Darunavir and Nefazodone interaction

Co-administration of darunavir and ritonavir and other drugs that inhibit CYP3A, or P-gp may decrease the clearance of darunavir and ritonavir and may result in increased plasma concentrations of darunavir and ritonavir (see Table 10 ).

Antidepressants : Selective Serotonin Reuptake Inhibitors (SSRIs): paroxetine, sertraline ↓ paroxetine ↓ sertraline If either sertraline or paroxetine is initiated in patients receiving PREZISTA/ritonavir, dose titrating the SSRI based on a clinical assessment of antidepressant response is recommended.

Monitor for antidepressant response in patients on a stable dose of sertraline or paroxetine who start treatment with PREZISTA/ritonavir.

Tricyclic Antidepressants (TCAs): amitriptyline, desipramine, imipramine, nortriptyline ↑ amitriptyline ↑ desipramine ↑ imipramine ↑ nortriptyline Use a lower dose of the tricyclic antidepressants and trazodone due to potential increased adverse events such as nausea, dizziness, hypotension and syncope.

…Astemizole, Cisapride, and Pimozide Interactions Terfenadine, astemizole, cisapride, and pimozide are all metabolized by the cytochrome P450 3A4 (CYP3A4) isozyme, and it has been demonstrated that ketoconazole, erythromycin, and other inhibitors of CYP3A4 can block the metabolism of these drugs, which can result in increased plasma concentrations of parent drug.

…nefazodone and its major metabolites are not altered in these “poor metabolizers.” Plasma concentrations of one minor metabolite (mCPP) are increased in this population; the adjustment of nefazodone dosage is not required when administered to “poor metabolizers.” Nefazodone and its metabolites have been shown in vitro to be extremely weak inhibitors of CYP2D6.