Signaquin (hydroxychloroquine) has been used widely for the treatment of arthritis and lupus. It increases pH within the cells and alters processes such as protein degradation in the cells. Its anti-rheumatic properties result from its interference with antigen processing in the cells. As far as malaria is concerned, hydroxychloroquine does not allow the malarial parasite to enter and infect the cells. The drug prevents the invasion of the parasite in the red blood cells.