Last modified: 2019-06-15
Abstract
Background: Drug-induced phototoxicity is an unfavorable skin reaction, and development of reliable screening strategy has been required.
Objective: This study aimed to establish a photosafety testing with use of a reactive oxygen species (ROS) assay and in vitro skin permeation test using Strat-M®, an artificial membrane.
Materials and Methods: Acridine (ACD), furosemide (FSM), hexachlorophene (HCP), 8-methoxypsoralen (MOP), norfloxacin (NFX), and promethazine (PMZ) were selected as test compounds, and the ROS assay was undertaken to evaluate photoreactivity of test compounds. To calculate steady-state concentration (Css), the in vitro skin permeation test was conducted on test compounds (1 mg/mL) using intact and methanol pre-treated Strat-M®.
Results: All tested compounds generated significant ROS under exposure to simulated sunlight, and the photoreactivity of ACD and HCP were higher than those for other 4 compounds. The Css values of ACD, FSM, HCP, MOP, NFX, and PMZ were calculated to be 23.4, 19.6, 20.5, 9.4, 5.9, and 38.1 mg/mL, respectively. The order of Css values in the Strat-M® was mostly in agreement with that in the dissected rat skin, suggesting the applicability of the in vitro skin permeation test with use of the Strat-M® as an alternative methodology. Based on both ROS and Css data of test compounds, the phototoxic risk was ranked as follows: ACD＞HCP＞PMZ＞FSM＞MOP＞NFX. The predicted phototoxic risk by the proposed screening system relatively corresponded to observed in vivo phototoxicity based on the colorimetrical changes in the rat skin (ACD≒HCP＞PMZ＞MOP＞FSM＞NFX).
Conclusion: The photosafety assessment, consisting of the ROS assay and in vitro skin permeation test using artificial membranes, would contribute to implementation of animal welfare and reliable photosafety prediction.