Based on theoretical considerations darunavir/cobicistat is expected to increase budesonide plasma concentrations. (CYP3A inhibition). Concomitant use of darunavir/cobicistat and corticosteroids (all routes of administration) that are metabolised by CYP3A may increase the risk of development of systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression. Co-administration with CYP3A-metabolised corticosteroids is not recommended unless the potential benefit to the patient outweighs the risk, in which case patients should be monitored for systemic corticosteroid effects. Alternative corticosteroids which are less dependent on CYP3A metabolism e.g. beclomethasone should be considered, particularly for long term use.

Coadministration is expected to decrease concentrations of darunavir and cobicistat and to increase concentrations of budesonide. Co-administration with systemic corticosteroids that induce CYP3A may result in loss of therapeutic effect and development of resistance to darunavir/cobicistat. Consider alternative 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 suppression. Alternative corticosteroids including beclomethasone 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.