Lopinavir (Figure 6) is an orally bioavailable, small peptidomimetic antiretroviral agent that acts as an HIV-1 aspartate competitive inhibitor [83]. The drug inhibits the cleavage of viral Gag-Pol polyprotein precursors into individual functional proteins required for infectious HIV. The inhibition eventually results in the formation of immature, noninfectious viral particles. The drug was approved by the U.S. FDA in combination with ritonavir (Figure 6), which is another antiretroviral aspartate protease inhibitor. Ritonavir does not only provide an additive effective, but it is also a pharmacokinetic booster, i.e., it inhibits the CYP3A-mediated metabolism of lopinavir and thus increases its plasma level [83,84]. Currently, lopinavir/ritonavir is being evaluated for the treatment of SARS-CoV-2 patients in more than 35 interventional trials alone or in conjugation with hydroxychloroquine, inhaled INF-α, INF-β 1b and hydroxychloroquine, or oseltamivir (an inhibitor of neuraminidase in influenza virus) (for details refer to clinicaltrials.gov).