Preparation and Characterization of Inhalable Ivermectin Powders as a Potential COVID-19 Therapy.

Background: Ivermectin has received worldwide attention as a potential COVID-19 treatment after showing antiviral activity against SARS-CoV-2 in vitro. However, the pharmacokinetic limitations associated with oral administration have been postulated as limiting factors to its bioavailability and efficacy. These limitations can be overcome by targeted delivery to the lungs. In this study, inhalable dry powders of ivermectin and lactose crystals were prepared and characterized for the potential treatment of COVID-19. Methods: Ivermectin was co-spray dried with lactose monohydrate crystals and conditioned by storage at two different relative humidity points (43% and 58% RH) for a week. The in vitro dispersion performance of the stored powders was examined using a medium-high resistance Osmohaler connecting to a next-generation impactor at 60 L/min flow rate. The solid-state characteristics including particle size distribution and morphology, crystallinity, and moisture sorption profiles of raw and spray-dried ivermectin samples were assessed by laser diffraction, scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption. Results: All the freshly spray-dried formulation (T0) and the conditioned samples could achieve the anticipated therapeutic dose with fine particle dose of 300 µg, FPF_recovered of 70%, and FPF_emitted of 83%. In addition, the formulations showed a similar volume median diameter of 4.3 µm and span of 1.9. The spray-dried formulations were stable even after conditioning and exposing to different RH points as ivermectin remained amorphous with predominantly crystalline lactose. Conclusion: An inhalable and stable dry powder of ivermectin and lactose crystals was successfully formulated. This powder inhaler ivermectin candidate therapy appears to be able to deliver doses that could be safe and effective to treat the SARS-COV-2 infection. Further development of this therapy is warranted.

Pharmacokinetics and safety of inhaled ivermectin in mice as a potential COVID-19 treatment.

Pharmacokinetic limitations associated with oral ivermectin may limit its success as a potential COVID-19 treatment based on in vitro experiments which demonstrate antiviral efficacy against SARS-CoV-2 at high concentrations. Targeted delivery to the lungs is a practical way to overcome these limitations and ensure the presence of a therapeutic concentration of the drug in a clinically critical site of viral pathology. In this study, the pharmacokinetics (PK) and safety of inhaled dry powders of ivermectin with lactose were investigated in healthy mice. Female BALB/c mice received ivermectin formulation by intratracheal administration at high (3.15 mg/kg) or low doses (2.04 mg/kg). Plasma, bronchoalveolar lavage fluid (BALF), lung, kidney, liver, and spleen were collected at predetermined time points up to 48 h and analyzed for PK. Histological evaluation of lungs was used to examine the safety of the formulation. Inhalation delivery of ivermectin formulation showed improved pharmacokinetic performance as it avoided protein binding encountered in systemic delivery and maintained a high exposure above the in vitro antiviral concentration in the respiratory tract for at least 24 h. The local toxicity was mild with less than 20% of the lung showing histological damage at 24 h, which resolved to 10% by 48 h.