Amodiaquine is an active ingredient used to treat malaria. It is used as a monotherapy and combination preparation, particularly against malaria tropica, which is caused by the unicellular parasite Plasmodium falciparum.
What is amodiaquine?
Amodiaquine is an active ingredient used to treat malaria. Amodiaquine is an aromatic hydrocarbon. It belongs to the 4-amino-choline group and is closely related to the active ingredient chloroquine. Just like chloroquine, amodiaquine is used against malaria, especially malaria tropica. Malaria tropica is caused by the unicellular parasite Plasmodium falciparum and is one of the most significant infectious diseases worldwide. In 2008, the WHO (World Health Organization) reported 243 million cases of the disease and well over 800,000 deaths. The main distribution area of malaria is in tropical Africa, but Asia and South America are also affected. Amodiaquine was formerly marketed under the trade name Camoquine in Europe and the United States. However, it is no longer commercially available there and is only used in areas with a high incidence of malaria. The active ingredient requires a prescription.
Pharmacologic action
The pharmacologic mode of action of amodiaquine is similar to that of the better-known active ingredient chloroquine. Both substances interfere with the reproductive cycle of the malaria parasite Plasmodium falciparum. These single-cell parasites live mainly in the red blood cells of humans and are transmitted by mosquitoes. If an Anopheles mosquito infected with Plasmodia bites a human, the pathogens first penetrate the liver. The so-called “liver phase” begins. In the next phase, the parasites pass into the blood and migrate into the red blood cells (erythrocytes). It is in this “erythrocytic phase” that the action of amodiaquine begins. The substance inhibits the crystallization of hemozoin. This is formed when the malaria pathogens break down the hemoglobin in the erythrocytes. If the hemozoin cannot be crystallized, the pathogen cannot obtain proteins from it for its metabolism and dies. In the past, chloroquine was the drug of choice for malaria and was used primarily in the 1950s and 1960s. Today, however, almost all strains of Plasmodium falciparum are resistant to chloroquine. As a result, the active ingredient amodiaquine gained importance, showing efficacy even in chloroquine-resistant parasites.
Medical application and use
Amodiaquine is used against the pathogen Plasmodium falciparum. This causes malaria tropica, which is considered the most dangerous form of malaria. In malaria tropica, a distinction is made between the complicated and uncomplicated course. In complicated malaria tropica, the central nervous system or the kidneys are involved. Other organ complications may also occur. This form of malaria is always an emergency and requires intensive medical care. Amodiaquine is only suitable for the treatment of uncomplicated malaria tropica. Amodiaquine is one of the drugs that work well even in pathogens that are resistant to other substances. Recently, researchers have increasingly been testing the use of amodiaquine in combination preparations. For example, it is being combined with the active ingredient artesunate, to which there is also as yet little resistance. Initial data show that the active ingredient amodiaquine is well effective and tolerated in combination with artesunate. The main indication for the use of artesunate / amodiaquine is the treatment of uncomplicated malaria tropica. The drug combination is used primarily when the corresponding Plasmodium strain is resistant to standard drugs.
Risks and side effects
Amodiaquine should be used only for short periods. When taken for prolonged periods, breakdown products of the drug cause liver damage and disorders of the hematopoietic system. Because of the severe side effects, amodiaquine monopreparations have been withdrawn from the market in Europe and the United States. However, because of its low price and good efficacy against chloroquine-resistant plasmodia, it is still widely used in non-European countries. In new preparations, amodiaquine is often used in combination with other active ingredients, for example with artesunate. In these combination preparations, the amodiaquine can be dosed lower. So far, no serious side effects have been observed with these drugs.Amodiaquine should never be used in people who already have liver disease or kidney damage.
