Niclosamide Inhalation Powder Made by Thin-Film Freezing: Pharmacokinetic and Toxicology Studies in Rats and Hamsters (preprint)

In this work, we have developed and tested in vivo a dry powder form of niclosamide made by thin-film freezing (TFF) and administered it by inhalation to rats and hamsters. The niclosamide dry powder, suitable for inhalation, is being developed as a therapeutic agent against COVID-19 infection. Niclosamide, a poorly water-soluble drug, is an interesting drug candidate because it was approved over 60 years ago for use as an anthelmintic medication, but recent studies demonstrated its potential as a broad-spectrum antiviral with a specific pharmacological effect against SARS-CoV-2 infection. In the past, clinical trials for other indications were terminated prior to completion due to low and highly variable oral bioavailability. In order to quickly address the current pandemic, targeting niclosamide directly to the lungs is rational to address the COVID-19 main clinical complications. Thin-film freezing technology was used to develop a niclosamide inhalation powder composition that exhibited acceptable aerosol performance with a fine particle fraction (FPF) of 86.0% and a mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of 1.11 μm and 2.84, respectively. This formulation not only proved to be safe after an acute three-day, multi-dose pharmacokinetic study in rats as evidenced by histopathology analysis, but also was able to achieve lung concentrations above the required IC 50 and IC 90 levels for at least 24 h after a single administration in a Syrian hamster model. To conclude, we successfully developed a niclosamide dry powder inhalation formulation by thin-film freezing for further scale-up and clinical testing against the COVID-19 infection. This approach overcomes niclosamide’s limitation of poor oral bioavailability by targeting the drug directly to the primary site of infection, the lungs.

In Vivo Pharmacokinetic Study of Remdesivir Dry Powder for Inhalation in Hamsters (preprint)

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 GS441524 (in human epithelial cells) over 20 hours. The half life of GS4412524 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 Cmax with shorter Tmax and lower AUC of GS441524, 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.