DRUG INTERACTIONS
No formal drug interaction studies have been performed with Dymista Nasal Spray. The drug interactions of the combination are expected to reflect those of the individual components.
Central Nervous System Depressants
Concurrent use of Dymista Nasal Spray with alcohol or other central nervous system depressants should be avoided because somnolence and impairment of central nervous system performance may occur [see Warnings and Precautions (5.1)].
Cytochrome P450 3A4
Ritonavir (a strong CYP3A4 inhibitor) significantly increased plasma fluticasone propionate exposure following administration of fluticasone propionate aqueous nasal spray, resulting in significantly reduced serum cortisol concentrations [see Clinical Pharmacology (12.3)]. During postmarketing use, there have been reports of clinically significant drug interactions in patients receiving fluticasone propionate and ritonavir, resulting in systemic corticosteroid effects including Cushing syndrome and adrenal suppression. Therefore, coadministration of fluticasone propionate and ritonavir is not recommended unless the potential benefit to the patient outweighs the risk of systemic corticosteroid side effects.
Ketoconazole (also a strong CYP3A4 inhibitor), administered in multiple 200 mg doses to steady-state, increased plasma exposure of fluticasone propionate, reduced plasma cortisol AUC, but had no effect on urinary excretion of cortisol, following administration of a single 1000 mcg dose of fluticasone propionate by oral inhalation route.
Caution should be exercised when Dymista Nasal Spray is coadministered with ketoconazole and other known strong CYP3A4 inhibitors.
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