Liverpool COVID-19 Interactions

No Interaction Expected

Nirmatrelvir/ritonavir (5 days)

Fulvestrant

Quality of Evidence: Very Low

Summary:

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. The metabolism of fulvestrant has not been fully evaluated: in vitro studies suggest the involvement of CYP3A4, however, non-P450 routes appear to be more predominant in vivo. Clinical interaction studies with ketoconazole (an inhibitor of CYP3A4) showed no clinically relevant effect on fulvestrant and no dose adjustment is necessary with CYP3A4 inhibitors, such as nirmatrelvir/ritonavir.

Description:

(See Summary)