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Artemisinin & malarial treatments Quick Facts: · The parasite which causes malaria has become increasingly resistant to single drug therapies such as chloroquine. · Artemisinin combination therapies (ACTs) are effective against drug-resistant malaria but are more expensive than monotherapies · WHO predicts a demand for 130 million courses of ACTs during 2006 · Longer term, up to half a billion courses of ACT may be needed each year requiring around 400 tons of artemisinin · Increased demand since 2004 has resulted in a shortage of artemisinin, leading to price increases of up to five fold The medicinal plant Artemisia annua is currently the sole source of artemisinin. Artemisinin demand The demand for artemisinin to combat malaria in the developing world is immense. Artemisinin Combination Therapies (ACTs) have now been adopted by 51 countries as first-line treatment in their national drug policies, and 24 are actually using ACTs. It has been estimated up to half a billion courses of artemisinin combination therapy (ACT) will be needed each year requiring around four hundred tons of artemisinin. ACTs are more expensive than other anti-malarial drugs. For instance Coartem ™ costs $2.40 compared with $0.1 for a course of quinine. Reducing the cost of artemisinin will reduce the cost of ACTs making them accessible to more people in countries where the annual health budget may be less than $4 per capita. Artemisinin chemistry Artemisinin is a sesquiterpene lactone derived from the Chinese medicinal plant, Artemisia annua. It contains an unusual trioxane ring which is thought to be responsible for its anti-malarial activity. Artemisinin for clinical use is usually derivatised at the C12 position to modulate its stability and solubility. The most common derivatives are dihydro artemisinin, artemether, arteether, artesunate and artelinate. Artemisinin anti-malarial activity The detailed mechanism by which Artemisinin and its derivatives kill the malarial parasite is the subject of much scientific debate and a consensus on its mode of action has yet to emerge. Artemisinin combination therapies The superiority of artemisinin combination therapies over monotherapies is well documented. The simultaneous use of two drugs with independent modes of action improves therapeutic efficacy and delays the development of resistance to the individual components of the combination. The World Health Organization (WHO) is calling for pharmaceutical companies to stop marketing artemisinin monotherapies to prevent development of resistance to artemisinin. Novartis offers Coartem ™ , which combines artemether and lumefantrine, at-cost for use in developing countries under an agreement with the World Health Organization. Coartem ™ is taken orally with fluids (preferably drinks containing fat, such as milk). A full treatment is a three-day course and the number of tablets per dose depends on body weight. Alternative sources of artemisinin Chemical synthesis of Artemisinin itself is not economically viable as A second alternative, which is under development by a consortium led by the Institute for One World Health, is the manufacture of artemisinin through fermentation. This technology involves production of an artemisinin precursor, artemisinic acid, by a strain of yeast which harbours genes derived from A. annua. The scientists involved in this consortium reported successful laboratory-scale production of artemisinic acid by yeast earlier this year. Both of these alternative sources of artemisinin are to be welcomed as part of the solution to artemisinin cost and security of supply. However Other applications of artemisinin Artemisinin is showing promise as an anti-cancer compound in in vitro models. It has also been proposed as useful in treatment of schistosomiasis, another important parasitic disease of the tropics.
Sources Report: ‘ Saving Time Buying Lives: Economics of Malaria Drugs in an Age of Resistance’ . This can be found at: http://www.nap.edu/catalog/11017.html WHO guidelines for the treatment of malaria. This can be found at http://www.who.int/malaria/docs/TreatmentGuidelines2006.pdf Meeting on the production of artemisinin and artemisinin-based combination therapies. The report from this meeting can be found on the WHO website www.who.int/malaria/docs/arusha-artemisinin-meeting.pdf
As Summarized by Centre for Novel Agricultural Products – Artemisia Projects |