Ramelteon metabolite M-II is the primary metabolite of Ramelteon and exhibits IC50 values of 208 pM and 1470 pM for human melatonin receptors (MT1 and MT2), respectively. Ramelteon itself is a selective melatonin receptor agonist.
Lopinavir Metabolite M-1, an active metabolite derived from Lopinavir, effectively inhibits the HIV protease enzyme with a Ki value of 0.7 pM. Additionally, in vitro studies have revealed notable antiviral properties associated with Lopinavir Metabolite M-1.