Artemesinin is best used for
Treatment of cerebral malaria:

IV Quinine: Needs continuous cardiac monitoring; can cause QTc prolongation, hypoglycemia
IV Artesunate has better efficacy and safer than quinine, 2.4 mg/kg IV BD. then OD
Exchange transfusion if parasite index is > 10%
Artemisinin (qinghaosu) acts rapidly against erythrocytic stages of malarial parasites. It is effective against complicated and multidrug resistant malaria. Due to their short half life, recrudescence is high if used alone, hence not useful for prophylaxis also.
Chloroquine sensitive falci and vivax: Chloroquine l g, 500mg at 6, 24,48 hrs, followed by Primaquine 15mg for 14 days
Chloroquine resistant, uncomplicated falciparum: Oral quinine. Mefloquine, Doxy, Clindamycin, Oral Artesunate
Relapse of malaria
Chronic malaria
Cerebral malaria
Recrudescent malaria