Clozapine and nirmatrelvir/ritonavir coadministration without apparent interaction in a patient with mild COVID-19 infection: A case with review of other clozapine-related CYP3A4 interactions

Although there are hypothetical concerns when initiating a CYP3A4 inhibitor with concomitant clozapine, the information derived from this case does not clearly support an interaction with the addition of nirmatrelvir/ritonavir during mild COVID-19 infection. It is important to understand the risks of withholding clozapine, although fortunately no psychiatric concerns developed. In reviewing the literature, CYP3A4 inhibitors or genetic polymorphisms seem to have a minimal impact on clozapine levels, although clinical monitoring is warranted.