Table 4.

The anticipated inhaled dose of some widely used anti-SARS-CoV-2 agents considering the reported in vitro half-maximal inhibitory concentration (IC₅₀) against SARS-CoV-2 (Austin and Okour, 2020; Sheahan et al., 2020, Li et al., 2022).

Drug Name	IC50 (μM)	IC50 (μg/mL)	Anticipated inhaled dose (μg)*
Nirmatrelvir**	0.18	0.1	2.5–10
Niclosamide	0.28	0.1	2.5–10
Molnupiravir	0.30	0.1	2.5–10
Hydroxychloroquine	0.72	0.2	5–20
Remdesivir	0.77	0.5	12.5–50
Nitazoxanide	2.12	0.7	17.5–70
Ivermectin	2.48	2.2	55–220
Nafamostat	22.5	7.8	195–780
Favipiravir	61.88	9.7	242.5–970
Penciclovir	95.96	24.3	607.5–2430
Ribavirin	109.5	26.7	667.5–2670
*Considering total alveolar fluid of 20 mL, 20–80% of drug deposition and 50% SARS-CoV-2 inhibition in the lung ** Nirmatrelvir is the main component of Paxlovid. In Paxlovid, nirmatrelvir is co-packaged with ritonavir.