Coartem: the journey to the clinic

Abstract

Artemisinin, from which the artemether component of Coartem (artemether/lumefantrine, AL) is derived, is obtained from the plant sweet wormwood (Artemisia annua) which has been used for over 2,000 years as a Chinese herbal remedy. Artemisinin was first identified by Chinese researchers as the active anti-malarial constituent of A. annua and its derivatives were found to be the most potent of all anti-malarial drugs. Artemether acts rapidly, reducing the infecting parasite biomass by approximately 10,000-fold per asexual life cycle. Lumefantrine, the other active constituent of AL, acts over a longer period to eliminate the residual 100-100,000 parasites that remain after artemether is cleared from the body and thus minimizes the risk of recrudescence. The two agents have different modes of action and act at different points in the parasite life cycle and show a synergistic action against Plasmodium falciparum in vitro. The combination of artemether and lumefantrine reduces the risk of resistance developing to either agent, and to date there are no reports of resistance to AL combined therapy in the malaria parasite that infects humans. Following a unique partnership agreement between Chinese authorities and Novartis, the manufacturer of AL, over 20 sponsored clinical studies have been undertaken in various malaria endemic regions and in travellers. These trials have involved more than 3,500 patients (including over 2,000 children), and led to identification of a six-dose, three-day regimen as the optimal dosing strategy for AL in uncomplicated falciparum malaria. AL has consistently shown 28-day polymerase chain (PCR)-corrected cure rates greater than 95% in the evaluable population, meeting WHO recommendations. More recently, Novartis and the Medicines for Malaria Venture have worked in partnership to develop Coartem Dispersible, a new formulation designed specifically to meet the specific needs of children with malaria. The dispersible tablets have shown similar high response rates to those observed with crushed standard tablets of AL. A partnership agreement between Novartis and WHO has seen over 250 million AL (Coartem) treatments (75% for children) being distributed to malaria patients in developing countries without profit, supported by training programmes and educational resources.

Figure 1

Chemical structures of artemether and lumefantrine.

Figure 2

Overview of the clinical development programme for AL.