It is a small, synthetic, azabicyclic molecule (Figure S4) that exhibits antiretroviral activity by blocking the interaction between HIV-1 glycoprotein 120 and chemokine receptor 5 (C-C motif receptor 5), on human CD4-presenting cells, that is necessary for HIV-1 to enter cells [116]. The drug was approved by the U.S. FDA in 2007 as an oral treatment for HIV-1. The drug is currently being evaluated in three clinical trials (NCT04441385, NCT04435522, and NCT04475991) for COVID-19 treatment. Recently, it was shown that maraviroc may act as a potential inhibitor of Mpro [117]. However, it appears that it is more realistic to assume that the drug is a viral entry inhibitor and potentially acts by blocking the interaction between the viral spike S protein and the host ACE2 receptor [118].