Pharmacokinetics of Enteral Lormetazepam in Mechanically Ventilated ICU Patients with COVID-19: An Adjunct Sedative Study

During the coronavirus disease 2019 (COVID-19) pandemic, sedative prescriptions surged, leading to shortages of midazolam. This study investigates lormetazepam as an adjunct sedative alternative to midazolam for mechanically ventilated patients with COVID-19. We aimed to determine the clinical pharmacokinetics (PK) of enterally administered lormetazepam and provide dosing recommendations.

Critically ill patients with acute respiratory distress syndrome (ARDS) or COVID-19 requiring mechanical ventilation were enrolled in April 2020. Lormetazepam 2 mg every 12 h was administered enterally. Blood samples were collected to quantify lormetazepam and its glucuronide. PK analysis was conducted using a one-compartment model with the Edsim++ KinPop plugin.

The primary PK parameters (means ± coefficient of variation [CV] %) for absorption constant (K_a), volume of distribution (V_d/F), and clearance (CL/F) were 6.4 h⁻¹, 207 L/70 kg, and 14.5 L/h/kg^0.75, respectively. V_d/F and CL/F median values were 2.64 L/kg and 2.53 mL/kg/min, respectively, with a half-life of 10.7 h. Lormetazepam’s median ratio to its glucuronide was 11.5. Trough-guided dosing suggested alternatives of 0.92 mg three times daily, 1.62 mg twice daily, or 5.36 mg once daily.

This is the first study to report a validated PK model for enterally administered lormetazepam as a sedative adjunct in critically ill adults on mechanical ventilation for ARDS and COVID-19. The model was internally validated using a bootstrap procedure. Adequate lormetazepam concentrations were achieved at prescribed doses, with no significant alterations in clearance or half-life. This population model may aid in dose optimization and sedation management for future intensive care unit (ICU) patients.