Quinine hydrochloride is a medication that is derived from the bark of the cinchona tree. It has been used for centuries as an antimalarial agent and is still used today for the treatment of malaria caused by Plasmodium falciparum, a type of parasite.Quinine hydrochloride works by interfering with the growth and reproduction of the malaria parasites in the red blood cells. It is primarily effective against the asexual form of the parasite, which is responsible for causing the symptoms of malaria.