- Subject is taking or has taken within the last two weeks of dosing monoamine oxidase inhibitors, antidepressants, atropine, beta-blocking or sympathomimetic drugs desferrioxamine, hepatotoxic drugs, drugs inducing liver microsomal enzyme, (such as phenytoin, carbamazepine, isoniazid and rifampicin), neuroleptic drugs, chlorzoxazone, CNS depressant drugs including barbiturates, hypnotics, opioid analgesics, anxiolytic sedatives, antipsychotics or is anticipated to require any of these medications at any time throughout the study