The pMDIs employing hydrofluoroalkane (HFA) propellants might be a suitable choice to formulate micronized versions of both lipophilic and hydrophilic therapeutic compounds, thus offering an edge over the nebulizer formulations that are typically suitable for hydrophilic drugs. The other important advantage the pMDI-HFA dosage forms can offer is a completely excipient free treatment, mainly because most of the emitted HFA propellant(s) would completely evaporate upon actuation of the inhaler owing to their very low boiling point. Such an excipient free treatment can be said to negate any excipient related exacerbations on the clinical outcomes mainly because the effect of commonly used excipients in inhalation product development on the SARS-CoV-2 proliferation and inflammation needs to completely investigated. Especially, in the case of DPIs that can use significant amounts of lactose as drug carriers the effect of lactose as an energy source to the viral proliferation may need to be investigated before making a final conclusion. Similarly, in the case of nebulizer formulations the different buffering agents and preservatives added to the formulation might need to be investigated for their effect on viral proliferation and inflammation.
