Why is this drug prescribed?

Aralen tablets contain the active ingredient chloroquine phosphate, which is an antimalarial drug, though it also has other uses, for example, in treating the autoimmune diseases rheumatoid arthritis and lupus erythematosus. Malaria is a potentially fatal disease caused by various types of single-celled parasites known as Plasmodium. Plasmodium are carried by mosquitoes and injected into the bloodstream during a bite from an infected mosquito. Once in the blood, the parasites travel to the liver, where they multiply. The parasites are then released back into the bloodstream where they invade the red blood cells and multiply again. An actual attack of malaria develops when the red blood cells burst, releasing a mass of parasites into the bloodstream. The attacks do not begin until a sufficient number of blood cells have been infected with parasites. Chloroquine works by attacking the parasites once they have entered the red blood cells. It kills the parasites and prevents them from multiplying further. It is not fully understood how chloroquine kills the parasites, but it is thought to work by blocking the action of a chemical that the parasites produce to protect themselves once inside the red blood cells. When inside the red blood cells, the malaria parasites digest the oxygen carrying pigment haemoglobin that is found in these cells. This divides the haemoglobin into two parts; haem and globin, and the haem part is toxic to the malaria parasite. To prevent itself from being damaged by haem, the malaria parasite produces a chemical that converts haem into a compound that is not toxic to them. Chloroquine blocks the action of this chemical. This causes the levels of the toxic haem to rise, thus killing the malaria parasites. Chloroquine can be used both to prevent and to treat malaria. For prevention it is usually taken in combination with another antimalarial drug called proguanil. However, the malaria parasite is resistant to these drugs in certain areas of the world, and it is important to check with your pharmacist which drugs are currently recommended to prevent malaria in the country you are travelling to. You can also check in the travel section of this site. If chloroquine is recommended for prevention it should be started a week before travel to the malarious region. It should then be taken throughout the stay, so that if you are bitten by an infected mosquito, there will be drug in your blood to prevent malaria developing. Chloroquine should be continued for a further four weeks after leaving the malarious area, so that there is still drug in the blood to kill any remaining parasites released from the liver into the red blood cells during this time. Higher doses than those used for preventing malaria are used to treat malaria infection. Chloroquine may be given by injection to treat malaria, if administration by mouth is not possible. However, chloroquine is no longer recommended for treating falciparum malaria, because there is widespread resistance of the Plasmodium falciparum parasite to chloroquine. Chloroquine is also active against other types of protozoa, including one called Entamoeba histolytica. Metronidazole is the drug of choice for infections with this parasite, but chloroquine can be used to treat liver infections if metronidazole is not available. Chloroquine also has anti-inflammatory activity and is sometimes used in high doses to treat the autoimmune diseases rheumatoid arthritis, systemic lupus erythematosus, and discoid lupus erythematosus. In these diseases, the body's immune system is overactive and causes inflammation that results in the disease symptoms. Chloroquine suppresses the inflammation and the disease process. In rheumatoid arthritis, chloroquine is known as a disease-modifying antirheumatic drug. It doesn't have an immediate effect, but requires four to six months of treatment for a full response. If there is no real benefit on the disease after taking this drug for six months, your doctor will usually ask you to stop taking it and try a different DMARD.

Treatments

* Prevention of malaria * Treatment of malaria * Infection of the liver with Entamoeba histolytica * Inflammatory disease of the joints * Systemic lupus erythematosus and discoid lupus erythematosus

What side effects can this drug cause?

* Disturbances of the gut such as diarrhoea, nausea, vomiting or abdominal pain * Headache * Skin rashes * Itching * Low blood pressure, this might make you feel dizzy * Visual disturbances * Loss of hair colour * Hair loss * Fits * Disturbance in the normal numbers of blood cells in the blood * Damage to the retina of the eye * Discolouration of skin, nails, or mucous membranes, eg inside of mouth * Hearing distubances, eg ringing in the ears or hearing loss * Anxiety, confusion, hallucinations or strange or abnormal thoughts * Weakening of muscles * Weakening of the heart muscle * Changes in the electrical signals in the heart * Liver disorders