Pharmacokinetics of oral artesunate in thai patients with uncomplicated falciparum malaria.

The pharmacokinetics of artesunate and its major plasma metabolite, dihydroartemisinin, were investigated in 11 Thai male patients with acute uncomplicated falciparum malaria during the acute and recovery phases. Patients were given an oral dose of 200mg artesunate (Guilin Pharmaceutical) on the first day, followed by 100mg 12 hours later, then 100mg daily for another 4 days (total dose of 700mg). All the patients showed a rapid initial response with median (range) parasite and fever clearance times of 30 (18 to 60) and 24 (4 to 94) hours, respectively; no patients showed reappearance of parasites during the 28-day follow-up period. No significant clinical adverse effects were detected in any patient. Acute phase malaria infection significantly influenced the pharmacokinetics of artesunate and its active metabolite, dihydroartemisinin. Maximum plasma drug concentration (C(max)), absorption half-life (t((1/2)a)), area under the plasma concentration-time curve from zero to the last observed time (AUC) and terminal elimination half-life (t((1/2)z)) of artesunate were decreased, while apparent total body clearance (CL/f) was increased during the acute phase, compared with the recovery phase. In addition, a decrease in the C(max) and an increase in the AUC(DHA/ARS ) ratio were found. Optimisation of therapy with oral artesunate should therefore be based on the kinetics of the drug and dihydroartemisinin in malaria patients with acute phase infection.