Let's see...
Supressed by the Chinese government, because they did not want to have to deal with the WHO and foreign researches and inspectors, due to it's (at the time) indirect ties to the American military...
A very low-bioavailability, making it a difficult to use and often ineffective drug; although showing greater efficacy as part of a combination treatment with several other anti-malarials...
Difficult and expensive to produce since the plants it's derived from do not produce it consistently; although there is a synthetic which has recently been created using Saccharomyces cerevisiae engineer to produce precursors, and is proving more effective than the plant-derived variant...
There is a major privately funded project underway to make the drug more cheaply and in larger volume by developing a process using the aforementioned synthesis pathway, and a major pharmaceutical manufacturer has already been signed to produce it, with the target of increasing the availability to meet current demand...
Several strains of malaria in parts of Southeast Asia have already developed a resistance to it...
I'm really not seeing how any of this is relevant.