Environmental photodegradation of mefenamic acid

Area of Science:

• Environmental Chemistry
• Photochemistry
• Pharmaceutical Pollution

Background:

• Pharmaceuticals and personal care products (PPCPs) are emerging environmental pollutants.
• Photolysis is a key degradation pathway for PPCPs in surface waters.
• Mefenamic acid (MEF) is a widely used non-steroidal anti-inflammatory drug (NSAID).

Purpose of the Study:

• To investigate the direct photolysis and photosensitization of mefenamic acid in aquatic environments.
• To elucidate the mechanisms of photosensitization involving dissolved organic matter.
• To assess the environmental persistence of mefenamic acid.

Main Methods:

• Direct photolysis quantum yield measurements.
• Photosensitization experiments using natural waters and model photosensitizers (fulvic acid, acetophenones, perinaphthenone).
• Quenching, sparging, and light-filtering techniques to identify reaction pathways.

Main Results:

• Direct photolysis quantum yield of mefenamic acid was low (1.5+/-0.3x10(-4)).
• Significant photosensitization was observed with dissolved organic matter and model sensitizers.
• Evidence suggests reaction with excited triplet-state dissolved organic matter is the primary photosensitization mechanism.

Conclusions:

• Mefenamic acid photodegradation in natural waters is influenced by both direct photolysis and indirect photosensitization.
• The persistence of mefenamic acid is controlled by a combination of these processes.
• Understanding these pathways is crucial for assessing the environmental fate of NSAIDs.