Treating Malaria with Artemisinin: Successes and Concerns

One of the significant recent breakthroughs in the management of falciparum malaria has been the use of the drug artemisinin as first line therapy for this potentially fatal disease. Artemisinin is derived from sweet wormwood, a plant that has been used by the Chinese to treat malaria for more than 500 years. Artemisinin acts more quickly than other antimalarials, but has a tendency for late recurrences, and requires the combination with another agent, usually lumifantrine, to be optimally effective. This combination of artemisinin and lumifantrine is currently marketed as Coartem, which has rapidly become the worldwide treatment of choice for falciparum malaria. Large plots of land, particularly in Africa have been given over to the cultivation of sweet wormwood, and small startup pharmaceutical companies in Africa and Asia are busy refining artemisinin compounds. Although there have been periodic shortages in the past, synthetic artemisinin has been developed, and should be available in 2010. The oral form is currently recommended only for moderate or uncomplicated falciparum malaria. Rectal and intravenous forms are available which compare favorably with intravenous quinine, the current standard for the treatment of severe, complicated malaria.
Several problems with artemisinin therapy have arisen recently.
1. Lack of product uniformity. It is estimated that up to 50% of artemisinin for sale in the private sector in Africa and SE Asia is substandard, and much is counterfeit.
2. Inadequate dosage. Even though relatively inexpensive in developing countries, the cost of a three day course is often far beyond the reach of many of the poor. Treatment with a single tablet is common, and is often not given in combination with another agent. This results in a high rate of recurrence, and a high risk of developing resistance.
3. Lack of availability in the US. Returning travelers with falciparum malaria were unable to obtain the drug. Fortunately in April 2009, the FDA approved the use of artemisinin combination therapy (ACT) for uncomplicated malaria. Unfortunately, it is quite expensive, $105 for a three-day course.
4. Resistance. Falciparum that is resistant to artemisinin has appeared in SE Asia, on the border between Cambodia and Thailand. Experts feel that this is a harbinger of the development of more widespread resistance in other parts of the world.
Artemisinin is an important new weapon in the war against malaria. However, we need to be aware that in spite of intensive (and expensive) efforts to control malaria, we are not there yet. Hopefully the efforts to produce an effective vaccine will bear fruit. Meanwhile we need to support continued research, and an all out effort to contain this complicated devastating disease.
Ref: Campbell, C.C. Malaria Control----Addressing Challenges to Ambitious Goals. NEJM 361: 522-24, 2009
Roger Boe MD