InVivoPharmacokinetic Study of Remdesivir Dry Powder for Inhalation in Hamsters

Remdesivir dry powder for inhalation was previously developed using thin film freezing (TFF). A single-dose 24-hour pharmacokinetic study in hamsters, a small animal model for SARS-CoV-2, demonstrated that pulmonary delivery of TFF remdesivir can achieve plasma remdesivir and GS-441524 levels higher than the reported EC₅₀s of both remdesivir and GS-441524 (in human epithelial cells) over 20 hours. The half-life of GS-4412524 following dry powder insufflation was about 7 hours, suggesting the dosing regimen would be twice daily administration. Although the remdesivir-Captisol^®(80/20 w/w) formulation showed faster and greater absorption of remdesivir and GS-4412524 in the lung, remdesivir-leucine (80/20 w/w) exhibited a greater C_maxwith shorter T_maxand lower AUC of GS-441524, indicating lower total drug exposure is required to achieve a high effective concentration against SAR-CoV-2. In conclusion, remdesivir dry powder for inhalation would be a promising alternative dosage form for the treatment of COVID-19 disease.