This small observational study found trough concentration in critically ill patients was much lower than that of healthy subjects in a previous clinical trial. This is cause for further pharmacokinetic research regarding optimal dosage and formulation for critically ill patients.
- The patients were administered 1600 mg of facipiravir twice daily on Day 1, followed by 600 mg twice daily from Day 2 to Day 5 (or more if needed). Trough levels were obtained
The clinical status after starting facipiravir was evaluated on Day 1–5, Day 7, and Day 14 by a seven-category ordinal scale
- Seven patients were enrolled in this study. Forty‐nine blood samples were obtained these patients for the study
Although some improvement was observed in three patients with COVID-19 by Day 14, it is unclear how facipiravir influenced this improvement. (Sample size was very limited)
- The facipiravir trough (after 8–12 h) concentrations of most samples (multiple samples for 5 of the 7 patients) were lower than the lower limit of quantification (1 µg/mL) and EC50 (9.7 µg/mL) against SARS‐CoV‐2 previously tested in vitro .