- Subjects who have received any prescribed and non-prescribed systemic or topical medication like analgesics, NSAIDs (except standard dose of a NSAID once a week for the treatment of headache), hypnotics, sedatives, narcotics, neuroleptics or other medications that may lower the seizure threshold, MAO-inhibitors, serotonin-reuptake-inhibitors, tricyclic antidepressants, other centrally acting substances and substances which are known to interact with the drug metabolizing enzymes (e.g., inhibitors or inducers of CYP3A4 or CYP2D6) four weeks prior to the start of the trial (i.e, first administration of IMP). Each case has to be decided upon individually by the investigator after consultation with the sponsor