Interaction entre Ritonavir et Venlafaxine

Therefore, the potential exists for a drug interaction between drugs that inhibit CYP2D6-mediated metabolism of venlafaxine, reducing the metabolism of venlafaxine to ODV, resulting in increased plasma concentrations of venlafaxine and decreased concentrations of the active metabolite.

Concomitant use of CYP3A4 inhibitors and venlafaxine may increase levels of venlafaxine and ODV.

Therefore, caution is advised if a patient’s therapy includes a CYP3A4 inhibitor and venlafaxine concomitantly.

Drugs that Inhibit Cytochrome P450 Isoenzymes CYP2D6 Inhibitors: In vitro and in vivo studies indicate that venlafaxine is metabolized to its active metabolite, ODV, by CYP2D6, the isoenzyme that is responsible for the genetic polymorphism seen in the metabolism of many antidepressants.

CYP2D6 inhibitors such as quinidine would be expected to do this, but the effect would be similar to what is seen in patients who are genetically CYP2D6 poor metabolizers [see Clinical Pharmacology ( 12.3 )] .

Antidepressants: nefazodone, selective serotonin reuptake inhibitors (SSRIs): e.g. fluoxetine, paroxetine, tricyclics: e.g. amitriptyline, nortriptyline ↑ antidepressants A dose decrease may be needed for these drugs when co-administered with ritonavir.

Antidepressant: bupropion ↓ bupropion ↓ active metabolite, hydroxybupropion Patients receiving ritonavir and bupropion concurrently should be monitored for an adequate clinical response to bupropion.

Antidepressant: desipramine ↑ desipramine Dosage reduction and concentration monitoring of desipramine is recommended.

Antidepressant: trazodone ↑ trazodone Adverse events of nausea, dizziness, hypotension and syncope have been observed following co-administration of trazodone and NORVIR.