Abstract

Background: Nirmatrelvir has been shown to reduce morbidity and mortality associated with COVID-19. However, it is underutilized due to concerns regarding COVID-19 symptom rebound following nirmatrelvir’s standard 5-days to 10-days course. This study aims to identify and evaluate a nirmatrelvir dosage regimen that lowers symptom rebound.

Methods: Based on nirmatrelvir pharmacokinetics, we propose a novel 8-days regimen, 2 doses twice-daily followed by 6 doses once-daily to reduce rebound frequency. We then carried out a retrospective case series study of clinical outcomes among our patients to investigate their frequency of COVID-19 symptom rebound following nirmatrelvir usage.

Results: Among the 58 prescribed case patients, 49 filled and initiated the prescription. Of those 49 patients, 4 took the medication for fewer than 5 days, 24 for 5 days and 21 for 7 days or 8 days. Among 5-day treatment cases (n=24), 8(33.3%) experienced clinical rebound, while among the 7-day or 8-day treatment cases (n=21), 2(9.5%) experienced rebound.

Conclusion: These findings suggest that a longer nirmatrelvir/ritonavir course might reduce rebound symptoms compared to the standard 5-days regimen.

Keywords: Paxlovid; COVID-19; Rebound; Nirmatrelvir