A method for estimating the risk of drug-induced phototoxicity and its application to smoothened inhibitors

The energy difference between the frontier-orbital HOMO–LUMO gaps calculated for the ground state of marketed oral drugs correlated with their observed phototoxicity. This molecular descriptor, together with their maximal molar absorptivity for UV light above 290 nm, can be used to predict phototoxicity risks. This is demonstrated for the phototoxicity mitigation of 1-piperazinyl phthalazines, a class of smoothened inhibitors.