Posterior Reversible Encephalopathy Syndrome in an Older Patient in the COVID-19 and Paxlovid Era

Nirmatrelvir/ritonavir (Paxlovid) has been prescribed increasingly for treatment of COVID-19. Due to ritonavir’s inhibition of CYP3A4, there are many medication interactions to consider. In this case, a 63-year-old woman recently treated with Paxlovid presented with symptoms mimicking previous episodes of lupus cerebritis. Imaging, however, revealed a pattern more consistent with posterior reversible encephalopathy syndrome. When Paxlovid therapy was initiated in the ambulatory setting, her amlodipine dose was decreased due to concern for interactions. Since Paxlovid is recommended for patients with high risk for progression to severe illness, this poses a unique challenge, especially in older patients with multiple comorbid conditions.