Table 2.

Overview of Mode of action[9]

Effect	Mechanism of action
Anti-infectious	Antimicrobial effects on HIV, coronavirus, influenza viruses.
Anti-inflammatory effects	Inhibition of phospholipase A2 and C. Inhibition of formation of IL1β, TNF-α. Inhibition of mast cells. Inhibition of Toll-like receptor 9 signal pathway.
Antiproliferative	Inhibits protein synthesis Promote chemo sensitization. Inhibit cell growth or cell death or both. Prevent mutations in cells with high mitotic rates.
Effect on coagulation	Inhibit platelet aggregation and adhesion. Inhibit formation of antiphospholipid antibody-β2-glycoprotein 1 complexes. Prevent antiphospholipid antibody binding of annexin-5
Immunological	Inhibits autoantigen processing (MHCII).
Response	Reduced stimulation of autoreactive CD4+ T cells Reduced cytokine production:  Reduces serum interleukin (IL)-1β, IL-6, IL-18, and tumor necrosis factor-alpha (TNF-α)(takes 3 months)[10]  IL-18, is the interferon gamma (IFN-γ)-inducing factor, thus its reduction affects the adaptive immunity.[11]  CQ inhibits macrophage TNF- α mRNA transcription and endotoxin induced secretion of TNF- α, IL-1, and IL-6. Binding to DNA and thus competitive inhibition of anti-DNA antibodies. Block of activation of innate and adaptive immunity process mediated by Toll-like receptors.[12]
Metabolic	Decreased hydroxylation of Vitamin D Lowered levels of LDL, Triglycerides and cholesterol. Increased excretion of porphyrin due to complex formation of HCQ with porphyrin
Photoprotective	Increased UV filtration? (Questionable relevance). It can cause spectral shift due to accumulation in melanin and increase in epidermal concentrations Inhibition of UV-induced inflammatory reactions