Paxlovid
- Nirmatrelvir is an orally administered antiviral agent inhibiting
the SARS-CoV-2 3-chymotrypsin–like cysteine protease enzyme (Mpro), also
referred to as 3C-like protease or nsp5 protease, which renders the
protein incapable of processing polyprotein precursors and prevents
viral replication
- Ritonavir is a CYP3A4 inhibitor and enhances nirmatrelvir’s
bioavailability
- EPIC-HR
showed in high risk, mild-mod (non hospitalised) patients f
COVID-19–related hospitalization or death by day 28 was 89% lower in the
treatment group than in the placebo group. There were 13 deaths, all in
the placebo group.
- No eGFR <30 in the group
Prescribing
Nirmatrelvir/Ritonavir for COVID-19 in Advanced CKD
- Nirmatrelvir has a molecular mass of 499.5 D, 35% is approximately
excreted by the kidneys, and it is 70% protein bound. Ritonavir is
mostly hepatically metabolized. Thus Nirmatrelvir will accumulate.
- Adverse events reported by >1% of the participants were
dysgeusia, nausea, vomiting, headache, diarrhea, and fever. In the phase
2 study with eGFR <30 ml/min per 1.73 m2, two of eight patients (25%)
reported dysgeusia and dry mouth compared with none in the other arms
with higher kidney function
- Hemodialysis will clear a clinically insignificant amount of
nirmatrelvir(, on the basis of what is known about its molecular size,
protein binding, and volume of distribution. (prob)
Summary of CKD/HD regime from Swampnil’s
paper
NB - Drug interactions: potent CYP3A4
inhibitor and an inducer of other cytochrome p450 enzymes - If used in
Tx patients even with eGFR >60 can spike tac levels 10x. proceed very
cautiously / stop tac if used at all. - Avoid in hepatic dysfn or eGFR
<30 in tx setting.
Tx
guideance
Summary of tx guidance