Photodegradation and photosensitization in pharmaceutical products:
Assessing drug phototoxicity
G. Cosa
Department of Chemistry and Biochemistry, University
of Texas at Austin, Austin, TX 78712, USA
Abstract: Toxic reactants are a common result of the interaction
of sunlight with pharmaceutical agents transported in the blood system
or applied topically. Over the past decade there has been a considerable
amount of research toward understanding both the unimolecular deactivation
pathway of photoexcited pharmaceutical products and their photosensitizing
capability in the presence of biological substrates. This work summarizes
recent developments in the study of the photodegradation mechanism of
ketoprofen, fenofibric acid, and tiaprofenic acid. An analysis of excited-state
electronic energy levels, the type of intermediates formed following
excitation, and transient intermediate lifetimes is presented. The analysis
involves both parent drugs and their major photoproducts. Phototoxicity,
usually the result of adverse photochemical reactions following direct
photoexcitation of the drugs, is shown to be strongly related to the
photoexcitation of photoproducts when high radiation dose conditions
prevail. The photoproducts are the species directly involved in photosensitizing
reactions.
[full text - pdf 261KB]
*Pure Appl. Chem. 76,
263-319 (2004). A collection of invited, peer-reviewed articles
by the winners of the 2003 IUPAC Prize for Young Chemists.
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