Photosensitizing Properties of the Topical Retinoid Drug Adapalene.

Photoreactivity is an important issue for topical drugs especially when these are applied on the sun-exposed skin area. In this context, third-generation retinoids are of special interest due to their conjugated chemical structure and their use in the treatment of acne. Herein, the phototoxic potential of one of these drugs, adapalene, is established using an in vitro 3T3 Neutral Red Uptake (NRU) test.

Environmentally sensitive fluorescence of the topical retinoid adapalene.

Intrinsic fluorescence of drugs brings valuable information on their localization in the organism and their interaction with key biomolecules. In this work, we investigate the absorption and emission properties of the topical retinoid adapalene in different solvents and biological media. While the UVA/UVB absorption band does not exhibit any significant solvent-dependent behavior, a strong positive solvatochromism is observed for the emission.