is a drug used to treat malaria
. Dihydroartemisinin is the active metabolite of all artemisinin
compounds (artemisinin, artesunate
, etc.) and is also available as a drug in itself. The lactone of artemisinin could selectively be reduced with mild hydride-reducing agents, such as sodium borohydride, potassium borohydride, and lithium borohydride to dihydroartemisinin (a lactol) in over 90% yield. It is a novel reduction, because normally lactone cannot be reduced with sodium borohydride under the same reaction conditions (0-5˚C, in methanol). Reduction with LiAlH4 leads to some rearranged products. It was surprising to find that the lactone was reduced, but that the peroxy group survived. However, the lactone of deoxyartemisinin resisted reduction with sodium borohydride and could only be reduced with isobutylaluminium hydride to the lactol, (deoxydihydroartimisinin). These results show that the peroxy group assists the reduction of lactone with sodium borohydride to a lactol, but not to the alcohol which is the over-reduction product. No clear evidence for this reduction process exists.
Dihydroartemisinin is available as a fixed drug combination with piperaquine
(each tablet contains 40 mg of dihydroartemisinin and 320 mg of piperaquine; trade name Artekin
, manufactured by Holleykin Pharmaceuticals
The adult dose is 1.6/12.8 mg/kg per dose (rounded up or down to the nearest half tablet) given at 0 h, 8 h, 24 h, and 48 h. Alternatively, the same total dose may be given once daily for three days.
Dihydroartemisinin is also sold in Africa as Cotecxin in 60 mg tablets, which is manufactured by Zhejiang Holley Nanhu Pharmaceutical Co., Ltd., in China.