Resistance of Plasmodium falciparum to antimalarial drugs is a major problem in malaria eradication. Artemisinin derivatives particularly in combination with other drugs are thus increasingly used to treat malaria.The study was designed to demonstrate resistance mitigating effect of Artemisia annua phytochemicals on Plasmodium berghei and P. yoelii. Swiss albino mice were inoculated with the murine plasmodia and thereafter treated for 4 days with the A. annua and with the pure artemisinin. After 4 days parasitemia was determined and effective doses 50 and 90 were calculated. The doses were utilised to determine concentrations to be used in resistance development.The ED50 AND ED90 with P. berghei were 1.43 and 7.18 mg/kg.day respectively. After 10 exposures and 20 exposures the ED50 were determined again and relative sensitivity index (RSI) was calculated as new ED50 /ED50 initial.
The RSI increased in artemisinin exposed parasites but the same was not true with Artemisia annua exposed parasites. Moreover on removal of drug pressure the acquired resistance was not stable and the parasites were more sensitive once more.