Artesunate and dihydroartemisinin blood and brain concentrations following intranasal administration of artesunate. (a) After IN administration, artesunate (ARS) blood concentration reached a very early Cmax (Tmax less than 15 min) and then rapidly converted, showing a short T1/2 (close to 15 min). DHA, its active metabolite, reached an early maximum between 15 and 30 min and then decreased with a T1/2 close to 15 min. (b) No ARS was detected in brains suggesting a prior metabolism before brain diffusion. DHA was detected in brain 15 min after IN administration. DHA brain concentrations globally followed blood concentrations and were about 60% of these.