Far from being a tropical disease of the past, with control within reach, malaria is the number one infectious disease in the world today. Notwithstanding that it was believed that malaria was close to becoming eradicated in the 1960's with the use of quinine, chloroquine and DDT, it was not. Rather malaria is an ever growing problem throughout the world. Approximately 200 million people in endemic areas are infected annually. Worldwide, over two million people die each year from malaria. This shocking reality is due in part to the emergence of drug resistant strains of Plasmodium falciparum, the most lethal malarial parasite known to date. More specifically, a high percentage of malaria today is caused by chloroquine-resistant Plasmodium falciparum.
Artemisinin (Qinghaosu), first isolated by the Chinese from the leaves of Artemisia annua in 1972, is known to be a fast acting, safe and effective drug against chloroquine-resistant and sensitive strains of Plasmodium falciparum, as well as against cerebral malaria. No side effects, common to many synthetic antimalarials, have been reported by the Chinese during the past six years of clinical use of artemisinin. Unfortunately, one of the disadvantages of artemisinin is that the compound is only sparingly soluble in either water or oils and thus not readily absorbable by the gastrointestinal tract. Another disadvantage of the drug resides in the fact that large doses (3.times.400 mg/day per patient) of the drug are required for therapeutic efficacy. A more ideal drug with enhanced antimalarial activity and improved physical and bioavailability properties is an urgent need to treat chloroquine-resistant malaria.