In vitro enzymatiske forsøg med humane levermikrosomer viste, at arsentrioxid ikke har nogen hæmmende virkning på substrater for de centrale cytochrom P450- enzymer såsom 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4/ 5, 4A9/ 11.
In vitro enzymatic studies with human liver microsomes revealed that arsenic trioxide has no inhibitory activity on substrates of the major cytochrome P450 enzymes such as 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4/ 5, 4A9/ 11.