Pharmacalogical and toxicology

Artemether is synthetised from Artemisinin using methanol and a catalyst in hydrochloric acid medium. This results in the production of predominantly βα-artemether. The alpha-epimer is also present and causes a difficult purification of the product. The pure alpha product behaves differently and has a melting point of 100 ℃ whereas the βα-epimer has a melting point of 84-86℃.
Both the alpha and theβα-epimers are active antimalarials.
It is the purification and separation of alpha fromβαthat leads to low yields and hence this increases the cost price of Artemether significantly.

Animal studies on acute toxicity show that the LD50 of Artemether in mice is a single i.g. administration of 895mg/kg and a single i.m. injection of 296mg/kg dose; in rats, the LD50 is a single i.m. injection of 597mg/kg dose. This proves the quite low toxicity of Artemether.

Artemether has major antimalarial properties. Chloroq-uine-resistant or multi-resistant strains of P.falciparum have a great susceptibility to Artemether. The schizont-icidal activity of Artemther is due to the destruction of the asexual erythrocytic forms of P.falciparum and P.vivax. Artemether is effective against all strains resistant to the other antimalarial agents. No cross-resistance is detected with chloroquine.