Cletoquine oxalate (Desethylhydroxychloroquine oxalate) is a major active metabolite of Hydroxychloroquine. Cletoquine oxalate is produced in the liver by CYP2D6, CYP3A4, CYP3A5, and CYP2C8 isoenzymes. Cletoquine oxalate is also a Chloroquine derivative and has the ability to against the chikungunya virus (CHIKV). Cletoquine oxalate has antimalarial effects and has the potential for autoimmune diseases treatment^[1][2]. IC50 & Target: Chikungunya virus (CHIKV)^[2] In Vivo: Hydroxychloroquine (5 mg/kg intravenously) is administered to BALB/c mice for blood and tissue to determine the content of Cletoquine (Desethylhydroxychloroquine). The tissue to blood concentration ratio (Kp) is ≥1, indicating accumulation of Cletoquine in tissues. The Cletoquine Kp ratio for the various tissues are observed in the descending order of liver (114.3)>kidney (24.4)>spleen (19.3)>lungs (16.5)>heart (5.5)^[3].