Chloroquine: Encyclopedia II - Chloroquine - Mechanism of action

Chloroquine - Mechanism of action

Inside the red blood cells, the parasite must degrade the hemoglobin for the acquisition of all the nutrients the parasite needs to survive and multiplicate inside the cell.

During this process, the parasite produces the toxic and soluble molecule heme. To avoid destruction by this molecule, the parasite aggregates heme to form hemozoin, an insoluble and non-toxic molecule.

Chloroquine interferes with this process and prevents the formation of hemazoine, which in turn leaves heme in an uncrystallised form. This has a toxic effect to the parasite, and is therefore killed by this molecule.

The effectiveness of chloroquine against the parasite has declined as some resistant forms of the parasite can effectively neutralise the drug by developing a mechanism that drains chloroquine away from the key area, preventing heme from reaching the necessary concentration.

Against rheumatoid arthritis, it operates by inhibiting lymphocyte proliferation, phospholipase A, release of enzymes from lysosomes, release of reactive oxygen species from macrophages, and production of IL-1.

Adapted from the Wikipedia article "Mechanism of action", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki