Lumefantrine is an antimalarial drug used in combination with artemether to treat uncomplicated malaria caused by Plasmodium falciparum in both adults and children. It works by inhibiting the parasite's ability to degrade hemoglobin, thus interfering with its growth and survival. Lumefantrine is highly effective when used in combination therapies and is often used in combination with other drugs like artemether for enhanced efficacy and to prevent resistance.