Venlafaxine quinidine

D6 Tricyclic antidepressants (TCAs), benztropine, perphenazine, clozapine, haloperidol, codeine/oxycodone, risperidone, class Ic antiarrhythmics, 3 blockers, trazodone, paroxetine, maprotiline, amoxapine, duloxetine, mirtazapine (partly), venlafaxine, bupropion Fluoxetine, paroxetine, duloxetine, hydroxybupropion, methadone, cimetidine, haloperidol, quinidine, ritonavir Phenobarbital, rifampin... 

Administration of the CYP2D6 inhibitor quinidine, 200 mg/day for 2 days, to the extensive metabolizers reduced the oral clearance of venlafaxine to the level seen in poor metabolizers. Quinidine had no effect on venlafaxine clearance in subjects who were poor metabolizers before treatment. The authors suggested that poor metabolizers may be at particular risk of venlafaxine toxicity, as could subjects who take inhibitors of CYP2D6. 

Pseudobulbar affect SSRI antidepressants 20-100 mg QD Tricyclic antidepressants 20-100 mg QHS Mirtazapine 15-30 mg QHS Venlafaxine 37.5-75 mg BID-TID Dextromethorphan/quinidine 30mg/30mg BID Lithium carbonate 300 mg QD-TID... 

Ajmaline, ajamlicine, flecainide, fluoxetine, isoniazid, ketoconazole, lobeline, nefazodone, paroxetine, (7 )-propaphenooe, quinidine, ritonavir, "statins," yohimbine, venlafaxine... 

The potency of sertraline and its N-demethylated metabolite, desmethylsertraline, and paroxetine for inhibiting P-gp was comparable with that of quinidine (35). Fluoxetine, norfluoxetine, fluvoxamine, reboxetine, and 0-demethylparoxetine showed intermediate inhibition, and citalopram, desmethylcitalopram, venlafaxine, and N-desmethylvenlafaxine showed only weak inhibition. No inhibition was found for 0-desmethylvenlafaxine. 

Theoretically the metabolism of venlafaxine may be inhibited by CYP2D6 inhibitors or substrates such as diphenhydramine, melperone, quinidine or thioridazine. CYP3A4 inhibitors such as ketoconazole may also have some effect. An isolated case describes a hypertensive crisis associated with venlafaxine and di-sulfiram. The manufacturers predict that the use of triptans with venlafaxine may have additive effects on serotonin, which could lead to the serotonin syndrome. 

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