Artemther & lumefantrine
Artemether & Lumefantrine are antimalarial medicines used to treat malaria.
Malaria
Malaria parasites inside red blood cells.
Malaria is an infectious disease spread through mosquito bites. It is a parasite that lives inside red blood cells and cause serious disease, including fatality.
In 2006, it is estimated that 880 million people were affected by malaria, and it caused nearly 1 million deaths. More than 90% of these occurred in sub-Saharan Africa.
Malaria parasites can be found inside red blood cells and liver cells of people that are infected with it. Symptoms are not constant, but come in waves, when red blood cells rupture to allow for the parasites to reproduce. Symptoms at this stage include fever.
Some of the known malaria parasites are: Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale.
Malaria is spread through mosquito bites from the Anopheles mosquito.
Look up the distribution of the Anopheles mosquito. Do you think it's possible for malaria to be present in Australia? Why?
Resistance
Malaria has been treated with chloroquine and hydroxychloroquine for decades, and it was effectively eradicated from most temperate countries in the 20th century. However, since the 1970s, it became evident that the parasites were becoming resistant to these medicines.
Resistance is the term used for when medicines are no longer effective against certain pathogens, usually because the pathogen has developed a defence mechanism against the medicine. It is an example of natural selection and evolution.
As a result, scientists need to keep working on new versions of medicines. Arthemether and lumefantrine are two examples of new medicines that have been developed to fight malaria.
Often, anti-parasitic, antibiotic and anti-viral medications are taken in combination where one tablet has two active ingredients. This gives the medicine a better chance at killing the pathogen quickly and less chance for the pathogen to develop resistance.
This is why the medicine combination artemether + lumefantrine is on the Essential Medicines list.
Artemisinin-based combination therapy
Artemether
Artemisinin is a natural product that was first extracted from the sweet wormwood plant, Artemisia annua. It is a traditional Chinese medicine, and was first extracted by Tu Youyou in 1972. People have known since ancient times that this medicine is effective against malaria. Tu Youyou was awarded the Nobel Prize in Physiology and Medicine for her discovery of artemisinin in 2015.
Since its discovery, scientists have been making modifications to the structure of artemisinin, trying to find even more effective antimalarials. Artemether is one of these medicines. Below you can compare the chemical structure and some properties of artemisinin, artemether and artesunate. The change to the chemical structure of these molecules is shown in pink.
Artemisinin, artemether and artesunate all work to kill malaria parasites in a similar way. They block the action of a protein in the cell membrane which normally facilitates the transport of calcium ions across the cell membrane. Calcium ions are important for cell-cell signalling.
Artemisinin
Isolated from sweet wormwood
Low pharmacokinetics
Low bioavailability
Artemether
Chemically altered in laboratory
Fat soluble
Higher bioavailability
Artesunate
Chemically altered in laboratory
Water soluble
Higher bioavailability
Lumefantrine
To help prevent malaria parasites from becoming resistant to artemisinin-based medicines, they are given in combination with other antimalarial medicines.
Artemether and lumefantrine complement each other working together to kill all the malaria parasites in the body.
By administering them in combination, any pathogens that are resistant to artemether will be killed by the lumefantrine. This kills the resistant pathogen before it has a chance to reproduce and spread to other hosts.
Lumefantrine works by distrupting a process in the parasite called haeme detoxification. Normally, the parasite breaks down human haemoglobin from red blood cells into a number of different products, including haeme, which is toxic to the parasite. But stopping this process, Lumefantrine effectively makes the parasite poison itself with haeme.