In vitro studies in human liver microsomes showed that risperidone at clinically relevant concentration does not substantially inhibit the metabolism of medicines metabolised by cytochrome P450 isozymes, including CYP 1A2, CYP 2A6, CYP 2C8/ 9/ 10, CYP 2D6, CYP 2E1, CYP 3A4, and CYP 3A5.