, a film coating of vinyl acetate containing oxyben-zone as an ultraviolet absorber has been shown11 to be effective in minimising the discoloration and photolytic degradation of sulfasomidine tablets.

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