Elevated tacrolimus blood concentration due to the interaction with
nirmatrelvir/ritonavir during COVID-19 treatment: a case report.
Abstract
Nirmatrelvir/ritonavir, a newly authorized drug for the treatment of
COVID-19, is a strong CYP3A4 inhibitor, which can interact with a large
number of drugs, such as tacrolimus, reducing its metabolism. The
reported case is a renal transplant patient who experienced a strong
increase in tacrolimus blood concentration (up to 112ng/ml, more than
ten times the reference range) when treated with both drugs at the same
time, which caused a neurological condition that required hospital
admission its control and treatment. The resolution of the symptoms was
rapid, but the elevation of tacrolimus concentration remained for
several days, even after discontinuation of both drugs. This study shows
the importance of developing a protocol for the management of this
interaction to guarantee the efficacy and safety of treatment with
nirmatrelvir/ritonavir in transplant patients.