These drugs could be divided into two main types: acridines, which include mepacrine (quinacrine), used since 1930, and quinoleines, which include chloroquine (amodiaquine), proguanil, chlorproguanil, pyrimethamine, primaquine, quinocide, pamaquine
. (49) After 1965, wartime conditions made it impossible to continue with anti-malaria activities, especially in the countryside, with DDT-resistance in Anopheles and drug-resistance in plasmodia adding to the difficulties created by human violence.
During early part of the 20th century, a series of organic compounds (beginning with methylene blue) were evaluated, which led to the discovery of pamaquine
and quinacrine and ultimately chloroquine, a 4-aminoquinoline.