Liverpool COVID-19 Interactions

No Interaction Expected

Nirmatrelvir/ritonavir (5 days)

Conjugated estrogens (HRT)

Quality of Evidence: Very Low

Summary:

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Metabolism of conjugated estrogens is complex and involves CYP3A4, CYP1A2 and glucuronidation. Nirmatrelvir/ritonavir is metabolized by CYP3A. Nirmatrelvir/ritonavir is a strong inhibitor of CYP3A4 and may increase the exposure of conjugated estrogens. However, no action is needed given the short duration of nirmatrelvir/ritonavir treatment.

Description:

(See Summary)