Darunavir and Deflazacort interaction

Moderate or strong CYP3A4 inhibitors: Give one third of the recommended dosage of EMFLAZA ( 7.1 )

Co-administration of deflazacort with clarithromycin, a strong CYP3A4 inhibitor, increased total exposure to 21-desDFZ by about 3-fold.

Therefore, give one third the recommended dosage of EMFLAZA when moderate or strong CYP3A4 inhibitors (e.g., clarithromycin, fluconazole, diltiazem, verapamil, grapefruit juice) are used concomitantly with EMFLAZA [see Dosage and Administration ( 2.5 ) and Clinical Pharmacology ( 12.3 )] .

CYP3A4 Inhibitors and Inducers Moderate or Strong CYP3A4 Inhibitors The active metabolite of deflazacort, 21-desDFZ, is a substrate of CYP3A4 [see Clinical Pharmacology ( 12.3 )] .

Corticosteroids: dexamethasone (systemic) ↓ darunavir Co-administration of PREZISTA/ritonavir with systemic dexamethasone or other systemic corticosteroids that induce CYP3A may result in loss of therapeutic effect and development of resistance to darunavir.

Consider alternative corticosteroids.

Corticosteroids primarily metabolized by CYP3A: e.g. betamethasone budesonide ciclesonide fluticasone methylprednisolone mometasone triamcinolone ↑ corticosteroids Co-administration with corticosteroids (all routes of administration) of which exposures are significantly increased by strong CYP3A inhibitors can increase the risk for Cushing's syndrome and adrenal…

Alternative corticosteroids including beclomethasone, prednisone, and prednisolone (for which PK and/or PD are less affected by strong CYP3A inhibitors relative to other steroids) should be considered, particularly for long term use.