- Subjects unable to stop medication within 48 prior the study begins that alters serotonin blood profiles , including paracetamol, cumarine, mephenesin, phenobarbital, acetanilide, ephedrine, amphetamine, phentolamin, phenacetin, methocarbamol, acetylsalicylic acid, levodopa, promethazine, isoniazid, methenamine, streptozocin, chlorpromazine