- must not be taking any of the following medications or substances within a minimum of 30 days: nicotine, any form; CYP2A6 inducers or inhibitors during the course of the study or within 30 days of the planned initial dose (your investigator will have a full list of these drugs); Monoamine oxidase inhibitors (with the exception of rasagiline, which is allowed)(your investigator will have a full list of these drugs); apokyn (apomorphine), due to its contraindication with ondansetron); warfarin.