Antagonistic effect w/ opioid-containing medicinal products. Bupropion: Enhanced catecholaminergic pathways w/ MAOIs. Reduced exposure w/ CYP2B6 inducers (eg, carbamazepine, phenytoin, ritonavir, efavirenz). Increased bupropion levels & lowered levels of its active metabolite w/ CYP2B6 substrates (eg, cyclophosphamide, ifosfamide) & CYP2B6 inhibitors (eg, orphenadrine, ticlopidine, clopidogrel); medicinal products that inhibit metabolism (eg, valproate). May affect medicinal products metabolised by CYP2D6 including antidepressants (SSRIs & TCAs, eg, desipramine, imipramine, paroxetine), antipsychotics (eg, haloperidol, risperidone & thioridazine), β-blockers (eg, metoprolol) & Type 1C antiarrhythmics (eg, propafenone & flecainide). Higher incidence of AR (eg, nausea, vomiting & neuropsychiatric AR) w/ levodopa or amantadine. Naltrexone: Altered exposure w/ UGT 1A2 & 2B7 inhibitors or inducers.