Chloroquine is a medication that is often used to treat or prevent malaria, which is a disease in which parasites infect and attack red blood cells. Although many strains of malaria are resistant to chloroquine, it can still be used as emergency treatment for malaria and several other disorders.
Components
Chloroquine, when taken orally, is typically taken in the form of chloroquine phosphate as a tablet, Drugs.com notes. Chloroquine phosphate tablets come in two dosages: 250 mg and 500 mg, which corresponds to 150 mg and 300 mg of chloroquine, respectively. Chloroquine phosphate tablets also contain inactive ingredients, including colloidal silicon dioxide and microcrystals of cellulose. Other inactive ingredients include either calcium or magnesium stearate and alkali chemicals, which help control the acid-base environment inside the tablets.
Indications
Chloroquine is effective against the asexual forms of the parasites responsible for producing malaria, Infomed explains. It is only effective against the parasite when it is living in red blood cells; consequently, it had no action against parasites that are living in the liver outside of red blood cells. It also is not effective against the gametocytes of the Plasmodium parasites, which are the sexually reproducing forms of the organism. When chloroquine was first discovered it was effective against all strains of the Plasmodium species, but many strains of Plasmodium falciparu--as well as some strains of Plasmodium vivax--have developed resistance to this drug.
Chloroquine can also be used to treat rheumatoid arthritis, lupus, porphyria cutanea tarda, sarcoidosis and liver abscesses caused by amoeba.
Mechanism
The way in which chloroquine is able to treat malaria is not entirely understood. Chloroquine reduces the production of certain enzymes, which can make it difficult for the parasites to survive within red blood cells. Chloroquine also appears to be able to interact with DNA, which could account for some of its anti-parasite activity.
Absorption and Distribution
Chloroquine is rapidly and almost totally absorbed by the gastrointestinal tract, which is why it is typically given orally. Once chloroquine gains access to the blood, approximately 55 percent of it binds to substances in the plasma, Drugs.com explains. Chloroquine is slowly excreted from the body in the urine, though this excretion can be sped up by acidification of the urine. Chloroquine becomes deposited in various tissues; between 200 and 700 times the concentration of the drug in the plasma can be deposited in the liver, lungs, kidneys and spleen. By the time chloroquine is excreted, approximately half of it has been metabolized. The main metabolite of chloroquine is called desethylchloroquine.
Side Effects
Chloroquine can be toxic to the liver and should be used carefully in patients who have a history of liver disease or who consume alcohol or take other potentially hepatotoxic drugs, such as acetaminophen, Medline Plus states. Chloroquine should also be used with care in patients who have hearing problems, as it can cause hearing loss. Patients taking chloroquine need to have their blood tested periodically, as the drug can destroy red blood cells. Patients taking chloroquine may suffer from retinal damage.
